source.tar.gz

src/000777 000000 000000 00000000000 13604431105 010014 5ustar00000000 000000 src/conditionals.c000666 000000 000000 00000050444 13206352046 012661 0ustar00000000 000000 #include "mpc.h"

#ifdef _WIN32

static char buffer[2048];

char* readline(char* prompt) {
  fputs(prompt, stdout);
  fgets(buffer, 2048, stdin);
  char* cpy = malloc(strlen(buffer)+1);
  strcpy(cpy, buffer);
  cpy[strlen(cpy)-1] = '\0';
  return cpy;
}

void add_history(char* unused) {}

#else
#include <editline/readline.h>
#include <editline/history.h>
#endif

/* Forward Declarations */

struct lval;
struct lenv;
typedef struct lval lval;
typedef struct lenv lenv;

/* Lisp Value */

enum { LVAL_ERR, LVAL_NUM, LVAL_SYM, LVAL_FUN, LVAL_SEXPR, LVAL_QEXPR };

typedef lval*(*lbuiltin)(lenv*, lval*);

struct lval {
  int type;

  /* Basic */
  long num;
  char* err;
  char* sym;
  
  /* Function */
  lbuiltin builtin;
  lenv* env;
  lval* formals;
  lval* body;
  
  /* Expression */
  int count;
  lval** cell;
};

lval* lval_num(long x) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_NUM;
  v->num = x;
  return v;
}

lval* lval_err(char* fmt, ...) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_ERR;  
  va_list va;
  va_start(va, fmt);  
  v->err = malloc(512);  
  vsnprintf(v->err, 511, fmt, va);  
  v->err = realloc(v->err, strlen(v->err)+1);
  va_end(va);  
  return v;
}

lval* lval_sym(char* s) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SYM;
  v->sym = malloc(strlen(s) + 1);
  strcpy(v->sym, s);
  return v;
}

lval* lval_builtin(lbuiltin func) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_FUN;
  v->builtin = func;
  return v;
}

lenv* lenv_new(void);

lval* lval_lambda(lval* formals, lval* body) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_FUN;  
  v->builtin = NULL;  
  v->env = lenv_new();  
  v->formals = formals;
  v->body = body;
  return v;  
}

lval* lval_sexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

lval* lval_qexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_QEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

void lenv_del(lenv* e);

void lval_del(lval* v) {

  switch (v->type) {
    case LVAL_NUM: break;
    case LVAL_FUN: 
      if (!v->builtin) {
        lenv_del(v->env);
        lval_del(v->formals);
        lval_del(v->body);
      }
    break;
    case LVAL_ERR: free(v->err); break;
    case LVAL_SYM: free(v->sym); break;
    case LVAL_QEXPR:
    case LVAL_SEXPR:
      for (int i = 0; i < v->count; i++) {
        lval_del(v->cell[i]);
      }
      free(v->cell);
    break;
  }
  
  free(v);
}

lenv* lenv_copy(lenv* e);

lval* lval_copy(lval* v) {
  lval* x = malloc(sizeof(lval));
  x->type = v->type;
  switch (v->type) {
    case LVAL_FUN:
      if (v->builtin) {
        x->builtin = v->builtin;
      } else {
        x->builtin = NULL;
        x->env = lenv_copy(v->env);
        x->formals = lval_copy(v->formals);
        x->body = lval_copy(v->body);
      }
    break;
    case LVAL_NUM: x->num = v->num; break;
    case LVAL_ERR: x->err = malloc(strlen(v->err) + 1);
      strcpy(x->err, v->err);
    break;
    case LVAL_SYM: x->sym = malloc(strlen(v->sym) + 1);
      strcpy(x->sym, v->sym);
    break;
    case LVAL_SEXPR:
    case LVAL_QEXPR:
      x->count = v->count;
      x->cell = malloc(sizeof(lval*) * x->count);
      for (int i = 0; i < x->count; i++) {
        x->cell[i] = lval_copy(v->cell[i]);
      }
    break;
  }
  return x;
}

lval* lval_add(lval* v, lval* x) {
  v->count++;
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  v->cell[v->count-1] = x;
  return v;
}

lval* lval_join(lval* x, lval* y) {  
  for (int i = 0; i < y->count; i++) {
    x = lval_add(x, y->cell[i]);
  }
  free(y->cell);
  free(y);  
  return x;
}

lval* lval_pop(lval* v, int i) {
  lval* x = v->cell[i];  
  memmove(&v->cell[i],
    &v->cell[i+1], sizeof(lval*) * (v->count-i-1));  
  v->count--;  
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  return x;
}

lval* lval_take(lval* v, int i) {
  lval* x = lval_pop(v, i);
  lval_del(v);
  return x;
}

void lval_print(lval* v);

void lval_print_expr(lval* v, char open, char close) {
  putchar(open);
  for (int i = 0; i < v->count; i++) {
    lval_print(v->cell[i]);    
    if (i != (v->count-1)) {
      putchar(' ');
    }
  }
  putchar(close);
}

void lval_print(lval* v) {
  switch (v->type) {
    case LVAL_FUN:
      if (v->builtin) {
        printf("<builtin>");
      } else {
        printf("(\\ ");
        lval_print(v->formals);
        putchar(' ');
        lval_print(v->body);
        putchar(')');
      }
    break;
    case LVAL_NUM:   printf("%li", v->num); break;
    case LVAL_ERR:   printf("Error: %s", v->err); break;
    case LVAL_SYM:   printf("%s", v->sym); break;
    case LVAL_SEXPR: lval_print_expr(v, '(', ')'); break;
    case LVAL_QEXPR: lval_print_expr(v, '{', '}'); break;
  }
}

void lval_println(lval* v) { lval_print(v); putchar('\n'); }

int lval_eq(lval* x, lval* y) {
  
  /* Different Types are always unequal */
  if (x->type != y->type) { return 0; }
  
  /* Compare Based upon type */
  switch (x->type) {
    /* Compare Number Value */
    case LVAL_NUM: return (x->num == y->num);
    
    /* Compare String Values */
    case LVAL_ERR: return (strcmp(x->err, y->err) == 0);
    case LVAL_SYM: return (strcmp(x->sym, y->sym) == 0);
    
    /* If Builtin compare functions, otherwise compare formals and body */
    case LVAL_FUN:
      if (x->builtin || y->builtin) {
        return x->builtin == y->builtin;
      } else {
        return lval_eq(x->formals, y->formals) && lval_eq(x->body, y->body);
      }
    
    /* If list compare every individual element */
    case LVAL_QEXPR:
    case LVAL_SEXPR:
      if (x->count != y->count) { return 0; }
      for (int i = 0; i < x->count; i++) {
        /* If any element not equal then whole list not equal */
        if (!lval_eq(x->cell[i], y->cell[i])) { return 0; }
      }
      /* Otherwise lists must be equal */
      return 1;
    break;
  }
  return 0;
}

char* ltype_name(int t) {
  switch(t) {
    case LVAL_FUN: return "Function";
    case LVAL_NUM: return "Number";
    case LVAL_ERR: return "Error";
    case LVAL_SYM: return "Symbol";
    case LVAL_SEXPR: return "S-Expression";
    case LVAL_QEXPR: return "Q-Expression";
    default: return "Unknown";
  }
}

/* Lisp Environment */

struct lenv {
  lenv* par;
  int count;
  char** syms;
  lval** vals;
};

lenv* lenv_new(void) {
  lenv* e = malloc(sizeof(lenv));
  e->par = NULL;
  e->count = 0;
  e->syms = NULL;
  e->vals = NULL;
  return e;
}

void lenv_del(lenv* e) {
  for (int i = 0; i < e->count; i++) {
    free(e->syms[i]);
    lval_del(e->vals[i]);
  }  
  free(e->syms);
  free(e->vals);
  free(e);
}

lenv* lenv_copy(lenv* e) {
  lenv* n = malloc(sizeof(lenv));
  n->par = e->par;
  n->count = e->count;
  n->syms = malloc(sizeof(char*) * n->count);
  n->vals = malloc(sizeof(lval*) * n->count);
  for (int i = 0; i < e->count; i++) {
    n->syms[i] = malloc(strlen(e->syms[i]) + 1);
    strcpy(n->syms[i], e->syms[i]);
    n->vals[i] = lval_copy(e->vals[i]);
  }
  return n;
}

lval* lenv_get(lenv* e, lval* k) {
  
  for (int i = 0; i < e->count; i++) {
    if (strcmp(e->syms[i], k->sym) == 0) { return lval_copy(e->vals[i]); }
  }
  
  if (e->par) {
    return lenv_get(e->par, k);
  } else {
    return lval_err("Unbound Symbol '%s'", k->sym);
  }
}

void lenv_put(lenv* e, lval* k, lval* v) {
  
  for (int i = 0; i < e->count; i++) {
    if (strcmp(e->syms[i], k->sym) == 0) {
      lval_del(e->vals[i]);
      e->vals[i] = lval_copy(v);
      return;
    }
  }
  
  e->count++;
  e->vals = realloc(e->vals, sizeof(lval*) * e->count);
  e->syms = realloc(e->syms, sizeof(char*) * e->count);  
  e->vals[e->count-1] = lval_copy(v);
  e->syms[e->count-1] = malloc(strlen(k->sym)+1);
  strcpy(e->syms[e->count-1], k->sym);
}

void lenv_def(lenv* e, lval* k, lval* v) {
  while (e->par) { e = e->par; }
  lenv_put(e, k, v);
}

/* Builtins */

#define LASSERT(args, cond, fmt, ...) \
  if (!(cond)) { lval* err = lval_err(fmt, ##__VA_ARGS__); lval_del(args); return err; }

#define LASSERT_TYPE(func, args, index, expect) \
  LASSERT(args, args->cell[index]->type == expect, \
    "Function '%s' passed incorrect type for argument %i. Got %s, Expected %s.", \
    func, index, ltype_name(args->cell[index]->type), ltype_name(expect))

#define LASSERT_NUM(func, args, num) \
  LASSERT(args, args->count == num, \
    "Function '%s' passed incorrect number of arguments. Got %i, Expected %i.", \
    func, args->count, num)

#define LASSERT_NOT_EMPTY(func, args, index) \
  LASSERT(args, args->cell[index]->count != 0, \
    "Function '%s' passed {} for argument %i.", func, index);
    
lval* lval_eval(lenv* e, lval* v);

lval* builtin_lambda(lenv* e, lval* a) {
  LASSERT_NUM("\\", a, 2);
  LASSERT_TYPE("\\", a, 0, LVAL_QEXPR);
  LASSERT_TYPE("\\", a, 1, LVAL_QEXPR);
  
  for (int i = 0; i < a->cell[0]->count; i++) {
    LASSERT(a, (a->cell[0]->cell[i]->type == LVAL_SYM),
      "Cannot define non-symbol. Got %s, Expected %s.",
      ltype_name(a->cell[0]->cell[i]->type), ltype_name(LVAL_SYM));
  }
  
  lval* formals = lval_pop(a, 0);
  lval* body = lval_pop(a, 0);
  lval_del(a);
  
  return lval_lambda(formals, body);
}

lval* builtin_list(lenv* e, lval* a) {
  a->type = LVAL_QEXPR;
  return a;
}

lval* builtin_head(lenv* e, lval* a) {
  LASSERT_NUM("head", a, 1);
  LASSERT_TYPE("head", a, 0, LVAL_QEXPR);
  LASSERT_NOT_EMPTY("head", a, 0);
  
  lval* v = lval_take(a, 0);  
  while (v->count > 1) { lval_del(lval_pop(v, 1)); }
  return v;
}

lval* builtin_tail(lenv* e, lval* a) {
  LASSERT_NUM("tail", a, 1);
  LASSERT_TYPE("tail", a, 0, LVAL_QEXPR);
  LASSERT_NOT_EMPTY("tail", a, 0);

  lval* v = lval_take(a, 0);  
  lval_del(lval_pop(v, 0));
  return v;
}

lval* builtin_eval(lenv* e, lval* a) {
  LASSERT_NUM("eval", a, 1);
  LASSERT_TYPE("eval", a, 0, LVAL_QEXPR);
  
  lval* x = lval_take(a, 0);
  x->type = LVAL_SEXPR;
  return lval_eval(e, x);
}

lval* builtin_join(lenv* e, lval* a) {
  
  for (int i = 0; i < a->count; i++) {
    LASSERT_TYPE("join", a, i, LVAL_QEXPR);
  }
  
  lval* x = lval_pop(a, 0);
  
  while (a->count) {
    lval* y = lval_pop(a, 0);
    x = lval_join(x, y);
  }
  
  lval_del(a);
  return x;
}

lval* builtin_op(lenv* e, lval* a, char* op) {
  
  for (int i = 0; i < a->count; i++) {
    LASSERT_TYPE(op, a, i, LVAL_NUM);
  }
  
  lval* x = lval_pop(a, 0);
  
  if ((strcmp(op, "-") == 0) && a->count == 0) { x->num = -x->num; }
  
  while (a->count > 0) {  
    lval* y = lval_pop(a, 0);
    
    if (strcmp(op, "+") == 0) { x->num += y->num; }
    if (strcmp(op, "-") == 0) { x->num -= y->num; }
    if (strcmp(op, "*") == 0) { x->num *= y->num; }
    if (strcmp(op, "/") == 0) {
      if (y->num == 0) {
        lval_del(x); lval_del(y);
        x = lval_err("Division By Zero.");
        break;
      }
      x->num /= y->num;
    }
    
    lval_del(y);
  }
  
  lval_del(a);
  return x;
}

lval* builtin_add(lenv* e, lval* a) { return builtin_op(e, a, "+"); }
lval* builtin_sub(lenv* e, lval* a) { return builtin_op(e, a, "-"); }
lval* builtin_mul(lenv* e, lval* a) { return builtin_op(e, a, "*"); }
lval* builtin_div(lenv* e, lval* a) { return builtin_op(e, a, "/"); }

lval* builtin_var(lenv* e, lval* a, char* func) {
  LASSERT_TYPE(func, a, 0, LVAL_QEXPR);
  
  lval* syms = a->cell[0];
  for (int i = 0; i < syms->count; i++) {
    LASSERT(a, (syms->cell[i]->type == LVAL_SYM),
      "Function '%s' cannot define non-symbol. "
      "Got %s, Expected %s.",
      func, ltype_name(syms->cell[i]->type), ltype_name(LVAL_SYM));
  }
  
  LASSERT(a, (syms->count == a->count-1),
    "Function '%s' passed too many arguments for symbols. "
    "Got %i, Expected %i.",
    func, syms->count, a->count-1);
    
  for (int i = 0; i < syms->count; i++) {
    if (strcmp(func, "def") == 0) { lenv_def(e, syms->cell[i], a->cell[i+1]); }
    if (strcmp(func, "=")   == 0) { lenv_put(e, syms->cell[i], a->cell[i+1]); } 
  }
  
  lval_del(a);
  return lval_sexpr();
}

lval* builtin_def(lenv* e, lval* a) { return builtin_var(e, a, "def"); }
lval* builtin_put(lenv* e, lval* a) { return builtin_var(e, a, "="); }

lval* builtin_ord(lenv* e, lval* a, char* op) {
  LASSERT_NUM(op, a, 2);
  LASSERT_TYPE(op, a, 0, LVAL_NUM);
  LASSERT_TYPE(op, a, 1, LVAL_NUM);
  
  int r;
  if (strcmp(op, ">")  == 0) {
    r = (a->cell[0]->num >  a->cell[1]->num);
  }
  if (strcmp(op, "<")  == 0) {
    r = (a->cell[0]->num <  a->cell[1]->num);
  }
  if (strcmp(op, ">=") == 0) {
    r = (a->cell[0]->num >= a->cell[1]->num);
  }
  if (strcmp(op, "<=") == 0) {
    r = (a->cell[0]->num <= a->cell[1]->num);
  }
  lval_del(a);
  return lval_num(r);
}

lval* builtin_gt(lenv* e, lval* a) {
  return builtin_ord(e, a, ">");
}

lval* builtin_lt(lenv* e, lval* a) {
  return builtin_ord(e, a, "<");
}

lval* builtin_ge(lenv* e, lval* a) {
  return builtin_ord(e, a, ">=");
}

lval* builtin_le(lenv* e, lval* a) {
  return builtin_ord(e, a, "<=");
}

lval* builtin_cmp(lenv* e, lval* a, char* op) {
  LASSERT_NUM(op, a, 2);
  int r;
  if (strcmp(op, "==") == 0) {
    r =  lval_eq(a->cell[0], a->cell[1]);
  }
  if (strcmp(op, "!=") == 0) {
    r = !lval_eq(a->cell[0], a->cell[1]);
  }
  lval_del(a);
  return lval_num(r);
}

lval* builtin_eq(lenv* e, lval* a) {
  return builtin_cmp(e, a, "==");
}

lval* builtin_ne(lenv* e, lval* a) {
  return builtin_cmp(e, a, "!=");
}

lval* builtin_if(lenv* e, lval* a) {
  LASSERT_NUM("if", a, 3);
  LASSERT_TYPE("if", a, 0, LVAL_NUM);
  LASSERT_TYPE("if", a, 1, LVAL_QEXPR);
  LASSERT_TYPE("if", a, 2, LVAL_QEXPR);
  
  /* Mark Both Expressions as evaluable */
  lval* x;
  a->cell[1]->type = LVAL_SEXPR;
  a->cell[2]->type = LVAL_SEXPR;
  
  if (a->cell[0]->num) {
    /* If condition is true evaluate first expression */
    x = lval_eval(e, lval_pop(a, 1));
  } else {
    /* Otherwise evaluate second expression */
    x = lval_eval(e, lval_pop(a, 2));
  }
  
  /* Delete argument list and return */
  lval_del(a);
  return x;
}

void lenv_add_builtin(lenv* e, char* name, lbuiltin func) {
  lval* k = lval_sym(name);
  lval* v = lval_builtin(func);
  lenv_put(e, k, v);
  lval_del(k); lval_del(v);
}

void lenv_add_builtins(lenv* e) {
  /* Variable Functions */
  lenv_add_builtin(e, "\\",  builtin_lambda); 
  lenv_add_builtin(e, "def", builtin_def);
  lenv_add_builtin(e, "=",   builtin_put);
  
  /* List Functions */
  lenv_add_builtin(e, "list", builtin_list);
  lenv_add_builtin(e, "head", builtin_head);
  lenv_add_builtin(e, "tail", builtin_tail);
  lenv_add_builtin(e, "eval", builtin_eval);
  lenv_add_builtin(e, "join", builtin_join);
  
  /* Mathematical Functions */
  lenv_add_builtin(e, "+", builtin_add);
  lenv_add_builtin(e, "-", builtin_sub);
  lenv_add_builtin(e, "*", builtin_mul);
  lenv_add_builtin(e, "/", builtin_div);
  
  /* Comparison Functions */
  lenv_add_builtin(e, "if",    builtin_if);
  lenv_add_builtin(e, "==",    builtin_eq);
  lenv_add_builtin(e, "!=",    builtin_ne);
  lenv_add_builtin(e, ">",  builtin_gt);
  lenv_add_builtin(e, "<",  builtin_lt);
  lenv_add_builtin(e, ">=", builtin_ge);
  lenv_add_builtin(e, "<=", builtin_le);
}

/* Evaluation */

lval* lval_call(lenv* e, lval* f, lval* a) {
  
  if (f->builtin) { return f->builtin(e, a); }
  
  int given = a->count;
  int total = f->formals->count;
  
  while (a->count) {
    
    if (f->formals->count == 0) {
      lval_del(a);
      return lval_err("Function passed too many arguments. "
        "Got %i, Expected %i.", given, total); 
    }
    
    lval* sym = lval_pop(f->formals, 0);
    
    if (strcmp(sym->sym, "&") == 0) {
      
      if (f->formals->count != 1) {
        lval_del(a);
        return lval_err("Function format invalid. "
          "Symbol '&' not followed by single symbol.");
      }
      
      lval* nsym = lval_pop(f->formals, 0);
      lenv_put(f->env, nsym, builtin_list(e, a));
      lval_del(sym); lval_del(nsym);
      break;
    }
    
    lval* val = lval_pop(a, 0);    
    lenv_put(f->env, sym, val);    
    lval_del(sym); lval_del(val);
  }
  
  lval_del(a);
  
  if (f->formals->count > 0 &&
    strcmp(f->formals->cell[0]->sym, "&") == 0) {
    
    if (f->formals->count != 2) {
      return lval_err("Function format invalid. "
        "Symbol '&' not followed by single symbol.");
    }
    
    lval_del(lval_pop(f->formals, 0));
    
    lval* sym = lval_pop(f->formals, 0);
    lval* val = lval_qexpr();    
    lenv_put(f->env, sym, val);
    lval_del(sym); lval_del(val);
  }
  
  if (f->formals->count == 0) {  
    f->env->par = e;    
    return builtin_eval(f->env, lval_add(lval_sexpr(), lval_copy(f->body)));
  } else {
    return lval_copy(f);
  }
  
}

lval* lval_eval_sexpr(lenv* e, lval* v) {
  
  for (int i = 0; i < v->count; i++) { v->cell[i] = lval_eval(e, v->cell[i]); }
  for (int i = 0; i < v->count; i++) { if (v->cell[i]->type == LVAL_ERR) { return lval_take(v, i); } }
  
  if (v->count == 0) { return v; }  
  if (v->count == 1) { return lval_eval(e, lval_take(v, 0)); }
  
  lval* f = lval_pop(v, 0);
  if (f->type != LVAL_FUN) {
    lval* err = lval_err(
      "S-Expression starts with incorrect type. "
      "Got %s, Expected %s.",
      ltype_name(f->type), ltype_name(LVAL_FUN));
    lval_del(f); lval_del(v);
    return err;
  }
  
  lval* result = lval_call(e, f, v);
  lval_del(f);
  return result;
}

lval* lval_eval(lenv* e, lval* v) {
  if (v->type == LVAL_SYM) {
    lval* x = lenv_get(e, v);
    lval_del(v);
    return x;
  }
  if (v->type == LVAL_SEXPR) { return lval_eval_sexpr(e, v); }
  return v;
}

/* Reading */

lval* lval_read_num(mpc_ast_t* t) {
  errno = 0;
  long x = strtol(t->contents, NULL, 10);
  return errno != ERANGE ? lval_num(x) : lval_err("Invalid Number.");
}

lval* lval_read(mpc_ast_t* t) {
  
  if (strstr(t->tag, "number")) { return lval_read_num(t); }
  if (strstr(t->tag, "symbol")) { return lval_sym(t->contents); }
  
  lval* x = NULL;
  if (strcmp(t->tag, ">") == 0) { x = lval_sexpr(); } 
  if (strstr(t->tag, "sexpr"))  { x = lval_sexpr(); }
  if (strstr(t->tag, "qexpr"))  { x = lval_qexpr(); }
  
  for (int i = 0; i < t->children_num; i++) {
    if (strcmp(t->children[i]->contents, "(") == 0) { continue; }
    if (strcmp(t->children[i]->contents, ")") == 0) { continue; }
    if (strcmp(t->children[i]->contents, "}") == 0) { continue; }
    if (strcmp(t->children[i]->contents, "{") == 0) { continue; }
    if (strcmp(t->children[i]->tag,  "regex") == 0) { continue; }
    x = lval_add(x, lval_read(t->children[i]));
  }
  
  return x;
}

/* Main */

int main(int argc, char** argv) {
  
  mpc_parser_t* Number = mpc_new("number");
  mpc_parser_t* Symbol = mpc_new("symbol");
  mpc_parser_t* Sexpr  = mpc_new("sexpr");
  mpc_parser_t* Qexpr  = mpc_new("qexpr");
  mpc_parser_t* Expr   = mpc_new("expr");
  mpc_parser_t* Lispy  = mpc_new("lispy");
  
  mpca_lang(MPCA_LANG_DEFAULT,
    "                                                     \
      number : /-?[0-9]+/ ;                               \
      symbol : /[a-zA-Z0-9_+\\-*\\/\\\\=<>!&]+/ ;         \
      sexpr  : '(' <expr>* ')' ;                          \
      qexpr  : '{' <expr>* '}' ;                          \
      expr   : <number> | <symbol> | <sexpr> | <qexpr> ;  \
      lispy  : /^/ <expr>* /$/ ;                          \
    ",
    Number, Symbol, Sexpr, Qexpr, Expr, Lispy);
  
  puts("Lispy Version 0.0.0.0.9");
  puts("Press Ctrl+c to Exit\n");
  
  lenv* e = lenv_new();
  lenv_add_builtins(e);
  
  while (1) {
  
    char* input = readline("lispy> ");
    add_history(input);
    
    mpc_result_t r;
    if (mpc_parse("<stdin>", input, Lispy, &r)) {
      
      lval* x = lval_eval(e, lval_read(r.output));
      lval_println(x);
      lval_del(x);
      
      mpc_ast_delete(r.output);
    } else {    
      mpc_err_print(r.error);
      mpc_err_delete(r.error);
    }
    
    free(input);
    
  }
  
  lenv_del(e);
  
  mpc_cleanup(6, Number, Symbol, Sexpr, Qexpr, Expr, Lispy);
  
  return 0;
}
src/doge_code.c000666 000000 000000 00000001232 13206352046 012072 0ustar00000000 000000 #include "mpc.h"

int main(int argc, char** argv) {

  /* Build a parser 'Adjective' to recognize descriptions */
  mpc_parser_t* Adjective = mpc_or(4, 
    mpc_sym("wow"), mpc_sym("many"),
    mpc_sym("so"),  mpc_sym("such")
  );

  /* Build a parser 'Noun' to recognize things */
  mpc_parser_t* Noun = mpc_or(5,
    mpc_sym("lisp"), mpc_sym("language"),
    mpc_sym("book"), mpc_sym("build"), 
    mpc_sym("c")
  );
  
  mpc_parser_t* Phrase = mpc_and(2, mpcf_strfold, 
    Adjective, Noun, free);
  
  mpc_parser_t* Doge = mpc_many(mpcf_strfold, Phrase);

  /* Do some parsing here... */
  
  mpc_delete(Doge);
  
  return 0;
  
}

src/doge_grammar.c000666 000000 000000 00000001433 13206352046 012611 0ustar00000000 000000 #include "mpc.h"

int main(int argc, char** argv) {

  mpc_parser_t* Adjective = mpc_new("adjective");
  mpc_parser_t* Noun      = mpc_new("noun");
  mpc_parser_t* Phrase    = mpc_new("phrase");
  mpc_parser_t* Doge      = mpc_new("doge");

  mpca_lang(MPCA_LANG_DEFAULT,
    "                                           \
      adjective : \"wow\" | \"many\"            \
                |  \"so\" | \"such\";           \
      noun      : \"lisp\" | \"language\"       \
                | \"book\" | \"build\" | \"c\"; \
      phrase    : <adjective> <noun>;           \
      doge      : <phrase>*;                    \
    ",
    Adjective, Noun, Phrase, Doge);

  /* Do some parsing here... */

  mpc_cleanup(4, Adjective, Noun, Phrase, Doge);
  
  return 0;
  
}
src/error_handling.c000666 000000 000000 00000007540 13206352046 013167 0ustar00000000 000000 #include "mpc.h"

#ifdef _WIN32

static char buffer[2048];

char* readline(char* prompt) {
  fputs(prompt, stdout);
  fgets(buffer, 2048, stdin);
  char* cpy = malloc(strlen(buffer)+1);
  strcpy(cpy, buffer);
  cpy[strlen(cpy)-1] = '\0';
  return cpy;
}

void add_history(char* unused) {}

#else
#include <editline/readline.h>
#include <editline/history.h>
#endif

/* Create Enumeration of Possible Error Types */
enum { LERR_DIV_ZERO, LERR_BAD_OP, LERR_BAD_NUM };

/* Create Enumeration of Possible lval Types */
enum { LVAL_NUM, LVAL_ERR };

/* Declare New lval Struct */
typedef struct {
  int type;
  long num;
  int err;
} lval;

/* Create a new number type lval */
lval lval_num(long x) {
  lval v;
  v.type = LVAL_NUM;
  v.num = x;
  return v;
}

/* Create a new error type lval */
lval lval_err(int x) {
  lval v;
  v.type = LVAL_ERR;
  v.err = x;
  return v;
}

/* Print an "lval" */
void lval_print(lval v) {
  switch (v.type) {
    /* In the case the type is a number print it */
    /* Then 'break' out of the switch. */
    case LVAL_NUM: printf("%li", v.num); break;
    
    /* In the case the type is an error */
    case LVAL_ERR:
      /* Check what type of error it is and print it */
      if (v.err == LERR_DIV_ZERO) {
        printf("Error: Division By Zero!");
      }
      if (v.err == LERR_BAD_OP)   {
        printf("Error: Invalid Operator!");
      }
      if (v.err == LERR_BAD_NUM)  {
        printf("Error: Invalid Number!");
      }
    break;
  }
}

/* Print an "lval" followed by a newline */
void lval_println(lval v) { lval_print(v); putchar('\n'); }

lval eval_op(lval x, char* op, lval y) {
  
  /* If either value is an error return it */
  if (x.type == LVAL_ERR) { return x; }
  if (y.type == LVAL_ERR) { return y; }
  
  /* Otherwise do maths on the number values */
  if (strcmp(op, "+") == 0) { return lval_num(x.num + y.num); }
  if (strcmp(op, "-") == 0) { return lval_num(x.num - y.num); }
  if (strcmp(op, "*") == 0) { return lval_num(x.num * y.num); }
  if (strcmp(op, "/") == 0) {
    /* If second operand is zero return error */
    return y.num == 0 
      ? lval_err(LERR_DIV_ZERO) 
      : lval_num(x.num / y.num);
  }
  
  return lval_err(LERR_BAD_OP);
}

lval eval(mpc_ast_t* t) {
  
  if (strstr(t->tag, "number")) {
    /* Check if there is some error in conversion */
    errno = 0;
    long x = strtol(t->contents, NULL, 10);
    return errno != ERANGE ? lval_num(x) : lval_err(LERR_BAD_NUM);
  }
  
  char* op = t->children[1]->contents;  
  lval x = eval(t->children[2]);
  
  int i = 3;
  while (strstr(t->children[i]->tag, "expr")) {
    x = eval_op(x, op, eval(t->children[i]));
    i++;
  }
  
  return x;  
}

int main(int argc, char** argv) {
  
  mpc_parser_t* Number = mpc_new("number");
  mpc_parser_t* Operator = mpc_new("operator");
  mpc_parser_t* Expr = mpc_new("expr");
  mpc_parser_t* Lispy = mpc_new("lispy");
  
  mpca_lang(MPCA_LANG_DEFAULT,
    "                                                     \
      number   : /-?[0-9]+/ ;                             \
      operator : '+' | '-' | '*' | '/' ;                  \
      expr     : <number> | '(' <operator> <expr>+ ')' ;  \
      lispy    : /^/ <operator> <expr>+ /$/ ;             \
    ",
    Number, Operator, Expr, Lispy);
  
  puts("Lispy Version 0.0.0.0.4");
  puts("Press Ctrl+c to Exit\n");
  
  while (1) {
  
    char* input = readline("lispy> ");
    add_history(input);
    
    mpc_result_t r;
    if (mpc_parse("<stdin>", input, Lispy, &r)) {
      lval result = eval(r.output);
      lval_println(result);
      mpc_ast_delete(r.output);
    } else {    
      mpc_err_print(r.error);
      mpc_err_delete(r.error);
    }
    
    free(input);
    
  }
  
  mpc_cleanup(4, Number, Operator, Expr, Lispy);
  
  return 0;
}
src/evaluation.c000666 000000 000000 00000004520 13206352046 012334 0ustar00000000 000000 #include "mpc.h"

#ifdef _WIN32

static char buffer[2048];

char* readline(char* prompt) {
  fputs(prompt, stdout);
  fgets(buffer, 2048, stdin);
  char* cpy = malloc(strlen(buffer)+1);
  strcpy(cpy, buffer);
  cpy[strlen(cpy)-1] = '\0';
  return cpy;
}

void add_history(char* unused) {}

#else
#include <editline/readline.h>
#include <editline/history.h>
#endif

/* Use operator string to see which operation to perform */
long eval_op(long x, char* op, long y) {
  if (strcmp(op, "+") == 0) { return x + y; }
  if (strcmp(op, "-") == 0) { return x - y; }
  if (strcmp(op, "*") == 0) { return x * y; }
  if (strcmp(op, "/") == 0) { return x / y; }
  return 0;
}

long eval(mpc_ast_t* t) {
  
  /* If tagged as number return it directly. */ 
  if (strstr(t->tag, "number")) {
    return atoi(t->contents);
  }
  
  /* The operator is always second child. */
  char* op = t->children[1]->contents;
  
  /* We store the third child in `x` */
  long x = eval(t->children[2]);
  
  /* Iterate the remaining children and combining. */
  int i = 3;
  while (strstr(t->children[i]->tag, "expr")) {
    x = eval_op(x, op, eval(t->children[i]));
    i++;
  }
  
  return x;  
}

int main(int argc, char** argv) {
  
  mpc_parser_t* Number = mpc_new("number");
  mpc_parser_t* Operator = mpc_new("operator");
  mpc_parser_t* Expr = mpc_new("expr");
  mpc_parser_t* Lispy = mpc_new("lispy");
  
  mpca_lang(MPCA_LANG_DEFAULT,
    "                                                     \
      number   : /-?[0-9]+/ ;                             \
      operator : '+' | '-' | '*' | '/' ;                  \
      expr     : <number> | '(' <operator> <expr>+ ')' ;  \
      lispy    : /^/ <operator> <expr>+ /$/ ;             \
    ",
    Number, Operator, Expr, Lispy);
  
  puts("Lispy Version 0.0.0.0.3");
  puts("Press Ctrl+c to Exit\n");
  
  while (1) {
  
    char* input = readline("lispy> ");
    add_history(input);
    
    mpc_result_t r;
    if (mpc_parse("<stdin>", input, Lispy, &r)) {
      
      long result = eval(r.output);
      printf("%li\n", result);
      mpc_ast_delete(r.output);
      
    } else {    
      mpc_err_print(r.error);
      mpc_err_delete(r.error);
    }
    
    free(input);
    
  }
  
  mpc_cleanup(4, Number, Operator, Expr, Lispy);
  
  return 0;
}
src/functions.c000666 000000 000000 00000044773 13206352046 012213 0ustar00000000 000000 #include "mpc.h"

#ifdef _WIN32

static char buffer[2048];

char* readline(char* prompt) {
  fputs(prompt, stdout);
  fgets(buffer, 2048, stdin);
  char* cpy = malloc(strlen(buffer)+1);
  strcpy(cpy, buffer);
  cpy[strlen(cpy)-1] = '\0';
  return cpy;
}

void add_history(char* unused) {}

#else
#include <editline/readline.h>
#include <editline/history.h>
#endif

/* Forward Declarations */

struct lval;
struct lenv;
typedef struct lval lval;
typedef struct lenv lenv;

/* Lisp Value */

enum { LVAL_ERR, LVAL_NUM, LVAL_SYM, LVAL_FUN, LVAL_SEXPR, LVAL_QEXPR };

typedef lval*(*lbuiltin)(lenv*, lval*);

struct lval {
  int type;

  /* Basic */
  long num;
  char* err;
  char* sym;
  
  /* Function */
  lbuiltin builtin;
  lenv* env;
  lval* formals;
  lval* body;
  
  /* Expression */
  int count;
  lval** cell;
};

lval* lval_num(long x) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_NUM;
  v->num = x;
  return v;
}

lval* lval_err(char* fmt, ...) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_ERR;  
  va_list va;
  va_start(va, fmt);  
  v->err = malloc(512);  
  vsnprintf(v->err, 511, fmt, va);  
  v->err = realloc(v->err, strlen(v->err)+1);
  va_end(va);  
  return v;
}

lval* lval_sym(char* s) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SYM;
  v->sym = malloc(strlen(s) + 1);
  strcpy(v->sym, s);
  return v;
}

lval* lval_builtin(lbuiltin func) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_FUN;
  v->builtin = func;
  return v;
}

lenv* lenv_new(void);

lval* lval_lambda(lval* formals, lval* body) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_FUN;
  
  /* Set Builtin to Null */
  v->builtin = NULL;
  
  /* Build new environment */
  v->env = lenv_new();
  
  /* Set Formals and Body */
  v->formals = formals;
  v->body = body;
  return v;  
}

lval* lval_sexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

lval* lval_qexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_QEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

void lenv_del(lenv* e);

void lval_del(lval* v) {

  switch (v->type) {
    case LVAL_NUM: break;
    case LVAL_FUN: 
      if (!v->builtin) {
        lenv_del(v->env);
        lval_del(v->formals);
        lval_del(v->body);
      }
    break;
    case LVAL_ERR: free(v->err); break;
    case LVAL_SYM: free(v->sym); break;
    case LVAL_QEXPR:
    case LVAL_SEXPR:
      for (int i = 0; i < v->count; i++) {
        lval_del(v->cell[i]);
      }
      free(v->cell);
    break;
  }
  
  free(v);
}

lenv* lenv_copy(lenv* e);

lval* lval_copy(lval* v) {
  lval* x = malloc(sizeof(lval));
  x->type = v->type;
  switch (v->type) {
    case LVAL_FUN:
      if (v->builtin) {
        x->builtin = v->builtin;
      } else {
        x->builtin = NULL;
        x->env = lenv_copy(v->env);
        x->formals = lval_copy(v->formals);
        x->body = lval_copy(v->body);
      }
    break;
    case LVAL_NUM: x->num = v->num; break;
    case LVAL_ERR: x->err = malloc(strlen(v->err) + 1);
      strcpy(x->err, v->err);
    break;
    case LVAL_SYM: x->sym = malloc(strlen(v->sym) + 1);
      strcpy(x->sym, v->sym);
    break;
    case LVAL_SEXPR:
    case LVAL_QEXPR:
      x->count = v->count;
      x->cell = malloc(sizeof(lval*) * x->count);
      for (int i = 0; i < x->count; i++) {
        x->cell[i] = lval_copy(v->cell[i]);
      }
    break;
  }
  return x;
}

lval* lval_add(lval* v, lval* x) {
  v->count++;
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  v->cell[v->count-1] = x;
  return v;
}

lval* lval_join(lval* x, lval* y) {  
  for (int i = 0; i < y->count; i++) {
    x = lval_add(x, y->cell[i]);
  }
  free(y->cell);
  free(y);  
  return x;
}

lval* lval_pop(lval* v, int i) {
  lval* x = v->cell[i];  
  memmove(&v->cell[i],
    &v->cell[i+1], sizeof(lval*) * (v->count-i-1));  
  v->count--;  
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  return x;
}

lval* lval_take(lval* v, int i) {
  lval* x = lval_pop(v, i);
  lval_del(v);
  return x;
}

void lval_print(lval* v);

void lval_print_expr(lval* v, char open, char close) {
  putchar(open);
  for (int i = 0; i < v->count; i++) {
    lval_print(v->cell[i]);    
    if (i != (v->count-1)) {
      putchar(' ');
    }
  }
  putchar(close);
}

void lval_print(lval* v) {
  switch (v->type) {
    case LVAL_FUN:
      if (v->builtin) {
        printf("<builtin>");
      } else {
        printf("(\\ "); lval_print(v->formals);
        putchar(' '); lval_print(v->body); putchar(')');
      }
    break;
    case LVAL_NUM:   printf("%li", v->num); break;
    case LVAL_ERR:   printf("Error: %s", v->err); break;
    case LVAL_SYM:   printf("%s", v->sym); break;
    case LVAL_SEXPR: lval_print_expr(v, '(', ')'); break;
    case LVAL_QEXPR: lval_print_expr(v, '{', '}'); break;
  }
}

void lval_println(lval* v) { lval_print(v); putchar('\n'); }

char* ltype_name(int t) {
  switch(t) {
    case LVAL_FUN: return "Function";
    case LVAL_NUM: return "Number";
    case LVAL_ERR: return "Error";
    case LVAL_SYM: return "Symbol";
    case LVAL_SEXPR: return "S-Expression";
    case LVAL_QEXPR: return "Q-Expression";
    default: return "Unknown";
  }
}

/* Lisp Environment */

struct lenv {
  lenv* par;
  int count;
  char** syms;
  lval** vals;
};

lenv* lenv_new(void) {
  lenv* e = malloc(sizeof(lenv));
  e->par = NULL;
  e->count = 0;
  e->syms = NULL;
  e->vals = NULL;
  return e;
}

void lenv_del(lenv* e) {
  for (int i = 0; i < e->count; i++) {
    free(e->syms[i]);
    lval_del(e->vals[i]);
  }  
  free(e->syms);
  free(e->vals);
  free(e);
}

lenv* lenv_copy(lenv* e) {
  lenv* n = malloc(sizeof(lenv));
  n->par = e->par;
  n->count = e->count;
  n->syms = malloc(sizeof(char*) * n->count);
  n->vals = malloc(sizeof(lval*) * n->count);
  for (int i = 0; i < e->count; i++) {
    n->syms[i] = malloc(strlen(e->syms[i]) + 1);
    strcpy(n->syms[i], e->syms[i]);
    n->vals[i] = lval_copy(e->vals[i]);
  }
  return n;
}

lval* lenv_get(lenv* e, lval* k) {
  
  for (int i = 0; i < e->count; i++) {
    if (strcmp(e->syms[i], k->sym) == 0) {
      return lval_copy(e->vals[i]);
    }
  }
  
  /* If no symbol check in parent otherwise error */
  if (e->par) {
    return lenv_get(e->par, k);
  } else {
    return lval_err("Unbound Symbol '%s'", k->sym);
  }
}

void lenv_put(lenv* e, lval* k, lval* v) {
  
  for (int i = 0; i < e->count; i++) {
    if (strcmp(e->syms[i], k->sym) == 0) {
      lval_del(e->vals[i]);
      e->vals[i] = lval_copy(v);
      return;
    }
  }

  
  e->count++;
  e->vals = realloc(e->vals, sizeof(lval*) * e->count);
  e->syms = realloc(e->syms, sizeof(char*) * e->count);  
  e->vals[e->count-1] = lval_copy(v);
  e->syms[e->count-1] = malloc(strlen(k->sym)+1);
  strcpy(e->syms[e->count-1], k->sym);
}

void lenv_def(lenv* e, lval* k, lval* v) {
  /* Iterate till e has no parent */
  while (e->par) { e = e->par; }
  /* Put value in e */
  lenv_put(e, k, v);
}

/* Builtins */

#define LASSERT(args, cond, fmt, ...) \
  if (!(cond)) { lval* err = lval_err(fmt, ##__VA_ARGS__); lval_del(args); return err; }

#define LASSERT_TYPE(func, args, index, expect) \
  LASSERT(args, args->cell[index]->type == expect, \
    "Function '%s' passed incorrect type for argument %i. " \
    "Got %s, Expected %s.", \
    func, index, ltype_name(args->cell[index]->type), ltype_name(expect))

#define LASSERT_NUM(func, args, num) \
  LASSERT(args, args->count == num, \
    "Function '%s' passed incorrect number of arguments. " \
    "Got %i, Expected %i.", \
    func, args->count, num)

#define LASSERT_NOT_EMPTY(func, args, index) \
  LASSERT(args, args->cell[index]->count != 0, \
    "Function '%s' passed {} for argument %i.", func, index);
    
lval* lval_eval(lenv* e, lval* v);

lval* builtin_lambda(lenv* e, lval* a) {
  /* Check Two arguments, each of which are Q-Expressions */
  LASSERT_NUM("\\", a, 2);
  LASSERT_TYPE("\\", a, 0, LVAL_QEXPR);
  LASSERT_TYPE("\\", a, 1, LVAL_QEXPR);
  
  /* Check first Q-Expression contains only Symbols */
  for (int i = 0; i < a->cell[0]->count; i++) {
    LASSERT(a, (a->cell[0]->cell[i]->type == LVAL_SYM),
      "Cannot define non-symbol. Got %s, Expected %s.",
      ltype_name(a->cell[0]->cell[i]->type),ltype_name(LVAL_SYM));
  }
  
  /* Pop first two arguments and pass them to lval_lambda */
  lval* formals = lval_pop(a, 0);
  lval* body = lval_pop(a, 0);
  lval_del(a);
  
  return lval_lambda(formals, body);
}

lval* builtin_list(lenv* e, lval* a) {
  a->type = LVAL_QEXPR;
  return a;
}

lval* builtin_head(lenv* e, lval* a) {
  LASSERT_NUM("head", a, 1);
  LASSERT_TYPE("head", a, 0, LVAL_QEXPR);
  LASSERT_NOT_EMPTY("head", a, 0);
  
  lval* v = lval_take(a, 0);  
  while (v->count > 1) { lval_del(lval_pop(v, 1)); }
  return v;
}

lval* builtin_tail(lenv* e, lval* a) {
  LASSERT_NUM("tail", a, 1);
  LASSERT_TYPE("tail", a, 0, LVAL_QEXPR);
  LASSERT_NOT_EMPTY("tail", a, 0);

  lval* v = lval_take(a, 0);  
  lval_del(lval_pop(v, 0));
  return v;
}

lval* builtin_eval(lenv* e, lval* a) {
  LASSERT_NUM("eval", a, 1);
  LASSERT_TYPE("eval", a, 0, LVAL_QEXPR);
  
  lval* x = lval_take(a, 0);
  x->type = LVAL_SEXPR;
  return lval_eval(e, x);
}

lval* builtin_join(lenv* e, lval* a) {
  
  for (int i = 0; i < a->count; i++) {
    LASSERT_TYPE("join", a, i, LVAL_QEXPR);
  }
  
  lval* x = lval_pop(a, 0);
  
  while (a->count) {
    lval* y = lval_pop(a, 0);
    x = lval_join(x, y);
  }
  
  lval_del(a);
  return x;
}

lval* builtin_op(lenv* e, lval* a, char* op) {
  
  for (int i = 0; i < a->count; i++) {
    LASSERT_TYPE(op, a, i, LVAL_NUM);
  }
  
  lval* x = lval_pop(a, 0);
  
  if ((strcmp(op, "-") == 0) && a->count == 0) { x->num = -x->num; }
  
  while (a->count > 0) {  
    lval* y = lval_pop(a, 0);
    
    if (strcmp(op, "+") == 0) { x->num += y->num; }
    if (strcmp(op, "-") == 0) { x->num -= y->num; }
    if (strcmp(op, "*") == 0) { x->num *= y->num; }
    if (strcmp(op, "/") == 0) {
      if (y->num == 0) {
        lval_del(x); lval_del(y);
        x = lval_err("Division By Zero.");
        break;
      }
      x->num /= y->num;
    }
    
    lval_del(y);
  }
  
  lval_del(a);
  return x;
}

lval* builtin_add(lenv* e, lval* a) { return builtin_op(e, a, "+"); }
lval* builtin_sub(lenv* e, lval* a) { return builtin_op(e, a, "-"); }
lval* builtin_mul(lenv* e, lval* a) { return builtin_op(e, a, "*"); }
lval* builtin_div(lenv* e, lval* a) { return builtin_op(e, a, "/"); }

lval* builtin_var(lenv* e, lval* a, char* func) {
  LASSERT_TYPE(func, a, 0, LVAL_QEXPR);
  
  lval* syms = a->cell[0];
  for (int i = 0; i < syms->count; i++) {
    LASSERT(a, (syms->cell[i]->type == LVAL_SYM),
      "Function '%s' cannot define non-symbol. "
      "Got %s, Expected %s.", func, 
      ltype_name(syms->cell[i]->type), ltype_name(LVAL_SYM));
  }
  
  LASSERT(a, (syms->count == a->count-1),
    "Function '%s' passed too many arguments for symbols. "
    "Got %i, Expected %i.", func, syms->count, a->count-1);
    
  for (int i = 0; i < syms->count; i++) {
    /* If 'def' define in globally. If 'put' define in locally */
    if (strcmp(func, "def") == 0) {
      lenv_def(e, syms->cell[i], a->cell[i+1]);
    }
    
    if (strcmp(func, "=")   == 0) {
      lenv_put(e, syms->cell[i], a->cell[i+1]);
    } 
  }
  
  lval_del(a);
  return lval_sexpr();
}

lval* builtin_def(lenv* e, lval* a) {
  return builtin_var(e, a, "def");
}

lval* builtin_put(lenv* e, lval* a) {
  return builtin_var(e, a, "=");
}

void lenv_add_builtin(lenv* e, char* name, lbuiltin func) {
  lval* k = lval_sym(name);
  lval* v = lval_builtin(func);
  lenv_put(e, k, v);
  lval_del(k); lval_del(v);
}

void lenv_add_builtins(lenv* e) {
  /* Variable Functions */
  lenv_add_builtin(e, "\\",  builtin_lambda); 
  lenv_add_builtin(e, "def", builtin_def);
  lenv_add_builtin(e, "=",   builtin_put);
  
  /* List Functions */
  lenv_add_builtin(e, "list", builtin_list);
  lenv_add_builtin(e, "head", builtin_head);
  lenv_add_builtin(e, "tail", builtin_tail);
  lenv_add_builtin(e, "eval", builtin_eval);
  lenv_add_builtin(e, "join", builtin_join);
  
  /* Mathematical Functions */
  lenv_add_builtin(e, "+", builtin_add);
  lenv_add_builtin(e, "-", builtin_sub);
  lenv_add_builtin(e, "*", builtin_mul);
  lenv_add_builtin(e, "/", builtin_div);
}

/* Evaluation */

lval* lval_call(lenv* e, lval* f, lval* a) {
  
  /* If Builtin then simply apply that */
  if (f->builtin) { return f->builtin(e, a); }
  
  /* Record Argument Counts */
  int given = a->count;
  int total = f->formals->count;
  
  /* While arguments still remain to be processed */
  while (a->count) {
    
    /* If we've ran out of formal arguments to bind */
    if (f->formals->count == 0) {
      lval_del(a);
      return lval_err("Function passed too many arguments. "
        "Got %i, Expected %i.", given, total); 
    }
    
    /* Pop the first symbol from the formals */
    lval* sym = lval_pop(f->formals, 0);
    
    /* Special Case to deal with '&' */
    if (strcmp(sym->sym, "&") == 0) {
      
      /* Ensure '&' is followed by another symbol */
      if (f->formals->count != 1) {
        lval_del(a);
        return lval_err("Function format invalid. "
          "Symbol '&' not followed by single symbol.");
      }
      
      /* Next formal should be bound to remaining arguments */
      lval* nsym = lval_pop(f->formals, 0);
      lenv_put(f->env, nsym, builtin_list(e, a));
      lval_del(sym); lval_del(nsym);
      break;
    }
    
    /* Pop the next argument from the list */
    lval* val = lval_pop(a, 0);
    
    /* Bind a copy into the function's environment */
    lenv_put(f->env, sym, val);
    
    /* Delete symbol and value */
    lval_del(sym); lval_del(val);
  }
  
  /* Argument list is now bound so can be cleaned up */
  lval_del(a);
  
  /* If '&' remains in formal list bind to empty list */
  if (f->formals->count > 0 &&
    strcmp(f->formals->cell[0]->sym, "&") == 0) {
    
    /* Check to ensure that & is not passed invalidly. */
    if (f->formals->count != 2) {
      return lval_err("Function format invalid. "
        "Symbol '&' not followed by single symbol.");
    }
    
    /* Pop and delete '&' symbol */
    lval_del(lval_pop(f->formals, 0));
    
    /* Pop next symbol and create empty list */
    lval* sym = lval_pop(f->formals, 0);
    lval* val = lval_qexpr();
    
    /* Bind to environment and delete */
    lenv_put(f->env, sym, val);
    lval_del(sym); lval_del(val);
  }
  
  /* If all formals have been bound evaluate */
  if (f->formals->count == 0) {
  
    /* Set environment parent to evaluation environment */
    f->env->par = e;
    
    /* Evaluate and return */
    return builtin_eval(f->env, 
      lval_add(lval_sexpr(), lval_copy(f->body)));
  } else {
    /* Otherwise return partially evaluated function */
    return lval_copy(f);
  }
  
}

lval* lval_eval_sexpr(lenv* e, lval* v) {
  
  for (int i = 0; i < v->count; i++) {
    v->cell[i] = lval_eval(e, v->cell[i]);
  }
  
  for (int i = 0; i < v->count; i++) {
    if (v->cell[i]->type == LVAL_ERR) { return lval_take(v, i); }
  }
  
  if (v->count == 0) { return v; }  
  if (v->count == 1) { return lval_eval(e, lval_take(v, 0)); }
  
  lval* f = lval_pop(v, 0);
  if (f->type != LVAL_FUN) {
    lval* err = lval_err(
      "S-Expression starts with incorrect type. "
      "Got %s, Expected %s.",
      ltype_name(f->type), ltype_name(LVAL_FUN));
    lval_del(f); lval_del(v);
    return err;
  }
  
  lval* result = lval_call(e, f, v);
  lval_del(f);
  return result;
}

lval* lval_eval(lenv* e, lval* v) {
  if (v->type == LVAL_SYM) {
    lval* x = lenv_get(e, v);
    lval_del(v);
    return x;
  }
  if (v->type == LVAL_SEXPR) { return lval_eval_sexpr(e, v); }
  return v;
}

/* Reading */

lval* lval_read_num(mpc_ast_t* t) {
  errno = 0;
  long x = strtol(t->contents, NULL, 10);
  return errno != ERANGE ? lval_num(x) : lval_err("Invalid Number.");
}

lval* lval_read(mpc_ast_t* t) {
  
  if (strstr(t->tag, "number")) { return lval_read_num(t); }
  if (strstr(t->tag, "symbol")) { return lval_sym(t->contents); }
  
  lval* x = NULL;
  if (strcmp(t->tag, ">") == 0) { x = lval_sexpr(); } 
  if (strstr(t->tag, "sexpr"))  { x = lval_sexpr(); }
  if (strstr(t->tag, "qexpr"))  { x = lval_qexpr(); }
  
  for (int i = 0; i < t->children_num; i++) {
    if (strcmp(t->children[i]->contents, "(") == 0) { continue; }
    if (strcmp(t->children[i]->contents, ")") == 0) { continue; }
    if (strcmp(t->children[i]->contents, "}") == 0) { continue; }
    if (strcmp(t->children[i]->contents, "{") == 0) { continue; }
    if (strcmp(t->children[i]->tag,  "regex") == 0) { continue; }
    x = lval_add(x, lval_read(t->children[i]));
  }
  
  return x;
}

/* Main */

int main(int argc, char** argv) {
  
  mpc_parser_t* Number = mpc_new("number");
  mpc_parser_t* Symbol = mpc_new("symbol");
  mpc_parser_t* Sexpr  = mpc_new("sexpr");
  mpc_parser_t* Qexpr  = mpc_new("qexpr");
  mpc_parser_t* Expr   = mpc_new("expr");
  mpc_parser_t* Lispy  = mpc_new("lispy");
  
  mpca_lang(MPCA_LANG_DEFAULT,
    "                                                     \
      number : /-?[0-9]+/ ;                               \
      symbol  : /[a-zA-Z0-9_+\\-*\\/\\\\=<>!&]+/ ;        \
      sexpr  : '(' <expr>* ')' ;                          \
      qexpr  : '{' <expr>* '}' ;                          \
      expr   : <number> | <symbol> | <sexpr> | <qexpr> ;  \
      lispy  : /^/ <expr>* /$/ ;                          \
    ",
    Number, Symbol, Sexpr, Qexpr, Expr, Lispy);
  
  puts("Lispy Version 0.0.0.0.8");
  puts("Press Ctrl+c to Exit\n");
  
  lenv* e = lenv_new();
  lenv_add_builtins(e);
  
  while (1) {
  
    char* input = readline("lispy> ");
    add_history(input);
    
    mpc_result_t r;
    if (mpc_parse("<stdin>", input, Lispy, &r)) {
      lval* x = lval_eval(e, lval_read(r.output));
      lval_println(x);
      lval_del(x);
      mpc_ast_delete(r.output);
    } else {    
      mpc_err_print(r.error);
      mpc_err_delete(r.error);
    }
    
    free(input);
    
  }
  
  lenv_del(e);
  
  mpc_cleanup(6, Number, Symbol, Sexpr, Qexpr, Expr, Lispy);
  
  return 0;
}
src/hand_rolled_parser.c000666 000000 000000 00000061414 13206352046 014021 0ustar00000000 000000 #include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <errno.h>

#ifdef _WIN32

static char buffer[2048];

char* readline(char* prompt) {
  fputs(prompt, stdout);
  fgets(buffer, 2048, stdin);
  char* cpy = malloc(strlen(buffer)+1);
  strcpy(cpy, buffer);
  cpy[strlen(cpy)-1] = '\0';
  return cpy;
}

void add_history(char* unused) {}

#else
#include <editline/readline.h>
#include <editline/history.h>
#endif

/* Forward Declarations */

struct lval;
struct lenv;
typedef struct lval lval;
typedef struct lenv lenv;

/* Lisp Value */

enum { LVAL_ERR, LVAL_NUM,   LVAL_SYM, LVAL_STR, 
       LVAL_FUN, LVAL_SEXPR, LVAL_QEXPR };
       
typedef lval*(*lbuiltin)(lenv*, lval*);

struct lval {
  int type;

  /* Basic */
  long num;
  char* err;
  char* sym;
  char* str;
  
  /* Function */
  lbuiltin builtin;
  lenv* env;
  lval* formals;
  lval* body;
  
  /* Expression */
  int count;
  lval** cell;
};

lval* lval_num(long x) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_NUM;
  v->num = x;
  return v;
}

lval* lval_err(char* fmt, ...) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_ERR;  
  va_list va;
  va_start(va, fmt);  
  v->err = malloc(512);  
  vsnprintf(v->err, 511, fmt, va);  
  v->err = realloc(v->err, strlen(v->err)+1);
  va_end(va);  
  return v;
}

lval* lval_sym(char* s) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SYM;
  v->sym = malloc(strlen(s) + 1);
  strcpy(v->sym, s);
  return v;
}

lval* lval_str(char* s) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_STR;
  v->str = malloc(strlen(s) + 1);
  strcpy(v->str, s);
  return v;
}

lval* lval_builtin(lbuiltin func) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_FUN;
  v->builtin = func;
  return v;
}

lenv* lenv_new(void);

lval* lval_lambda(lval* formals, lval* body) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_FUN;  
  v->builtin = NULL;  
  v->env = lenv_new();  
  v->formals = formals;
  v->body = body;
  return v;  
}

lval* lval_sexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

lval* lval_qexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_QEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

void lenv_del(lenv* e);

void lval_del(lval* v) {

  switch (v->type) {
    case LVAL_NUM: break;
    case LVAL_FUN: 
      if (!v->builtin) {
        lenv_del(v->env);
        lval_del(v->formals);
        lval_del(v->body);
      }
    break;
    case LVAL_ERR: free(v->err); break;
    case LVAL_SYM: free(v->sym); break;
    case LVAL_STR: free(v->str); break;
    case LVAL_QEXPR:
    case LVAL_SEXPR:
      for (int i = 0; i < v->count; i++) {
        lval_del(v->cell[i]);
      }
      free(v->cell);
    break;
  }
  
  free(v);
}

lenv* lenv_copy(lenv* e);

lval* lval_copy(lval* v) {
  lval* x = malloc(sizeof(lval));
  x->type = v->type;
  switch (v->type) {
    case LVAL_FUN:
      if (v->builtin) {
        x->builtin = v->builtin;
      } else {
        x->builtin = NULL;
        x->env = lenv_copy(v->env);
        x->formals = lval_copy(v->formals);
        x->body = lval_copy(v->body);
      }
    break;
    case LVAL_NUM: x->num = v->num; break;
    case LVAL_ERR: x->err = malloc(strlen(v->err) + 1);
      strcpy(x->err, v->err);
    break;
    case LVAL_SYM: x->sym = malloc(strlen(v->sym) + 1);
      strcpy(x->sym, v->sym);
    break;
    case LVAL_STR: x->str = malloc(strlen(v->str) + 1);
      strcpy(x->str, v->str);
    break;
    case LVAL_SEXPR:
    case LVAL_QEXPR:
      x->count = v->count;
      x->cell = malloc(sizeof(lval*) * x->count);
      for (int i = 0; i < x->count; i++) {
        x->cell[i] = lval_copy(v->cell[i]);
      }
    break;
  }
  return x;
}

lval* lval_add(lval* v, lval* x) {
  v->count++;
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  v->cell[v->count-1] = x;
  return v;
}

lval* lval_join(lval* x, lval* y) {  
  for (int i = 0; i < y->count; i++) {
    x = lval_add(x, y->cell[i]);
  }
  free(y->cell);
  free(y);  
  return x;
}

lval* lval_pop(lval* v, int i) {
  lval* x = v->cell[i];  
  memmove(&v->cell[i],
    &v->cell[i+1], sizeof(lval*) * (v->count-i-1));  
  v->count--;  
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  return x;
}

lval* lval_take(lval* v, int i) {
  lval* x = lval_pop(v, i);
  lval_del(v);
  return x;
}

void lval_print(lval* v);

void lval_print_expr(lval* v, char open, char close) {
  putchar(open);
  for (int i = 0; i < v->count; i++) {
    lval_print(v->cell[i]);    
    if (i != (v->count-1)) {
      putchar(' ');
    }
  }
  putchar(close);
}

/* Possible unescapable characters */
char* lval_str_unescapable = "abfnrtv\\\'\"";

/* Function to unescape characters */
char lval_str_unescape(char x) {
  switch (x) {
    case 'a':  return '\a';
    case 'b':  return '\b';
    case 'f':  return '\f';
    case 'n':  return '\n';
    case 'r':  return '\r';
    case 't':  return '\t';
    case 'v':  return '\v';
    case '\\': return '\\';
    case '\'': return '\'';
    case '\"': return '\"';
  }
  return '\0';
}

/* List of possible escapable characters */
char* lval_str_escapable = "\a\b\f\n\r\t\v\\\'\"";

/* Function to escape characters */
char* lval_str_escape(char x) {
  switch (x) {
    case '\a': return "\\a";
    case '\b': return "\\b";
    case '\f': return "\\f";
    case '\n': return "\\n";
    case '\r': return "\\r";
    case '\t': return "\\t";
    case '\v': return "\\v";
    case '\\': return "\\\\";
    case '\'': return "\\\'";
    case '\"': return "\\\"";
  }
  return "";
}

void lval_print_str(lval* v) {
  putchar('"');
  /* Loop over the characters in the string */
  for (int i = 0; i < strlen(v->str); i++) {
    if (strchr(lval_str_escapable, v->str[i])) {
      /* If the character is escapable then escape it */
      printf("%s", lval_str_escape(v->str[i]));
    } else {
      /* Otherwise print character as it is */
      putchar(v->str[i]);
    }
  }
  putchar('"');
}

void lval_print(lval* v) {
  switch (v->type) {
    case LVAL_FUN:
      if (v->builtin) {
        printf("<builtin>");
      } else {
        printf("(\\ ");
        lval_print(v->formals);
        putchar(' ');
        lval_print(v->body);
        putchar(')');
      }
    break;
    case LVAL_NUM:   printf("%li", v->num); break;
    case LVAL_ERR:   printf("Error: %s", v->err); break;
    case LVAL_SYM:   printf("%s", v->sym); break;
    case LVAL_STR:   lval_print_str(v); break;
    case LVAL_SEXPR: lval_print_expr(v, '(', ')'); break;
    case LVAL_QEXPR: lval_print_expr(v, '{', '}'); break;
  }
}

void lval_println(lval* v) { lval_print(v); putchar('\n'); }

int lval_eq(lval* x, lval* y) {
  
  if (x->type != y->type) { return 0; }
  
  switch (x->type) {
    case LVAL_NUM: return (x->num == y->num);    
    case LVAL_ERR: return (strcmp(x->err, y->err) == 0);
    case LVAL_SYM: return (strcmp(x->sym, y->sym) == 0);    
    case LVAL_STR: return (strcmp(x->str, y->str) == 0);    
    case LVAL_FUN: 
      if (x->builtin || y->builtin) {
        return x->builtin == y->builtin;
      } else {
        return lval_eq(x->formals, y->formals) && lval_eq(x->body, y->body);
      }    
    case LVAL_QEXPR:
    case LVAL_SEXPR:
      if (x->count != y->count) { return 0; }
      for (int i = 0; i < x->count; i++) {
        if (!lval_eq(x->cell[i], y->cell[i])) { return 0; }
      }
      return 1;
    break;
  }
  return 0;
}

char* ltype_name(int t) {
  switch(t) {
    case LVAL_FUN: return "Function";
    case LVAL_NUM: return "Number";
    case LVAL_ERR: return "Error";
    case LVAL_SYM: return "Symbol";
    case LVAL_STR: return "String";
    case LVAL_SEXPR: return "S-Expression";
    case LVAL_QEXPR: return "Q-Expression";
    default: return "Unknown";
  }
}

/* Lisp Environment */

struct lenv {
  lenv* par;
  int count;
  char** syms;
  lval** vals;
};

lenv* lenv_new(void) {
  lenv* e = malloc(sizeof(lenv));
  e->par = NULL;
  e->count = 0;
  e->syms = NULL;
  e->vals = NULL;
  return e;
}

void lenv_del(lenv* e) {
  for (int i = 0; i < e->count; i++) {
    free(e->syms[i]);
    lval_del(e->vals[i]);
  }  
  free(e->syms);
  free(e->vals);
  free(e);
}

lenv* lenv_copy(lenv* e) {
  lenv* n = malloc(sizeof(lenv));
  n->par = e->par;
  n->count = e->count;
  n->syms = malloc(sizeof(char*) * n->count);
  n->vals = malloc(sizeof(lval*) * n->count);
  for (int i = 0; i < e->count; i++) {
    n->syms[i] = malloc(strlen(e->syms[i]) + 1);
    strcpy(n->syms[i], e->syms[i]);
    n->vals[i] = lval_copy(e->vals[i]);
  }
  return n;
}

lval* lenv_get(lenv* e, lval* k) {
  
  for (int i = 0; i < e->count; i++) {
    if (strcmp(e->syms[i], k->sym) == 0) { return lval_copy(e->vals[i]); }
  }
  
  if (e->par) {
    return lenv_get(e->par, k);
  } else {
    return lval_err("Unbound Symbol '%s'", k->sym);
  }
}

void lenv_put(lenv* e, lval* k, lval* v) {
  
  for (int i = 0; i < e->count; i++) {
    if (strcmp(e->syms[i], k->sym) == 0) {
      lval_del(e->vals[i]);
      e->vals[i] = lval_copy(v);
      return;
    }
  }
  
  e->count++;
  e->vals = realloc(e->vals, sizeof(lval*) * e->count);
  e->syms = realloc(e->syms, sizeof(char*) * e->count);  
  e->vals[e->count-1] = lval_copy(v);
  e->syms[e->count-1] = malloc(strlen(k->sym)+1);
  strcpy(e->syms[e->count-1], k->sym);
}

void lenv_def(lenv* e, lval* k, lval* v) {
  while (e->par) { e = e->par; }
  lenv_put(e, k, v);
}

/* Builtins */

#define LASSERT(args, cond, fmt, ...) \
  if (!(cond)) { lval* err = lval_err(fmt, ##__VA_ARGS__); lval_del(args); return err; }

#define LASSERT_TYPE(func, args, index, expect) \
  LASSERT(args, args->cell[index]->type == expect, \
    "Function '%s' passed incorrect type for argument %i. Got %s, Expected %s.", \
    func, index, ltype_name(args->cell[index]->type), ltype_name(expect))

#define LASSERT_NUM(func, args, num) \
  LASSERT(args, args->count == num, \
    "Function '%s' passed incorrect number of arguments. Got %i, Expected %i.", \
    func, args->count, num)

#define LASSERT_NOT_EMPTY(func, args, index) \
  LASSERT(args, args->cell[index]->count != 0, \
    "Function '%s' passed {} for argument %i.", func, index);

lval* lval_eval(lenv* e, lval* v);

lval* builtin_lambda(lenv* e, lval* a) {
  LASSERT_NUM("\\", a, 2);
  LASSERT_TYPE("\\", a, 0, LVAL_QEXPR);
  LASSERT_TYPE("\\", a, 1, LVAL_QEXPR);
  
  for (int i = 0; i < a->cell[0]->count; i++) {
    LASSERT(a, (a->cell[0]->cell[i]->type == LVAL_SYM),
      "Cannot define non-symbol. Got %s, Expected %s.",
      ltype_name(a->cell[0]->cell[i]->type), ltype_name(LVAL_SYM));
  }
  
  lval* formals = lval_pop(a, 0);
  lval* body = lval_pop(a, 0);
  lval_del(a);
  
  return lval_lambda(formals, body);
}

lval* builtin_list(lenv* e, lval* a) {
  a->type = LVAL_QEXPR;
  return a;
}

lval* builtin_head(lenv* e, lval* a) {
  LASSERT_NUM("head", a, 1);
  LASSERT_TYPE("head", a, 0, LVAL_QEXPR);
  LASSERT_NOT_EMPTY("head", a, 0);
  
  lval* v = lval_take(a, 0);  
  while (v->count > 1) { lval_del(lval_pop(v, 1)); }
  return v;
}

lval* builtin_tail(lenv* e, lval* a) {
  LASSERT_NUM("tail", a, 1);
  LASSERT_TYPE("tail", a, 0, LVAL_QEXPR);
  LASSERT_NOT_EMPTY("tail", a, 0);

  lval* v = lval_take(a, 0);  
  lval_del(lval_pop(v, 0));
  return v;
}

lval* builtin_eval(lenv* e, lval* a) {
  LASSERT_NUM("eval", a, 1);
  LASSERT_TYPE("eval", a, 0, LVAL_QEXPR);
  
  lval* x = lval_take(a, 0);
  x->type = LVAL_SEXPR;
  return lval_eval(e, x);
}

lval* builtin_join(lenv* e, lval* a) {
  
  for (int i = 0; i < a->count; i++) {
    LASSERT_TYPE("join", a, i, LVAL_QEXPR);
  }
  
  lval* x = lval_pop(a, 0);
  
  while (a->count) {
    lval* y = lval_pop(a, 0);
    x = lval_join(x, y);
  }
  
  lval_del(a);
  return x;
}

lval* builtin_op(lenv* e, lval* a, char* op) {
  
  for (int i = 0; i < a->count; i++) {
    LASSERT_TYPE(op, a, i, LVAL_NUM);
  }
  
  lval* x = lval_pop(a, 0);
  
  if ((strcmp(op, "-") == 0) && a->count == 0) { x->num = -x->num; }
  
  while (a->count > 0) {  
    lval* y = lval_pop(a, 0);
    
    if (strcmp(op, "+") == 0) { x->num += y->num; }
    if (strcmp(op, "-") == 0) { x->num -= y->num; }
    if (strcmp(op, "*") == 0) { x->num *= y->num; }
    if (strcmp(op, "/") == 0) {
      if (y->num == 0) {
        lval_del(x); lval_del(y);
        x = lval_err("Division By Zero.");
        break;
      }
      x->num /= y->num;
    }
    
    lval_del(y);
  }
  
  lval_del(a);
  return x;
}

lval* builtin_add(lenv* e, lval* a) { return builtin_op(e, a, "+"); }
lval* builtin_sub(lenv* e, lval* a) { return builtin_op(e, a, "-"); }
lval* builtin_mul(lenv* e, lval* a) { return builtin_op(e, a, "*"); }
lval* builtin_div(lenv* e, lval* a) { return builtin_op(e, a, "/"); }

lval* builtin_var(lenv* e, lval* a, char* func) {
  LASSERT_TYPE(func, a, 0, LVAL_QEXPR);
  
  lval* syms = a->cell[0];
  for (int i = 0; i < syms->count; i++) {
    LASSERT(a, (syms->cell[i]->type == LVAL_SYM),
      "Function '%s' cannot define non-symbol. "
      "Got %s, Expected %s.",
      func, ltype_name(syms->cell[i]->type), ltype_name(LVAL_SYM));
  }
  
  LASSERT(a, (syms->count == a->count-1),
    "Function '%s' passed too many arguments for symbols. "
    "Got %i, Expected %i.",
    func, syms->count, a->count-1);
    
  for (int i = 0; i < syms->count; i++) {
    if (strcmp(func, "def") == 0) { lenv_def(e, syms->cell[i], a->cell[i+1]); }
    if (strcmp(func, "=")   == 0) { lenv_put(e, syms->cell[i], a->cell[i+1]); } 
  }
  
  lval_del(a);
  return lval_sexpr();
}

lval* builtin_def(lenv* e, lval* a) { return builtin_var(e, a, "def"); }
lval* builtin_put(lenv* e, lval* a) { return builtin_var(e, a, "="); }

lval* builtin_ord(lenv* e, lval* a, char* op) {
  LASSERT_NUM(op, a, 2);
  LASSERT_TYPE(op, a, 0, LVAL_NUM);
  LASSERT_TYPE(op, a, 1, LVAL_NUM);
  
  int r;
  if (strcmp(op, ">")  == 0) { r = (a->cell[0]->num >  a->cell[1]->num); }
  if (strcmp(op, "<")  == 0) { r = (a->cell[0]->num <  a->cell[1]->num); }
  if (strcmp(op, ">=") == 0) { r = (a->cell[0]->num >= a->cell[1]->num); }
  if (strcmp(op, "<=") == 0) { r = (a->cell[0]->num <= a->cell[1]->num); }
  lval_del(a);
  return lval_num(r);
}

lval* builtin_gt(lenv* e, lval* a) { return builtin_ord(e, a, ">");  }
lval* builtin_lt(lenv* e, lval* a) { return builtin_ord(e, a, "<");  }
lval* builtin_ge(lenv* e, lval* a) { return builtin_ord(e, a, ">="); }
lval* builtin_le(lenv* e, lval* a) { return builtin_ord(e, a, "<="); }

lval* builtin_cmp(lenv* e, lval* a, char* op) {
  LASSERT_NUM(op, a, 2);
  int r;
  if (strcmp(op, "==") == 0) { r =  lval_eq(a->cell[0], a->cell[1]); }
  if (strcmp(op, "!=") == 0) { r = !lval_eq(a->cell[0], a->cell[1]); }
  lval_del(a);
  return lval_num(r);
}

lval* builtin_eq(lenv* e, lval* a) { return builtin_cmp(e, a, "=="); }
lval* builtin_ne(lenv* e, lval* a) { return builtin_cmp(e, a, "!="); }

lval* builtin_if(lenv* e, lval* a) {
  LASSERT_NUM("if", a, 3);
  LASSERT_TYPE("if", a, 0, LVAL_NUM);
  LASSERT_TYPE("if", a, 1, LVAL_QEXPR);
  LASSERT_TYPE("if", a, 2, LVAL_QEXPR);
  
  lval* x;
  a->cell[1]->type = LVAL_SEXPR;
  a->cell[2]->type = LVAL_SEXPR;
  
  if (a->cell[0]->num) {
    x = lval_eval(e, lval_pop(a, 1));
  } else {
    x = lval_eval(e, lval_pop(a, 2));
  }
  
  lval_del(a);
  return x;
}

/* Change forward declaration */
lval* lval_read_expr(char* s, int* i, char end);

lval* builtin_load(lenv* e, lval* a) {
  LASSERT_NUM("load", a, 1);
  LASSERT_TYPE("load", a, 0, LVAL_STR);
  
  /* Open file and check it exists */
  FILE* f = fopen(a->cell[0]->str, "rb");
  if (f == NULL) {
    lval* err = lval_err("Could not load Library %s", a->cell[0]->str);
    lval_del(a);
    return err;
  }
  
  /* Read File Contents */
  fseek(f, 0, SEEK_END);
  long length = ftell(f);
  fseek(f, 0, SEEK_SET);
  char* input = calloc(length+1, 1);
  fread(input, 1, length, f);
  fclose(f);
  
  /* Read from input to create an S-Expr */
  int pos = 0;
  lval* expr = lval_read_expr(input, &pos, '\0');
  free(input);
  
  /* Evaluate all expressions contained in S-Expr */
  if (expr->type != LVAL_ERR) {
    while (expr->count) {
      lval* x = lval_eval(e, lval_pop(expr, 0));
      if (x->type == LVAL_ERR) { lval_println(x); }
      lval_del(x);
    }
  } else {
    lval_println(expr);
  }
  
  lval_del(expr);    
  lval_del(a);
  
  return lval_sexpr();
}

lval* builtin_print(lenv* e, lval* a) {  
  for (int i = 0; i < a->count; i++) {
    lval_print(a->cell[i]); putchar(' ');
  }
  putchar('\n');
  lval_del(a);
  return lval_sexpr();
}

lval* builtin_error(lenv* e, lval* a) {
  LASSERT_NUM("error", a, 1);
  LASSERT_TYPE("error", a, 0, LVAL_STR);
  lval* err = lval_err(a->cell[0]->str);  
  lval_del(a);
  return err;
}

void lenv_add_builtin(lenv* e, char* name, lbuiltin func) {
  lval* k = lval_sym(name);
  lval* v = lval_builtin(func);
  lenv_put(e, k, v);
  lval_del(k); lval_del(v);
}

void lenv_add_builtins(lenv* e) {
  /* Variable Functions */
  lenv_add_builtin(e, "\\",  builtin_lambda); 
  lenv_add_builtin(e, "def", builtin_def);
  lenv_add_builtin(e, "=",   builtin_put);
  
  /* List Functions */
  lenv_add_builtin(e, "list", builtin_list);
  lenv_add_builtin(e, "head", builtin_head);
  lenv_add_builtin(e, "tail", builtin_tail);
  lenv_add_builtin(e, "eval", builtin_eval);
  lenv_add_builtin(e, "join", builtin_join);
  
  /* Mathematical Functions */
  lenv_add_builtin(e, "+", builtin_add);
  lenv_add_builtin(e, "-", builtin_sub);
  lenv_add_builtin(e, "*", builtin_mul);
  lenv_add_builtin(e, "/", builtin_div);
  
  /* Comparison Functions */
  lenv_add_builtin(e, "if", builtin_if);
  lenv_add_builtin(e, "==", builtin_eq);
  lenv_add_builtin(e, "!=", builtin_ne);
  lenv_add_builtin(e, ">",  builtin_gt);
  lenv_add_builtin(e, "<",  builtin_lt);
  lenv_add_builtin(e, ">=", builtin_ge);
  lenv_add_builtin(e, "<=", builtin_le);
  
  /* String Functions */
  lenv_add_builtin(e, "load",  builtin_load); 
  lenv_add_builtin(e, "error", builtin_error);
  lenv_add_builtin(e, "print", builtin_print);
}

/* Evaluation */

lval* lval_call(lenv* e, lval* f, lval* a) {
  
  if (f->builtin) { return f->builtin(e, a); }
  
  int given = a->count;
  int total = f->formals->count;
  
  while (a->count) {
    
    if (f->formals->count == 0) {
      lval_del(a);
      return lval_err("Function passed too many arguments. "
        "Got %i, Expected %i.", given, total); 
    }
    
    lval* sym = lval_pop(f->formals, 0);
    
    if (strcmp(sym->sym, "&") == 0) {
      
      if (f->formals->count != 1) {
        lval_del(a);
        return lval_err("Function format invalid. "
          "Symbol '&' not followed by single symbol.");
      }
      
      lval* nsym = lval_pop(f->formals, 0);
      lenv_put(f->env, nsym, builtin_list(e, a));
      lval_del(sym); lval_del(nsym);
      break;
    }
    
    lval* val = lval_pop(a, 0);    
    lenv_put(f->env, sym, val);    
    lval_del(sym); lval_del(val);
  }
  
  lval_del(a);
  
  if (f->formals->count > 0 &&
    strcmp(f->formals->cell[0]->sym, "&") == 0) {
    
    if (f->formals->count != 2) {
      return lval_err("Function format invalid. "
        "Symbol '&' not followed by single symbol.");
    }
    
    lval_del(lval_pop(f->formals, 0));
    
    lval* sym = lval_pop(f->formals, 0);
    lval* val = lval_qexpr();    
    lenv_put(f->env, sym, val);
    lval_del(sym); lval_del(val);
  }
  
  if (f->formals->count == 0) {  
    f->env->par = e;    
    return builtin_eval(f->env, lval_add(lval_sexpr(), lval_copy(f->body)));
  } else {
    return lval_copy(f);
  }
  
}

lval* lval_eval_sexpr(lenv* e, lval* v) {
  
  for (int i = 0; i < v->count; i++) { v->cell[i] = lval_eval(e, v->cell[i]); }
  for (int i = 0; i < v->count; i++) { if (v->cell[i]->type == LVAL_ERR) { return lval_take(v, i); } }
  
  if (v->count == 0) { return v; }  
  if (v->count == 1) { return lval_eval(e, lval_take(v, 0)); }
  
  lval* f = lval_pop(v, 0);
  if (f->type != LVAL_FUN) {
    lval* err = lval_err(
      "S-Expression starts with incorrect type. "
      "Got %s, Expected %s.",
      ltype_name(f->type), ltype_name(LVAL_FUN));
    lval_del(f); lval_del(v);
    return err;
  }
  
  lval* result = lval_call(e, f, v);
  lval_del(f);
  return result;
}

lval* lval_eval(lenv* e, lval* v) {
  if (v->type == LVAL_SYM) {
    lval* x = lenv_get(e, v);
    lval_del(v);
    return x;
  }
  if (v->type == LVAL_SEXPR) { return lval_eval_sexpr(e, v); }
  return v;
}

/* Reading */

lval* lval_read_sym(char* s, int* i) {
  
  /* Allocate Empty String */
  char* part = calloc(1,1);
  
  /* While valid identifier characters */
  while (strchr(
      "abcdefghijklmnopqrstuvwxyz"
      "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
      "0123456789_+-*\\/=<>!&", s[*i]) && s[*i] != '\0') {
    
    /* Append character to end of string */
    part = realloc(part, strlen(part)+2);
    part[strlen(part)+1] = '\0';
    part[strlen(part)+0] = s[*i];
    (*i)++;
  }
  
  /* Check if Identifier looks like number */
  int is_num = strchr("-0123456789", part[0]) != NULL;
  for (int j = 1; j < strlen(part); j++) {
    if (strchr("0123456789", part[j]) == NULL) { is_num = 0; break; }
  }
  if (strlen(part) == 1 && part[0] == '-') { is_num = 0; }
  
  /* Add Symbol or Number as lval */
  lval* x = NULL;
  if (is_num) {
    errno = 0;
    long v = strtol(part, NULL, 10);
    x = (errno != ERANGE) ? lval_num(v) : lval_err("Invalid Number %s", part);
  } else {
    x = lval_sym(part);
  }
  
  /* Free temp string */
  free(part);
  
  /* Return lval */
  return x;
}

lval* lval_read_str(char* s, int* i) {
  
  /* Allocate empty string */
  char* part = calloc(1,1);
  
  /* More forward one step past initial " character */
  (*i)++;
  while (s[*i] != '"') {
    
    char c = s[*i];
    
    /* If end of input then there is an unterminated string literal */
    if (c == '\0') {
      free(part);
      return lval_err("Unexpected end of input");
    }
    
    /* If backslash then unescape character after it */
    if (c == '\\') {
      (*i)++;
      /* Check next character is escapable */
      if (strchr(lval_str_unescapable, s[*i])) {        
        c = lval_str_unescape(s[*i]);
      } else {
        free(part);
        return lval_err("Invalid escape sequence \\%c", s[*i]);
      }
    }
    
    /* Append character to string */
    part = realloc(part, strlen(part)+2);
    part[strlen(part)+1] = '\0';
    part[strlen(part)+0] = c;
    (*i)++;    
  }
  /* Move forward past final " character */
  (*i)++;
  
  lval* x = lval_str(part);
  
  /* free temp string */
  free(part);
  
  return x;
}

lval* lval_read(char* s, int* i);

lval* lval_read_expr(char* s, int* i, char end) {
  
  /* Either create new qexpr or sexpr */
  lval* x = (end == '}') ? lval_qexpr() : lval_sexpr();
  
  /* While not at end character keep reading lvals */
  while (s[*i] != end) {
    lval* y = lval_read(s, i);
    /* If an error then return this and stop */
    if (y->type == LVAL_ERR) {
      lval_del(x);
      return y;
    } else {
      lval_add(x, y);
    }
  }

  /* Move past end character */
  (*i)++;
  
  return x;

}

lval* lval_read(char* s, int* i) {
  
  /* Skip all trailing whitespace and comments */
  while (strchr(" \t\v\r\n;", s[*i]) && s[*i] != '\0') {
    if (s[*i] == ';') {
      while (s[*i] != '\n' && s[*i] != '\0') { (*i)++; }
    }
    (*i)++;
  }
  
  lval* x = NULL;

  /* If we reach end of input then we're missing something */
  if (s[*i] == '\0') {
    return lval_err("Unexpected end of input");
  }
  
  /* If next character is ( then read S-Expr */
  else if (s[*i] == '(') {
    (*i)++;
    x = lval_read_expr(s, i, ')');
  }
  
  /* If next character is { then read Q-Expr */
  else if (s[*i] == '{') {
    (*i)++;
    x = lval_read_expr(s, i, '}');
  }
  
  /* If next character is part of a symbol then read symbol */
  else if (strchr(
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789_+-*\\/=<>!&", s[*i])) {
    x = lval_read_sym(s, i);
  }
  
  /* If next character is " then read string */
  else if (strchr("\"", s[*i])) {
    x = lval_read_str(s, i);
  }
  
  /* Encountered some unexpected character */
  else {
    x = lval_err("Unexpected character %c", s[*i]);
  }
  
  /* Skip all trailing whitespace and comments */
  while (strchr(" \t\v\r\n;", s[*i]) && s[*i] != '\0') {
    if (s[*i] == ';') {
      while (s[*i] != '\n' && s[*i] != '\0') { (*i)++; }
    }
    (*i)++;
  }
  
  return x;
  
}

/* Main */    

int main(int argc, char** argv) {
  
  lenv* e = lenv_new();
  lenv_add_builtins(e);
  
  /* Interactive Prompt */
  if (argc == 1) {
  
    puts("Lispy Version 0.0.0.1.1");
    puts("Press Ctrl+c to Exit\n");
  
    while (1) {
    
      char* input = readline("lispy> ");
      add_history(input);
      
      /* Read from input to create an S-Expr */
      int pos = 0;
      lval* expr = lval_read_expr(input, &pos, '\0');
      
      /* Evaluate and print input */
      lval* x = lval_eval(e, expr);
      lval_println(x);
      lval_del(x);
      
      free(input);
    }
  }
  
  /* Supplied with list of files */
  if (argc >= 2) {  
    for (int i = 1; i < argc; i++) {
      lval* args = lval_add(lval_sexpr(), lval_str(argv[i]));
      lval* x = builtin_load(e, args);      
      if (x->type == LVAL_ERR) { lval_println(x); }
      lval_del(x);
    }
  }
  
  lenv_del(e);
  
  return 0;
}
src/hello_world.c000666 000000 000000 00000000143 13206344553 012500 0ustar00000000 000000 #include <stdio.h>

int main(int argc, char** argv) {
  puts("Hello, world!");
  return 0;
}
src/hello_world.lspy000666 000000 000000 00000000026 13206344553 013245 0ustar00000000 000000 (print "Hello World!")src/Makefile000666 000000 000000 00000001137 13206352046 011462 0ustar00000000 000000 CC = cc
CFLAGS = -std=c99 -Wall -g
LFLAGS = 
FILES = hello_world prompt doge_code doge_grammar parsing evaluation error_handling s_expressions q_expressions variables functions conditionals strings hand_rolled_parser
PLATFORM = $(shell uname)

ifeq ($(findstring Linux,$(PLATFORM)),Linux)
	LFLAGS += -ledit -lm
	FILES += prompt_unix
endif

ifeq ($(findstring Darwin,$(PLATFORM)),Darwin)
	LFLAGS += -ledit -lm
	FILES += prompt_unix
endif

ifeq ($(findstring MINGW,$(PLATFORM)),MINGW)
	FILES += prompt_windows
endif

all: $(FILES)

%: %.c mpc.c
	$(CC) $(CFLAGS) $^ $(LFLAGS) -o $@
  
src/mpc.c000666 000000 000000 00000331030 13405464046 010750 0ustar00000000 000000 #include "mpc.h"

/*
** State Type
*/

static mpc_state_t mpc_state_invalid(void) {
  mpc_state_t s;
  s.pos = -1;
  s.row = -1;
  s.col = -1;
  s.term = 0;
  return s;
}

static mpc_state_t mpc_state_new(void) {
  mpc_state_t s;
  s.pos = 0;
  s.row = 0;
  s.col = 0;
  s.term = 0;
  return s;
}

/*
** Input Type
*/

/*
** In mpc the input type has three modes of
** operation: String, File and Pipe.
**
** String is easy. The whole contents are
** loaded into a buffer and scanned through.
** The cursor can jump around at will making
** backtracking easy.
**
** The second is a File which is also somewhat
** easy. The contents are never loaded into
** memory but backtracking can still be achieved
** by seeking in the file at different positions.
**
** The final mode is Pipe. This is the difficult
** one. As we assume pipes cannot be seeked - and
** only support a single character lookahead at
** any point, when the input is marked for a
** potential backtracking we start buffering any
** input.
**
** This means that if we are requested to seek
** back we can simply start reading from the
** buffer instead of the input.
**
** Of course using `mpc_predictive` will disable
** backtracking and make LL(1) grammars easy
** to parse for all input methods.
**
*/

enum {
  MPC_INPUT_STRING = 0,
  MPC_INPUT_FILE   = 1,
  MPC_INPUT_PIPE   = 2
};

enum {
  MPC_INPUT_MARKS_MIN = 32
};

enum {
  MPC_INPUT_MEM_NUM = 512
};

typedef struct {
  char mem[64];
} mpc_mem_t;

typedef struct {

  int type;
  char *filename;
  mpc_state_t state;

  char *string;
  char *buffer;
  FILE *file;

  int suppress;
  int backtrack;
  int marks_slots;
  int marks_num;
  mpc_state_t *marks;

  char *lasts;
  char last;

  size_t mem_index;
  char mem_full[MPC_INPUT_MEM_NUM];
  mpc_mem_t mem[MPC_INPUT_MEM_NUM];

} mpc_input_t;

static mpc_input_t *mpc_input_new_string(const char *filename, const char *string) {

  mpc_input_t *i = malloc(sizeof(mpc_input_t));

  i->filename = malloc(strlen(filename) + 1);
  strcpy(i->filename, filename);
  i->type = MPC_INPUT_STRING;

  i->state = mpc_state_new();

  i->string = malloc(strlen(string) + 1);
  strcpy(i->string, string);
  i->buffer = NULL;
  i->file = NULL;

  i->suppress = 0;
  i->backtrack = 1;
  i->marks_num = 0;
  i->marks_slots = MPC_INPUT_MARKS_MIN;
  i->marks = malloc(sizeof(mpc_state_t) * i->marks_slots);
  i->lasts = malloc(sizeof(char) * i->marks_slots);
  i->last = '\0';

  i->mem_index = 0;
  memset(i->mem_full, 0, sizeof(char) * MPC_INPUT_MEM_NUM);

  return i;
}

static mpc_input_t *mpc_input_new_nstring(const char *filename, const char *string, size_t length) {

  mpc_input_t *i = malloc(sizeof(mpc_input_t));

  i->filename = malloc(strlen(filename) + 1);
  strcpy(i->filename, filename);
  i->type = MPC_INPUT_STRING;

  i->state = mpc_state_new();

  i->string = malloc(length + 1);
  strncpy(i->string, string, length);
  i->string[length] = '\0';
  i->buffer = NULL;
  i->file = NULL;

  i->suppress = 0;
  i->backtrack = 1;
  i->marks_num = 0;
  i->marks_slots = MPC_INPUT_MARKS_MIN;
  i->marks = malloc(sizeof(mpc_state_t) * i->marks_slots);
  i->lasts = malloc(sizeof(char) * i->marks_slots);
  i->last = '\0';

  i->mem_index = 0;
  memset(i->mem_full, 0, sizeof(char) * MPC_INPUT_MEM_NUM);

  return i;

}

static mpc_input_t *mpc_input_new_pipe(const char *filename, FILE *pipe) {

  mpc_input_t *i = malloc(sizeof(mpc_input_t));

  i->filename = malloc(strlen(filename) + 1);
  strcpy(i->filename, filename);

  i->type = MPC_INPUT_PIPE;
  i->state = mpc_state_new();

  i->string = NULL;
  i->buffer = NULL;
  i->file = pipe;

  i->suppress = 0;
  i->backtrack = 1;
  i->marks_num = 0;
  i->marks_slots = MPC_INPUT_MARKS_MIN;
  i->marks = malloc(sizeof(mpc_state_t) * i->marks_slots);
  i->lasts = malloc(sizeof(char) * i->marks_slots);
  i->last = '\0';

  i->mem_index = 0;
  memset(i->mem_full, 0, sizeof(char) * MPC_INPUT_MEM_NUM);

  return i;

}

static mpc_input_t *mpc_input_new_file(const char *filename, FILE *file) {

  mpc_input_t *i = malloc(sizeof(mpc_input_t));

  i->filename = malloc(strlen(filename) + 1);
  strcpy(i->filename, filename);
  i->type = MPC_INPUT_FILE;
  i->state = mpc_state_new();

  i->string = NULL;
  i->buffer = NULL;
  i->file = file;

  i->suppress = 0;
  i->backtrack = 1;
  i->marks_num = 0;
  i->marks_slots = MPC_INPUT_MARKS_MIN;
  i->marks = malloc(sizeof(mpc_state_t) * i->marks_slots);
  i->lasts = malloc(sizeof(char) * i->marks_slots);
  i->last = '\0';

  i->mem_index = 0;
  memset(i->mem_full, 0, sizeof(char) * MPC_INPUT_MEM_NUM);

  return i;
}

static void mpc_input_delete(mpc_input_t *i) {

  free(i->filename);

  if (i->type == MPC_INPUT_STRING) { free(i->string); }
  if (i->type == MPC_INPUT_PIPE) { free(i->buffer); }

  free(i->marks);
  free(i->lasts);
  free(i);
}

static int mpc_mem_ptr(mpc_input_t *i, void *p) {
  return
    (char*)p >= (char*)(i->mem) &&
    (char*)p <  (char*)(i->mem) + (MPC_INPUT_MEM_NUM * sizeof(mpc_mem_t));
}

static void *mpc_malloc(mpc_input_t *i, size_t n) {
  size_t j;
  char *p;

  if (n > sizeof(mpc_mem_t)) { return malloc(n); }

  j = i->mem_index;
  do {
    if (!i->mem_full[i->mem_index]) {
      p = (void*)(i->mem + i->mem_index);
      i->mem_full[i->mem_index] = 1;
      i->mem_index = (i->mem_index+1) % MPC_INPUT_MEM_NUM;
      return p;
    }
    i->mem_index = (i->mem_index+1) % MPC_INPUT_MEM_NUM;
  } while (j != i->mem_index);

  return malloc(n);
}

static void *mpc_calloc(mpc_input_t *i, size_t n, size_t m) {
  char *x = mpc_malloc(i, n * m);
  memset(x, 0, n * m);
  return x;
}

static void mpc_free(mpc_input_t *i, void *p) {
  size_t j;
  if (!mpc_mem_ptr(i, p)) { free(p); return; }
  j = ((size_t)(((char*)p) - ((char*)i->mem))) / sizeof(mpc_mem_t);
  i->mem_full[j] = 0;
}

static void *mpc_realloc(mpc_input_t *i, void *p, size_t n) {

  char *q = NULL;

  if (!mpc_mem_ptr(i, p)) { return realloc(p, n); }

  if (n > sizeof(mpc_mem_t)) {
    q = malloc(n);
    memcpy(q, p, sizeof(mpc_mem_t));
    mpc_free(i, p);
    return q;
  }

  return p;
}

static void *mpc_export(mpc_input_t *i, void *p) {
  char *q = NULL;
  if (!mpc_mem_ptr(i, p)) { return p; }
  q = malloc(sizeof(mpc_mem_t));
  memcpy(q, p, sizeof(mpc_mem_t));
  mpc_free(i, p);
  return q;
}

static void mpc_input_backtrack_disable(mpc_input_t *i) { i->backtrack--; }
static void mpc_input_backtrack_enable(mpc_input_t *i) { i->backtrack++; }

static void mpc_input_suppress_disable(mpc_input_t *i) { i->suppress--; }
static void mpc_input_suppress_enable(mpc_input_t *i) { i->suppress++; }

static void mpc_input_mark(mpc_input_t *i) {

  if (i->backtrack < 1) { return; }

  i->marks_num++;

  if (i->marks_num > i->marks_slots) {
    i->marks_slots = i->marks_num + i->marks_num / 2;
    i->marks = realloc(i->marks, sizeof(mpc_state_t) * i->marks_slots);
    i->lasts = realloc(i->lasts, sizeof(char) * i->marks_slots);
  }

  i->marks[i->marks_num-1] = i->state;
  i->lasts[i->marks_num-1] = i->last;

  if (i->type == MPC_INPUT_PIPE && i->marks_num == 1) {
    i->buffer = calloc(1, 1);
  }

}

static void mpc_input_unmark(mpc_input_t *i) {

  if (i->backtrack < 1) { return; }

  i->marks_num--;

  if (i->marks_slots > i->marks_num + i->marks_num / 2
  &&  i->marks_slots > MPC_INPUT_MARKS_MIN) {
    i->marks_slots =
      i->marks_num > MPC_INPUT_MARKS_MIN ?
      i->marks_num : MPC_INPUT_MARKS_MIN;
    i->marks = realloc(i->marks, sizeof(mpc_state_t) * i->marks_slots);
    i->lasts = realloc(i->lasts, sizeof(char) * i->marks_slots);
  }

  if (i->type == MPC_INPUT_PIPE && i->marks_num == 0) {
    free(i->buffer);
    i->buffer = NULL;
  }

}

static void mpc_input_rewind(mpc_input_t *i) {

  if (i->backtrack < 1) { return; }

  i->state = i->marks[i->marks_num-1];
  i->last  = i->lasts[i->marks_num-1];

  if (i->type == MPC_INPUT_FILE) {
    fseek(i->file, i->state.pos, SEEK_SET);
  }

  mpc_input_unmark(i);
}

static int mpc_input_buffer_in_range(mpc_input_t *i) {
  return i->state.pos < (long)(strlen(i->buffer) + i->marks[0].pos);
}

static char mpc_input_buffer_get(mpc_input_t *i) {
  return i->buffer[i->state.pos - i->marks[0].pos];
}

static char mpc_input_getc(mpc_input_t *i) {

  char c = '\0';

  switch (i->type) {

    case MPC_INPUT_STRING: return i->string[i->state.pos];
    case MPC_INPUT_FILE: c = fgetc(i->file); return c;
    case MPC_INPUT_PIPE:

      if (!i->buffer) { c = getc(i->file); return c; }

      if (i->buffer && mpc_input_buffer_in_range(i)) {
        c = mpc_input_buffer_get(i);
        return c;
      } else {
        c = getc(i->file);
        return c;
      }

    default: return c;
  }
}

static char mpc_input_peekc(mpc_input_t *i) {

  char c = '\0';

  switch (i->type) {
    case MPC_INPUT_STRING: return i->string[i->state.pos];
    case MPC_INPUT_FILE:

      c = fgetc(i->file);
      if (feof(i->file)) { return '\0'; }

      fseek(i->file, -1, SEEK_CUR);
      return c;

    case MPC_INPUT_PIPE:

      if (!i->buffer) {
        c = getc(i->file);
        if (feof(i->file)) { return '\0'; }
        ungetc(c, i->file);
        return c;
      }

      if (i->buffer && mpc_input_buffer_in_range(i)) {
        return mpc_input_buffer_get(i);
      } else {
        c = getc(i->file);
        if (feof(i->file)) { return '\0'; }
        ungetc(c, i->file);
        return c;
      }

    default: return c;
  }

}

static int mpc_input_terminated(mpc_input_t *i) {
  return mpc_input_peekc(i) == '\0';
}

static int mpc_input_failure(mpc_input_t *i, char c) {

  switch (i->type) {
    case MPC_INPUT_STRING: { break; }
    case MPC_INPUT_FILE: fseek(i->file, -1, SEEK_CUR); { break; }
    case MPC_INPUT_PIPE: {

      if (!i->buffer) { ungetc(c, i->file); break; }

      if (i->buffer && mpc_input_buffer_in_range(i)) {
        break;
      } else {
        ungetc(c, i->file);
      }
    }
    default: { break; }
  }
  return 0;
}

static int mpc_input_success(mpc_input_t *i, char c, char **o) {

  if (i->type == MPC_INPUT_PIPE
  &&  i->buffer && !mpc_input_buffer_in_range(i)) {
    i->buffer = realloc(i->buffer, strlen(i->buffer) + 2);
    i->buffer[strlen(i->buffer) + 1] = '\0';
    i->buffer[strlen(i->buffer) + 0] = c;
  }

  i->last = c;
  i->state.pos++;
  i->state.col++;

  if (c == '\n') {
    i->state.col = 0;
    i->state.row++;
  }

  if (o) {
    (*o) = mpc_malloc(i, 2);
    (*o)[0] = c;
    (*o)[1] = '\0';
  }

  return 1;
}

static int mpc_input_any(mpc_input_t *i, char **o) {
  char x;
  if (mpc_input_terminated(i)) { return 0; }
  x = mpc_input_getc(i);
  return mpc_input_success(i, x, o);
}

static int mpc_input_char(mpc_input_t *i, char c, char **o) {
  char x;
  if (mpc_input_terminated(i)) { return 0; }
  x = mpc_input_getc(i);
  return x == c ? mpc_input_success(i, x, o) : mpc_input_failure(i, x);
}

static int mpc_input_range(mpc_input_t *i, char c, char d, char **o) {
  char x;
  if (mpc_input_terminated(i)) { return 0; }
  x = mpc_input_getc(i);
  return x >= c && x <= d ? mpc_input_success(i, x, o) : mpc_input_failure(i, x);  
}

static int mpc_input_oneof(mpc_input_t *i, const char *c, char **o) {
  char x;
  if (mpc_input_terminated(i)) { return 0; }
  x = mpc_input_getc(i);
  return strchr(c, x) != 0 ? mpc_input_success(i, x, o) : mpc_input_failure(i, x);  
}

static int mpc_input_noneof(mpc_input_t *i, const char *c, char **o) {
  char x;
  if (mpc_input_terminated(i)) { return 0; }
  x = mpc_input_getc(i);
  return strchr(c, x) == 0 ? mpc_input_success(i, x, o) : mpc_input_failure(i, x);  
}

static int mpc_input_satisfy(mpc_input_t *i, int(*cond)(char), char **o) {
  char x;
  if (mpc_input_terminated(i)) { return 0; }
  x = mpc_input_getc(i);
  return cond(x) ? mpc_input_success(i, x, o) : mpc_input_failure(i, x);  
}

static int mpc_input_string(mpc_input_t *i, const char *c, char **o) {

  const char *x = c;

  mpc_input_mark(i);
  while (*x) {
    if (!mpc_input_char(i, *x, NULL)) {
      mpc_input_rewind(i);
      return 0;
    }
    x++;
  }
  mpc_input_unmark(i);

  *o = mpc_malloc(i, strlen(c) + 1);
  strcpy(*o, c);
  return 1;
}

static int mpc_input_anchor(mpc_input_t* i, int(*f)(char,char), char **o) {
  *o = NULL;
  return f(i->last, mpc_input_peekc(i));
}

static int mpc_input_soi(mpc_input_t* i, char **o) {
  *o = NULL;
  return i->last == '\0';
}

static int mpc_input_eoi(mpc_input_t* i, char **o) {
  *o = NULL;
  if (i->state.term) {
    return 0;
  } else if (mpc_input_terminated(i)) {
    i->state.term = 1;
    return 1;
  } else {
    return 0;
  }
}

static mpc_state_t *mpc_input_state_copy(mpc_input_t *i) {
  mpc_state_t *r = mpc_malloc(i, sizeof(mpc_state_t));
  memcpy(r, &i->state, sizeof(mpc_state_t));
  return r;
}

/*
** Error Type
*/

void mpc_err_delete(mpc_err_t *x) {
  int i;
  for (i = 0; i < x->expected_num; i++) { free(x->expected[i]); }
  free(x->expected);
  free(x->filename);
  free(x->failure);
  free(x);
}

void mpc_err_print(mpc_err_t *x) {
  mpc_err_print_to(x, stdout);
}

void mpc_err_print_to(mpc_err_t *x, FILE *f) {
  char *str = mpc_err_string(x);
  fprintf(f, "%s", str);
  free(str);
}

static void mpc_err_string_cat(char *buffer, int *pos, int *max, char const *fmt, ...) {
  /* TODO: Error Checking on Length */
  int left = ((*max) - (*pos));
  va_list va;
  va_start(va, fmt);
  if (left < 0) { left = 0;}
  (*pos) += vsprintf(buffer + (*pos), fmt, va);
  va_end(va);
}

static char char_unescape_buffer[4];

static const char *mpc_err_char_unescape(char c) {

  char_unescape_buffer[0] = '\'';
  char_unescape_buffer[1] = ' ';
  char_unescape_buffer[2] = '\'';
  char_unescape_buffer[3] = '\0';

  switch (c) {
    case '\a': return "bell";
    case '\b': return "backspace";
    case '\f': return "formfeed";
    case '\r': return "carriage return";
    case '\v': return "vertical tab";
    case '\0': return "end of input";
    case '\n': return "newline";
    case '\t': return "tab";
    case ' ' : return "space";
    default:
      char_unescape_buffer[1] = c;
      return char_unescape_buffer;
  }

}

char *mpc_err_string(mpc_err_t *x) {

  int i;
  int pos = 0;
  int max = 1023;
  char *buffer = calloc(1, 1024);

  if (x->failure) {
    mpc_err_string_cat(buffer, &pos, &max,
    "%s: error: %s\n", x->filename, x->failure);
    return buffer;
  }

  mpc_err_string_cat(buffer, &pos, &max,
    "%s:%i:%i: error: expected ", x->filename, x->state.row+1, x->state.col+1);

  if (x->expected_num == 0) { mpc_err_string_cat(buffer, &pos, &max, "ERROR: NOTHING EXPECTED"); }
  if (x->expected_num == 1) { mpc_err_string_cat(buffer, &pos, &max, "%s", x->expected[0]); }
  if (x->expected_num >= 2) {

    for (i = 0; i < x->expected_num-2; i++) {
      mpc_err_string_cat(buffer, &pos, &max, "%s, ", x->expected[i]);
    }

    mpc_err_string_cat(buffer, &pos, &max, "%s or %s",
      x->expected[x->expected_num-2],
      x->expected[x->expected_num-1]);
  }

  mpc_err_string_cat(buffer, &pos, &max, " at ");
  mpc_err_string_cat(buffer, &pos, &max, mpc_err_char_unescape(x->recieved));
  mpc_err_string_cat(buffer, &pos, &max, "\n");

  return realloc(buffer, strlen(buffer) + 1);
}

static mpc_err_t *mpc_err_new(mpc_input_t *i, const char *expected) {
  mpc_err_t *x;
  if (i->suppress) { return NULL; }
  x = mpc_malloc(i, sizeof(mpc_err_t));
  x->filename = mpc_malloc(i, strlen(i->filename) + 1);
  strcpy(x->filename, i->filename);
  x->state = i->state;
  x->expected_num = 1;
  x->expected = mpc_malloc(i, sizeof(char*));
  x->expected[0] = mpc_malloc(i, strlen(expected) + 1);
  strcpy(x->expected[0], expected);
  x->failure = NULL;
  x->recieved = mpc_input_peekc(i);
  return x;
}

static mpc_err_t *mpc_err_fail(mpc_input_t *i, const char *failure) {
  mpc_err_t *x;
  if (i->suppress) { return NULL; }
  x = mpc_malloc(i, sizeof(mpc_err_t));
  x->filename = mpc_malloc(i, strlen(i->filename) + 1);
  strcpy(x->filename, i->filename);
  x->state = i->state;
  x->expected_num = 0;
  x->expected = NULL;
  x->failure = mpc_malloc(i, strlen(failure) + 1);
  strcpy(x->failure, failure);
  x->recieved = ' ';
  return x;
}

static mpc_err_t *mpc_err_file(const char *filename, const char *failure) {
  mpc_err_t *x;
  x = malloc(sizeof(mpc_err_t));
  x->filename = malloc(strlen(filename) + 1);
  strcpy(x->filename, filename);
  x->state = mpc_state_new();
  x->expected_num = 0;
  x->expected = NULL;
  x->failure = malloc(strlen(failure) + 1);
  strcpy(x->failure, failure);
  x->recieved = ' ';
  return x;
}

static void mpc_err_delete_internal(mpc_input_t *i, mpc_err_t *x) {
  int j;
  if (x == NULL) { return; }
  for (j = 0; j < x->expected_num; j++) { mpc_free(i, x->expected[j]); }
  mpc_free(i, x->expected);
  mpc_free(i, x->filename);
  mpc_free(i, x->failure);
  mpc_free(i, x);
}

static mpc_err_t *mpc_err_export(mpc_input_t *i, mpc_err_t *x) {
  int j;
  for (j = 0; j < x->expected_num; j++) {
    x->expected[j] = mpc_export(i, x->expected[j]);
  }
  x->expected = mpc_export(i, x->expected);
  x->filename = mpc_export(i, x->filename);
  x->failure = mpc_export(i, x->failure);
  return mpc_export(i, x);
}

static int mpc_err_contains_expected(mpc_input_t *i, mpc_err_t *x, char *expected) {
  int j;
  (void)i;
  for (j = 0; j < x->expected_num; j++) {
    if (strcmp(x->expected[j], expected) == 0) { return 1; }
  }
  return 0;
}

static void mpc_err_add_expected(mpc_input_t *i, mpc_err_t *x, char *expected) {
  (void)i;
  x->expected_num++;
  x->expected = mpc_realloc(i, x->expected, sizeof(char*) * x->expected_num);
  x->expected[x->expected_num-1] = mpc_malloc(i, strlen(expected) + 1);
  strcpy(x->expected[x->expected_num-1], expected);
}

static mpc_err_t *mpc_err_or(mpc_input_t *i, mpc_err_t** x, int n) {

  int j, k, fst;
  mpc_err_t *e;

  fst = -1;
  for (j = 0; j < n; j++) {
    if (x[j] != NULL) { fst = j; }
  }

  if (fst == -1) { return NULL; }

  e = mpc_malloc(i, sizeof(mpc_err_t));
  e->state = mpc_state_invalid();
  e->expected_num = 0;
  e->expected = NULL;
  e->failure = NULL;
  e->filename = mpc_malloc(i, strlen(x[fst]->filename)+1);
  strcpy(e->filename, x[fst]->filename);

  for (j = 0; j < n; j++) {
    if (x[j] == NULL) { continue; }
    if (x[j]->state.pos > e->state.pos) { e->state = x[j]->state; }
  }

  for (j = 0; j < n; j++) {
    if (x[j] == NULL) { continue; }
    if (x[j]->state.pos < e->state.pos) { continue; }

    if (x[j]->failure) {
      e->failure = mpc_malloc(i, strlen(x[j]->failure)+1);
      strcpy(e->failure, x[j]->failure);
      break;
    }

    e->recieved = x[j]->recieved;

    for (k = 0; k < x[j]->expected_num; k++) {
      if (!mpc_err_contains_expected(i, e, x[j]->expected[k])) {
        mpc_err_add_expected(i, e, x[j]->expected[k]);
      }
    }
  }

  for (j = 0; j < n; j++) {
    if (x[j] == NULL) { continue; }
    mpc_err_delete_internal(i, x[j]);
  }

  return e;
}

static mpc_err_t *mpc_err_repeat(mpc_input_t *i, mpc_err_t *x, const char *prefix) {

  int j = 0;
  size_t l = 0;
  char *expect = NULL;

  if (x == NULL) { return NULL; }

  if (x->expected_num == 0) {
    expect = mpc_calloc(i, 1, 1);
    x->expected_num = 1;
    x->expected = mpc_realloc(i, x->expected, sizeof(char*) * x->expected_num);
    x->expected[0] = expect;
    return x;
  }

  else if (x->expected_num == 1) {
    expect = mpc_malloc(i, strlen(prefix) + strlen(x->expected[0]) + 1);
    strcpy(expect, prefix);
    strcat(expect, x->expected[0]);
    mpc_free(i, x->expected[0]);
    x->expected[0] = expect;
    return x;
  }

  else if (x->expected_num > 1) {

    l += strlen(prefix);
    for (j = 0; j < x->expected_num-2; j++) {
      l += strlen(x->expected[j]) + strlen(", ");
    }
    l += strlen(x->expected[x->expected_num-2]);
    l += strlen(" or ");
    l += strlen(x->expected[x->expected_num-1]);

    expect = mpc_malloc(i, l + 1);

    strcpy(expect, prefix);
    for (j = 0; j < x->expected_num-2; j++) {
      strcat(expect, x->expected[j]); strcat(expect, ", ");
    }
    strcat(expect, x->expected[x->expected_num-2]);
    strcat(expect, " or ");
    strcat(expect, x->expected[x->expected_num-1]);

    for (j = 0; j < x->expected_num; j++) { mpc_free(i, x->expected[j]); }

    x->expected_num = 1;
    x->expected = mpc_realloc(i, x->expected, sizeof(char*) * x->expected_num);
    x->expected[0] = expect;
    return x;
  }

  return NULL;
}

static mpc_err_t *mpc_err_many1(mpc_input_t *i, mpc_err_t *x) {
  return mpc_err_repeat(i, x, "one or more of ");
}

static mpc_err_t *mpc_err_count(mpc_input_t *i, mpc_err_t *x, int n) {
  mpc_err_t *y;
  int digits = n/10 + 1;
  char *prefix;
  prefix = mpc_malloc(i, digits + strlen(" of ") + 1);
  sprintf(prefix, "%i of ", n);
  y = mpc_err_repeat(i, x, prefix);
  mpc_free(i, prefix);
  return y;
}

static mpc_err_t *mpc_err_merge(mpc_input_t *i, mpc_err_t *x, mpc_err_t *y) {
  mpc_err_t *errs[2];
  errs[0] = x;
  errs[1] = y;
  return mpc_err_or(i, errs, 2);
}

/*
** Parser Type
*/

enum {
  MPC_TYPE_UNDEFINED  = 0,
  MPC_TYPE_PASS       = 1,
  MPC_TYPE_FAIL       = 2,
  MPC_TYPE_LIFT       = 3,
  MPC_TYPE_LIFT_VAL   = 4,
  MPC_TYPE_EXPECT     = 5,
  MPC_TYPE_ANCHOR     = 6,
  MPC_TYPE_STATE      = 7,

  MPC_TYPE_ANY        = 8,
  MPC_TYPE_SINGLE     = 9,
  MPC_TYPE_ONEOF      = 10,
  MPC_TYPE_NONEOF     = 11,
  MPC_TYPE_RANGE      = 12,
  MPC_TYPE_SATISFY    = 13,
  MPC_TYPE_STRING     = 14,

  MPC_TYPE_APPLY      = 15,
  MPC_TYPE_APPLY_TO   = 16,
  MPC_TYPE_PREDICT    = 17,
  MPC_TYPE_NOT        = 18,
  MPC_TYPE_MAYBE      = 19,
  MPC_TYPE_MANY       = 20,
  MPC_TYPE_MANY1      = 21,
  MPC_TYPE_COUNT      = 22,

  MPC_TYPE_OR         = 23,
  MPC_TYPE_AND        = 24,

  MPC_TYPE_CHECK      = 25,
  MPC_TYPE_CHECK_WITH = 26,

  MPC_TYPE_SOI        = 27,
  MPC_TYPE_EOI        = 28
};

typedef struct { char *m; } mpc_pdata_fail_t;
typedef struct { mpc_ctor_t lf; void *x; } mpc_pdata_lift_t;
typedef struct { mpc_parser_t *x; char *m; } mpc_pdata_expect_t;
typedef struct { int(*f)(char,char); } mpc_pdata_anchor_t;
typedef struct { char x; } mpc_pdata_single_t;
typedef struct { char x; char y; } mpc_pdata_range_t;
typedef struct { int(*f)(char); } mpc_pdata_satisfy_t;
typedef struct { char *x; } mpc_pdata_string_t;
typedef struct { mpc_parser_t *x; mpc_apply_t f; } mpc_pdata_apply_t;
typedef struct { mpc_parser_t *x; mpc_apply_to_t f; void *d; } mpc_pdata_apply_to_t;
typedef struct { mpc_parser_t *x; mpc_check_t f; char *e; } mpc_pdata_check_t;
typedef struct { mpc_parser_t *x; mpc_check_with_t f; void *d; char *e; } mpc_pdata_check_with_t;
typedef struct { mpc_parser_t *x; } mpc_pdata_predict_t;
typedef struct { mpc_parser_t *x; mpc_dtor_t dx; mpc_ctor_t lf; } mpc_pdata_not_t;
typedef struct { int n; mpc_fold_t f; mpc_parser_t *x; mpc_dtor_t dx; } mpc_pdata_repeat_t;
typedef struct { int n; mpc_parser_t **xs; } mpc_pdata_or_t;
typedef struct { int n; mpc_fold_t f; mpc_parser_t **xs; mpc_dtor_t *dxs;  } mpc_pdata_and_t;

typedef union {
  mpc_pdata_fail_t fail;
  mpc_pdata_lift_t lift;
  mpc_pdata_expect_t expect;
  mpc_pdata_anchor_t anchor;
  mpc_pdata_single_t single;
  mpc_pdata_range_t range;
  mpc_pdata_satisfy_t satisfy;
  mpc_pdata_string_t string;
  mpc_pdata_apply_t apply;
  mpc_pdata_apply_to_t apply_to;
  mpc_pdata_check_t check;
  mpc_pdata_check_with_t check_with;
  mpc_pdata_predict_t predict;
  mpc_pdata_not_t not;
  mpc_pdata_repeat_t repeat;
  mpc_pdata_and_t and;
  mpc_pdata_or_t or;
} mpc_pdata_t;

struct mpc_parser_t {
  char *name;
  mpc_pdata_t data;
  char type;
  char retained;
};

static mpc_val_t *mpcf_input_nth_free(mpc_input_t *i, int n, mpc_val_t **xs, int x) {
  int j;
  for (j = 0; j < n; j++) { if (j != x) { mpc_free(i, xs[j]); } }
  return xs[x];
}

static mpc_val_t *mpcf_input_fst_free(mpc_input_t *i, int n, mpc_val_t **xs) { return mpcf_input_nth_free(i, n, xs, 0); }
static mpc_val_t *mpcf_input_snd_free(mpc_input_t *i, int n, mpc_val_t **xs) { return mpcf_input_nth_free(i, n, xs, 1); }
static mpc_val_t *mpcf_input_trd_free(mpc_input_t *i, int n, mpc_val_t **xs) { return mpcf_input_nth_free(i, n, xs, 2); }

static mpc_val_t *mpcf_input_strfold(mpc_input_t *i, int n, mpc_val_t **xs) {
  int j;
  size_t l = 0;
  if (n == 0) { return mpc_calloc(i, 1, 1); }
  for (j = 0; j < n; j++) { l += strlen(xs[j]); }
  xs[0] = mpc_realloc(i, xs[0], l + 1);
  for (j = 1; j < n; j++) { strcat(xs[0], xs[j]); mpc_free(i, xs[j]); }
  return xs[0];
}

static mpc_val_t *mpcf_input_state_ast(mpc_input_t *i, int n, mpc_val_t **xs) {
  mpc_state_t *s = ((mpc_state_t**)xs)[0];
  mpc_ast_t *a = ((mpc_ast_t**)xs)[1];
  a = mpc_ast_state(a, *s);
  mpc_free(i, s);
  (void) n;
  return a;
}

static mpc_val_t *mpc_parse_fold(mpc_input_t *i, mpc_fold_t f, int n, mpc_val_t **xs) {
  int j;
  if (f == mpcf_null)      { return mpcf_null(n, xs); }
  if (f == mpcf_fst)       { return mpcf_fst(n, xs); }
  if (f == mpcf_snd)       { return mpcf_snd(n, xs); }
  if (f == mpcf_trd)       { return mpcf_trd(n, xs); }
  if (f == mpcf_fst_free)  { return mpcf_input_fst_free(i, n, xs); }
  if (f == mpcf_snd_free)  { return mpcf_input_snd_free(i, n, xs); }
  if (f == mpcf_trd_free)  { return mpcf_input_trd_free(i, n, xs); }
  if (f == mpcf_strfold)   { return mpcf_input_strfold(i, n, xs); }
  if (f == mpcf_state_ast) { return mpcf_input_state_ast(i, n, xs); }
  for (j = 0; j < n; j++) { xs[j] = mpc_export(i, xs[j]); }
  return f(j, xs);
}

static mpc_val_t *mpcf_input_free(mpc_input_t *i, mpc_val_t *x) {
  mpc_free(i, x);
  return NULL;
}

static mpc_val_t *mpcf_input_str_ast(mpc_input_t *i, mpc_val_t *c) {
  mpc_ast_t *a = mpc_ast_new("", c);
  mpc_free(i, c);
  return a;
}

static mpc_val_t *mpc_parse_apply(mpc_input_t *i, mpc_apply_t f, mpc_val_t *x) {
  if (f == mpcf_free)     { return mpcf_input_free(i, x); }
  if (f == mpcf_str_ast)  { return mpcf_input_str_ast(i, x); }
  return f(mpc_export(i, x));
}

static mpc_val_t *mpc_parse_apply_to(mpc_input_t *i, mpc_apply_to_t f, mpc_val_t *x, mpc_val_t *d) {
  return f(mpc_export(i, x), d);
}

static void mpc_parse_dtor(mpc_input_t *i, mpc_dtor_t d, mpc_val_t *x) {
  if (d == free) { mpc_free(i, x); return; }
  d(mpc_export(i, x));
}

enum {
  MPC_PARSE_STACK_MIN = 4
};

#define MPC_SUCCESS(x) r->output = x; return 1
#define MPC_FAILURE(x) r->error = x; return 0
#define MPC_PRIMITIVE(x) \
  if (x) { MPC_SUCCESS(r->output); } \
  else { MPC_FAILURE(NULL); }

static int mpc_parse_run(mpc_input_t *i, mpc_parser_t *p, mpc_result_t *r, mpc_err_t **e) {

  int j = 0, k = 0;
  mpc_result_t results_stk[MPC_PARSE_STACK_MIN];
  mpc_result_t *results;
  int results_slots = MPC_PARSE_STACK_MIN;

  switch (p->type) {

    /* Basic Parsers */

    case MPC_TYPE_ANY:     MPC_PRIMITIVE(mpc_input_any(i, (char**)&r->output));
    case MPC_TYPE_SINGLE:  MPC_PRIMITIVE(mpc_input_char(i, p->data.single.x, (char**)&r->output));
    case MPC_TYPE_RANGE:   MPC_PRIMITIVE(mpc_input_range(i, p->data.range.x, p->data.range.y, (char**)&r->output));
    case MPC_TYPE_ONEOF:   MPC_PRIMITIVE(mpc_input_oneof(i, p->data.string.x, (char**)&r->output));
    case MPC_TYPE_NONEOF:  MPC_PRIMITIVE(mpc_input_noneof(i, p->data.string.x, (char**)&r->output));
    case MPC_TYPE_SATISFY: MPC_PRIMITIVE(mpc_input_satisfy(i, p->data.satisfy.f, (char**)&r->output));
    case MPC_TYPE_STRING:  MPC_PRIMITIVE(mpc_input_string(i, p->data.string.x, (char**)&r->output));
    case MPC_TYPE_ANCHOR:  MPC_PRIMITIVE(mpc_input_anchor(i, p->data.anchor.f, (char**)&r->output));
    case MPC_TYPE_SOI:     MPC_PRIMITIVE(mpc_input_soi(i, (char**)&r->output));
    case MPC_TYPE_EOI:     MPC_PRIMITIVE(mpc_input_eoi(i, (char**)&r->output));

    /* Other parsers */

    case MPC_TYPE_UNDEFINED: MPC_FAILURE(mpc_err_fail(i, "Parser Undefined!"));
    case MPC_TYPE_PASS:      MPC_SUCCESS(NULL);
    case MPC_TYPE_FAIL:      MPC_FAILURE(mpc_err_fail(i, p->data.fail.m));
    case MPC_TYPE_LIFT:      MPC_SUCCESS(p->data.lift.lf());
    case MPC_TYPE_LIFT_VAL:  MPC_SUCCESS(p->data.lift.x);
    case MPC_TYPE_STATE:     MPC_SUCCESS(mpc_input_state_copy(i));

    /* Application Parsers */

    case MPC_TYPE_APPLY:
      if (mpc_parse_run(i, p->data.apply.x, r, e)) {
        MPC_SUCCESS(mpc_parse_apply(i, p->data.apply.f, r->output));
      } else {
        MPC_FAILURE(r->output);
      }

    case MPC_TYPE_APPLY_TO:
      if (mpc_parse_run(i, p->data.apply_to.x, r, e)) {
        MPC_SUCCESS(mpc_parse_apply_to(i, p->data.apply_to.f, r->output, p->data.apply_to.d));
      } else {
        MPC_FAILURE(r->error);
      }

    case MPC_TYPE_CHECK:
      if (mpc_parse_run(i, p->data.check.x, r, e)) {
        if (p->data.check.f(&r->output)) {
          MPC_SUCCESS(r->output);
        } else {
          MPC_FAILURE(mpc_err_fail(i, p->data.check.e));
        }
      } else {
        MPC_FAILURE(r->error);
      }

    case MPC_TYPE_CHECK_WITH:
      if (mpc_parse_run(i, p->data.check_with.x, r, e)) {
        if (p->data.check_with.f(&r->output, p->data.check_with.d)) {
          MPC_SUCCESS(r->output);
        } else {
          MPC_FAILURE(mpc_err_fail(i, p->data.check_with.e));
        }
      } else {
        MPC_FAILURE(r->error);
      }

    case MPC_TYPE_EXPECT:
      mpc_input_suppress_enable(i);
      if (mpc_parse_run(i, p->data.expect.x, r, e)) {
        mpc_input_suppress_disable(i);
        MPC_SUCCESS(r->output);
      } else {
        mpc_input_suppress_disable(i);
        MPC_FAILURE(mpc_err_new(i, p->data.expect.m));
      }

    case MPC_TYPE_PREDICT:
      mpc_input_backtrack_disable(i);
      if (mpc_parse_run(i, p->data.predict.x, r, e)) {
        mpc_input_backtrack_enable(i);
        MPC_SUCCESS(r->output);
      } else {
        mpc_input_backtrack_enable(i);
        MPC_FAILURE(r->error);
      }

    /* Optional Parsers */

    /* TODO: Update Not Error Message */

    case MPC_TYPE_NOT:
      mpc_input_mark(i);
      mpc_input_suppress_enable(i);
      if (mpc_parse_run(i, p->data.not.x, r, e)) {
        mpc_input_rewind(i);
        mpc_input_suppress_disable(i);
        mpc_parse_dtor(i, p->data.not.dx, r->output);
        MPC_FAILURE(mpc_err_new(i, "opposite"));
      } else {
        mpc_input_unmark(i);
        mpc_input_suppress_disable(i);
        MPC_SUCCESS(p->data.not.lf());
      }

    case MPC_TYPE_MAYBE:
      if (mpc_parse_run(i, p->data.not.x, r, e)) {
        MPC_SUCCESS(r->output);
      } else {
        *e = mpc_err_merge(i, *e, r->error);
        MPC_SUCCESS(p->data.not.lf());
      }

    /* Repeat Parsers */

    case MPC_TYPE_MANY:

      results = results_stk;

      while (mpc_parse_run(i, p->data.repeat.x, &results[j], e)) {
        j++;
        if (j == MPC_PARSE_STACK_MIN) {
          results_slots = j + j / 2;
          results = mpc_malloc(i, sizeof(mpc_result_t) * results_slots);
          memcpy(results, results_stk, sizeof(mpc_result_t) * MPC_PARSE_STACK_MIN);
        } else if (j >= results_slots) {
          results_slots = j + j / 2;
          results = mpc_realloc(i, results, sizeof(mpc_result_t) * results_slots);
        }
      }

      *e = mpc_err_merge(i, *e, results[j].error);

      MPC_SUCCESS(
        mpc_parse_fold(i, p->data.repeat.f, j, (mpc_val_t**)results);
        if (j >= MPC_PARSE_STACK_MIN) { mpc_free(i, results); });

    case MPC_TYPE_MANY1:

      results = results_stk;

      while (mpc_parse_run(i, p->data.repeat.x, &results[j], e)) {
        j++;
        if (j == MPC_PARSE_STACK_MIN) {
          results_slots = j + j / 2;
          results = mpc_malloc(i, sizeof(mpc_result_t) * results_slots);
          memcpy(results, results_stk, sizeof(mpc_result_t) * MPC_PARSE_STACK_MIN);
        } else if (j >= results_slots) {
          results_slots = j + j / 2;
          results = mpc_realloc(i, results, sizeof(mpc_result_t) * results_slots);
        }
      }

      if (j == 0) {
        MPC_FAILURE(
          mpc_err_many1(i, results[j].error);
          if (j >= MPC_PARSE_STACK_MIN) { mpc_free(i, results); });
      } else {

        *e = mpc_err_merge(i, *e, results[j].error);

        MPC_SUCCESS(
          mpc_parse_fold(i, p->data.repeat.f, j, (mpc_val_t**)results);
          if (j >= MPC_PARSE_STACK_MIN) { mpc_free(i, results); });
      }

    case MPC_TYPE_COUNT:

      results = p->data.repeat.n > MPC_PARSE_STACK_MIN
        ? mpc_malloc(i, sizeof(mpc_result_t) * p->data.repeat.n)
        : results_stk;

      while (mpc_parse_run(i, p->data.repeat.x, &results[j], e)) {
        j++;
        if (j == p->data.repeat.n) { break; }
      }

      if (j == p->data.repeat.n) {
        MPC_SUCCESS(
          mpc_parse_fold(i, p->data.repeat.f, j, (mpc_val_t**)results);
          if (p->data.repeat.n > MPC_PARSE_STACK_MIN) { mpc_free(i, results); });
      } else {
        for (k = 0; k < j; k++) {
          mpc_parse_dtor(i, p->data.repeat.dx, results[k].output);
        }
        MPC_FAILURE(
          mpc_err_count(i, results[j].error, p->data.repeat.n);
          if (p->data.repeat.n > MPC_PARSE_STACK_MIN) { mpc_free(i, results); });
      }

    /* Combinatory Parsers */

    case MPC_TYPE_OR:

      if (p->data.or.n == 0) { MPC_SUCCESS(NULL); }

      results = p->data.or.n > MPC_PARSE_STACK_MIN
        ? mpc_malloc(i, sizeof(mpc_result_t) * p->data.or.n)
        : results_stk;

      for (j = 0; j < p->data.or.n; j++) {
        if (mpc_parse_run(i, p->data.or.xs[j], &results[j], e)) {
          MPC_SUCCESS(results[j].output;
            if (p->data.or.n > MPC_PARSE_STACK_MIN) { mpc_free(i, results); });
        } else {
          *e = mpc_err_merge(i, *e, results[j].error);
        }
      }

      MPC_FAILURE(NULL;
        if (p->data.or.n > MPC_PARSE_STACK_MIN) { mpc_free(i, results); });

    case MPC_TYPE_AND:

      if (p->data.and.n == 0) { MPC_SUCCESS(NULL); }

      results = p->data.or.n > MPC_PARSE_STACK_MIN
        ? mpc_malloc(i, sizeof(mpc_result_t) * p->data.or.n)
        : results_stk;

      mpc_input_mark(i);
      for (j = 0; j < p->data.and.n; j++) {
        if (!mpc_parse_run(i, p->data.and.xs[j], &results[j], e)) {
          mpc_input_rewind(i);
          for (k = 0; k < j; k++) {
            mpc_parse_dtor(i, p->data.and.dxs[k], results[k].output);
          }
          MPC_FAILURE(results[j].error;
            if (p->data.or.n > MPC_PARSE_STACK_MIN) { mpc_free(i, results); });
        }
      }
      mpc_input_unmark(i);
      MPC_SUCCESS(
        mpc_parse_fold(i, p->data.and.f, j, (mpc_val_t**)results);
        if (p->data.or.n > MPC_PARSE_STACK_MIN) { mpc_free(i, results); });

    /* End */

    default:

      MPC_FAILURE(mpc_err_fail(i, "Unknown Parser Type Id!"));
  }

  return 0;

}

#undef MPC_SUCCESS
#undef MPC_FAILURE
#undef MPC_PRIMITIVE

int mpc_parse_input(mpc_input_t *i, mpc_parser_t *p, mpc_result_t *r) {
  int x;
  mpc_err_t *e = mpc_err_fail(i, "Unknown Error");
  e->state = mpc_state_invalid();
  x = mpc_parse_run(i, p, r, &e);
  if (x) {
    mpc_err_delete_internal(i, e);
    r->output = mpc_export(i, r->output);
  } else {
    r->error = mpc_err_export(i, mpc_err_merge(i, e, r->error));
  }
  return x;
}

int mpc_parse(const char *filename, const char *string, mpc_parser_t *p, mpc_result_t *r) {
  int x;
  mpc_input_t *i = mpc_input_new_string(filename, string);
  x = mpc_parse_input(i, p, r);
  mpc_input_delete(i);
  return x;
}

int mpc_nparse(const char *filename, const char *string, size_t length, mpc_parser_t *p, mpc_result_t *r) {
  int x;
  mpc_input_t *i = mpc_input_new_nstring(filename, string, length);
  x = mpc_parse_input(i, p, r);
  mpc_input_delete(i);
  return x;
}

int mpc_parse_file(const char *filename, FILE *file, mpc_parser_t *p, mpc_result_t *r) {
  int x;
  mpc_input_t *i = mpc_input_new_file(filename, file);
  x = mpc_parse_input(i, p, r);
  mpc_input_delete(i);
  return x;
}

int mpc_parse_pipe(const char *filename, FILE *pipe, mpc_parser_t *p, mpc_result_t *r) {
  int x;
  mpc_input_t *i = mpc_input_new_pipe(filename, pipe);
  x = mpc_parse_input(i, p, r);
  mpc_input_delete(i);
  return x;
}

int mpc_parse_contents(const char *filename, mpc_parser_t *p, mpc_result_t *r) {

  FILE *f = fopen(filename, "rb");
  int res;

  if (f == NULL) {
    r->output = NULL;
    r->error = mpc_err_file(filename, "Unable to open file!");
    return 0;
  }

  res = mpc_parse_file(filename, f, p, r);
  fclose(f);
  return res;
}

/*
** Building a Parser
*/

static void mpc_undefine_unretained(mpc_parser_t *p, int force);

static void mpc_undefine_or(mpc_parser_t *p) {

  int i;
  for (i = 0; i < p->data.or.n; i++) {
    mpc_undefine_unretained(p->data.or.xs[i], 0);
  }
  free(p->data.or.xs);

}

static void mpc_undefine_and(mpc_parser_t *p) {

  int i;
  for (i = 0; i < p->data.and.n; i++) {
    mpc_undefine_unretained(p->data.and.xs[i], 0);
  }
  free(p->data.and.xs);
  free(p->data.and.dxs);

}

static void mpc_undefine_unretained(mpc_parser_t *p, int force) {

  if (p->retained && !force) { return; }

  switch (p->type) {

    case MPC_TYPE_FAIL: free(p->data.fail.m); break;

    case MPC_TYPE_ONEOF:
    case MPC_TYPE_NONEOF:
    case MPC_TYPE_STRING:
      free(p->data.string.x);
      break;

    case MPC_TYPE_APPLY:    mpc_undefine_unretained(p->data.apply.x, 0);    break;
    case MPC_TYPE_APPLY_TO: mpc_undefine_unretained(p->data.apply_to.x, 0); break;
    case MPC_TYPE_PREDICT:  mpc_undefine_unretained(p->data.predict.x, 0);  break;

    case MPC_TYPE_MAYBE:
    case MPC_TYPE_NOT:
      mpc_undefine_unretained(p->data.not.x, 0);
      break;

    case MPC_TYPE_EXPECT:
      mpc_undefine_unretained(p->data.expect.x, 0);
      free(p->data.expect.m);
      break;

    case MPC_TYPE_MANY:
    case MPC_TYPE_MANY1:
    case MPC_TYPE_COUNT:
      mpc_undefine_unretained(p->data.repeat.x, 0);
      break;

    case MPC_TYPE_OR:  mpc_undefine_or(p);  break;
    case MPC_TYPE_AND: mpc_undefine_and(p); break;

    case MPC_TYPE_CHECK:
      mpc_undefine_unretained(p->data.check.x, 0);
      free(p->data.check.e);
      break;

    case MPC_TYPE_CHECK_WITH:
      mpc_undefine_unretained(p->data.check_with.x, 0);
      free(p->data.check_with.e);
      break;

    default: break;
  }

  if (!force) {
    free(p->name);
    free(p);
  }

}

void mpc_delete(mpc_parser_t *p) {
  if (p->retained) {

    if (p->type != MPC_TYPE_UNDEFINED) {
      mpc_undefine_unretained(p, 0);
    }

    free(p->name);
    free(p);

  } else {
    mpc_undefine_unretained(p, 0);
  }
}

static void mpc_soft_delete(mpc_val_t *x) {
  mpc_undefine_unretained(x, 0);
}

static mpc_parser_t *mpc_undefined(void) {
  mpc_parser_t *p = calloc(1, sizeof(mpc_parser_t));
  p->retained = 0;
  p->type = MPC_TYPE_UNDEFINED;
  p->name = NULL;
  return p;
}

mpc_parser_t *mpc_new(const char *name) {
  mpc_parser_t *p = mpc_undefined();
  p->retained = 1;
  p->name = realloc(p->name, strlen(name) + 1);
  strcpy(p->name, name);
  return p;
}

mpc_parser_t *mpc_copy(mpc_parser_t *a) {
  int i = 0;
  mpc_parser_t *p;

  if (a->retained) { return a; }

  p = mpc_undefined();
  p->retained = a->retained;
  p->type = a->type;
  p->data = a->data;

  if (a->name) {
    p->name = malloc(strlen(a->name)+1);
    strcpy(p->name, a->name);
  }

  switch (a->type) {

    case MPC_TYPE_FAIL:
      p->data.fail.m = malloc(strlen(a->data.fail.m)+1);
      strcpy(p->data.fail.m, a->data.fail.m);
    break;

    case MPC_TYPE_ONEOF:
    case MPC_TYPE_NONEOF:
    case MPC_TYPE_STRING:
      p->data.string.x = malloc(strlen(a->data.string.x)+1);
      strcpy(p->data.string.x, a->data.string.x);
      break;

    case MPC_TYPE_APPLY:    p->data.apply.x    = mpc_copy(a->data.apply.x);    break;
    case MPC_TYPE_APPLY_TO: p->data.apply_to.x = mpc_copy(a->data.apply_to.x); break;
    case MPC_TYPE_PREDICT:  p->data.predict.x  = mpc_copy(a->data.predict.x);  break;

    case MPC_TYPE_MAYBE:
    case MPC_TYPE_NOT:
      p->data.not.x = mpc_copy(a->data.not.x);
      break;

    case MPC_TYPE_EXPECT:
      p->data.expect.x = mpc_copy(a->data.expect.x);
      p->data.expect.m = malloc(strlen(a->data.expect.m)+1);
      strcpy(p->data.expect.m, a->data.expect.m);
      break;

    case MPC_TYPE_MANY:
    case MPC_TYPE_MANY1:
    case MPC_TYPE_COUNT:
      p->data.repeat.x = mpc_copy(a->data.repeat.x);
      break;

    case MPC_TYPE_OR:
      p->data.or.xs = malloc(a->data.or.n * sizeof(mpc_parser_t*));
      for (i = 0; i < a->data.or.n; i++) {
        p->data.or.xs[i] = mpc_copy(a->data.or.xs[i]);
      }
    break;
    case MPC_TYPE_AND:
      p->data.and.xs = malloc(a->data.and.n * sizeof(mpc_parser_t*));
      for (i = 0; i < a->data.and.n; i++) {
        p->data.and.xs[i] = mpc_copy(a->data.and.xs[i]);
      }
      p->data.and.dxs = malloc((a->data.and.n-1) * sizeof(mpc_dtor_t));
      for (i = 0; i < a->data.and.n-1; i++) {
        p->data.and.dxs[i] = a->data.and.dxs[i];
      }
    break;

    case MPC_TYPE_CHECK:
      p->data.check.x      = mpc_copy(a->data.check.x);
      p->data.check.e      = malloc(strlen(a->data.check.e)+1);
      strcpy(p->data.check.e, a->data.check.e);
      break;
    case MPC_TYPE_CHECK_WITH:
      p->data.check_with.x = mpc_copy(a->data.check_with.x);
      p->data.check_with.e = malloc(strlen(a->data.check_with.e)+1);
      strcpy(p->data.check_with.e, a->data.check_with.e);
      break;

    default: break;
  }


  return p;
}

mpc_parser_t *mpc_undefine(mpc_parser_t *p) {
  mpc_undefine_unretained(p, 1);
  p->type = MPC_TYPE_UNDEFINED;
  return p;
}

mpc_parser_t *mpc_define(mpc_parser_t *p, mpc_parser_t *a) {

  if (p->retained) {
    p->type = a->type;
    p->data = a->data;
  } else {
    mpc_parser_t *a2 = mpc_failf("Attempt to assign to Unretained Parser!");
    p->type = a2->type;
    p->data = a2->data;
    free(a2);
  }

  free(a);
  return p;
}

void mpc_cleanup(int n, ...) {
  int i;
  mpc_parser_t **list = malloc(sizeof(mpc_parser_t*) * n);

  va_list va;
  va_start(va, n);
  for (i = 0; i < n; i++) { list[i] = va_arg(va, mpc_parser_t*); }
  for (i = 0; i < n; i++) { mpc_undefine(list[i]); }
  for (i = 0; i < n; i++) { mpc_delete(list[i]); }
  va_end(va);

  free(list);
}

mpc_parser_t *mpc_pass(void) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_PASS;
  return p;
}

mpc_parser_t *mpc_fail(const char *m) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_FAIL;
  p->data.fail.m = malloc(strlen(m) + 1);
  strcpy(p->data.fail.m, m);
  return p;
}

/*
** As `snprintf` is not ANSI standard this
** function `mpc_failf` should be considered
** unsafe.
**
** You have a few options if this is going to be
** trouble.
**
** - Ensure the format string does not exceed
**   the buffer length using precision specifiers
**   such as `%.512s`.
**
** - Patch this function in your code base to
**   use `snprintf` or whatever variant your
**   system supports.
**
** - Avoid it altogether.
**
*/

mpc_parser_t *mpc_failf(const char *fmt, ...) {

  va_list va;
  char *buffer;

  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_FAIL;

  va_start(va, fmt);
  buffer = malloc(2048);
  vsprintf(buffer, fmt, va);
  va_end(va);

  buffer = realloc(buffer, strlen(buffer) + 1);
  p->data.fail.m = buffer;
  return p;

}

mpc_parser_t *mpc_lift_val(mpc_val_t *x) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_LIFT_VAL;
  p->data.lift.x = x;
  return p;
}

mpc_parser_t *mpc_lift(mpc_ctor_t lf) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_LIFT;
  p->data.lift.lf = lf;
  return p;
}

mpc_parser_t *mpc_anchor(int(*f)(char,char)) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_ANCHOR;
  p->data.anchor.f = f;
  return mpc_expect(p, "anchor");
}

mpc_parser_t *mpc_state(void) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_STATE;
  return p;
}

mpc_parser_t *mpc_expect(mpc_parser_t *a, const char *expected) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_EXPECT;
  p->data.expect.x = a;
  p->data.expect.m = malloc(strlen(expected) + 1);
  strcpy(p->data.expect.m, expected);
  return p;
}

/*
** As `snprintf` is not ANSI standard this
** function `mpc_expectf` should be considered
** unsafe.
**
** You have a few options if this is going to be
** trouble.
**
** - Ensure the format string does not exceed
**   the buffer length using precision specifiers
**   such as `%.512s`.
**
** - Patch this function in your code base to
**   use `snprintf` or whatever variant your
**   system supports.
**
** - Avoid it altogether.
**
*/

mpc_parser_t *mpc_expectf(mpc_parser_t *a, const char *fmt, ...) {
  va_list va;
  char *buffer;

  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_EXPECT;

  va_start(va, fmt);
  buffer = malloc(2048);
  vsprintf(buffer, fmt, va);
  va_end(va);

  buffer = realloc(buffer, strlen(buffer) + 1);
  p->data.expect.x = a;
  p->data.expect.m = buffer;
  return p;
}

/*
** Basic Parsers
*/

mpc_parser_t *mpc_any(void) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_ANY;
  return mpc_expect(p, "any character");
}

mpc_parser_t *mpc_char(char c) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_SINGLE;
  p->data.single.x = c;
  return mpc_expectf(p, "'%c'", c);
}

mpc_parser_t *mpc_range(char s, char e) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_RANGE;
  p->data.range.x = s;
  p->data.range.y = e;
  return mpc_expectf(p, "character between '%c' and '%c'", s, e);
}

mpc_parser_t *mpc_oneof(const char *s) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_ONEOF;
  p->data.string.x = malloc(strlen(s) + 1);
  strcpy(p->data.string.x, s);
  return mpc_expectf(p, "one of '%s'", s);
}

mpc_parser_t *mpc_noneof(const char *s) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_NONEOF;
  p->data.string.x = malloc(strlen(s) + 1);
  strcpy(p->data.string.x, s);
  return mpc_expectf(p, "none of '%s'", s);

}

mpc_parser_t *mpc_satisfy(int(*f)(char)) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_SATISFY;
  p->data.satisfy.f = f;
  return mpc_expectf(p, "character satisfying function %p", f);
}

mpc_parser_t *mpc_string(const char *s) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_STRING;
  p->data.string.x = malloc(strlen(s) + 1);
  strcpy(p->data.string.x, s);
  return mpc_expectf(p, "\"%s\"", s);
}

/*
** Core Parsers
*/

mpc_parser_t *mpc_apply(mpc_parser_t *a, mpc_apply_t f) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_APPLY;
  p->data.apply.x = a;
  p->data.apply.f = f;
  return p;
}

mpc_parser_t *mpc_apply_to(mpc_parser_t *a, mpc_apply_to_t f, void *x) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_APPLY_TO;
  p->data.apply_to.x = a;
  p->data.apply_to.f = f;
  p->data.apply_to.d = x;
  return p;
}

mpc_parser_t *mpc_check(mpc_parser_t *a, mpc_check_t f, const char *e) {
  mpc_parser_t  *p = mpc_undefined();
  p->type          = MPC_TYPE_CHECK;
  p->data.check.x  = a;
  p->data.check.f  = f;
  p->data.check.e  = malloc(strlen(e) + 1);
  strcpy(p->data.check.e, e);
  return p;
}

mpc_parser_t *mpc_check_with(mpc_parser_t *a, mpc_check_with_t f, void *x, const char *e) {
  mpc_parser_t  *p     = mpc_undefined();
  p->type              = MPC_TYPE_CHECK_WITH;
  p->data.check_with.x = a;
  p->data.check_with.f = f;
  p->data.check_with.d = x;
  p->data.check_with.e = malloc(strlen(e) + 1);
  strcpy(p->data.check_with.e, e);
  return p;
}

mpc_parser_t *mpc_checkf(mpc_parser_t *a, mpc_check_t f, const char *fmt, ...) {
  va_list        va;
  char          *buffer;
  mpc_parser_t  *p;

  va_start(va, fmt);
  buffer = malloc(2048);
  vsprintf(buffer, fmt, va);
  va_end(va);

  p = mpc_check (a, f, buffer);
  free (buffer);

  return p;
}

mpc_parser_t *mpc_check_withf(mpc_parser_t *a, mpc_check_with_t f, void *x, const char *fmt, ...) {
  va_list        va;
  char          *buffer;
  mpc_parser_t  *p;

  va_start(va, fmt);
  buffer = malloc(2048);
  vsprintf(buffer, fmt, va);
  va_end(va);

  p = mpc_check_with (a, f, x, buffer);
  free (buffer);

  return p;
}

mpc_parser_t *mpc_predictive(mpc_parser_t *a) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_PREDICT;
  p->data.predict.x = a;
  return p;
}

mpc_parser_t *mpc_not_lift(mpc_parser_t *a, mpc_dtor_t da, mpc_ctor_t lf) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_NOT;
  p->data.not.x = a;
  p->data.not.dx = da;
  p->data.not.lf = lf;
  return p;
}

mpc_parser_t *mpc_not(mpc_parser_t *a, mpc_dtor_t da) {
  return mpc_not_lift(a, da, mpcf_ctor_null);
}

mpc_parser_t *mpc_maybe_lift(mpc_parser_t *a, mpc_ctor_t lf) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_MAYBE;
  p->data.not.x = a;
  p->data.not.lf = lf;
  return p;
}

mpc_parser_t *mpc_maybe(mpc_parser_t *a) {
  return mpc_maybe_lift(a, mpcf_ctor_null);
}

mpc_parser_t *mpc_many(mpc_fold_t f, mpc_parser_t *a) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_MANY;
  p->data.repeat.x = a;
  p->data.repeat.f = f;
  return p;
}

mpc_parser_t *mpc_many1(mpc_fold_t f, mpc_parser_t *a) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_MANY1;
  p->data.repeat.x = a;
  p->data.repeat.f = f;
  return p;
}

mpc_parser_t *mpc_count(int n, mpc_fold_t f, mpc_parser_t *a, mpc_dtor_t da) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_COUNT;
  p->data.repeat.n = n;
  p->data.repeat.f = f;
  p->data.repeat.x = a;
  p->data.repeat.dx = da;
  return p;
}

mpc_parser_t *mpc_or(int n, ...) {

  int i;
  va_list va;

  mpc_parser_t *p = mpc_undefined();

  p->type = MPC_TYPE_OR;
  p->data.or.n = n;
  p->data.or.xs = malloc(sizeof(mpc_parser_t*) * n);

  va_start(va, n);
  for (i = 0; i < n; i++) {
    p->data.or.xs[i] = va_arg(va, mpc_parser_t*);
  }
  va_end(va);

  return p;
}

mpc_parser_t *mpc_and(int n, mpc_fold_t f, ...) {

  int i;
  va_list va;

  mpc_parser_t *p = mpc_undefined();

  p->type = MPC_TYPE_AND;
  p->data.and.n = n;
  p->data.and.f = f;
  p->data.and.xs = malloc(sizeof(mpc_parser_t*) * n);
  p->data.and.dxs = malloc(sizeof(mpc_dtor_t) * (n-1));

  va_start(va, f);
  for (i = 0; i < n; i++) {
    p->data.and.xs[i] = va_arg(va, mpc_parser_t*);
  }
  for (i = 0; i < (n-1); i++) {
    p->data.and.dxs[i] = va_arg(va, mpc_dtor_t);
  }
  va_end(va);

  return p;
}

/*
** Common Parsers
*/

mpc_parser_t *mpc_soi(void) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_SOI;
  return mpc_expect(p, "start of input");
}

mpc_parser_t *mpc_eoi(void) {
  mpc_parser_t *p = mpc_undefined();
  p->type = MPC_TYPE_EOI;
  return mpc_expect(p, "end of input");
}

static int mpc_boundary_anchor(char prev, char next) {
  const char* word = "abcdefghijklmnopqrstuvwxyz"
                     "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                     "0123456789_";
  if ( strchr(word, next) &&  prev == '\0') { return 1; }
  if ( strchr(word, prev) &&  next == '\0') { return 1; }
  if ( strchr(word, next) && !strchr(word, prev)) { return 1; }
  if (!strchr(word, next) &&  strchr(word, prev)) { return 1; }
  return 0;
}

static int mpc_boundary_newline_anchor(char prev, char next) {
  (void)next;
  return prev == '\n';
}

mpc_parser_t *mpc_boundary(void) { return mpc_expect(mpc_anchor(mpc_boundary_anchor), "word boundary"); }
mpc_parser_t *mpc_boundary_newline(void) { return mpc_expect(mpc_anchor(mpc_boundary_newline_anchor), "start of newline"); }

mpc_parser_t *mpc_whitespace(void) { return mpc_expect(mpc_oneof(" \f\n\r\t\v"), "whitespace"); }
mpc_parser_t *mpc_whitespaces(void) { return mpc_expect(mpc_many(mpcf_strfold, mpc_whitespace()), "spaces"); }
mpc_parser_t *mpc_blank(void) { return mpc_expect(mpc_apply(mpc_whitespaces(), mpcf_free), "whitespace"); }

mpc_parser_t *mpc_newline(void) { return mpc_expect(mpc_char('\n'), "newline"); }
mpc_parser_t *mpc_tab(void) { return mpc_expect(mpc_char('\t'), "tab"); }
mpc_parser_t *mpc_escape(void) { return mpc_and(2, mpcf_strfold, mpc_char('\\'), mpc_any(), free); }

mpc_parser_t *mpc_digit(void) { return mpc_expect(mpc_oneof("0123456789"), "digit"); }
mpc_parser_t *mpc_hexdigit(void) { return mpc_expect(mpc_oneof("0123456789ABCDEFabcdef"), "hex digit"); }
mpc_parser_t *mpc_octdigit(void) { return mpc_expect(mpc_oneof("01234567"), "oct digit"); }
mpc_parser_t *mpc_digits(void) { return mpc_expect(mpc_many1(mpcf_strfold, mpc_digit()), "digits"); }
mpc_parser_t *mpc_hexdigits(void) { return mpc_expect(mpc_many1(mpcf_strfold, mpc_hexdigit()), "hex digits"); }
mpc_parser_t *mpc_octdigits(void) { return mpc_expect(mpc_many1(mpcf_strfold, mpc_octdigit()), "oct digits"); }

mpc_parser_t *mpc_lower(void) { return mpc_expect(mpc_oneof("abcdefghijklmnopqrstuvwxyz"), "lowercase letter"); }
mpc_parser_t *mpc_upper(void) { return mpc_expect(mpc_oneof("ABCDEFGHIJKLMNOPQRSTUVWXYZ"), "uppercase letter"); }
mpc_parser_t *mpc_alpha(void) { return mpc_expect(mpc_oneof("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"), "letter"); }
mpc_parser_t *mpc_underscore(void) { return mpc_expect(mpc_char('_'), "underscore"); }
mpc_parser_t *mpc_alphanum(void) { return mpc_expect(mpc_or(3, mpc_alpha(), mpc_digit(), mpc_underscore()), "alphanumeric"); }

mpc_parser_t *mpc_int(void) { return mpc_expect(mpc_apply(mpc_digits(), mpcf_int), "integer"); }
mpc_parser_t *mpc_hex(void) { return mpc_expect(mpc_apply(mpc_hexdigits(), mpcf_hex), "hexadecimal"); }
mpc_parser_t *mpc_oct(void) { return mpc_expect(mpc_apply(mpc_octdigits(), mpcf_oct), "octadecimal"); }
mpc_parser_t *mpc_number(void) { return mpc_expect(mpc_or(3, mpc_int(), mpc_hex(), mpc_oct()), "number"); }

mpc_parser_t *mpc_real(void) {

  /* [+-]?\d+(\.\d+)?([eE][+-]?[0-9]+)? */

  mpc_parser_t *p0, *p1, *p2, *p30, *p31, *p32, *p3;

  p0 = mpc_maybe_lift(mpc_oneof("+-"), mpcf_ctor_str);
  p1 = mpc_digits();
  p2 = mpc_maybe_lift(mpc_and(2, mpcf_strfold, mpc_char('.'), mpc_digits(), free), mpcf_ctor_str);
  p30 = mpc_oneof("eE");
  p31 = mpc_maybe_lift(mpc_oneof("+-"), mpcf_ctor_str);
  p32 = mpc_digits();
  p3 = mpc_maybe_lift(mpc_and(3, mpcf_strfold, p30, p31, p32, free, free), mpcf_ctor_str);

  return mpc_expect(mpc_and(4, mpcf_strfold, p0, p1, p2, p3, free, free, free), "real");

}

mpc_parser_t *mpc_float(void) {
  return mpc_expect(mpc_apply(mpc_real(), mpcf_float), "float");
}

mpc_parser_t *mpc_char_lit(void) {
  return mpc_expect(mpc_between(mpc_or(2, mpc_escape(), mpc_any()), free, "'", "'"), "char");
}

mpc_parser_t *mpc_string_lit(void) {
  mpc_parser_t *strchar = mpc_or(2, mpc_escape(), mpc_noneof("\""));
  return mpc_expect(mpc_between(mpc_many(mpcf_strfold, strchar), free, "\"", "\""), "string");
}

mpc_parser_t *mpc_regex_lit(void) {
  mpc_parser_t *regexchar = mpc_or(2, mpc_escape(), mpc_noneof("/"));
  return mpc_expect(mpc_between(mpc_many(mpcf_strfold, regexchar), free, "/", "/"), "regex");
}

mpc_parser_t *mpc_ident(void) {
  mpc_parser_t *p0, *p1;
  p0 = mpc_or(2, mpc_alpha(), mpc_underscore());
  p1 = mpc_many(mpcf_strfold, mpc_alphanum());
  return mpc_and(2, mpcf_strfold, p0, p1, free);
}

/*
** Useful Parsers
*/

mpc_parser_t *mpc_startwith(mpc_parser_t *a) { return mpc_and(2, mpcf_snd, mpc_soi(), a, mpcf_dtor_null); }
mpc_parser_t *mpc_endwith(mpc_parser_t *a, mpc_dtor_t da) { return mpc_and(2, mpcf_fst, a, mpc_eoi(), da); }
mpc_parser_t *mpc_whole(mpc_parser_t *a, mpc_dtor_t da) { return mpc_and(3, mpcf_snd, mpc_soi(), a, mpc_eoi(), mpcf_dtor_null, da); }

mpc_parser_t *mpc_stripl(mpc_parser_t *a) { return mpc_and(2, mpcf_snd, mpc_blank(), a, mpcf_dtor_null); }
mpc_parser_t *mpc_stripr(mpc_parser_t *a) { return mpc_and(2, mpcf_fst, a, mpc_blank(), mpcf_dtor_null); }
mpc_parser_t *mpc_strip(mpc_parser_t *a) { return mpc_and(3, mpcf_snd, mpc_blank(), a, mpc_blank(), mpcf_dtor_null, mpcf_dtor_null); }
mpc_parser_t *mpc_tok(mpc_parser_t *a) { return mpc_and(2, mpcf_fst, a, mpc_blank(), mpcf_dtor_null); }
mpc_parser_t *mpc_sym(const char *s) { return mpc_tok(mpc_string(s)); }

mpc_parser_t *mpc_total(mpc_parser_t *a, mpc_dtor_t da) { return mpc_whole(mpc_strip(a), da); }

mpc_parser_t *mpc_between(mpc_parser_t *a, mpc_dtor_t ad, const char *o, const char *c) {
  return mpc_and(3, mpcf_snd_free,
    mpc_string(o), a, mpc_string(c),
    free, ad);
}

mpc_parser_t *mpc_parens(mpc_parser_t *a, mpc_dtor_t ad)   { return mpc_between(a, ad, "(", ")"); }
mpc_parser_t *mpc_braces(mpc_parser_t *a, mpc_dtor_t ad)   { return mpc_between(a, ad, "<", ">"); }
mpc_parser_t *mpc_brackets(mpc_parser_t *a, mpc_dtor_t ad) { return mpc_between(a, ad, "{", "}"); }
mpc_parser_t *mpc_squares(mpc_parser_t *a, mpc_dtor_t ad)  { return mpc_between(a, ad, "[", "]"); }

mpc_parser_t *mpc_tok_between(mpc_parser_t *a, mpc_dtor_t ad, const char *o, const char *c) {
  return mpc_and(3, mpcf_snd_free,
    mpc_sym(o), mpc_tok(a), mpc_sym(c),
    free, ad);
}

mpc_parser_t *mpc_tok_parens(mpc_parser_t *a, mpc_dtor_t ad)   { return mpc_tok_between(a, ad, "(", ")"); }
mpc_parser_t *mpc_tok_braces(mpc_parser_t *a, mpc_dtor_t ad)   { return mpc_tok_between(a, ad, "<", ">"); }
mpc_parser_t *mpc_tok_brackets(mpc_parser_t *a, mpc_dtor_t ad) { return mpc_tok_between(a, ad, "{", "}"); }
mpc_parser_t *mpc_tok_squares(mpc_parser_t *a, mpc_dtor_t ad)  { return mpc_tok_between(a, ad, "[", "]"); }

/*
** Regular Expression Parsers
*/

/*
** So here is a cute bootstrapping.
**
** I'm using the previously defined
** mpc constructs and functions to
** parse the user regex string and
** construct a parser from it.
**
** As it turns out lots of the standard
** mpc functions look a lot like `fold`
** functions and so can be used indirectly
** by many of the parsing functions to build
** a parser directly - as we are parsing.
**
** This is certainly something that
** would be less elegant/interesting
** in a two-phase parser which first
** builds an AST and then traverses it
** to generate the object.
**
** This whole thing acts as a great
** case study for how trivial it can be
** to write a great parser in a few
** lines of code using mpc.
*/

/*
**
**  ### Regular Expression Grammar
**
**      <regex> : <term> | (<term> "|" <regex>)
**
**      <term> : <factor>*
**
**      <factor> : <base>
**               | <base> "*"
**               | <base> "+"
**               | <base> "?"
**               | <base> "{" <digits> "}"
**
**      <base> : <char>
**             | "\" <char>
**             | "(" <regex> ")"
**             | "[" <range> "]"
*/

static mpc_val_t *mpcf_re_or(int n, mpc_val_t **xs) {
  (void) n;
  if (xs[1] == NULL) { return xs[0]; }
  else { return mpc_or(2, xs[0], xs[1]); }
}

static mpc_val_t *mpcf_re_and(int n, mpc_val_t **xs) {
  int i;
  mpc_parser_t *p = mpc_lift(mpcf_ctor_str);
  for (i = 0; i < n; i++) {
    p = mpc_and(2, mpcf_strfold, p, xs[i], free);
  }
  return p;
}

static mpc_val_t *mpcf_re_repeat(int n, mpc_val_t **xs) {
  int num;
  (void) n;
  if (xs[1] == NULL) { return xs[0]; }
  switch(((char*)xs[1])[0])
  {
    case '*': { free(xs[1]); return mpc_many(mpcf_strfold, xs[0]); }; break;
    case '+': { free(xs[1]); return mpc_many1(mpcf_strfold, xs[0]); }; break;
    case '?': { free(xs[1]); return mpc_maybe_lift(xs[0], mpcf_ctor_str); }; break;
    default:
      num = *(int*)xs[1];
      free(xs[1]);
  }

  return mpc_count(num, mpcf_strfold, xs[0], free);
}

static mpc_parser_t *mpc_re_escape_char(char c) {
  switch (c) {
    case 'a': return mpc_char('\a');
    case 'f': return mpc_char('\f');
    case 'n': return mpc_char('\n');
    case 'r': return mpc_char('\r');
    case 't': return mpc_char('\t');
    case 'v': return mpc_char('\v');
    case 'b': return mpc_and(2, mpcf_snd, mpc_boundary(), mpc_lift(mpcf_ctor_str), free);
    case 'B': return mpc_not_lift(mpc_boundary(), free, mpcf_ctor_str);
    case 'A': return mpc_and(2, mpcf_snd, mpc_soi(), mpc_lift(mpcf_ctor_str), free);
    case 'Z': return mpc_and(2, mpcf_snd, mpc_eoi(), mpc_lift(mpcf_ctor_str), free);
    case 'd': return mpc_digit();
    case 'D': return mpc_not_lift(mpc_digit(), free, mpcf_ctor_str);
    case 's': return mpc_whitespace();
    case 'S': return mpc_not_lift(mpc_whitespace(), free, mpcf_ctor_str);
    case 'w': return mpc_alphanum();
    case 'W': return mpc_not_lift(mpc_alphanum(), free, mpcf_ctor_str);
    default: return NULL;
  }
}

static mpc_val_t *mpcf_re_escape(mpc_val_t *x, void* data) {

  int mode = *((int*)data);
  char *s = x;
  mpc_parser_t *p;

  /* Any Character */
  if (s[0] == '.') {
    free(s);
    if (mode & MPC_RE_DOTALL) {
      return mpc_any();
    } else {
      return mpc_expect(mpc_noneof("\n"), "any character except a newline");
    }
  }

  /* Start of Input */
  if (s[0] == '^') {
    free(s);
    if (mode & MPC_RE_MULTILINE) {
      return mpc_and(2, mpcf_snd, mpc_or(2, mpc_soi(), mpc_boundary_newline()), mpc_lift(mpcf_ctor_str), free);
    } else {
      return mpc_and(2, mpcf_snd, mpc_soi(), mpc_lift(mpcf_ctor_str), free);
    }
  }

  /* End of Input */
  if (s[0] == '$') {
    free(s);
    if (mode & MPC_RE_MULTILINE) {
      return mpc_or(2,
        mpc_newline(),
        mpc_and(2, mpcf_snd, mpc_eoi(), mpc_lift(mpcf_ctor_str), free));
    } else {
      return mpc_or(2,
        mpc_and(2, mpcf_fst, mpc_newline(), mpc_eoi(), free),
        mpc_and(2, mpcf_snd, mpc_eoi(), mpc_lift(mpcf_ctor_str), free));
    }
  }

  /* Regex Escape */
  if (s[0] == '\\') {
    p = mpc_re_escape_char(s[1]);
    p = (p == NULL) ? mpc_char(s[1]) : p;
    free(s);
    return p;
  }

  /* Regex Standard */
  p = mpc_char(s[0]);
  free(s);
  return p;
}

static const char *mpc_re_range_escape_char(char c) {
  switch (c) {
    case '-': return "-";
    case 'a': return "\a";
    case 'f': return "\f";
    case 'n': return "\n";
    case 'r': return "\r";
    case 't': return "\t";
    case 'v': return "\v";
    case 'b': return "\b";
    case 'd': return "0123456789";
    case 's': return " \f\n\r\t\v";
    case 'w': return "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_";
    default: return NULL;
  }
}

static mpc_val_t *mpcf_re_range(mpc_val_t *x) {

  mpc_parser_t *out;
  size_t i, j;
  size_t start, end;
  const char *tmp = NULL;
  const char *s = x;
  int comp = s[0] == '^' ? 1 : 0;
  char *range = calloc(1,1);

  if (s[0] == '\0') { free(range); free(x); return mpc_fail("Invalid Regex Range Expression"); }
  if (s[0] == '^' &&
      s[1] == '\0') { free(range); free(x); return mpc_fail("Invalid Regex Range Expression"); }

  for (i = comp; i < strlen(s); i++){

    /* Regex Range Escape */
    if (s[i] == '\\') {
      tmp = mpc_re_range_escape_char(s[i+1]);
      if (tmp != NULL) {
        range = realloc(range, strlen(range) + strlen(tmp) + 1);
        strcat(range, tmp);
      } else {
        range = realloc(range, strlen(range) + 1 + 1);
        range[strlen(range) + 1] = '\0';
        range[strlen(range) + 0] = s[i+1];
      }
      i++;
    }

    /* Regex Range...Range */
    else if (s[i] == '-') {
      if (s[i+1] == '\0' || i == 0) {
          range = realloc(range, strlen(range) + strlen("-") + 1);
          strcat(range, "-");
      } else {
        start = s[i-1]+1;
        end = s[i+1]-1;
        for (j = start; j <= end; j++) {
          range = realloc(range, strlen(range) + 1 + 1 + 1);
          range[strlen(range) + 1] = '\0';
          range[strlen(range) + 0] = (char)j;
        }
      }
    }

    /* Regex Range Normal */
    else {
      range = realloc(range, strlen(range) + 1 + 1);
      range[strlen(range) + 1] = '\0';
      range[strlen(range) + 0] = s[i];
    }

  }

  out = comp == 1 ? mpc_noneof(range) : mpc_oneof(range);

  free(x);
  free(range);

  return out;
}

mpc_parser_t *mpc_re(const char *re) {
  return mpc_re_mode(re, MPC_RE_DEFAULT);
}

mpc_parser_t *mpc_re_mode(const char *re, int mode) {

  char *err_msg;
  mpc_parser_t *err_out;
  mpc_result_t r;
  mpc_parser_t *Regex, *Term, *Factor, *Base, *Range, *RegexEnclose;

  Regex  = mpc_new("regex");
  Term   = mpc_new("term");
  Factor = mpc_new("factor");
  Base   = mpc_new("base");
  Range  = mpc_new("range");

  mpc_define(Regex, mpc_and(2, mpcf_re_or,
    Term,
    mpc_maybe(mpc_and(2, mpcf_snd_free, mpc_char('|'), Regex, free)),
    (mpc_dtor_t)mpc_delete
  ));

  mpc_define(Term, mpc_many(mpcf_re_and, Factor));

  mpc_define(Factor, mpc_and(2, mpcf_re_repeat,
    Base,
    mpc_or(5,
      mpc_char('*'), mpc_char('+'), mpc_char('?'),
      mpc_brackets(mpc_int(), free),
      mpc_pass()),
    (mpc_dtor_t)mpc_delete
  ));

  mpc_define(Base, mpc_or(4,
    mpc_parens(Regex, (mpc_dtor_t)mpc_delete),
    mpc_squares(Range, (mpc_dtor_t)mpc_delete),
    mpc_apply_to(mpc_escape(), mpcf_re_escape, &mode),
    mpc_apply_to(mpc_noneof(")|"), mpcf_re_escape, &mode)
  ));

  mpc_define(Range, mpc_apply(
    mpc_many(mpcf_strfold, mpc_or(2, mpc_escape(), mpc_noneof("]"))),
    mpcf_re_range
  ));

  RegexEnclose = mpc_whole(mpc_predictive(Regex), (mpc_dtor_t)mpc_delete);

  mpc_optimise(RegexEnclose);
  mpc_optimise(Regex);
  mpc_optimise(Term);
  mpc_optimise(Factor);
  mpc_optimise(Base);
  mpc_optimise(Range);

  if(!mpc_parse("<mpc_re_compiler>", re, RegexEnclose, &r)) {
    err_msg = mpc_err_string(r.error);
    err_out = mpc_failf("Invalid Regex: %s", err_msg);
    mpc_err_delete(r.error);
    free(err_msg);
    r.output = err_out;
  }

  mpc_cleanup(6, RegexEnclose, Regex, Term, Factor, Base, Range);

  mpc_optimise(r.output);

  return r.output;

}

/*
** Common Fold Functions
*/

void mpcf_dtor_null(mpc_val_t *x) { (void) x; return; }

mpc_val_t *mpcf_ctor_null(void) { return NULL; }
mpc_val_t *mpcf_ctor_str(void) { return calloc(1, 1); }
mpc_val_t *mpcf_free(mpc_val_t *x) { free(x); return NULL; }

mpc_val_t *mpcf_int(mpc_val_t *x) {
  int *y = malloc(sizeof(int));
  *y = strtol(x, NULL, 10);
  free(x);
  return y;
}

mpc_val_t *mpcf_hex(mpc_val_t *x) {
  int *y = malloc(sizeof(int));
  *y = strtol(x, NULL, 16);
  free(x);
  return y;
}

mpc_val_t *mpcf_oct(mpc_val_t *x) {
  int *y = malloc(sizeof(int));
  *y = strtol(x, NULL, 8);
  free(x);
  return y;
}

mpc_val_t *mpcf_float(mpc_val_t *x) {
  float *y = malloc(sizeof(float));
  *y = strtod(x, NULL);
  free(x);
  return y;
}

mpc_val_t *mpcf_strtriml(mpc_val_t *x) {
  char *s = x;
  while (isspace((unsigned char)*s)) {
    memmove(s, s+1, strlen(s));
  }
  return s;
}

mpc_val_t *mpcf_strtrimr(mpc_val_t *x) {
  char *s = x;
  size_t l = strlen(s);
  while (isspace((unsigned char)s[l-1])) {
    s[l-1] = '\0'; l--;
  }
  return s;
}

mpc_val_t *mpcf_strtrim(mpc_val_t *x) {
  return mpcf_strtriml(mpcf_strtrimr(x));
}

static const char mpc_escape_input_c[]  = {
  '\a', '\b', '\f', '\n', '\r',
  '\t', '\v', '\\', '\'', '\"', '\0'};

static const char *mpc_escape_output_c[] = {
  "\\a", "\\b", "\\f", "\\n", "\\r", "\\t",
  "\\v", "\\\\", "\\'", "\\\"", "\\0", NULL};

static const char mpc_escape_input_raw_re[] = { '/' };
static const char *mpc_escape_output_raw_re[] = { "\\/", NULL };

static const char mpc_escape_input_raw_cstr[] = { '"' };
static const char *mpc_escape_output_raw_cstr[] = { "\\\"", NULL };

static const char mpc_escape_input_raw_cchar[] = { '\'' };
static const char *mpc_escape_output_raw_cchar[] = { "\\'", NULL };

static mpc_val_t *mpcf_escape_new(mpc_val_t *x, const char *input, const char **output) {

  int i;
  int found;
  char buff[2];
  char *s = x;
  char *y = calloc(1, 1);

  while (*s) {

    i = 0;
    found = 0;

    while (output[i]) {
      if (*s == input[i]) {
        y = realloc(y, strlen(y) + strlen(output[i]) + 1);
        strcat(y, output[i]);
        found = 1;
        break;
      }
      i++;
    }

    if (!found) {
      y = realloc(y, strlen(y) + 2);
      buff[0] = *s; buff[1] = '\0';
      strcat(y, buff);
    }

    s++;
  }


  return y;
}

static mpc_val_t *mpcf_unescape_new(mpc_val_t *x, const char *input, const char **output) {

  int i;
  int found = 0;
  char buff[2];
  char *s = x;
  char *y = calloc(1, 1);

  while (*s) {

    i = 0;
    found = 0;

    while (output[i]) {
      if ((*(s+0)) == output[i][0] &&
          (*(s+1)) == output[i][1]) {
        y = realloc(y, strlen(y) + 1 + 1);
        buff[0] = input[i]; buff[1] = '\0';
        strcat(y, buff);
        found = 1;
        s++;
        break;
      }
      i++;
    }

    if (!found) {
      y = realloc(y, strlen(y) + 1 + 1);
      buff[0] = *s; buff[1] = '\0';
      strcat(y, buff);
    }

    if (*s == '\0') { break; }
    else { s++; }
  }

  return y;

}

mpc_val_t *mpcf_escape(mpc_val_t *x) {
  mpc_val_t *y = mpcf_escape_new(x, mpc_escape_input_c, mpc_escape_output_c);
  free(x);
  return y;
}

mpc_val_t *mpcf_unescape(mpc_val_t *x) {
  mpc_val_t *y = mpcf_unescape_new(x, mpc_escape_input_c, mpc_escape_output_c);
  free(x);
  return y;
}

mpc_val_t *mpcf_escape_regex(mpc_val_t *x) {
  mpc_val_t *y = mpcf_escape_new(x, mpc_escape_input_raw_re, mpc_escape_output_raw_re);
  free(x);
  return y;
}

mpc_val_t *mpcf_unescape_regex(mpc_val_t *x) {
  mpc_val_t *y = mpcf_unescape_new(x, mpc_escape_input_raw_re, mpc_escape_output_raw_re);
  free(x);
  return y;
}

mpc_val_t *mpcf_escape_string_raw(mpc_val_t *x) {
  mpc_val_t *y = mpcf_escape_new(x, mpc_escape_input_raw_cstr, mpc_escape_output_raw_cstr);
  free(x);
  return y;
}

mpc_val_t *mpcf_unescape_string_raw(mpc_val_t *x) {
  mpc_val_t *y = mpcf_unescape_new(x, mpc_escape_input_raw_cstr, mpc_escape_output_raw_cstr);
  free(x);
  return y;
}

mpc_val_t *mpcf_escape_char_raw(mpc_val_t *x) {
  mpc_val_t *y = mpcf_escape_new(x, mpc_escape_input_raw_cchar, mpc_escape_output_raw_cchar);
  free(x);
  return y;
}

mpc_val_t *mpcf_unescape_char_raw(mpc_val_t *x) {
  mpc_val_t *y = mpcf_unescape_new(x, mpc_escape_input_raw_cchar, mpc_escape_output_raw_cchar);
  free(x);
  return y;
}

mpc_val_t *mpcf_null(int n, mpc_val_t** xs) { (void) n; (void) xs; return NULL; }
mpc_val_t *mpcf_fst(int n, mpc_val_t **xs) { (void) n; return xs[0]; }
mpc_val_t *mpcf_snd(int n, mpc_val_t **xs) { (void) n; return xs[1]; }
mpc_val_t *mpcf_trd(int n, mpc_val_t **xs) { (void) n; return xs[2]; }

static mpc_val_t *mpcf_nth_free(int n, mpc_val_t **xs, int x) {
  int i;
  for (i = 0; i < n; i++) {
    if (i != x) { free(xs[i]); }
  }
  return xs[x];
}

mpc_val_t *mpcf_fst_free(int n, mpc_val_t **xs) { return mpcf_nth_free(n, xs, 0); }
mpc_val_t *mpcf_snd_free(int n, mpc_val_t **xs) { return mpcf_nth_free(n, xs, 1); }
mpc_val_t *mpcf_trd_free(int n, mpc_val_t **xs) { return mpcf_nth_free(n, xs, 2); }

mpc_val_t *mpcf_freefold(int n, mpc_val_t **xs) {
  int i;
  for (i = 0; i < n; i++) {
    free(xs[i]);
  }
  return NULL;
}

mpc_val_t *mpcf_strfold(int n, mpc_val_t **xs) {
  int i;
  size_t l = 0;

  if (n == 0) { return calloc(1, 1); }

  for (i = 0; i < n; i++) { l += strlen(xs[i]); }

  xs[0] = realloc(xs[0], l + 1);

  for (i = 1; i < n; i++) {
    strcat(xs[0], xs[i]); free(xs[i]);
  }

  return xs[0];
}

mpc_val_t *mpcf_maths(int n, mpc_val_t **xs) {
  int **vs = (int**)xs;
  (void) n;

  switch(((char*)xs[1])[0])
  {
    case '*': { *vs[0] *= *vs[2]; }; break;
    case '/': { *vs[0] /= *vs[2]; }; break;
    case '%': { *vs[0] %= *vs[2]; }; break;
    case '+': { *vs[0] += *vs[2]; }; break;
    case '-': { *vs[0] -= *vs[2]; }; break;
    default: break;
  }

  free(xs[1]); free(xs[2]);

  return xs[0];
}

/*
** Printing
*/

static void mpc_print_unretained(mpc_parser_t *p, int force) {

  /* TODO: Print Everything Escaped */

  int i;
  char *s, *e;
  char buff[2];

  if (p->retained && !force) {;
    if (p->name) { printf("<%s>", p->name); }
    else { printf("<anon>"); }
    return;
  }

  if (p->type == MPC_TYPE_UNDEFINED) { printf("<?>"); }
  if (p->type == MPC_TYPE_PASS)   { printf("<:>"); }
  if (p->type == MPC_TYPE_FAIL)   { printf("<!>"); }
  if (p->type == MPC_TYPE_LIFT)   { printf("<#>"); }
  if (p->type == MPC_TYPE_STATE)  { printf("<S>"); }
  if (p->type == MPC_TYPE_ANCHOR) { printf("<@>"); }
  if (p->type == MPC_TYPE_EXPECT) {
    printf("%s", p->data.expect.m);
    /*mpc_print_unretained(p->data.expect.x, 0);*/
  }

  if (p->type == MPC_TYPE_ANY) { printf("<.>"); }
  if (p->type == MPC_TYPE_SATISFY) { printf("<f>"); }

  if (p->type == MPC_TYPE_SINGLE) {
    buff[0] = p->data.single.x; buff[1] = '\0';
    s = mpcf_escape_new(
      buff,
      mpc_escape_input_c,
      mpc_escape_output_c);
    printf("'%s'", s);
    free(s);
  }

  if (p->type == MPC_TYPE_RANGE) {
    buff[0] = p->data.range.x; buff[1] = '\0';
    s = mpcf_escape_new(
      buff,
      mpc_escape_input_c,
      mpc_escape_output_c);
    buff[0] = p->data.range.y; buff[1] = '\0';
    e = mpcf_escape_new(
      buff,
      mpc_escape_input_c,
      mpc_escape_output_c);
    printf("[%s-%s]", s, e);
    free(s);
    free(e);
  }

  if (p->type == MPC_TYPE_ONEOF) {
    s = mpcf_escape_new(
      p->data.string.x,
      mpc_escape_input_c,
      mpc_escape_output_c);
    printf("[%s]", s);
    free(s);
  }

  if (p->type == MPC_TYPE_NONEOF) {
    s = mpcf_escape_new(
      p->data.string.x,
      mpc_escape_input_c,
      mpc_escape_output_c);
    printf("[^%s]", s);
    free(s);
  }

  if (p->type == MPC_TYPE_STRING) {
    s = mpcf_escape_new(
      p->data.string.x,
      mpc_escape_input_c,
      mpc_escape_output_c);
    printf("\"%s\"", s);
    free(s);
  }

  if (p->type == MPC_TYPE_APPLY)    { mpc_print_unretained(p->data.apply.x, 0); }
  if (p->type == MPC_TYPE_APPLY_TO) { mpc_print_unretained(p->data.apply_to.x, 0); }
  if (p->type == MPC_TYPE_PREDICT)  { mpc_print_unretained(p->data.predict.x, 0); }

  if (p->type == MPC_TYPE_NOT)   { mpc_print_unretained(p->data.not.x, 0); printf("!"); }
  if (p->type == MPC_TYPE_MAYBE) { mpc_print_unretained(p->data.not.x, 0); printf("?"); }

  if (p->type == MPC_TYPE_MANY)  { mpc_print_unretained(p->data.repeat.x, 0); printf("*"); }
  if (p->type == MPC_TYPE_MANY1) { mpc_print_unretained(p->data.repeat.x, 0); printf("+"); }
  if (p->type == MPC_TYPE_COUNT) { mpc_print_unretained(p->data.repeat.x, 0); printf("{%i}", p->data.repeat.n); }

  if (p->type == MPC_TYPE_OR) {
    printf("(");
    for(i = 0; i < p->data.or.n-1; i++) {
      mpc_print_unretained(p->data.or.xs[i], 0);
      printf(" | ");
    }
    mpc_print_unretained(p->data.or.xs[p->data.or.n-1], 0);
    printf(")");
  }

  if (p->type == MPC_TYPE_AND) {
    printf("(");
    for(i = 0; i < p->data.and.n-1; i++) {
      mpc_print_unretained(p->data.and.xs[i], 0);
      printf(" ");
    }
    mpc_print_unretained(p->data.and.xs[p->data.and.n-1], 0);
    printf(")");
  }

  if (p->type == MPC_TYPE_CHECK) {
    mpc_print_unretained(p->data.check.x, 0);
    printf("->?");
  }
  if (p->type == MPC_TYPE_CHECK_WITH) {
    mpc_print_unretained(p->data.check_with.x, 0);
    printf("->?");
  }

}

void mpc_print(mpc_parser_t *p) {
  mpc_print_unretained(p, 1);
  printf("\n");
}

/*
** Testing
*/

/*
** These functions are slightly unwieldy and
** also the whole of the testing suite for mpc
** mpc is pretty shaky.
**
** It could do with a lot more tests and more
** precision. Currently I am only really testing
** changes off of the examples.
**
*/

int mpc_test_fail(mpc_parser_t *p, const char *s, const void *d,
  int(*tester)(const void*, const void*),
  mpc_dtor_t destructor,
  void(*printer)(const void*)) {
  mpc_result_t r;
  (void) printer;
  if (mpc_parse("<test>", s, p, &r)) {

    if (tester(r.output, d)) {
      destructor(r.output);
      return 0;
    } else {
      destructor(r.output);
      return 1;
    }

  } else {
    mpc_err_delete(r.error);
    return 1;
  }

}

int mpc_test_pass(mpc_parser_t *p, const char *s, const void *d,
  int(*tester)(const void*, const void*),
  mpc_dtor_t destructor,
  void(*printer)(const void*)) {

  mpc_result_t r;
  if (mpc_parse("<test>", s, p, &r)) {

    if (tester(r.output, d)) {
      destructor(r.output);
      return 1;
    } else {
      printf("Got "); printer(r.output); printf("\n");
      printf("Expected "); printer(d); printf("\n");
      destructor(r.output);
      return 0;
    }

  } else {
    mpc_err_print(r.error);
    mpc_err_delete(r.error);
    return 0;

  }

}


/*
** AST
*/

void mpc_ast_delete(mpc_ast_t *a) {

  int i;

  if (a == NULL) { return; }

  for (i = 0; i < a->children_num; i++) {
    mpc_ast_delete(a->children[i]);
  }

  free(a->children);
  free(a->tag);
  free(a->contents);
  free(a);

}

static void mpc_ast_delete_no_children(mpc_ast_t *a) {
  free(a->children);
  free(a->tag);
  free(a->contents);
  free(a);
}

mpc_ast_t *mpc_ast_new(const char *tag, const char *contents) {

  mpc_ast_t *a = malloc(sizeof(mpc_ast_t));

  a->tag = malloc(strlen(tag) + 1);
  strcpy(a->tag, tag);

  a->contents = malloc(strlen(contents) + 1);
  strcpy(a->contents, contents);

  a->state = mpc_state_new();

  a->children_num = 0;
  a->children = NULL;
  return a;

}

mpc_ast_t *mpc_ast_build(int n, const char *tag, ...) {

  mpc_ast_t *a = mpc_ast_new(tag, "");

  int i;
  va_list va;
  va_start(va, tag);

  for (i = 0; i < n; i++) {
    mpc_ast_add_child(a, va_arg(va, mpc_ast_t*));
  }

  va_end(va);

  return a;

}

mpc_ast_t *mpc_ast_add_root(mpc_ast_t *a) {

  mpc_ast_t *r;

  if (a == NULL) { return a; }
  if (a->children_num == 0) { return a; }
  if (a->children_num == 1) { return a; }

  r = mpc_ast_new(">", "");
  mpc_ast_add_child(r, a);
  return r;
}

int mpc_ast_eq(mpc_ast_t *a, mpc_ast_t *b) {

  int i;

  if (strcmp(a->tag, b->tag) != 0) { return 0; }
  if (strcmp(a->contents, b->contents) != 0) { return 0; }
  if (a->children_num != b->children_num) { return 0; }

  for (i = 0; i < a->children_num; i++) {
    if (!mpc_ast_eq(a->children[i], b->children[i])) { return 0; }
  }

  return 1;
}

mpc_ast_t *mpc_ast_add_child(mpc_ast_t *r, mpc_ast_t *a) {
  r->children_num++;
  r->children = realloc(r->children, sizeof(mpc_ast_t*) * r->children_num);
  r->children[r->children_num-1] = a;
  return r;
}

mpc_ast_t *mpc_ast_add_tag(mpc_ast_t *a, const char *t) {
  if (a == NULL) { return a; }
  a->tag = realloc(a->tag, strlen(t) + 1 + strlen(a->tag) + 1);
  memmove(a->tag + strlen(t) + 1, a->tag, strlen(a->tag)+1);
  memmove(a->tag, t, strlen(t));
  memmove(a->tag + strlen(t), "|", 1);
  return a;
}

mpc_ast_t *mpc_ast_add_root_tag(mpc_ast_t *a, const char *t) {
  if (a == NULL) { return a; }
  a->tag = realloc(a->tag, (strlen(t)-1) + strlen(a->tag) + 1);
  memmove(a->tag + (strlen(t)-1), a->tag, strlen(a->tag)+1);
  memmove(a->tag, t, (strlen(t)-1));
  return a;
}

mpc_ast_t *mpc_ast_tag(mpc_ast_t *a, const char *t) {
  a->tag = realloc(a->tag, strlen(t) + 1);
  strcpy(a->tag, t);
  return a;
}

mpc_ast_t *mpc_ast_state(mpc_ast_t *a, mpc_state_t s) {
  if (a == NULL) { return a; }
  a->state = s;
  return a;
}

static void mpc_ast_print_depth(mpc_ast_t *a, int d, FILE *fp) {

  int i;

  if (a == NULL) {
    fprintf(fp, "NULL\n");
    return;
  }

  for (i = 0; i < d; i++) { fprintf(fp, "  "); }

  if (strlen(a->contents)) {
    fprintf(fp, "%s:%lu:%lu '%s'\n", a->tag,
      (long unsigned int)(a->state.row+1),
      (long unsigned int)(a->state.col+1),
      a->contents);
  } else {
    fprintf(fp, "%s \n", a->tag);
  }

  for (i = 0; i < a->children_num; i++) {
    mpc_ast_print_depth(a->children[i], d+1, fp);
  }

}

void mpc_ast_print(mpc_ast_t *a) {
  mpc_ast_print_depth(a, 0, stdout);
}

void mpc_ast_print_to(mpc_ast_t *a, FILE *fp) {
  mpc_ast_print_depth(a, 0, fp);
}

int mpc_ast_get_index(mpc_ast_t *ast, const char *tag) {
  return mpc_ast_get_index_lb(ast, tag, 0);
}

int mpc_ast_get_index_lb(mpc_ast_t *ast, const char *tag, int lb) {
  int i;

  for(i=lb; i<ast->children_num; i++) {
    if(strcmp(ast->children[i]->tag, tag) == 0) {
      return i;
    }
  }

  return -1;
}

mpc_ast_t *mpc_ast_get_child(mpc_ast_t *ast, const char *tag) {
  return mpc_ast_get_child_lb(ast, tag, 0);
}

mpc_ast_t *mpc_ast_get_child_lb(mpc_ast_t *ast, const char *tag, int lb) {
  int i;

  for(i=lb; i<ast->children_num; i++) {
    if(strcmp(ast->children[i]->tag, tag) == 0) {
      return ast->children[i];
    }
  }

  return NULL;
}

mpc_ast_trav_t *mpc_ast_traverse_start(mpc_ast_t *ast,
                                       mpc_ast_trav_order_t order)
{
  mpc_ast_trav_t *trav, *n_trav;
  mpc_ast_t *cnode = ast;

  /* Create the traversal structure */
  trav = malloc(sizeof(mpc_ast_trav_t));
  trav->curr_node = cnode;
  trav->parent = NULL;
  trav->curr_child = 0;
  trav->order = order;

  /* Get start node */
  switch(order) {
    case mpc_ast_trav_order_pre:
      /* Nothing else is needed for pre order start */
      break;

    case mpc_ast_trav_order_post:
      while(cnode->children_num > 0) {
        cnode = cnode->children[0];

        n_trav = malloc(sizeof(mpc_ast_trav_t));
        n_trav->curr_node = cnode;
        n_trav->parent = trav;
        n_trav->curr_child = 0;
        n_trav->order = order;

        trav = n_trav;
      }

      break;

    default:
      /* Unreachable, but compiler complaints */
      break;
  }

  return trav;
}

mpc_ast_t *mpc_ast_traverse_next(mpc_ast_trav_t **trav) {
  mpc_ast_trav_t *n_trav, *to_free;
  mpc_ast_t *ret = NULL;
  int cchild;

  /* The end of traversal was reached */
  if(*trav == NULL) return NULL;

  switch((*trav)->order) {
    case mpc_ast_trav_order_pre:
      ret = (*trav)->curr_node;

      /* If there aren't any more children, go up */
      while(*trav != NULL &&
        (*trav)->curr_child >= (*trav)->curr_node->children_num)
      {
        to_free = *trav;
        *trav = (*trav)->parent;
        free(to_free);
      }

      /* If trav is NULL, the end was reached */
      if(*trav == NULL) {
        break;
      }

      /* Go to next child */
      n_trav = malloc(sizeof(mpc_ast_trav_t));

      cchild = (*trav)->curr_child;
      n_trav->curr_node = (*trav)->curr_node->children[cchild];
      n_trav->parent = *trav;
      n_trav->curr_child = 0;
      n_trav->order = (*trav)->order;

      (*trav)->curr_child++;
      *trav = n_trav;

      break;

    case mpc_ast_trav_order_post:
      ret = (*trav)->curr_node;

      /* Move up tree to the parent If the parent doesn't have any more nodes,
       * then this is the current node. If it does, move down to its left most
       * child. Also, free the previous traversal node */
      to_free = *trav;
      *trav = (*trav)->parent;
      free(to_free);

      if(*trav == NULL)
        break;

      /* Next child */
      (*trav)->curr_child++;

      /* If there aren't any more children, this is the next node */
      if((*trav)->curr_child >= (*trav)->curr_node->children_num) {
        break;
      }

      /* If there are still more children, find the leftmost child from this
       * node */
      while((*trav)->curr_node->children_num > 0) {
        n_trav = malloc(sizeof(mpc_ast_trav_t));

        cchild = (*trav)->curr_child;
        n_trav->curr_node = (*trav)->curr_node->children[cchild];
        n_trav->parent = *trav;
        n_trav->curr_child = 0;
        n_trav->order = (*trav)->order;

        *trav = n_trav;
      }

    default:
      /* Unreachable, but compiler complaints */
      break;
  }

  return ret;
}

void mpc_ast_traverse_free(mpc_ast_trav_t **trav) {
  mpc_ast_trav_t *n_trav;

  /* Go through parents until all are free */
  while(*trav != NULL) {
      n_trav = (*trav)->parent;
      free(*trav);
      *trav = n_trav;
  }
}

mpc_val_t *mpcf_fold_ast(int n, mpc_val_t **xs) {

  int i, j;
  mpc_ast_t** as = (mpc_ast_t**)xs;
  mpc_ast_t *r;

  if (n == 0) { return NULL; }
  if (n == 1) { return xs[0]; }
  if (n == 2 && xs[1] == NULL) { return xs[0]; }
  if (n == 2 && xs[0] == NULL) { return xs[1]; }

  r = mpc_ast_new(">", "");

  for (i = 0; i < n; i++) {

    if (as[i] == NULL) { continue; }

    if        (as[i] && as[i]->children_num == 0) {
      mpc_ast_add_child(r, as[i]);
    } else if (as[i] && as[i]->children_num == 1) {
      mpc_ast_add_child(r, mpc_ast_add_root_tag(as[i]->children[0], as[i]->tag));
      mpc_ast_delete_no_children(as[i]);
    } else if (as[i] && as[i]->children_num >= 2) {
      for (j = 0; j < as[i]->children_num; j++) {
        mpc_ast_add_child(r, as[i]->children[j]);
      }
      mpc_ast_delete_no_children(as[i]);
    }

  }

  if (r->children_num) {
    r->state = r->children[0]->state;
  }

  return r;
}

mpc_val_t *mpcf_str_ast(mpc_val_t *c) {
  mpc_ast_t *a = mpc_ast_new("", c);
  free(c);
  return a;
}

mpc_val_t *mpcf_state_ast(int n, mpc_val_t **xs) {
  mpc_state_t *s = ((mpc_state_t**)xs)[0];
  mpc_ast_t *a = ((mpc_ast_t**)xs)[1];
  (void)n;
  a = mpc_ast_state(a, *s);
  free(s);
  return a;
}

mpc_parser_t *mpca_state(mpc_parser_t *a) {
  return mpc_and(2, mpcf_state_ast, mpc_state(), a, free);
}

mpc_parser_t *mpca_tag(mpc_parser_t *a, const char *t) {
  return mpc_apply_to(a, (mpc_apply_to_t)mpc_ast_tag, (void*)t);
}

mpc_parser_t *mpca_add_tag(mpc_parser_t *a, const char *t) {
  return mpc_apply_to(a, (mpc_apply_to_t)mpc_ast_add_tag, (void*)t);
}

mpc_parser_t *mpca_root(mpc_parser_t *a) {
  return mpc_apply(a, (mpc_apply_t)mpc_ast_add_root);
}

mpc_parser_t *mpca_not(mpc_parser_t *a) { return mpc_not(a, (mpc_dtor_t)mpc_ast_delete); }
mpc_parser_t *mpca_maybe(mpc_parser_t *a) { return mpc_maybe(a); }
mpc_parser_t *mpca_many(mpc_parser_t *a) { return mpc_many(mpcf_fold_ast, a); }
mpc_parser_t *mpca_many1(mpc_parser_t *a) { return mpc_many1(mpcf_fold_ast, a); }
mpc_parser_t *mpca_count(int n, mpc_parser_t *a) { return mpc_count(n, mpcf_fold_ast, a, (mpc_dtor_t)mpc_ast_delete); }

mpc_parser_t *mpca_or(int n, ...) {

  int i;
  va_list va;

  mpc_parser_t *p = mpc_undefined();

  p->type = MPC_TYPE_OR;
  p->data.or.n = n;
  p->data.or.xs = malloc(sizeof(mpc_parser_t*) * n);

  va_start(va, n);
  for (i = 0; i < n; i++) {
    p->data.or.xs[i] = va_arg(va, mpc_parser_t*);
  }
  va_end(va);

  return p;

}

mpc_parser_t *mpca_and(int n, ...) {

  int i;
  va_list va;

  mpc_parser_t *p = mpc_undefined();

  p->type = MPC_TYPE_AND;
  p->data.and.n = n;
  p->data.and.f = mpcf_fold_ast;
  p->data.and.xs = malloc(sizeof(mpc_parser_t*) * n);
  p->data.and.dxs = malloc(sizeof(mpc_dtor_t) * (n-1));

  va_start(va, n);
  for (i = 0; i < n; i++) {
    p->data.and.xs[i] = va_arg(va, mpc_parser_t*);
  }
  for (i = 0; i < (n-1); i++) {
    p->data.and.dxs[i] = (mpc_dtor_t)mpc_ast_delete;
  }
  va_end(va);

  return p;
}

mpc_parser_t *mpca_total(mpc_parser_t *a) { return mpc_total(a, (mpc_dtor_t)mpc_ast_delete); }

/*
** Grammar Parser
*/

/*
** This is another interesting bootstrapping.
**
** Having a general purpose AST type allows
** users to specify the grammar alone and
** let all fold rules be automatically taken
** care of by existing functions.
**
** You don't get to control the type spat
** out but this means you can make a nice
** parser to take in some grammar in nice
** syntax and spit out a parser that works.
**
** The grammar for this looks surprisingly
** like regex but the main difference is that
** it is now whitespace insensitive and the
** base type takes literals of some form.
*/

/*
**
**  ### Grammar Grammar
**
**      <grammar> : (<term> "|" <grammar>) | <term>
**
**      <term> : <factor>*
**
**      <factor> : <base>
**               | <base> "*"
**               | <base> "+"
**               | <base> "?"
**               | <base> "{" <digits> "}"
**
**      <base> : "<" (<digits> | <ident>) ">"
**             | <string_lit>
**             | <char_lit>
**             | <regex_lit> <regex_mode>
**             | "(" <grammar> ")"
*/

typedef struct {
  va_list *va;
  int parsers_num;
  mpc_parser_t **parsers;
  int flags;
} mpca_grammar_st_t;

static mpc_val_t *mpcaf_grammar_or(int n, mpc_val_t **xs) {
  (void) n;
  if (xs[1] == NULL) { return xs[0]; }
  else { return mpca_or(2, xs[0], xs[1]); }
}

static mpc_val_t *mpcaf_grammar_and(int n, mpc_val_t **xs) {
  int i;
  mpc_parser_t *p = mpc_pass();
  for (i = 0; i < n; i++) {
    if (xs[i] != NULL) { p = mpca_and(2, p, xs[i]); }
  }
  return p;
}

static mpc_val_t *mpcaf_grammar_repeat(int n, mpc_val_t **xs) {
  int num;
  (void) n;
  if (xs[1] == NULL) { return xs[0]; }
  switch(((char*)xs[1])[0])
  {
    case '*': { free(xs[1]); return mpca_many(xs[0]); }; break;
    case '+': { free(xs[1]); return mpca_many1(xs[0]); }; break;
    case '?': { free(xs[1]); return mpca_maybe(xs[0]); }; break;
    case '!': { free(xs[1]); return mpca_not(xs[0]); }; break;
    default:
      num = *((int*)xs[1]);
      free(xs[1]);
  }
  return mpca_count(num, xs[0]);
}

static mpc_val_t *mpcaf_grammar_string(mpc_val_t *x, void *s) {
  mpca_grammar_st_t *st = s;
  char *y = mpcf_unescape(x);
  mpc_parser_t *p = (st->flags & MPCA_LANG_WHITESPACE_SENSITIVE) ? mpc_string(y) : mpc_tok(mpc_string(y));
  free(y);
  return mpca_state(mpca_tag(mpc_apply(p, mpcf_str_ast), "string"));
}

static mpc_val_t *mpcaf_grammar_char(mpc_val_t *x, void *s) {
  mpca_grammar_st_t *st = s;
  char *y = mpcf_unescape(x);
  mpc_parser_t *p = (st->flags & MPCA_LANG_WHITESPACE_SENSITIVE) ? mpc_char(y[0]) : mpc_tok(mpc_char(y[0]));
  free(y);
  return mpca_state(mpca_tag(mpc_apply(p, mpcf_str_ast), "char"));
}

static mpc_val_t *mpcaf_fold_regex(int n, mpc_val_t **xs) {
  char *y = xs[0];
  char *m = xs[1];
  mpca_grammar_st_t *st = xs[2];
  mpc_parser_t *p;
  int mode = MPC_RE_DEFAULT;

  (void)n;
  if (strchr(m, 'm')) { mode |= MPC_RE_MULTILINE; }
  if (strchr(m, 's')) { mode |= MPC_RE_DOTALL; }
  y = mpcf_unescape_regex(y);
  p = (st->flags & MPCA_LANG_WHITESPACE_SENSITIVE) ? mpc_re_mode(y, mode) : mpc_tok(mpc_re_mode(y, mode));
  free(y);
  free(m);

  return mpca_state(mpca_tag(mpc_apply(p, mpcf_str_ast), "regex"));
}

/* Should this just use `isdigit` instead? */
static int is_number(const char* s) {
  size_t i;
  for (i = 0; i < strlen(s); i++) { if (!strchr("0123456789", s[i])) { return 0; } }
  return 1;
}

static mpc_parser_t *mpca_grammar_find_parser(char *x, mpca_grammar_st_t *st) {

  int i;
  mpc_parser_t *p;

  /* Case of Number */
  if (is_number(x)) {

    i = strtol(x, NULL, 10);

    while (st->parsers_num <= i) {
      st->parsers_num++;
      st->parsers = realloc(st->parsers, sizeof(mpc_parser_t*) * st->parsers_num);
      st->parsers[st->parsers_num-1] = va_arg(*st->va, mpc_parser_t*);
      if (st->parsers[st->parsers_num-1] == NULL) {
        return mpc_failf("No Parser in position %i! Only supplied %i Parsers!", i, st->parsers_num);
      }
    }

    return st->parsers[st->parsers_num-1];

  /* Case of Identifier */
  } else {

    /* Search Existing Parsers */
    for (i = 0; i < st->parsers_num; i++) {
      mpc_parser_t *q = st->parsers[i];
      if (q == NULL) { return mpc_failf("Unknown Parser '%s'!", x); }
      if (q->name && strcmp(q->name, x) == 0) { return q; }
    }

    /* Search New Parsers */
    while (1) {

      p = va_arg(*st->va, mpc_parser_t*);

      st->parsers_num++;
      st->parsers = realloc(st->parsers, sizeof(mpc_parser_t*) * st->parsers_num);
      st->parsers[st->parsers_num-1] = p;

      if (p == NULL || p->name == NULL) { return mpc_failf("Unknown Parser '%s'!", x); }
      if (p->name && strcmp(p->name, x) == 0) { return p; }

    }

  }

}

static mpc_val_t *mpcaf_grammar_id(mpc_val_t *x, void *s) {

  mpca_grammar_st_t *st = s;
  mpc_parser_t *p = mpca_grammar_find_parser(x, st);
  free(x);

  if (p->name) {
    return mpca_state(mpca_root(mpca_add_tag(p, p->name)));
  } else {
    return mpca_state(mpca_root(p));
  }
}

mpc_parser_t *mpca_grammar_st(const char *grammar, mpca_grammar_st_t *st) {

  char *err_msg;
  mpc_parser_t *err_out;
  mpc_result_t r;
  mpc_parser_t *GrammarTotal, *Grammar, *Term, *Factor, *Base;

  GrammarTotal = mpc_new("grammar_total");
  Grammar = mpc_new("grammar");
  Term = mpc_new("term");
  Factor = mpc_new("factor");
  Base = mpc_new("base");

  mpc_define(GrammarTotal,
    mpc_predictive(mpc_total(Grammar, mpc_soft_delete))
  );

  mpc_define(Grammar, mpc_and(2, mpcaf_grammar_or,
    Term,
    mpc_maybe(mpc_and(2, mpcf_snd_free, mpc_sym("|"), Grammar, free)),
    mpc_soft_delete
  ));

  mpc_define(Term, mpc_many1(mpcaf_grammar_and, Factor));

  mpc_define(Factor, mpc_and(2, mpcaf_grammar_repeat,
    Base,
      mpc_or(6,
        mpc_sym("*"),
        mpc_sym("+"),
        mpc_sym("?"),
        mpc_sym("!"),
        mpc_tok_brackets(mpc_int(), free),
        mpc_pass()),
    mpc_soft_delete
  ));

  mpc_define(Base, mpc_or(5,
    mpc_apply_to(mpc_tok(mpc_string_lit()), mpcaf_grammar_string, st),
    mpc_apply_to(mpc_tok(mpc_char_lit()),   mpcaf_grammar_char, st),
    mpc_tok(mpc_and(3, mpcaf_fold_regex, mpc_regex_lit(), mpc_many(mpcf_strfold, mpc_oneof("ms")), mpc_lift_val(st), free, free)),
    mpc_apply_to(mpc_tok_braces(mpc_or(2, mpc_digits(), mpc_ident()), free), mpcaf_grammar_id, st),
    mpc_tok_parens(Grammar, mpc_soft_delete)
  ));

  mpc_optimise(GrammarTotal);
  mpc_optimise(Grammar);
  mpc_optimise(Factor);
  mpc_optimise(Term);
  mpc_optimise(Base);

  if(!mpc_parse("<mpc_grammar_compiler>", grammar, GrammarTotal, &r)) {
    err_msg = mpc_err_string(r.error);
    err_out = mpc_failf("Invalid Grammar: %s", err_msg);
    mpc_err_delete(r.error);
    free(err_msg);
    r.output = err_out;
  }

  mpc_cleanup(5, GrammarTotal, Grammar, Term, Factor, Base);

  mpc_optimise(r.output);

  return (st->flags & MPCA_LANG_PREDICTIVE) ? mpc_predictive(r.output) : r.output;

}

mpc_parser_t *mpca_grammar(int flags, const char *grammar, ...) {
  mpca_grammar_st_t st;
  mpc_parser_t *res;
  va_list va;
  va_start(va, grammar);

  st.va = &va;
  st.parsers_num = 0;
  st.parsers = NULL;
  st.flags = flags;

  res = mpca_grammar_st(grammar, &st);
  free(st.parsers);
  va_end(va);
  return res;
}

typedef struct {
  char *ident;
  char *name;
  mpc_parser_t *grammar;
} mpca_stmt_t;

static mpc_val_t *mpca_stmt_afold(int n, mpc_val_t **xs) {
  mpca_stmt_t *stmt = malloc(sizeof(mpca_stmt_t));
  stmt->ident = ((char**)xs)[0];
  stmt->name = ((char**)xs)[1];
  stmt->grammar = ((mpc_parser_t**)xs)[3];
  (void) n;
  free(((char**)xs)[2]);
  free(((char**)xs)[4]);

  return stmt;
}

static mpc_val_t *mpca_stmt_fold(int n, mpc_val_t **xs) {

  int i;
  mpca_stmt_t **stmts = malloc(sizeof(mpca_stmt_t*) * (n+1));

  for (i = 0; i < n; i++) {
    stmts[i] = xs[i];
  }
  stmts[n] = NULL;

  return stmts;
}

static void mpca_stmt_list_delete(mpc_val_t *x) {

  mpca_stmt_t **stmts = x;

  while(*stmts) {
    mpca_stmt_t *stmt = *stmts;
    free(stmt->ident);
    free(stmt->name);
    mpc_soft_delete(stmt->grammar);
    free(stmt);
    stmts++;
  }
  free(x);

}

static mpc_val_t *mpca_stmt_list_apply_to(mpc_val_t *x, void *s) {

  mpca_grammar_st_t *st = s;
  mpca_stmt_t *stmt;
  mpca_stmt_t **stmts = x;
  mpc_parser_t *left;

  while(*stmts) {
    stmt = *stmts;
    left = mpca_grammar_find_parser(stmt->ident, st);
    if (st->flags & MPCA_LANG_PREDICTIVE) { stmt->grammar = mpc_predictive(stmt->grammar); }
    if (stmt->name) { stmt->grammar = mpc_expect(stmt->grammar, stmt->name); }
    mpc_optimise(stmt->grammar);
    mpc_define(left, stmt->grammar);
    free(stmt->ident);
    free(stmt->name);
    free(stmt);
    stmts++;
  }

  free(x);

  return NULL;
}

static mpc_err_t *mpca_lang_st(mpc_input_t *i, mpca_grammar_st_t *st) {

  mpc_result_t r;
  mpc_err_t *e;
  mpc_parser_t *Lang, *Stmt, *Grammar, *Term, *Factor, *Base;

  Lang    = mpc_new("lang");
  Stmt    = mpc_new("stmt");
  Grammar = mpc_new("grammar");
  Term    = mpc_new("term");
  Factor  = mpc_new("factor");
  Base    = mpc_new("base");

  mpc_define(Lang, mpc_apply_to(
    mpc_total(mpc_predictive(mpc_many(mpca_stmt_fold, Stmt)), mpca_stmt_list_delete),
    mpca_stmt_list_apply_to, st
  ));

  mpc_define(Stmt, mpc_and(5, mpca_stmt_afold,
    mpc_tok(mpc_ident()), mpc_maybe(mpc_tok(mpc_string_lit())), mpc_sym(":"), Grammar, mpc_sym(";"),
    free, free, free, mpc_soft_delete
  ));

  mpc_define(Grammar, mpc_and(2, mpcaf_grammar_or,
      Term,
      mpc_maybe(mpc_and(2, mpcf_snd_free, mpc_sym("|"), Grammar, free)),
      mpc_soft_delete
  ));

  mpc_define(Term, mpc_many1(mpcaf_grammar_and, Factor));

  mpc_define(Factor, mpc_and(2, mpcaf_grammar_repeat,
    Base,
      mpc_or(6,
        mpc_sym("*"),
        mpc_sym("+"),
        mpc_sym("?"),
        mpc_sym("!"),
        mpc_tok_brackets(mpc_int(), free),
        mpc_pass()),
    mpc_soft_delete
  ));

  mpc_define(Base, mpc_or(5,
    mpc_apply_to(mpc_tok(mpc_string_lit()), mpcaf_grammar_string, st),
    mpc_apply_to(mpc_tok(mpc_char_lit()),   mpcaf_grammar_char, st),
    mpc_tok(mpc_and(3, mpcaf_fold_regex, mpc_regex_lit(), mpc_many(mpcf_strfold, mpc_oneof("ms")), mpc_lift_val(st), free, free)),
    mpc_apply_to(mpc_tok_braces(mpc_or(2, mpc_digits(), mpc_ident()), free), mpcaf_grammar_id, st),
    mpc_tok_parens(Grammar, mpc_soft_delete)
  ));

  mpc_optimise(Lang);
  mpc_optimise(Stmt);
  mpc_optimise(Grammar);
  mpc_optimise(Term);
  mpc_optimise(Factor);
  mpc_optimise(Base);

  if (!mpc_parse_input(i, Lang, &r)) {
    e = r.error;
  } else {
    e = NULL;
  }

  mpc_cleanup(6, Lang, Stmt, Grammar, Term, Factor, Base);

  return e;
}

mpc_err_t *mpca_lang_file(int flags, FILE *f, ...) {
  mpca_grammar_st_t st;
  mpc_input_t *i;
  mpc_err_t *err;

  va_list va;
  va_start(va, f);

  st.va = &va;
  st.parsers_num = 0;
  st.parsers = NULL;
  st.flags = flags;

  i = mpc_input_new_file("<mpca_lang_file>", f);
  err = mpca_lang_st(i, &st);
  mpc_input_delete(i);

  free(st.parsers);
  va_end(va);
  return err;
}

mpc_err_t *mpca_lang_pipe(int flags, FILE *p, ...) {
  mpca_grammar_st_t st;
  mpc_input_t *i;
  mpc_err_t *err;

  va_list va;
  va_start(va, p);

  st.va = &va;
  st.parsers_num = 0;
  st.parsers = NULL;
  st.flags = flags;

  i = mpc_input_new_pipe("<mpca_lang_pipe>", p);
  err = mpca_lang_st(i, &st);
  mpc_input_delete(i);

  free(st.parsers);
  va_end(va);
  return err;
}

mpc_err_t *mpca_lang(int flags, const char *language, ...) {

  mpca_grammar_st_t st;
  mpc_input_t *i;
  mpc_err_t *err;

  va_list va;
  va_start(va, language);

  st.va = &va;
  st.parsers_num = 0;
  st.parsers = NULL;
  st.flags = flags;

  i = mpc_input_new_string("<mpca_lang>", language);
  err = mpca_lang_st(i, &st);
  mpc_input_delete(i);

  free(st.parsers);
  va_end(va);
  return err;
}

mpc_err_t *mpca_lang_contents(int flags, const char *filename, ...) {

  mpca_grammar_st_t st;
  mpc_input_t *i;
  mpc_err_t *err;

  va_list va;

  FILE *f = fopen(filename, "rb");

  if (f == NULL) {
    err = mpc_err_file(filename, "Unable to open file!");
    return err;
  }

  va_start(va, filename);

  st.va = &va;
  st.parsers_num = 0;
  st.parsers = NULL;
  st.flags = flags;

  i = mpc_input_new_file(filename, f);
  err = mpca_lang_st(i, &st);
  mpc_input_delete(i);

  free(st.parsers);
  va_end(va);

  fclose(f);

  return err;
}

static int mpc_nodecount_unretained(mpc_parser_t* p, int force) {

  int i, total;

  if (p->retained && !force) { return 0; }

  if (p->type == MPC_TYPE_EXPECT) { return 1 + mpc_nodecount_unretained(p->data.expect.x, 0); }

  if (p->type == MPC_TYPE_APPLY)    { return 1 + mpc_nodecount_unretained(p->data.apply.x, 0); }
  if (p->type == MPC_TYPE_APPLY_TO) { return 1 + mpc_nodecount_unretained(p->data.apply_to.x, 0); }
  if (p->type == MPC_TYPE_PREDICT)  { return 1 + mpc_nodecount_unretained(p->data.predict.x, 0); }

  if (p->type == MPC_TYPE_CHECK)    { return 1 + mpc_nodecount_unretained(p->data.check.x, 0); }
  if (p->type == MPC_TYPE_CHECK_WITH) { return 1 + mpc_nodecount_unretained(p->data.check_with.x, 0); }

  if (p->type == MPC_TYPE_NOT)   { return 1 + mpc_nodecount_unretained(p->data.not.x, 0); }
  if (p->type == MPC_TYPE_MAYBE) { return 1 + mpc_nodecount_unretained(p->data.not.x, 0); }

  if (p->type == MPC_TYPE_MANY)  { return 1 + mpc_nodecount_unretained(p->data.repeat.x, 0); }
  if (p->type == MPC_TYPE_MANY1) { return 1 + mpc_nodecount_unretained(p->data.repeat.x, 0); }
  if (p->type == MPC_TYPE_COUNT) { return 1 + mpc_nodecount_unretained(p->data.repeat.x, 0); }

  if (p->type == MPC_TYPE_OR) {
    total = 1;
    for(i = 0; i < p->data.or.n; i++) {
      total += mpc_nodecount_unretained(p->data.or.xs[i], 0);
    }
    return total;
  }

  if (p->type == MPC_TYPE_AND) {
    total = 1;
    for(i = 0; i < p->data.and.n; i++) {
      total += mpc_nodecount_unretained(p->data.and.xs[i], 0);
    }
    return total;
  }

  return 1;

}

void mpc_stats(mpc_parser_t* p) {
  printf("Stats\n");
  printf("=====\n");
  printf("Node Count: %i\n", mpc_nodecount_unretained(p, 1));
}

static void mpc_optimise_unretained(mpc_parser_t *p, int force) {

  int i, n, m;
  mpc_parser_t *t;

  if (p->retained && !force) { return; }

  /* Optimise Subexpressions */

  if (p->type == MPC_TYPE_EXPECT)     { mpc_optimise_unretained(p->data.expect.x, 0); }
  if (p->type == MPC_TYPE_APPLY)      { mpc_optimise_unretained(p->data.apply.x, 0); }
  if (p->type == MPC_TYPE_APPLY_TO)   { mpc_optimise_unretained(p->data.apply_to.x, 0); }
  if (p->type == MPC_TYPE_CHECK)      { mpc_optimise_unretained(p->data.check.x, 0); }
  if (p->type == MPC_TYPE_CHECK_WITH) { mpc_optimise_unretained(p->data.check_with.x, 0); }
  if (p->type == MPC_TYPE_PREDICT)    { mpc_optimise_unretained(p->data.predict.x, 0); }
  if (p->type == MPC_TYPE_NOT)        { mpc_optimise_unretained(p->data.not.x, 0); }
  if (p->type == MPC_TYPE_MAYBE)      { mpc_optimise_unretained(p->data.not.x, 0); }
  if (p->type == MPC_TYPE_MANY)       { mpc_optimise_unretained(p->data.repeat.x, 0); }
  if (p->type == MPC_TYPE_MANY1)      { mpc_optimise_unretained(p->data.repeat.x, 0); }
  if (p->type == MPC_TYPE_COUNT)      { mpc_optimise_unretained(p->data.repeat.x, 0); }

  if (p->type == MPC_TYPE_OR) {
    for(i = 0; i < p->data.or.n; i++) {
      mpc_optimise_unretained(p->data.or.xs[i], 0);
    }
  }

  if (p->type == MPC_TYPE_AND) {
    for(i = 0; i < p->data.and.n; i++) {
      mpc_optimise_unretained(p->data.and.xs[i], 0);
    }
  }

  /* Perform optimisations */

  while (1) {

    /* Merge rhs `or` */
    if (p->type == MPC_TYPE_OR
    &&  p->data.or.xs[p->data.or.n-1]->type == MPC_TYPE_OR
    && !p->data.or.xs[p->data.or.n-1]->retained) {
      t = p->data.or.xs[p->data.or.n-1];
      n = p->data.or.n; m = t->data.or.n;
      p->data.or.n = n + m - 1;
      p->data.or.xs = realloc(p->data.or.xs, sizeof(mpc_parser_t*) * (n + m -1));
      memmove(p->data.or.xs + n - 1, t->data.or.xs, m * sizeof(mpc_parser_t*));
      free(t->data.or.xs); free(t->name); free(t);
      continue;
    }

    /* Merge lhs `or` */
    if (p->type == MPC_TYPE_OR
    &&  p->data.or.xs[0]->type == MPC_TYPE_OR
    && !p->data.or.xs[0]->retained) {
      t = p->data.or.xs[0];
      n = p->data.or.n; m = t->data.or.n;
      p->data.or.n = n + m - 1;
      p->data.or.xs = realloc(p->data.or.xs, sizeof(mpc_parser_t*) * (n + m -1));
      memmove(p->data.or.xs + m, p->data.or.xs + 1, (n - 1) * sizeof(mpc_parser_t*));
      memmove(p->data.or.xs, t->data.or.xs, m * sizeof(mpc_parser_t*));
      free(t->data.or.xs); free(t->name); free(t);
      continue;
    }

    /* Remove ast `pass` */
    if (p->type == MPC_TYPE_AND
    &&  p->data.and.n == 2
    &&  p->data.and.xs[0]->type == MPC_TYPE_PASS
    && !p->data.and.xs[0]->retained
    &&  p->data.and.f == mpcf_fold_ast) {
      t = p->data.and.xs[1];
      mpc_delete(p->data.and.xs[0]);
      free(p->data.and.xs); free(p->data.and.dxs); free(p->name);
      memcpy(p, t, sizeof(mpc_parser_t));
      free(t);
      continue;
    }

    /* Merge ast lhs `and` */
    if (p->type == MPC_TYPE_AND
    &&  p->data.and.f == mpcf_fold_ast
    &&  p->data.and.xs[0]->type == MPC_TYPE_AND
    && !p->data.and.xs[0]->retained
    &&  p->data.and.xs[0]->data.and.f == mpcf_fold_ast) {
      t = p->data.and.xs[0];
      n = p->data.and.n; m = t->data.and.n;
      p->data.and.n = n + m - 1;
      p->data.and.xs = realloc(p->data.and.xs, sizeof(mpc_parser_t*) * (n + m - 1));
      p->data.and.dxs = realloc(p->data.and.dxs, sizeof(mpc_dtor_t) * (n + m - 1 - 1));
      memmove(p->data.and.xs + m, p->data.and.xs + 1, (n - 1) * sizeof(mpc_parser_t*));
      memmove(p->data.and.xs, t->data.and.xs, m * sizeof(mpc_parser_t*));
      for (i = 0; i < p->data.and.n-1; i++) { p->data.and.dxs[i] = (mpc_dtor_t)mpc_ast_delete; }
      free(t->data.and.xs); free(t->data.and.dxs); free(t->name); free(t);
      continue;
    }

    /* Merge ast rhs `and` */
    if (p->type == MPC_TYPE_AND
    &&  p->data.and.f == mpcf_fold_ast
    &&  p->data.and.xs[p->data.and.n-1]->type == MPC_TYPE_AND
    && !p->data.and.xs[p->data.and.n-1]->retained
    &&  p->data.and.xs[p->data.and.n-1]->data.and.f == mpcf_fold_ast) {
      t = p->data.and.xs[p->data.and.n-1];
      n = p->data.and.n; m = t->data.and.n;
      p->data.and.n = n + m - 1;
      p->data.and.xs = realloc(p->data.and.xs, sizeof(mpc_parser_t*) * (n + m -1));
      p->data.and.dxs = realloc(p->data.and.dxs, sizeof(mpc_dtor_t) * (n + m - 1 - 1));
      memmove(p->data.and.xs + n - 1, t->data.and.xs, m * sizeof(mpc_parser_t*));
      for (i = 0; i < p->data.and.n-1; i++) { p->data.and.dxs[i] = (mpc_dtor_t)mpc_ast_delete; }
      free(t->data.and.xs); free(t->data.and.dxs); free(t->name); free(t);
      continue;
    }

    /* Remove re `lift` */
    if (p->type == MPC_TYPE_AND
    &&  p->data.and.n == 2
    &&  p->data.and.xs[0]->type == MPC_TYPE_LIFT
    &&  p->data.and.xs[0]->data.lift.lf == mpcf_ctor_str
    && !p->data.and.xs[0]->retained
    &&  p->data.and.f == mpcf_strfold) {
      t = p->data.and.xs[1];
      mpc_delete(p->data.and.xs[0]);
      free(p->data.and.xs); free(p->data.and.dxs); free(p->name);
      memcpy(p, t, sizeof(mpc_parser_t));
      free(t);
      continue;
    }

    /* Merge re lhs `and` */
    if (p->type == MPC_TYPE_AND
    &&  p->data.and.f == mpcf_strfold
    &&  p->data.and.xs[0]->type == MPC_TYPE_AND
    && !p->data.and.xs[0]->retained
    &&  p->data.and.xs[0]->data.and.f == mpcf_strfold) {
      t = p->data.and.xs[0];
      n = p->data.and.n; m = t->data.and.n;
      p->data.and.n = n + m - 1;
      p->data.and.xs = realloc(p->data.and.xs, sizeof(mpc_parser_t*) * (n + m - 1));
      p->data.and.dxs = realloc(p->data.and.dxs, sizeof(mpc_dtor_t) * (n + m - 1 - 1));
      memmove(p->data.and.xs + m, p->data.and.xs + 1, (n - 1) * sizeof(mpc_parser_t*));
      memmove(p->data.and.xs, t->data.and.xs, m * sizeof(mpc_parser_t*));
      for (i = 0; i < p->data.and.n-1; i++) { p->data.and.dxs[i] = free; }
      free(t->data.and.xs); free(t->data.and.dxs); free(t->name); free(t);
      continue;
    }

    /* Merge re rhs `and` */
    if (p->type == MPC_TYPE_AND
    &&  p->data.and.f == mpcf_strfold
    &&  p->data.and.xs[p->data.and.n-1]->type == MPC_TYPE_AND
    && !p->data.and.xs[p->data.and.n-1]->retained
    &&  p->data.and.xs[p->data.and.n-1]->data.and.f == mpcf_strfold) {
      t = p->data.and.xs[p->data.and.n-1];
      n = p->data.and.n; m = t->data.and.n;
      p->data.and.n = n + m - 1;
      p->data.and.xs = realloc(p->data.and.xs, sizeof(mpc_parser_t*) * (n + m -1));
      p->data.and.dxs = realloc(p->data.and.dxs, sizeof(mpc_dtor_t) * (n + m - 1 - 1));
      memmove(p->data.and.xs + n - 1, t->data.and.xs, m * sizeof(mpc_parser_t*));
      for (i = 0; i < p->data.and.n-1; i++) { p->data.and.dxs[i] = free; }
      free(t->data.and.xs); free(t->data.and.dxs); free(t->name); free(t);
      continue;
    }

    return;

  }

}

void mpc_optimise(mpc_parser_t *p) {
  mpc_optimise_unretained(p, 1);
}

src/mpc.h000666 000000 000000 00000025603 13405464046 010763 0ustar00000000 000000 /*
** mpc - Micro Parser Combinator library for C
**
** https://github.com/orangeduck/mpc
**
** Daniel Holden - contact@daniel-holden.com
** Licensed under BSD3
*/

#ifndef mpc_h
#define mpc_h

#ifdef __cplusplus
extern "C" {
#endif

#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <math.h>
#include <errno.h>
#include <ctype.h>

/*
** State Type
*/

typedef struct {
  long pos;
  long row;
  long col;
  int term;
} mpc_state_t;

/*
** Error Type
*/

typedef struct {
  mpc_state_t state;
  int expected_num;
  char *filename;
  char *failure;
  char **expected;
  char recieved;
} mpc_err_t;

void mpc_err_delete(mpc_err_t *e);
char *mpc_err_string(mpc_err_t *e);
void mpc_err_print(mpc_err_t *e);
void mpc_err_print_to(mpc_err_t *e, FILE *f);

/*
** Parsing
*/

typedef void mpc_val_t;

typedef union {
  mpc_err_t *error;
  mpc_val_t *output;
} mpc_result_t;

struct mpc_parser_t;
typedef struct mpc_parser_t mpc_parser_t;

int mpc_parse(const char *filename, const char *string, mpc_parser_t *p, mpc_result_t *r);
int mpc_nparse(const char *filename, const char *string, size_t length, mpc_parser_t *p, mpc_result_t *r);
int mpc_parse_file(const char *filename, FILE *file, mpc_parser_t *p, mpc_result_t *r);
int mpc_parse_pipe(const char *filename, FILE *pipe, mpc_parser_t *p, mpc_result_t *r);
int mpc_parse_contents(const char *filename, mpc_parser_t *p, mpc_result_t *r);

/*
** Function Types
*/

typedef void(*mpc_dtor_t)(mpc_val_t*);
typedef mpc_val_t*(*mpc_ctor_t)(void);

typedef mpc_val_t*(*mpc_apply_t)(mpc_val_t*);
typedef mpc_val_t*(*mpc_apply_to_t)(mpc_val_t*,void*);
typedef mpc_val_t*(*mpc_fold_t)(int,mpc_val_t**);

typedef int(*mpc_check_t)(mpc_val_t**);
typedef int(*mpc_check_with_t)(mpc_val_t**,void*);

/*
** Building a Parser
*/

mpc_parser_t *mpc_new(const char *name);
mpc_parser_t *mpc_copy(mpc_parser_t *a);
mpc_parser_t *mpc_define(mpc_parser_t *p, mpc_parser_t *a);
mpc_parser_t *mpc_undefine(mpc_parser_t *p);

void mpc_delete(mpc_parser_t *p);
void mpc_cleanup(int n, ...);

/*
** Basic Parsers
*/

mpc_parser_t *mpc_any(void);
mpc_parser_t *mpc_char(char c);
mpc_parser_t *mpc_range(char s, char e);
mpc_parser_t *mpc_oneof(const char *s);
mpc_parser_t *mpc_noneof(const char *s);
mpc_parser_t *mpc_satisfy(int(*f)(char));
mpc_parser_t *mpc_string(const char *s);

/*
** Other Parsers
*/

mpc_parser_t *mpc_pass(void);
mpc_parser_t *mpc_fail(const char *m);
mpc_parser_t *mpc_failf(const char *fmt, ...);
mpc_parser_t *mpc_lift(mpc_ctor_t f);
mpc_parser_t *mpc_lift_val(mpc_val_t *x);
mpc_parser_t *mpc_anchor(int(*f)(char,char));
mpc_parser_t *mpc_state(void);

/*
** Combinator Parsers
*/

mpc_parser_t *mpc_expect(mpc_parser_t *a, const char *e);
mpc_parser_t *mpc_expectf(mpc_parser_t *a, const char *fmt, ...);
mpc_parser_t *mpc_apply(mpc_parser_t *a, mpc_apply_t f);
mpc_parser_t *mpc_apply_to(mpc_parser_t *a, mpc_apply_to_t f, void *x);
mpc_parser_t *mpc_check(mpc_parser_t *a, mpc_check_t f, const char *e);
mpc_parser_t *mpc_check_with(mpc_parser_t *a, mpc_check_with_t f, void *x, const char *e);
mpc_parser_t *mpc_checkf(mpc_parser_t *a, mpc_check_t f, const char *fmt, ...);
mpc_parser_t *mpc_check_withf(mpc_parser_t *a, mpc_check_with_t f, void *x, const char *fmt, ...);

mpc_parser_t *mpc_not(mpc_parser_t *a, mpc_dtor_t da);
mpc_parser_t *mpc_not_lift(mpc_parser_t *a, mpc_dtor_t da, mpc_ctor_t lf);
mpc_parser_t *mpc_maybe(mpc_parser_t *a);
mpc_parser_t *mpc_maybe_lift(mpc_parser_t *a, mpc_ctor_t lf);

mpc_parser_t *mpc_many(mpc_fold_t f, mpc_parser_t *a);
mpc_parser_t *mpc_many1(mpc_fold_t f, mpc_parser_t *a);
mpc_parser_t *mpc_count(int n, mpc_fold_t f, mpc_parser_t *a, mpc_dtor_t da);

mpc_parser_t *mpc_or(int n, ...);
mpc_parser_t *mpc_and(int n, mpc_fold_t f, ...);

mpc_parser_t *mpc_predictive(mpc_parser_t *a);

/*
** Common Parsers
*/

mpc_parser_t *mpc_eoi(void);
mpc_parser_t *mpc_soi(void);

mpc_parser_t *mpc_boundary(void);
mpc_parser_t *mpc_boundary_newline(void);

mpc_parser_t *mpc_whitespace(void);
mpc_parser_t *mpc_whitespaces(void);
mpc_parser_t *mpc_blank(void);

mpc_parser_t *mpc_newline(void);
mpc_parser_t *mpc_tab(void);
mpc_parser_t *mpc_escape(void);

mpc_parser_t *mpc_digit(void);
mpc_parser_t *mpc_hexdigit(void);
mpc_parser_t *mpc_octdigit(void);
mpc_parser_t *mpc_digits(void);
mpc_parser_t *mpc_hexdigits(void);
mpc_parser_t *mpc_octdigits(void);

mpc_parser_t *mpc_lower(void);
mpc_parser_t *mpc_upper(void);
mpc_parser_t *mpc_alpha(void);
mpc_parser_t *mpc_underscore(void);
mpc_parser_t *mpc_alphanum(void);

mpc_parser_t *mpc_int(void);
mpc_parser_t *mpc_hex(void);
mpc_parser_t *mpc_oct(void);
mpc_parser_t *mpc_number(void);

mpc_parser_t *mpc_real(void);
mpc_parser_t *mpc_float(void);

mpc_parser_t *mpc_char_lit(void);
mpc_parser_t *mpc_string_lit(void);
mpc_parser_t *mpc_regex_lit(void);

mpc_parser_t *mpc_ident(void);

/*
** Useful Parsers
*/

mpc_parser_t *mpc_startwith(mpc_parser_t *a);
mpc_parser_t *mpc_endwith(mpc_parser_t *a, mpc_dtor_t da);
mpc_parser_t *mpc_whole(mpc_parser_t *a, mpc_dtor_t da);

mpc_parser_t *mpc_stripl(mpc_parser_t *a);
mpc_parser_t *mpc_stripr(mpc_parser_t *a);
mpc_parser_t *mpc_strip(mpc_parser_t *a);
mpc_parser_t *mpc_tok(mpc_parser_t *a); 
mpc_parser_t *mpc_sym(const char *s);
mpc_parser_t *mpc_total(mpc_parser_t *a, mpc_dtor_t da);

mpc_parser_t *mpc_between(mpc_parser_t *a, mpc_dtor_t ad, const char *o, const char *c);
mpc_parser_t *mpc_parens(mpc_parser_t *a, mpc_dtor_t ad);
mpc_parser_t *mpc_braces(mpc_parser_t *a, mpc_dtor_t ad);
mpc_parser_t *mpc_brackets(mpc_parser_t *a, mpc_dtor_t ad);
mpc_parser_t *mpc_squares(mpc_parser_t *a, mpc_dtor_t ad);

mpc_parser_t *mpc_tok_between(mpc_parser_t *a, mpc_dtor_t ad, const char *o, const char *c);
mpc_parser_t *mpc_tok_parens(mpc_parser_t *a, mpc_dtor_t ad);
mpc_parser_t *mpc_tok_braces(mpc_parser_t *a, mpc_dtor_t ad);
mpc_parser_t *mpc_tok_brackets(mpc_parser_t *a, mpc_dtor_t ad);
mpc_parser_t *mpc_tok_squares(mpc_parser_t *a, mpc_dtor_t ad);

/*
** Common Function Parameters
*/

void mpcf_dtor_null(mpc_val_t *x);

mpc_val_t *mpcf_ctor_null(void);
mpc_val_t *mpcf_ctor_str(void);

mpc_val_t *mpcf_free(mpc_val_t *x);
mpc_val_t *mpcf_int(mpc_val_t *x);
mpc_val_t *mpcf_hex(mpc_val_t *x);
mpc_val_t *mpcf_oct(mpc_val_t *x);
mpc_val_t *mpcf_float(mpc_val_t *x);
mpc_val_t *mpcf_strtriml(mpc_val_t *x);
mpc_val_t *mpcf_strtrimr(mpc_val_t *x);
mpc_val_t *mpcf_strtrim(mpc_val_t *x);

mpc_val_t *mpcf_escape(mpc_val_t *x);
mpc_val_t *mpcf_escape_regex(mpc_val_t *x);
mpc_val_t *mpcf_escape_string_raw(mpc_val_t *x);
mpc_val_t *mpcf_escape_char_raw(mpc_val_t *x);

mpc_val_t *mpcf_unescape(mpc_val_t *x);
mpc_val_t *mpcf_unescape_regex(mpc_val_t *x);
mpc_val_t *mpcf_unescape_string_raw(mpc_val_t *x);
mpc_val_t *mpcf_unescape_char_raw(mpc_val_t *x);

mpc_val_t *mpcf_null(int n, mpc_val_t** xs);
mpc_val_t *mpcf_fst(int n, mpc_val_t** xs);
mpc_val_t *mpcf_snd(int n, mpc_val_t** xs);
mpc_val_t *mpcf_trd(int n, mpc_val_t** xs);

mpc_val_t *mpcf_fst_free(int n, mpc_val_t** xs);
mpc_val_t *mpcf_snd_free(int n, mpc_val_t** xs);
mpc_val_t *mpcf_trd_free(int n, mpc_val_t** xs);
mpc_val_t *mpcf_all_free(int n, mpc_val_t** xs);

mpc_val_t *mpcf_strfold(int n, mpc_val_t** xs);
mpc_val_t *mpcf_maths(int n, mpc_val_t** xs);

/*
** Regular Expression Parsers
*/

enum {
  MPC_RE_DEFAULT   = 0,
  MPC_RE_M         = 1,
  MPC_RE_S         = 2,
  MPC_RE_MULTILINE = 1,
  MPC_RE_DOTALL    = 2
};

mpc_parser_t *mpc_re(const char *re);
mpc_parser_t *mpc_re_mode(const char *re, int mode);
  
/*
** AST
*/

typedef struct mpc_ast_t {
  char *tag;
  char *contents;
  mpc_state_t state;
  int children_num;
  struct mpc_ast_t** children;
} mpc_ast_t;

mpc_ast_t *mpc_ast_new(const char *tag, const char *contents);
mpc_ast_t *mpc_ast_build(int n, const char *tag, ...);
mpc_ast_t *mpc_ast_add_root(mpc_ast_t *a);
mpc_ast_t *mpc_ast_add_child(mpc_ast_t *r, mpc_ast_t *a);
mpc_ast_t *mpc_ast_add_tag(mpc_ast_t *a, const char *t);
mpc_ast_t *mpc_ast_add_root_tag(mpc_ast_t *a, const char *t);
mpc_ast_t *mpc_ast_tag(mpc_ast_t *a, const char *t);
mpc_ast_t *mpc_ast_state(mpc_ast_t *a, mpc_state_t s);

void mpc_ast_delete(mpc_ast_t *a);
void mpc_ast_print(mpc_ast_t *a);
void mpc_ast_print_to(mpc_ast_t *a, FILE *fp);

int mpc_ast_get_index(mpc_ast_t *ast, const char *tag);
int mpc_ast_get_index_lb(mpc_ast_t *ast, const char *tag, int lb);
mpc_ast_t *mpc_ast_get_child(mpc_ast_t *ast, const char *tag);
mpc_ast_t *mpc_ast_get_child_lb(mpc_ast_t *ast, const char *tag, int lb);

typedef enum {
  mpc_ast_trav_order_pre,
  mpc_ast_trav_order_post
} mpc_ast_trav_order_t;

typedef struct mpc_ast_trav_t {
  mpc_ast_t             *curr_node;
  struct mpc_ast_trav_t *parent;
  int                    curr_child;
  mpc_ast_trav_order_t   order;
} mpc_ast_trav_t;

mpc_ast_trav_t *mpc_ast_traverse_start(mpc_ast_t *ast,
                                       mpc_ast_trav_order_t order);

mpc_ast_t *mpc_ast_traverse_next(mpc_ast_trav_t **trav);

void mpc_ast_traverse_free(mpc_ast_trav_t **trav);

/*
** Warning: This function currently doesn't test for equality of the `state` member!
*/
int mpc_ast_eq(mpc_ast_t *a, mpc_ast_t *b);

mpc_val_t *mpcf_fold_ast(int n, mpc_val_t **as);
mpc_val_t *mpcf_str_ast(mpc_val_t *c);
mpc_val_t *mpcf_state_ast(int n, mpc_val_t **xs);

mpc_parser_t *mpca_tag(mpc_parser_t *a, const char *t);
mpc_parser_t *mpca_add_tag(mpc_parser_t *a, const char *t);
mpc_parser_t *mpca_root(mpc_parser_t *a);
mpc_parser_t *mpca_state(mpc_parser_t *a);
mpc_parser_t *mpca_total(mpc_parser_t *a);

mpc_parser_t *mpca_not(mpc_parser_t *a);
mpc_parser_t *mpca_maybe(mpc_parser_t *a);

mpc_parser_t *mpca_many(mpc_parser_t *a);
mpc_parser_t *mpca_many1(mpc_parser_t *a);
mpc_parser_t *mpca_count(int n, mpc_parser_t *a);

mpc_parser_t *mpca_or(int n, ...);
mpc_parser_t *mpca_and(int n, ...);

enum {
  MPCA_LANG_DEFAULT              = 0,
  MPCA_LANG_PREDICTIVE           = 1,
  MPCA_LANG_WHITESPACE_SENSITIVE = 2
};

mpc_parser_t *mpca_grammar(int flags, const char *grammar, ...);

mpc_err_t *mpca_lang(int flags, const char *language, ...);
mpc_err_t *mpca_lang_file(int flags, FILE *f, ...);
mpc_err_t *mpca_lang_pipe(int flags, FILE *f, ...);
mpc_err_t *mpca_lang_contents(int flags, const char *filename, ...);

/*
** Misc
*/


void mpc_print(mpc_parser_t *p);
void mpc_optimise(mpc_parser_t *p);
void mpc_stats(mpc_parser_t *p);

int mpc_test_pass(mpc_parser_t *p, const char *s, const void *d,
  int(*tester)(const void*, const void*), 
  mpc_dtor_t destructor, 
  void(*printer)(const void*));

int mpc_test_fail(mpc_parser_t *p, const char *s, const void *d,
  int(*tester)(const void*, const void*),
  mpc_dtor_t destructor,
  void(*printer)(const void*));

#ifdef __cplusplus
}
#endif

#endif
src/parsing.c000666 000000 000000 00000003331 13206352046 011627 0ustar00000000 000000 #include "mpc.h"

#ifdef _WIN32

static char buffer[2048];

char* readline(char* prompt) {
  fputs(prompt, stdout);
  fgets(buffer, 2048, stdin);
  char* cpy = malloc(strlen(buffer)+1);
  strcpy(cpy, buffer);
  cpy[strlen(cpy)-1] = '\0';
  return cpy;
}

void add_history(char* unused) {}

#else
#include <editline/readline.h>
#include <editline/history.h>
#endif

int main(int argc, char** argv) {
  
  /* Create Some Parsers */
  mpc_parser_t* Number   = mpc_new("number");
  mpc_parser_t* Operator = mpc_new("operator");
  mpc_parser_t* Expr     = mpc_new("expr");
  mpc_parser_t* Lispy    = mpc_new("lispy");
  
  /* Define them with the following Language */
  mpca_lang(MPCA_LANG_DEFAULT,
    "                                                     \
      number   : /-?[0-9]+/ ;                             \
      operator : '+' | '-' | '*' | '/' ;                  \
      expr     : <number> | '(' <operator> <expr>+ ')' ;  \
      lispy    : /^/ <operator> <expr>+ /$/ ;             \
    ",
    Number, Operator, Expr, Lispy);
  
  puts("Lispy Version 0.0.0.0.2");
  puts("Press Ctrl+c to Exit\n");
  
  while (1) {
  
    char* input = readline("lispy> ");
    add_history(input);
    
    /* Attempt to parse the user input */
    mpc_result_t r;
    if (mpc_parse("<stdin>", input, Lispy, &r)) {
      /* On success print and delete the AST */
      mpc_ast_print(r.output);
      mpc_ast_delete(r.output);
    } else {
      /* Otherwise print and delete the Error */
      mpc_err_print(r.error);
      mpc_err_delete(r.error);
    }
    
    free(input);
  }
  
  /* Undefine and delete our parsers */
  mpc_cleanup(4, Number, Operator, Expr, Lispy);
  
  return 0;
}
src/prelude.lspy000666 000000 000000 00000010335 13206352046 012373 0ustar00000000 000000 ;;;
;;;   Lispy Standard Prelude
;;;

;;; Atoms
(def {nil} {})
(def {true} 1)
(def {false} 0)

;;; Functional Functions

; Function Definitions
(def {fun} (\ {f b} {
  def (head f) (\ (tail f) b)
}))

; Open new scope
(fun {let b} {
  ((\ {_} b) ())
})

; Unpack List to Function
(fun {unpack f l} {
  eval (join (list f) l)
})

; Unapply List to Function
(fun {pack f & xs} {f xs})

; Curried and Uncurried calling
(def {curry} unpack)
(def {uncurry} pack)

; Perform Several things in Sequence
(fun {do & l} {
  if (== l nil)
    {nil}
    {last l}
})

;;; Logical Functions

; Logical Functions
(fun {not x}   {- 1 x})
(fun {or x y}  {+ x y})
(fun {and x y} {* x y})


;;; Numeric Functions

; Minimum of Arguments
(fun {min & xs} {
  if (== (tail xs) nil) {fst xs}
    {do 
      (= {rest} (unpack min (tail xs)))
      (= {item} (fst xs))
      (if (< item rest) {item} {rest})
    }
})

; Maximum of Arguments
(fun {max & xs} {
  if (== (tail xs) nil) {fst xs}
    {do 
      (= {rest} (unpack max (tail xs)))
      (= {item} (fst xs))
      (if (> item rest) {item} {rest})
    }  
})

;;; Conditional Functions

(fun {select & cs} {
  if (== cs nil)
    {error "No Selection Found"}
    {if (fst (fst cs)) {snd (fst cs)} {unpack select (tail cs)}}
})

(fun {case x & cs} {
  if (== cs nil)
    {error "No Case Found"}
    {if (== x (fst (fst cs))) {snd (fst cs)} {
	  unpack case (join (list x) (tail cs))}}
})

(def {otherwise} true)


;;; Misc Functions

(fun {flip f a b} {f b a})
(fun {ghost & xs} {eval xs})
(fun {comp f g x} {f (g x)})

;;; List Functions

; First, Second, or Third Item in List
(fun {fst l} { eval (head l) })
(fun {snd l} { eval (head (tail l)) })
(fun {trd l} { eval (head (tail (tail l))) })

; List Length
(fun {len l} {
  if (== l nil)
    {0}
    {+ 1 (len (tail l))}
})

; Nth item in List
(fun {nth n l} {
  if (== n 0)
    {fst l}
    {nth (- n 1) (tail l)}
})

; Last item in List
(fun {last l} {nth (- (len l) 1) l})

; Apply Function to List
(fun {map f l} {
  if (== l nil)
    {nil}
    {join (list (f (fst l))) (map f (tail l))}
})

; Apply Filter to List
(fun {filter f l} {
  if (== l nil)
    {nil}
    {join (if (f (fst l)) {head l} {nil}) (filter f (tail l))}
})

; Return all of list but last element
(fun {init l} {
  if (== (tail l) nil)
    {nil}
    {join (head l) (init (tail l))}
})

; Reverse List
(fun {reverse l} {
  if (== l nil)
    {nil}
    {join (reverse (tail l)) (head l)}
})

; Fold Left
(fun {foldl f z l} {
  if (== l nil) 
    {z}
    {foldl f (f z (fst l)) (tail l)}
})

; Fold Right
(fun {foldr f z l} {
  if (== l nil) 
    {z}
    {f (fst l) (foldr f z (tail l))}
})

(fun {sum l} {foldl + 0 l})
(fun {product l} {foldl * 1 l})

; Take N items
(fun {take n l} {
  if (== n 0)
    {nil}
    {join (head l) (take (- n 1) (tail l))}
})

; Drop N items
(fun {drop n l} {
  if (== n 0)
    {l}
    {drop (- n 1) (tail l)}
})

; Split at N
(fun {split n l} {list (take n l) (drop n l)})

; Take While
(fun {take-while f l} {
  if (not (unpack f (head l)))
    {nil}
    {join (head l) (take-while f (tail l))}
})

; Drop While
(fun {drop-while f l} {
  if (not (unpack f (head l)))
    {l}
    {drop-while f (tail l)}
})

; Element of List
(fun {elem x l} {
  if (== l nil)
    {false}
    {if (== x (fst l)) {true} {elem x (tail l)}}
})

; Find element in list of pairs
(fun {lookup x l} {
  if (== l nil)
    {error "No Element Found"}
    {do
      (= {key} (fst (fst l)))
      (= {val} (snd (fst l)))
      (if (== key x) {val} {lookup x (tail l)})
    }
})

; Zip two lists together into a list of pairs
(fun {zip x y} {
  if (or (== x nil) (== y nil))
    {nil}
    {join (list (join (head x) (head y))) (zip (tail x) (tail y))}
})

; Unzip a list of pairs into two lists
(fun {unzip l} {
  if (== l nil)
    {{nil nil}}
    {do
      (= {x} (fst l))
      (= {xs} (unzip (tail l)))
      (list (join (head x) (fst xs)) (join (tail x) (snd xs)))
    }
})

;;; Other Fun

; Fibonacci
(fun {fib n} {
  select
    { (== n 0) 0 }
    { (== n 1) 1 }
    { otherwise (+ (fib (- n 1)) (fib (- n 2))) }
})

src/prompt.c000666 000000 000000 00000001700 13206352046 011503 0ustar00000000 000000 #include <stdio.h>
#include <stdlib.h>

/* If we are compiling on Windows compile these functions */
#ifdef _WIN32
#include <string.h>

static char buffer[2048];

/* Fake readline function */
char* readline(char* prompt) {
  fputs(prompt, stdout);
  fgets(buffer, 2048, stdin);
  char* cpy = malloc(strlen(buffer)+1);
  strcpy(cpy, buffer);
  cpy[strlen(cpy)-1] = '\0';
  return cpy;
}

/* Fake add_history function */
void add_history(char* unused) {}

/* Otherwise include the editline headers */
#else
#include <editline/readline.h>
#include <editline/history.h>
#endif

int main(int argc, char** argv) {
   
  puts("Lispy Version 0.0.0.0.1");
  puts("Press Ctrl+c to Exit\n");
   
  while (1) {
    
    /* Now in either case readline will be correctly defined */
    char* input = readline("lispy> ");
    add_history(input);

    printf("No you're a %s\n", input);
    free(input);
    
  }
  
  return 0;
}
src/prompt_unix.c000666 000000 000000 00000001172 13206344553 012555 0ustar00000000 000000 #include <stdio.h>
#include <stdlib.h>

#include <editline/readline.h>
#include <editline/history.h>

int main(int argc, char** argv) {
   
  /* Print Version and Exit Information */
  puts("Lispy Version 0.0.0.0.1");
  puts("Press Ctrl+c to Exit\n");
   
  /* In a never ending loop */
  while (1) {
    
    /* Output our prompt and get input */
    char* input = readline("lispy> ");
    
    /* Add input to history */
    add_history(input);
    
    /* Echo input back to user */    
    printf("No you're a %s\n", input);

    /* Free retrived input */
    free(input);
    
  }
  
  return 0;
}
src/prompt_windows.c000666 000000 000000 00000001053 13206352046 013256 0ustar00000000 000000 #include <stdio.h>

/* Declare a buffer for user input of size 2048 */
static char input[2048];

int main(int argc, char** argv) {

  /* Print Version and Exit Information */
  puts("Lispy Version 0.0.0.0.1");
  puts("Press Ctrl+c to Exit\n");

  /* In a never ending loop */
  while (1) {

    /* Output our prompt */
    fputs("lispy> ", stdout);

    /* Read a line of user input of maximum size 2048 */
    fgets(input, 2048, stdin);

    /* Echo input back to user */
    printf("No you're a %s", input);
  }

  return 0;
}
src/q_expressions.c000666 000000 000000 00000021703 13206352046 013071 0ustar00000000 000000 #include "mpc.h"

#ifdef _WIN32

static char buffer[2048];

char* readline(char* prompt) {
  fputs(prompt, stdout);
  fgets(buffer, 2048, stdin);
  char* cpy = malloc(strlen(buffer)+1);
  strcpy(cpy, buffer);
  cpy[strlen(cpy)-1] = '\0';
  return cpy;
}

void add_history(char* unused) {}

#else
#include <editline/readline.h>
#include <editline/history.h>
#endif

/* Add QEXPR as possible lval type */
enum { LVAL_ERR, LVAL_NUM, LVAL_SYM, LVAL_SEXPR, LVAL_QEXPR };

typedef struct lval {
  int type;
  long num;
  char* err;
  char* sym;
  int count;
  struct lval** cell;
} lval;

lval* lval_num(long x) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_NUM;
  v->num = x;
  return v;
}

lval* lval_err(char* m) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_ERR;
  v->err = malloc(strlen(m) + 1);
  strcpy(v->err, m);
  return v;
}

lval* lval_sym(char* s) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SYM;
  v->sym = malloc(strlen(s) + 1);
  strcpy(v->sym, s);
  return v;
}

lval* lval_sexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

/* A pointer to a new empty Qexpr lval */
lval* lval_qexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_QEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

void lval_del(lval* v) {

  switch (v->type) {
    case LVAL_NUM: break;
    case LVAL_ERR: free(v->err); break;
    case LVAL_SYM: free(v->sym); break;
    
    /* If Qexpr or Sexpr then delete all elements inside */
    case LVAL_QEXPR:
    case LVAL_SEXPR:
      for (int i = 0; i < v->count; i++) {
        lval_del(v->cell[i]);
      }
      /* Also free the memory allocated to contain the pointers */
      free(v->cell);
    break;
  }
  
  free(v);
}

lval* lval_add(lval* v, lval* x) {
  v->count++;
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  v->cell[v->count-1] = x;
  return v;
}

lval* lval_pop(lval* v, int i) {
  lval* x = v->cell[i];
  memmove(&v->cell[i], &v->cell[i+1],
    sizeof(lval*) * (v->count-i-1));
  v->count--;
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  return x;
}

lval* lval_join(lval* x, lval* y) {

  while (y->count) {
    x = lval_add(x, lval_pop(y, 0));
  }

  lval_del(y);  
  return x;
}

lval* lval_take(lval* v, int i) {
  lval* x = lval_pop(v, i);
  lval_del(v);
  return x;
}

void lval_print(lval* v);

void lval_expr_print(lval* v, char open, char close) {
  putchar(open);
  for (int i = 0; i < v->count; i++) {
    
    lval_print(v->cell[i]);
    
    if (i != (v->count-1)) {
      putchar(' ');
    }
  }
  putchar(close);
}

void lval_print(lval* v) {
  switch (v->type) {
    case LVAL_NUM:   printf("%li", v->num); break;
    case LVAL_ERR:   printf("Error: %s", v->err); break;
    case LVAL_SYM:   printf("%s", v->sym); break;
    case LVAL_SEXPR: lval_expr_print(v, '(', ')'); break;
    case LVAL_QEXPR: lval_expr_print(v, '{', '}'); break;
  }
}

void lval_println(lval* v) { lval_print(v); putchar('\n'); }

#define LASSERT(args, cond, err) \
  if (!(cond)) { lval_del(args); return lval_err(err); }
  
lval* lval_eval(lval* v);

lval* builtin_list(lval* a) {
  a->type = LVAL_QEXPR;
  return a;
}

lval* builtin_head(lval* a) {
  LASSERT(a, a->count == 1,
    "Function 'head' passed too many arguments.");
  LASSERT(a, a->cell[0]->type == LVAL_QEXPR,
    "Function 'head' passed incorrect type.");
  LASSERT(a, a->cell[0]->count != 0,
    "Function 'head' passed {}.");
  
  lval* v = lval_take(a, 0);  
  while (v->count > 1) { lval_del(lval_pop(v, 1)); }
  return v;
}

lval* builtin_tail(lval* a) {
  LASSERT(a, a->count == 1,
    "Function 'tail' passed too many arguments.");
  LASSERT(a, a->cell[0]->type == LVAL_QEXPR,
    "Function 'tail' passed incorrect type.");
  LASSERT(a, a->cell[0]->count != 0,
    "Function 'tail' passed {}.");

  lval* v = lval_take(a, 0);  
  lval_del(lval_pop(v, 0));
  return v;
}

lval* builtin_eval(lval* a) {
  LASSERT(a, a->count == 1,
    "Function 'eval' passed too many arguments.");
  LASSERT(a, a->cell[0]->type == LVAL_QEXPR,
    "Function 'eval' passed incorrect type.");
  
  lval* x = lval_take(a, 0);
  x->type = LVAL_SEXPR;
  return lval_eval(x);
}

lval* builtin_join(lval* a) {

  for (int i = 0; i < a->count; i++) {
    LASSERT(a, a->cell[i]->type == LVAL_QEXPR,
      "Function 'join' passed incorrect type.");
  }
  
  lval* x = lval_pop(a, 0);
  
  while (a->count) {
    x = lval_join(x, lval_pop(a, 0));
  }
  
  lval_del(a);
  return x;
}

lval* builtin_op(lval* a, char* op) {
  
  for (int i = 0; i < a->count; i++) {
    if (a->cell[i]->type != LVAL_NUM) {
      lval_del(a);
      return lval_err("Cannot operate on non-number!");
    }
  }
  
  lval* x = lval_pop(a, 0);
  if ((strcmp(op, "-") == 0) && a->count == 0) { x->num = -x->num; }
  
  while (a->count > 0) {
  
    lval* y = lval_pop(a, 0);
    
    if (strcmp(op, "+") == 0) { x->num += y->num; }
    if (strcmp(op, "-") == 0) { x->num -= y->num; }
    if (strcmp(op, "*") == 0) { x->num *= y->num; }
    if (strcmp(op, "/") == 0) {
      if (y->num == 0) {
        lval_del(x); lval_del(y);
        x = lval_err("Division By Zero.");
        break;
      }
      x->num /= y->num;
    }
    
    lval_del(y);
  }
  
  lval_del(a);
  return x;
}

lval* builtin(lval* a, char* func) {
  if (strcmp("list", func) == 0) { return builtin_list(a); }
  if (strcmp("head", func) == 0) { return builtin_head(a); }
  if (strcmp("tail", func) == 0) { return builtin_tail(a); }
  if (strcmp("join", func) == 0) { return builtin_join(a); }
  if (strcmp("eval", func) == 0) { return builtin_eval(a); }
  if (strstr("+-/*", func)) { return builtin_op(a, func); }
  lval_del(a);
  return lval_err("Unknown Function!");
}

lval* lval_eval_sexpr(lval* v) {
  
  for (int i = 0; i < v->count; i++) {
    v->cell[i] = lval_eval(v->cell[i]);
  }
  
  for (int i = 0; i < v->count; i++) {
    if (v->cell[i]->type == LVAL_ERR) { return lval_take(v, i); }
  }
  
  if (v->count == 0) { return v; }
  
  if (v->count == 1) { return lval_take(v, 0); }
  
  lval* f = lval_pop(v, 0);
  if (f->type != LVAL_SYM) {
    lval_del(f); lval_del(v);
    return lval_err("S-expression Does not start with symbol.");
  }
  
  /* Call builtin with operator */
  lval* result = builtin(v, f->sym);
  lval_del(f);
  return result;
}

lval* lval_eval(lval* v) {
  if (v->type == LVAL_SEXPR) { return lval_eval_sexpr(v); }
  return v;
}

lval* lval_read_num(mpc_ast_t* t) {
  errno = 0;
  long x = strtol(t->contents, NULL, 10);
  return errno != ERANGE ? lval_num(x) : lval_err("invalid number");
}

lval* lval_read(mpc_ast_t* t) {
  
  if (strstr(t->tag, "number")) { return lval_read_num(t); }
  if (strstr(t->tag, "symbol")) { return lval_sym(t->contents); }
  
  lval* x = NULL;
  if (strcmp(t->tag, ">") == 0) { x = lval_sexpr(); } 
  if (strstr(t->tag, "sexpr"))  { x = lval_sexpr(); }
  if (strstr(t->tag, "qexpr"))  { x = lval_qexpr(); }
  
  for (int i = 0; i < t->children_num; i++) {
    if (strcmp(t->children[i]->contents, "(") == 0) { continue; }
    if (strcmp(t->children[i]->contents, ")") == 0) { continue; }
    if (strcmp(t->children[i]->contents, "}") == 0) { continue; }
    if (strcmp(t->children[i]->contents, "{") == 0) { continue; }
    if (strcmp(t->children[i]->tag,  "regex") == 0) { continue; }
    x = lval_add(x, lval_read(t->children[i]));
  }
  
  return x;
}

int main(int argc, char** argv) {
  
  mpc_parser_t* Number = mpc_new("number");
  mpc_parser_t* Symbol = mpc_new("symbol");
  mpc_parser_t* Sexpr  = mpc_new("sexpr");
  mpc_parser_t* Qexpr  = mpc_new("qexpr");
  mpc_parser_t* Expr   = mpc_new("expr");
  mpc_parser_t* Lispy  = mpc_new("lispy");
  
  mpca_lang(MPCA_LANG_DEFAULT,
    "                                                    \
      number : /-?[0-9]+/ ;                              \
      symbol : \"list\" | \"head\" | \"tail\" | \"eval\" \
             | \"join\" | '+' | '-' | '*' | '/' ;        \
      sexpr  : '(' <expr>* ')' ;                         \
      qexpr  : '{' <expr>* '}' ;                         \
      expr   : <number> | <symbol> | <sexpr> | <qexpr> ; \
      lispy  : /^/ <expr>* /$/ ;                         \
    ",
    Number, Symbol, Sexpr, Qexpr, Expr, Lispy);
  
  puts("Lispy Version 0.0.0.0.6");
  puts("Press Ctrl+c to Exit\n");
  
  while (1) {
  
    char* input = readline("lispy> ");
    add_history(input);
    
    mpc_result_t r;
    if (mpc_parse("<stdin>", input, Lispy, &r)) {
      lval* x = lval_eval(lval_read(r.output));
      lval_println(x);
      lval_del(x);
      mpc_ast_delete(r.output);
    } else {    
      mpc_err_print(r.error);
      mpc_err_delete(r.error);
    }
    
    free(input);
    
  }
  
  mpc_cleanup(6, Number, Symbol, Sexpr, Qexpr, Expr, Lispy);
  
  return 0;
}
src/strings.c000666 000000 000000 00000057653 13206352046 011675 0ustar00000000 000000 #include "mpc.h"

#ifdef _WIN32

static char buffer[2048];

char* readline(char* prompt) {
  fputs(prompt, stdout);
  fgets(buffer, 2048, stdin);
  char* cpy = malloc(strlen(buffer)+1);
  strcpy(cpy, buffer);
  cpy[strlen(cpy)-1] = '\0';
  return cpy;
}

void add_history(char* unused) {}

#else
#include <editline/readline.h>
#include <editline/history.h>
#endif

/* Parser Declariations */

mpc_parser_t* Number; 
mpc_parser_t* Symbol; 
mpc_parser_t* String; 
mpc_parser_t* Comment;
mpc_parser_t* Sexpr;  
mpc_parser_t* Qexpr;  
mpc_parser_t* Expr; 
mpc_parser_t* Lispy;

/* Forward Declarations */

struct lval;
struct lenv;
typedef struct lval lval;
typedef struct lenv lenv;

/* Lisp Value */

enum { LVAL_ERR, LVAL_NUM,   LVAL_SYM, LVAL_STR, 
       LVAL_FUN, LVAL_SEXPR, LVAL_QEXPR };
       
typedef lval*(*lbuiltin)(lenv*, lval*);

struct lval {
  int type;

  /* Basic */
  long num;
  char* err;
  char* sym;
  char* str;
  
  /* Function */
  lbuiltin builtin;
  lenv* env;
  lval* formals;
  lval* body;
  
  /* Expression */
  int count;
  lval** cell;
};

lval* lval_num(long x) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_NUM;
  v->num = x;
  return v;
}

lval* lval_err(char* fmt, ...) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_ERR;  
  va_list va;
  va_start(va, fmt);  
  v->err = malloc(512);  
  vsnprintf(v->err, 511, fmt, va);  
  v->err = realloc(v->err, strlen(v->err)+1);
  va_end(va);  
  return v;
}

lval* lval_sym(char* s) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SYM;
  v->sym = malloc(strlen(s) + 1);
  strcpy(v->sym, s);
  return v;
}

lval* lval_str(char* s) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_STR;
  v->str = malloc(strlen(s) + 1);
  strcpy(v->str, s);
  return v;
}

lval* lval_builtin(lbuiltin func) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_FUN;
  v->builtin = func;
  return v;
}

lenv* lenv_new(void);

lval* lval_lambda(lval* formals, lval* body) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_FUN;  
  v->builtin = NULL;  
  v->env = lenv_new();  
  v->formals = formals;
  v->body = body;
  return v;  
}

lval* lval_sexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

lval* lval_qexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_QEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

void lenv_del(lenv* e);

void lval_del(lval* v) {

  switch (v->type) {
    case LVAL_NUM: break;
    case LVAL_FUN: 
      if (!v->builtin) {
        lenv_del(v->env);
        lval_del(v->formals);
        lval_del(v->body);
      }
    break;
    case LVAL_ERR: free(v->err); break;
    case LVAL_SYM: free(v->sym); break;
    case LVAL_STR: free(v->str); break;
    case LVAL_QEXPR:
    case LVAL_SEXPR:
      for (int i = 0; i < v->count; i++) {
        lval_del(v->cell[i]);
      }
      free(v->cell);
    break;
  }
  
  free(v);
}

lenv* lenv_copy(lenv* e);

lval* lval_copy(lval* v) {
  lval* x = malloc(sizeof(lval));
  x->type = v->type;
  switch (v->type) {
    case LVAL_FUN:
      if (v->builtin) {
        x->builtin = v->builtin;
      } else {
        x->builtin = NULL;
        x->env = lenv_copy(v->env);
        x->formals = lval_copy(v->formals);
        x->body = lval_copy(v->body);
      }
    break;
    case LVAL_NUM: x->num = v->num; break;
    case LVAL_ERR: x->err = malloc(strlen(v->err) + 1);
      strcpy(x->err, v->err);
    break;
    case LVAL_SYM: x->sym = malloc(strlen(v->sym) + 1);
      strcpy(x->sym, v->sym);
    break;
    case LVAL_STR: x->str = malloc(strlen(v->str) + 1);
      strcpy(x->str, v->str);
    break;
    case LVAL_SEXPR:
    case LVAL_QEXPR:
      x->count = v->count;
      x->cell = malloc(sizeof(lval*) * x->count);
      for (int i = 0; i < x->count; i++) {
        x->cell[i] = lval_copy(v->cell[i]);
      }
    break;
  }
  return x;
}

lval* lval_add(lval* v, lval* x) {
  v->count++;
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  v->cell[v->count-1] = x;
  return v;
}

lval* lval_join(lval* x, lval* y) {  
  for (int i = 0; i < y->count; i++) {
    x = lval_add(x, y->cell[i]);
  }
  free(y->cell);
  free(y);  
  return x;
}

lval* lval_pop(lval* v, int i) {
  lval* x = v->cell[i];  
  memmove(&v->cell[i],
    &v->cell[i+1], sizeof(lval*) * (v->count-i-1));  
  v->count--;  
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  return x;
}

lval* lval_take(lval* v, int i) {
  lval* x = lval_pop(v, i);
  lval_del(v);
  return x;
}

void lval_print(lval* v);

void lval_print_expr(lval* v, char open, char close) {
  putchar(open);
  for (int i = 0; i < v->count; i++) {
    lval_print(v->cell[i]);    
    if (i != (v->count-1)) {
      putchar(' ');
    }
  }
  putchar(close);
}

void lval_print_str(lval* v) {
  /* Make a Copy of the string */
  char* escaped = malloc(strlen(v->str)+1);
  strcpy(escaped, v->str);
  /* Pass it through the escape function */
  escaped = mpcf_escape(escaped);
  /* Print it between " characters */
  printf("\"%s\"", escaped);
  /* free the copied string */
  free(escaped);
}

void lval_print(lval* v) {
  switch (v->type) {
    case LVAL_FUN:
      if (v->builtin) {
        printf("<builtin>");
      } else {
        printf("(\\ ");
        lval_print(v->formals);
        putchar(' ');
        lval_print(v->body);
        putchar(')');
      }
    break;
    case LVAL_NUM:   printf("%li", v->num); break;
    case LVAL_ERR:   printf("Error: %s", v->err); break;
    case LVAL_SYM:   printf("%s", v->sym); break;
    case LVAL_STR:   lval_print_str(v); break;
    case LVAL_SEXPR: lval_print_expr(v, '(', ')'); break;
    case LVAL_QEXPR: lval_print_expr(v, '{', '}'); break;
  }
}

void lval_println(lval* v) { lval_print(v); putchar('\n'); }

int lval_eq(lval* x, lval* y) {
  
  if (x->type != y->type) { return 0; }
  
  switch (x->type) {
    case LVAL_NUM: return (x->num == y->num);    
    case LVAL_ERR: return (strcmp(x->err, y->err) == 0);
    case LVAL_SYM: return (strcmp(x->sym, y->sym) == 0);    
    case LVAL_STR: return (strcmp(x->str, y->str) == 0);    
    case LVAL_FUN: 
      if (x->builtin || y->builtin) {
        return x->builtin == y->builtin;
      } else {
        return lval_eq(x->formals, y->formals) && lval_eq(x->body, y->body);
      }    
    case LVAL_QEXPR:
    case LVAL_SEXPR:
      if (x->count != y->count) { return 0; }
      for (int i = 0; i < x->count; i++) {
        if (!lval_eq(x->cell[i], y->cell[i])) { return 0; }
      }
      return 1;
    break;
  }
  return 0;
}

char* ltype_name(int t) {
  switch(t) {
    case LVAL_FUN: return "Function";
    case LVAL_NUM: return "Number";
    case LVAL_ERR: return "Error";
    case LVAL_SYM: return "Symbol";
    case LVAL_STR: return "String";
    case LVAL_SEXPR: return "S-Expression";
    case LVAL_QEXPR: return "Q-Expression";
    default: return "Unknown";
  }
}

/* Lisp Environment */

struct lenv {
  lenv* par;
  int count;
  char** syms;
  lval** vals;
};

lenv* lenv_new(void) {
  lenv* e = malloc(sizeof(lenv));
  e->par = NULL;
  e->count = 0;
  e->syms = NULL;
  e->vals = NULL;
  return e;
}

void lenv_del(lenv* e) {
  for (int i = 0; i < e->count; i++) {
    free(e->syms[i]);
    lval_del(e->vals[i]);
  }  
  free(e->syms);
  free(e->vals);
  free(e);
}

lenv* lenv_copy(lenv* e) {
  lenv* n = malloc(sizeof(lenv));
  n->par = e->par;
  n->count = e->count;
  n->syms = malloc(sizeof(char*) * n->count);
  n->vals = malloc(sizeof(lval*) * n->count);
  for (int i = 0; i < e->count; i++) {
    n->syms[i] = malloc(strlen(e->syms[i]) + 1);
    strcpy(n->syms[i], e->syms[i]);
    n->vals[i] = lval_copy(e->vals[i]);
  }
  return n;
}

lval* lenv_get(lenv* e, lval* k) {
  
  for (int i = 0; i < e->count; i++) {
    if (strcmp(e->syms[i], k->sym) == 0) { return lval_copy(e->vals[i]); }
  }
  
  if (e->par) {
    return lenv_get(e->par, k);
  } else {
    return lval_err("Unbound Symbol '%s'", k->sym);
  }
}

void lenv_put(lenv* e, lval* k, lval* v) {
  
  for (int i = 0; i < e->count; i++) {
    if (strcmp(e->syms[i], k->sym) == 0) {
      lval_del(e->vals[i]);
      e->vals[i] = lval_copy(v);
      return;
    }
  }
  
  e->count++;
  e->vals = realloc(e->vals, sizeof(lval*) * e->count);
  e->syms = realloc(e->syms, sizeof(char*) * e->count);  
  e->vals[e->count-1] = lval_copy(v);
  e->syms[e->count-1] = malloc(strlen(k->sym)+1);
  strcpy(e->syms[e->count-1], k->sym);
}

void lenv_def(lenv* e, lval* k, lval* v) {
  while (e->par) { e = e->par; }
  lenv_put(e, k, v);
}

/* Builtins */

#define LASSERT(args, cond, fmt, ...) \
  if (!(cond)) { lval* err = lval_err(fmt, ##__VA_ARGS__); lval_del(args); return err; }

#define LASSERT_TYPE(func, args, index, expect) \
  LASSERT(args, args->cell[index]->type == expect, \
    "Function '%s' passed incorrect type for argument %i. Got %s, Expected %s.", \
    func, index, ltype_name(args->cell[index]->type), ltype_name(expect))

#define LASSERT_NUM(func, args, num) \
  LASSERT(args, args->count == num, \
    "Function '%s' passed incorrect number of arguments. Got %i, Expected %i.", \
    func, args->count, num)

#define LASSERT_NOT_EMPTY(func, args, index) \
  LASSERT(args, args->cell[index]->count != 0, \
    "Function '%s' passed {} for argument %i.", func, index);

lval* lval_eval(lenv* e, lval* v);

lval* builtin_lambda(lenv* e, lval* a) {
  LASSERT_NUM("\\", a, 2);
  LASSERT_TYPE("\\", a, 0, LVAL_QEXPR);
  LASSERT_TYPE("\\", a, 1, LVAL_QEXPR);
  
  for (int i = 0; i < a->cell[0]->count; i++) {
    LASSERT(a, (a->cell[0]->cell[i]->type == LVAL_SYM),
      "Cannot define non-symbol. Got %s, Expected %s.",
      ltype_name(a->cell[0]->cell[i]->type), ltype_name(LVAL_SYM));
  }
  
  lval* formals = lval_pop(a, 0);
  lval* body = lval_pop(a, 0);
  lval_del(a);
  
  return lval_lambda(formals, body);
}

lval* builtin_list(lenv* e, lval* a) {
  a->type = LVAL_QEXPR;
  return a;
}

lval* builtin_head(lenv* e, lval* a) {
  LASSERT_NUM("head", a, 1);
  LASSERT_TYPE("head", a, 0, LVAL_QEXPR);
  LASSERT_NOT_EMPTY("head", a, 0);
  
  lval* v = lval_take(a, 0);  
  while (v->count > 1) { lval_del(lval_pop(v, 1)); }
  return v;
}

lval* builtin_tail(lenv* e, lval* a) {
  LASSERT_NUM("tail", a, 1);
  LASSERT_TYPE("tail", a, 0, LVAL_QEXPR);
  LASSERT_NOT_EMPTY("tail", a, 0);

  lval* v = lval_take(a, 0);  
  lval_del(lval_pop(v, 0));
  return v;
}

lval* builtin_eval(lenv* e, lval* a) {
  LASSERT_NUM("eval", a, 1);
  LASSERT_TYPE("eval", a, 0, LVAL_QEXPR);
  
  lval* x = lval_take(a, 0);
  x->type = LVAL_SEXPR;
  return lval_eval(e, x);
}

lval* builtin_join(lenv* e, lval* a) {
  
  for (int i = 0; i < a->count; i++) {
    LASSERT_TYPE("join", a, i, LVAL_QEXPR);
  }
  
  lval* x = lval_pop(a, 0);
  
  while (a->count) {
    lval* y = lval_pop(a, 0);
    x = lval_join(x, y);
  }
  
  lval_del(a);
  return x;
}

lval* builtin_op(lenv* e, lval* a, char* op) {
  
  for (int i = 0; i < a->count; i++) {
    LASSERT_TYPE(op, a, i, LVAL_NUM);
  }
  
  lval* x = lval_pop(a, 0);
  
  if ((strcmp(op, "-") == 0) && a->count == 0) { x->num = -x->num; }
  
  while (a->count > 0) {  
    lval* y = lval_pop(a, 0);
    
    if (strcmp(op, "+") == 0) { x->num += y->num; }
    if (strcmp(op, "-") == 0) { x->num -= y->num; }
    if (strcmp(op, "*") == 0) { x->num *= y->num; }
    if (strcmp(op, "/") == 0) {
      if (y->num == 0) {
        lval_del(x); lval_del(y);
        x = lval_err("Division By Zero.");
        break;
      }
      x->num /= y->num;
    }
    
    lval_del(y);
  }
  
  lval_del(a);
  return x;
}

lval* builtin_add(lenv* e, lval* a) { return builtin_op(e, a, "+"); }
lval* builtin_sub(lenv* e, lval* a) { return builtin_op(e, a, "-"); }
lval* builtin_mul(lenv* e, lval* a) { return builtin_op(e, a, "*"); }
lval* builtin_div(lenv* e, lval* a) { return builtin_op(e, a, "/"); }

lval* builtin_var(lenv* e, lval* a, char* func) {
  LASSERT_TYPE(func, a, 0, LVAL_QEXPR);
  
  lval* syms = a->cell[0];
  for (int i = 0; i < syms->count; i++) {
    LASSERT(a, (syms->cell[i]->type == LVAL_SYM),
      "Function '%s' cannot define non-symbol. "
      "Got %s, Expected %s.",
      func, ltype_name(syms->cell[i]->type), ltype_name(LVAL_SYM));
  }
  
  LASSERT(a, (syms->count == a->count-1),
    "Function '%s' passed too many arguments for symbols. "
    "Got %i, Expected %i.",
    func, syms->count, a->count-1);
    
  for (int i = 0; i < syms->count; i++) {
    if (strcmp(func, "def") == 0) { lenv_def(e, syms->cell[i], a->cell[i+1]); }
    if (strcmp(func, "=")   == 0) { lenv_put(e, syms->cell[i], a->cell[i+1]); } 
  }
  
  lval_del(a);
  return lval_sexpr();
}

lval* builtin_def(lenv* e, lval* a) { return builtin_var(e, a, "def"); }
lval* builtin_put(lenv* e, lval* a) { return builtin_var(e, a, "="); }

lval* builtin_ord(lenv* e, lval* a, char* op) {
  LASSERT_NUM(op, a, 2);
  LASSERT_TYPE(op, a, 0, LVAL_NUM);
  LASSERT_TYPE(op, a, 1, LVAL_NUM);
  
  int r;
  if (strcmp(op, ">")  == 0) { r = (a->cell[0]->num >  a->cell[1]->num); }
  if (strcmp(op, "<")  == 0) { r = (a->cell[0]->num <  a->cell[1]->num); }
  if (strcmp(op, ">=") == 0) { r = (a->cell[0]->num >= a->cell[1]->num); }
  if (strcmp(op, "<=") == 0) { r = (a->cell[0]->num <= a->cell[1]->num); }
  lval_del(a);
  return lval_num(r);
}

lval* builtin_gt(lenv* e, lval* a) { return builtin_ord(e, a, ">");  }
lval* builtin_lt(lenv* e, lval* a) { return builtin_ord(e, a, "<");  }
lval* builtin_ge(lenv* e, lval* a) { return builtin_ord(e, a, ">="); }
lval* builtin_le(lenv* e, lval* a) { return builtin_ord(e, a, "<="); }

lval* builtin_cmp(lenv* e, lval* a, char* op) {
  LASSERT_NUM(op, a, 2);
  int r;
  if (strcmp(op, "==") == 0) { r =  lval_eq(a->cell[0], a->cell[1]); }
  if (strcmp(op, "!=") == 0) { r = !lval_eq(a->cell[0], a->cell[1]); }
  lval_del(a);
  return lval_num(r);
}

lval* builtin_eq(lenv* e, lval* a) { return builtin_cmp(e, a, "=="); }
lval* builtin_ne(lenv* e, lval* a) { return builtin_cmp(e, a, "!="); }

lval* builtin_if(lenv* e, lval* a) {
  LASSERT_NUM("if", a, 3);
  LASSERT_TYPE("if", a, 0, LVAL_NUM);
  LASSERT_TYPE("if", a, 1, LVAL_QEXPR);
  LASSERT_TYPE("if", a, 2, LVAL_QEXPR);
  
  lval* x;
  a->cell[1]->type = LVAL_SEXPR;
  a->cell[2]->type = LVAL_SEXPR;
  
  if (a->cell[0]->num) {
    x = lval_eval(e, lval_pop(a, 1));
  } else {
    x = lval_eval(e, lval_pop(a, 2));
  }
  
  lval_del(a);
  return x;
}

lval* lval_read(mpc_ast_t* t);

lval* builtin_load(lenv* e, lval* a) {
  LASSERT_NUM("load", a, 1);
  LASSERT_TYPE("load", a, 0, LVAL_STR);
  
  /* Parse File given by string name */
  mpc_result_t r;
  if (mpc_parse_contents(a->cell[0]->str, Lispy, &r)) {
    
    /* Read contents */
    lval* expr = lval_read(r.output);
    mpc_ast_delete(r.output);

    /* Evaluate each Expression */
    while (expr->count) {
      lval* x = lval_eval(e, lval_pop(expr, 0));
      /* If Evaluation leads to error print it */
      if (x->type == LVAL_ERR) { lval_println(x); }
      lval_del(x);
    }
    
    /* Delete expressions and arguments */
    lval_del(expr);    
    lval_del(a);
    
    /* Return empty list */
    return lval_sexpr();
    
  } else {
    /* Get Parse Error as String */
    char* err_msg = mpc_err_string(r.error);
    mpc_err_delete(r.error);
    
    /* Create new error message using it */
    lval* err = lval_err("Could not load Library %s", err_msg);
    free(err_msg);
    lval_del(a);
    
    /* Cleanup and return error */
    return err;
  }
}

lval* builtin_print(lenv* e, lval* a) {
  
  /* Print each argument followed by a space */
  for (int i = 0; i < a->count; i++) {
    lval_print(a->cell[i]); putchar(' ');
  }
  
  /* Print a newline and delete arguments */
  putchar('\n');
  lval_del(a);
  
  return lval_sexpr();
}

lval* builtin_error(lenv* e, lval* a) {
  LASSERT_NUM("error", a, 1);
  LASSERT_TYPE("error", a, 0, LVAL_STR);
  
  /* Construct Error from first argument */
  lval* err = lval_err(a->cell[0]->str);
  
  /* Delete arguments and return */
  lval_del(a);
  return err;
}

void lenv_add_builtin(lenv* e, char* name, lbuiltin func) {
  lval* k = lval_sym(name);
  lval* v = lval_builtin(func);
  lenv_put(e, k, v);
  lval_del(k); lval_del(v);
}

void lenv_add_builtins(lenv* e) {
  /* Variable Functions */
  lenv_add_builtin(e, "\\",  builtin_lambda); 
  lenv_add_builtin(e, "def", builtin_def);
  lenv_add_builtin(e, "=",   builtin_put);
  
  /* List Functions */
  lenv_add_builtin(e, "list", builtin_list);
  lenv_add_builtin(e, "head", builtin_head);
  lenv_add_builtin(e, "tail", builtin_tail);
  lenv_add_builtin(e, "eval", builtin_eval);
  lenv_add_builtin(e, "join", builtin_join);
  
  /* Mathematical Functions */
  lenv_add_builtin(e, "+", builtin_add);
  lenv_add_builtin(e, "-", builtin_sub);
  lenv_add_builtin(e, "*", builtin_mul);
  lenv_add_builtin(e, "/", builtin_div);
  
  /* Comparison Functions */
  lenv_add_builtin(e, "if", builtin_if);
  lenv_add_builtin(e, "==", builtin_eq);
  lenv_add_builtin(e, "!=", builtin_ne);
  lenv_add_builtin(e, ">",  builtin_gt);
  lenv_add_builtin(e, "<",  builtin_lt);
  lenv_add_builtin(e, ">=", builtin_ge);
  lenv_add_builtin(e, "<=", builtin_le);
  
  /* String Functions */
  lenv_add_builtin(e, "load",  builtin_load); 
  lenv_add_builtin(e, "error", builtin_error);
  lenv_add_builtin(e, "print", builtin_print);
}

/* Evaluation */

lval* lval_call(lenv* e, lval* f, lval* a) {
  
  if (f->builtin) { return f->builtin(e, a); }
  
  int given = a->count;
  int total = f->formals->count;
  
  while (a->count) {
    
    if (f->formals->count == 0) {
      lval_del(a);
      return lval_err("Function passed too many arguments. "
        "Got %i, Expected %i.", given, total); 
    }
    
    lval* sym = lval_pop(f->formals, 0);
    
    if (strcmp(sym->sym, "&") == 0) {
      
      if (f->formals->count != 1) {
        lval_del(a);
        return lval_err("Function format invalid. "
          "Symbol '&' not followed by single symbol.");
      }
      
      lval* nsym = lval_pop(f->formals, 0);
      lenv_put(f->env, nsym, builtin_list(e, a));
      lval_del(sym); lval_del(nsym);
      break;
    }
    
    lval* val = lval_pop(a, 0);    
    lenv_put(f->env, sym, val);    
    lval_del(sym); lval_del(val);
  }
  
  lval_del(a);
  
  if (f->formals->count > 0 &&
    strcmp(f->formals->cell[0]->sym, "&") == 0) {
    
    if (f->formals->count != 2) {
      return lval_err("Function format invalid. "
        "Symbol '&' not followed by single symbol.");
    }
    
    lval_del(lval_pop(f->formals, 0));
    
    lval* sym = lval_pop(f->formals, 0);
    lval* val = lval_qexpr();    
    lenv_put(f->env, sym, val);
    lval_del(sym); lval_del(val);
  }
  
  if (f->formals->count == 0) {  
    f->env->par = e;    
    return builtin_eval(f->env, lval_add(lval_sexpr(), lval_copy(f->body)));
  } else {
    return lval_copy(f);
  }
  
}

lval* lval_eval_sexpr(lenv* e, lval* v) {
  
  for (int i = 0; i < v->count; i++) { v->cell[i] = lval_eval(e, v->cell[i]); }
  for (int i = 0; i < v->count; i++) { if (v->cell[i]->type == LVAL_ERR) { return lval_take(v, i); } }
  
  if (v->count == 0) { return v; }  
  if (v->count == 1) { return lval_eval(e, lval_take(v, 0)); }
  
  lval* f = lval_pop(v, 0);
  if (f->type != LVAL_FUN) {
    lval* err = lval_err(
      "S-Expression starts with incorrect type. "
      "Got %s, Expected %s.",
      ltype_name(f->type), ltype_name(LVAL_FUN));
    lval_del(f); lval_del(v);
    return err;
  }
  
  lval* result = lval_call(e, f, v);
  lval_del(f);
  return result;
}

lval* lval_eval(lenv* e, lval* v) {
  if (v->type == LVAL_SYM) {
    lval* x = lenv_get(e, v);
    lval_del(v);
    return x;
  }
  if (v->type == LVAL_SEXPR) { return lval_eval_sexpr(e, v); }
  return v;
}

/* Reading */

lval* lval_read_num(mpc_ast_t* t) {
  errno = 0;
  long x = strtol(t->contents, NULL, 10);
  return errno != ERANGE ? lval_num(x) : lval_err("Invalid Number.");
}

lval* lval_read_str(mpc_ast_t* t) {
  /* Cut off the final quote character */
  t->contents[strlen(t->contents)-1] = '\0';
  /* Copy the string missing out the first quote character */
  char* unescaped = malloc(strlen(t->contents+1)+1);
  strcpy(unescaped, t->contents+1);
  /* Pass through the unescape function */
  unescaped = mpcf_unescape(unescaped);
  /* Construct a new lval using the string */
  lval* str = lval_str(unescaped);
  /* Free the string and return */
  free(unescaped);
  return str;
}

lval* lval_read(mpc_ast_t* t) {
  
  if (strstr(t->tag, "number")) { return lval_read_num(t); }
  if (strstr(t->tag, "string")) { return lval_read_str(t); }
  if (strstr(t->tag, "symbol")) { return lval_sym(t->contents); }
  
  lval* x = NULL;
  if (strcmp(t->tag, ">") == 0) { x = lval_sexpr(); } 
  if (strstr(t->tag, "sexpr"))  { x = lval_sexpr(); }
  if (strstr(t->tag, "qexpr"))  { x = lval_qexpr(); }
  
  for (int i = 0; i < t->children_num; i++) {
    if (strcmp(t->children[i]->contents, "(") == 0) { continue; }
    if (strcmp(t->children[i]->contents, ")") == 0) { continue; }
    if (strcmp(t->children[i]->contents, "}") == 0) { continue; }
    if (strcmp(t->children[i]->contents, "{") == 0) { continue; }
    if (strcmp(t->children[i]->tag,  "regex") == 0) { continue; }
    if (strstr(t->children[i]->tag, "comment")) { continue; }
    x = lval_add(x, lval_read(t->children[i]));
  }
  
  return x;
}

/* Main */

int main(int argc, char** argv) {
  
  Number  = mpc_new("number");
  Symbol  = mpc_new("symbol");
  String  = mpc_new("string");
  Comment = mpc_new("comment");
  Sexpr   = mpc_new("sexpr");
  Qexpr   = mpc_new("qexpr");
  Expr    = mpc_new("expr");
  Lispy   = mpc_new("lispy");
  
  mpca_lang(MPCA_LANG_DEFAULT,
    "                                              \
      number  : /-?[0-9]+/ ;                       \
      symbol  : /[a-zA-Z0-9_+\\-*\\/\\\\=<>!&]+/ ; \
      string  : /\"(\\\\.|[^\"])*\"/ ;             \
      comment : /;[^\\r\\n]*/ ;                    \
      sexpr   : '(' <expr>* ')' ;                  \
      qexpr   : '{' <expr>* '}' ;                  \
      expr    : <number>  | <symbol> | <string>    \
              | <comment> | <sexpr>  | <qexpr>;    \
      lispy   : /^/ <expr>* /$/ ;                  \
    ",
    Number, Symbol, String, Comment, Sexpr, Qexpr, Expr, Lispy);
  
  lenv* e = lenv_new();
  lenv_add_builtins(e);
  
  /* Interactive Prompt */
  if (argc == 1) {
  
    puts("Lispy Version 0.0.0.1.0");
    puts("Press Ctrl+c to Exit\n");
  
    while (1) {
    
      char* input = readline("lispy> ");
      add_history(input);
      
      mpc_result_t r;
      if (mpc_parse("<stdin>", input, Lispy, &r)) {
        
        lval* x = lval_eval(e, lval_read(r.output));
        lval_println(x);
        lval_del(x);
        
        mpc_ast_delete(r.output);
      } else {    
        mpc_err_print(r.error);
        mpc_err_delete(r.error);
      }
      
      free(input);
      
    }
  }
  
  /* Supplied with list of files */
  if (argc >= 2) {
  
    /* loop over each supplied filename (starting from 1) */
    for (int i = 1; i < argc; i++) {
      
      /* Argument list with a single argument, the filename */
      lval* args = lval_add(lval_sexpr(), lval_str(argv[i]));
      
      /* Pass to builtin load and get the result */
      lval* x = builtin_load(e, args);
      
      /* If the result is an error be sure to print it */
      if (x->type == LVAL_ERR) { lval_println(x); }
      lval_del(x);
    }
  }
  
  lenv_del(e);
  
  mpc_cleanup(8, 
    Number, Symbol, String, Comment, 
    Sexpr,  Qexpr,  Expr,   Lispy);
  
  return 0;
}
src/s_expressions.c000666 000000 000000 00000017171 13206352046 013077 0ustar00000000 000000 #include "mpc.h"

#ifdef _WIN32

static char buffer[2048];

char* readline(char* prompt) {
  fputs(prompt, stdout);
  fgets(buffer, 2048, stdin);
  char* cpy = malloc(strlen(buffer)+1);
  strcpy(cpy, buffer);
  cpy[strlen(cpy)-1] = '\0';
  return cpy;
}

void add_history(char* unused) {}

#else
#include <editline/readline.h>
#include <editline/history.h>
#endif

/* Add SYM and SEXPR as possible lval types */
enum { LVAL_ERR, LVAL_NUM, LVAL_SYM, LVAL_SEXPR };

typedef struct lval {
  int type;
  long num;
  /* Error and Symbol types have some string data */
  char* err;
  char* sym;
  /* Count and Pointer to a list of "lval*"; */
  int count;
  struct lval** cell;
} lval;

/* Construct a pointer to a new Number lval */ 
lval* lval_num(long x) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_NUM;
  v->num = x;
  return v;
}

/* Construct a pointer to a new Error lval */ 
lval* lval_err(char* m) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_ERR;
  v->err = malloc(strlen(m) + 1);
  strcpy(v->err, m);
  return v;
}

/* Construct a pointer to a new Symbol lval */ 
lval* lval_sym(char* s) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SYM;
  v->sym = malloc(strlen(s) + 1);
  strcpy(v->sym, s);
  return v;
}

/* A pointer to a new empty Sexpr lval */
lval* lval_sexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

void lval_del(lval* v) {

  switch (v->type) {
    /* Do nothing special for number type */
    case LVAL_NUM: break;
    
    /* For Err or Sym free the string data */
    case LVAL_ERR: free(v->err); break;
    case LVAL_SYM: free(v->sym); break;
    
    /* If Sexpr then delete all elements inside */
    case LVAL_SEXPR:
      for (int i = 0; i < v->count; i++) {
        lval_del(v->cell[i]);
      }
      /* Also free the memory allocated to contain the pointers */
      free(v->cell);
    break;
  }
  
  /* Free the memory allocated for the "lval" struct itself */
  free(v);
}

lval* lval_add(lval* v, lval* x) {
  v->count++;
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  v->cell[v->count-1] = x;
  return v;
}

lval* lval_pop(lval* v, int i) {
  /* Find the item at "i" */
  lval* x = v->cell[i];
  
  /* Shift memory after the item at "i" over the top */
  memmove(&v->cell[i], &v->cell[i+1],
    sizeof(lval*) * (v->count-i-1));
  
  /* Decrease the count of items in the list */
  v->count--;
  
  /* Reallocate the memory used */
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  return x;
}

lval* lval_take(lval* v, int i) {
  lval* x = lval_pop(v, i);
  lval_del(v);
  return x;
}

void lval_print(lval* v);

void lval_expr_print(lval* v, char open, char close) {
  putchar(open);
  for (int i = 0; i < v->count; i++) {
    
    /* Print Value contained within */
    lval_print(v->cell[i]);
    
    /* Don't print trailing space if last element */
    if (i != (v->count-1)) {
      putchar(' ');
    }
  }
  putchar(close);
}

void lval_print(lval* v) {
  switch (v->type) {
    case LVAL_NUM:   printf("%li", v->num); break;
    case LVAL_ERR:   printf("Error: %s", v->err); break;
    case LVAL_SYM:   printf("%s", v->sym); break;
    case LVAL_SEXPR: lval_expr_print(v, '(', ')'); break;
  }
}

void lval_println(lval* v) { lval_print(v); putchar('\n'); }

lval* builtin_op(lval* a, char* op) {
  
  /* Ensure all arguments are numbers */
  for (int i = 0; i < a->count; i++) {
    if (a->cell[i]->type != LVAL_NUM) {
      lval_del(a);
      return lval_err("Cannot operate on non-number!");
    }
  }
  
  /* Pop the first element */
  lval* x = lval_pop(a, 0);
  
  /* If no arguments and sub then perform unary negation */
  if ((strcmp(op, "-") == 0) && a->count == 0) {
    x->num = -x->num;
  }
  
  /* While there are still elements remaining */
  while (a->count > 0) {
  
    /* Pop the next element */
    lval* y = lval_pop(a, 0);
    
    /* Perform operation */
    if (strcmp(op, "+") == 0) { x->num += y->num; }
    if (strcmp(op, "-") == 0) { x->num -= y->num; }
    if (strcmp(op, "*") == 0) { x->num *= y->num; }
    if (strcmp(op, "/") == 0) {
      if (y->num == 0) {
        lval_del(x); lval_del(y);
        x = lval_err("Division By Zero.");
        break;
      }
      x->num /= y->num;
    }
    
    /* Delete element now finished with */
    lval_del(y);
  }
  
  /* Delete input expression and return result */
  lval_del(a);
  return x;
}

lval* lval_eval(lval* v);

lval* lval_eval_sexpr(lval* v) {
  
  /* Evaluate Children */
  for (int i = 0; i < v->count; i++) {
    v->cell[i] = lval_eval(v->cell[i]);
  }
  
  /* Error Checking */
  for (int i = 0; i < v->count; i++) {
    if (v->cell[i]->type == LVAL_ERR) { return lval_take(v, i); }
  }
  
  /* Empty Expression */
  if (v->count == 0) { return v; }
  
  /* Single Expression */
  if (v->count == 1) { return lval_take(v, 0); }
  
  /* Ensure First Element is Symbol */
  lval* f = lval_pop(v, 0);
  if (f->type != LVAL_SYM) {
    lval_del(f); lval_del(v);
    return lval_err("S-expression Does not start with symbol.");
  }
  
  /* Call builtin with operator */
  lval* result = builtin_op(v, f->sym);
  lval_del(f);
  return result;
}

lval* lval_eval(lval* v) {
  /* Evaluate Sexpressions */
  if (v->type == LVAL_SEXPR) { return lval_eval_sexpr(v); }
  /* All other lval types remain the same */
  return v;
}

lval* lval_read_num(mpc_ast_t* t) {
  errno = 0;
  long x = strtol(t->contents, NULL, 10);
  return errno != ERANGE ?
    lval_num(x) : lval_err("invalid number");
}

lval* lval_read(mpc_ast_t* t) {
  
  /* If Symbol or Number return conversion to that type */
  if (strstr(t->tag, "number")) { return lval_read_num(t); }
  if (strstr(t->tag, "symbol")) { return lval_sym(t->contents); }
  
  /* If root (>) or sexpr then create empty list */
  lval* x = NULL;
  if (strcmp(t->tag, ">") == 0) { x = lval_sexpr(); } 
  if (strstr(t->tag, "sexpr"))  { x = lval_sexpr(); }
  
  /* Fill this list with any valid expression contained within */
  for (int i = 0; i < t->children_num; i++) {
    if (strcmp(t->children[i]->contents, "(") == 0) { continue; }
    if (strcmp(t->children[i]->contents, ")") == 0) { continue; }
    if (strcmp(t->children[i]->tag,  "regex") == 0) { continue; }
    x = lval_add(x, lval_read(t->children[i]));
  }
  
  return x;
}

int main(int argc, char** argv) {
  
  mpc_parser_t* Number = mpc_new("number");
  mpc_parser_t* Symbol = mpc_new("symbol");
  mpc_parser_t* Sexpr  = mpc_new("sexpr");
  mpc_parser_t* Expr   = mpc_new("expr");
  mpc_parser_t* Lispy  = mpc_new("lispy");
  
  mpca_lang(MPCA_LANG_DEFAULT,
    "                                          \
      number : /-?[0-9]+/ ;                    \
      symbol : '+' | '-' | '*' | '/' ;         \
      sexpr  : '(' <expr>* ')' ;               \
      expr   : <number> | <symbol> | <sexpr> ; \
      lispy  : /^/ <expr>* /$/ ;               \
    ",
    Number, Symbol, Sexpr, Expr, Lispy);
  
  puts("Lispy Version 0.0.0.0.5");
  puts("Press Ctrl+c to Exit\n");
  
  while (1) {
  
    char* input = readline("lispy> ");
    add_history(input);
    
    mpc_result_t r;
    if (mpc_parse("<stdin>", input, Lispy, &r)) {
      lval* x = lval_eval(lval_read(r.output));
      lval_println(x);
      lval_del(x);
      mpc_ast_delete(r.output);
    } else {    
      mpc_err_print(r.error);
      mpc_err_delete(r.error);
    }
    
    free(input);
    
  }
  
  mpc_cleanup(5, Number, Symbol, Sexpr, Expr, Lispy);
  
  return 0;
}
src/variables.c000666 000000 000000 00000034675 13206352046 012153 0ustar00000000 000000 #include "mpc.h"

#ifdef _WIN32

static char buffer[2048];

char* readline(char* prompt) {
  fputs(prompt, stdout);
  fgets(buffer, 2048, stdin);
  char* cpy = malloc(strlen(buffer)+1);
  strcpy(cpy, buffer);
  cpy[strlen(cpy)-1] = '\0';
  return cpy;
}

void add_history(char* unused) {}

#else
#include <editline/readline.h>
#include <editline/history.h>
#endif

/* Forward Declarations */

struct lval;
struct lenv;
typedef struct lval lval;
typedef struct lenv lenv;

/* Lisp Value */

enum { LVAL_ERR, LVAL_NUM,   LVAL_SYM, 
       LVAL_FUN, LVAL_SEXPR, LVAL_QEXPR };

typedef lval*(*lbuiltin)(lenv*, lval*);

struct lval {
  int type;
  long num;
  char* err;
  char* sym;
  lbuiltin fun;
  int count;
  lval** cell;
};

lval* lval_num(long x) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_NUM;
  v->num = x;
  return v;
}

lval* lval_err(char* fmt, ...) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_ERR;
  
  /* Create a va list and initialize it */
  va_list va;
  va_start(va, fmt);
  
  /* Allocate 512 bytes of space */
  v->err = malloc(512);
  
  /* printf the error string with a maximum of 511 characters */
  vsnprintf(v->err, 511, fmt, va);
  
  /* Reallocate to number of bytes actually used */
  v->err = realloc(v->err, strlen(v->err)+1);
  
  /* Cleanup our va list */
  va_end(va);
  
  return v;
}

lval* lval_sym(char* s) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SYM;
  v->sym = malloc(strlen(s) + 1);
  strcpy(v->sym, s);
  return v;
}

lval* lval_fun(lbuiltin func) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_FUN;
  v->fun = func;
  return v;
}

lval* lval_sexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_SEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

lval* lval_qexpr(void) {
  lval* v = malloc(sizeof(lval));
  v->type = LVAL_QEXPR;
  v->count = 0;
  v->cell = NULL;
  return v;
}

void lval_del(lval* v) {

  switch (v->type) {
    case LVAL_NUM: break;
    case LVAL_FUN: break;
    case LVAL_ERR: free(v->err); break;
    case LVAL_SYM: free(v->sym); break;
    case LVAL_QEXPR:
    case LVAL_SEXPR:
      for (int i = 0; i < v->count; i++) {
        lval_del(v->cell[i]);
      }
      free(v->cell);
    break;
  }
  
  free(v);
}

lval* lval_copy(lval* v) {

  lval* x = malloc(sizeof(lval));
  x->type = v->type;
  
  switch (v->type) {
    
    /* Copy Functions and Numbers Directly */
    case LVAL_FUN: x->fun = v->fun; break;
    case LVAL_NUM: x->num = v->num; break;
    
    /* Copy Strings using malloc and strcpy */
    case LVAL_ERR:
      x->err = malloc(strlen(v->err) + 1);
      strcpy(x->err, v->err); break;
      
    case LVAL_SYM:
      x->sym = malloc(strlen(v->sym) + 1);
      strcpy(x->sym, v->sym); break;
    
    /* Copy Lists by copying each sub-expression */
    case LVAL_SEXPR:
    case LVAL_QEXPR:
      x->count = v->count;
      x->cell = malloc(sizeof(lval*) * x->count);
      for (int i = 0; i < x->count; i++) {
        x->cell[i] = lval_copy(v->cell[i]);
      }
    break;
  }
  
  return x;
}

lval* lval_add(lval* v, lval* x) {
  v->count++;
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  v->cell[v->count-1] = x;
  return v;
}

lval* lval_join(lval* x, lval* y) {  
  for (int i = 0; i < y->count; i++) {
    x = lval_add(x, y->cell[i]);
  }
  free(y->cell);
  free(y);  
  return x;
}

lval* lval_pop(lval* v, int i) {
  lval* x = v->cell[i];  
  memmove(&v->cell[i], &v->cell[i+1],
    sizeof(lval*) * (v->count-i-1));  
  v->count--;  
  v->cell = realloc(v->cell, sizeof(lval*) * v->count);
  return x;
}

lval* lval_take(lval* v, int i) {
  lval* x = lval_pop(v, i);
  lval_del(v);
  return x;
}

void lval_print(lval* v);

void lval_print_expr(lval* v, char open, char close) {
  putchar(open);
  for (int i = 0; i < v->count; i++) {
    lval_print(v->cell[i]);    
    if (i != (v->count-1)) {
      putchar(' ');
    }
  }
  putchar(close);
}

void lval_print(lval* v) {
  switch (v->type) {
    case LVAL_FUN:   printf("<function>"); break;
    case LVAL_NUM:   printf("%li", v->num); break;
    case LVAL_ERR:   printf("Error: %s", v->err); break;
    case LVAL_SYM:   printf("%s", v->sym); break;
    case LVAL_SEXPR: lval_print_expr(v, '(', ')'); break;
    case LVAL_QEXPR: lval_print_expr(v, '{', '}'); break;
  }
}

void lval_println(lval* v) { lval_print(v); putchar('\n'); }

char* ltype_name(int t) {
  switch(t) {
    case LVAL_FUN: return "Function";
    case LVAL_NUM: return "Number";
    case LVAL_ERR: return "Error";
    case LVAL_SYM: return "Symbol";
    case LVAL_SEXPR: return "S-Expression";
    case LVAL_QEXPR: return "Q-Expression";
    default: return "Unknown";
  }
}

/* Lisp Environment */

struct lenv {
  int count;
  char** syms;
  lval** vals;
};

lenv* lenv_new(void) {

  /* Initialize struct */
  lenv* e = malloc(sizeof(lenv));
  e->count = 0;
  e->syms = NULL;
  e->vals = NULL;
  return e;
  
}

void lenv_del(lenv* e) {
  
  /* Iterate over all items in environment deleting them */
  for (int i = 0; i < e->count; i++) {
    free(e->syms[i]);
    lval_del(e->vals[i]);
  }
  
  /* Free allocated memory for lists */
  free(e->syms);
  free(e->vals);
  free(e);
}

lval* lenv_get(lenv* e, lval* k) {
  
  /* Iterate over all items in environment */
  for (int i = 0; i < e->count; i++) {
    /* Check if the stored string matches the symbol string */
    /* If it does, return a copy of the value */
    if (strcmp(e->syms[i], k->sym) == 0) {
      return lval_copy(e->vals[i]);
    }
  }
  /* If no symbol found return error */
  return lval_err("Unbound Symbol '%s'", k->sym);
}

void lenv_put(lenv* e, lval* k, lval* v) {
  
  /* Iterate over all items in environment */
  /* This is to see if variable already exists */
  for (int i = 0; i < e->count; i++) {
  
    /* If variable is found delete item at that position */
    /* And replace with variable supplied by user */
    if (strcmp(e->syms[i], k->sym) == 0) {
      lval_del(e->vals[i]);
      e->vals[i] = lval_copy(v);
      return;
    }
  }
  
  /* If no existing entry found allocate space for new entry */
  e->count++;
  e->vals = realloc(e->vals, sizeof(lval*) * e->count);
  e->syms = realloc(e->syms, sizeof(char*) * e->count);
  
  /* Copy contents of lval and symbol string into new location */
  e->vals[e->count-1] = lval_copy(v);
  e->syms[e->count-1] = malloc(strlen(k->sym)+1);
  strcpy(e->syms[e->count-1], k->sym);
}

/* Builtins */

#define LASSERT(args, cond, fmt, ...) \
  if (!(cond)) { lval* err = lval_err(fmt, ##__VA_ARGS__); lval_del(args); return err; }

#define LASSERT_TYPE(func, args, index, expect) \
  LASSERT(args, args->cell[index]->type == expect, \
    "Function '%s' passed incorrect type for argument %i. Got %s, Expected %s.", \
    func, index, ltype_name(args->cell[index]->type), ltype_name(expect))

#define LASSERT_NUM(func, args, num) \
  LASSERT(args, args->count == num, \
    "Function '%s' passed incorrect number of arguments. Got %i, Expected %i.", \
    func, args->count, num)

#define LASSERT_NOT_EMPTY(func, args, index) \
  LASSERT(args, args->cell[index]->count != 0, \
    "Function '%s' passed {} for argument %i.", func, index);


lval* lval_eval(lenv* e, lval* v);

lval* builtin_list(lenv* e, lval* a) {
  a->type = LVAL_QEXPR;
  return a;
}

lval* builtin_head(lenv* e, lval* a) {
  LASSERT_NUM("head", a, 1);
  LASSERT_TYPE("head", a, 0, LVAL_QEXPR);
  LASSERT_NOT_EMPTY("head", a, 0);
  
  lval* v = lval_take(a, 0);  
  while (v->count > 1) { lval_del(lval_pop(v, 1)); }
  return v;
}

lval* builtin_tail(lenv* e, lval* a) {
  LASSERT_NUM("tail", a, 1);
  LASSERT_TYPE("tail", a, 0, LVAL_QEXPR);
  LASSERT_NOT_EMPTY("tail", a, 0);

  lval* v = lval_take(a, 0);  
  lval_del(lval_pop(v, 0));
  return v;
}

lval* builtin_eval(lenv* e, lval* a) {
  LASSERT_NUM("eval", a, 1);
  LASSERT_TYPE("eval", a, 0, LVAL_QEXPR);
  
  lval* x = lval_take(a, 0);
  x->type = LVAL_SEXPR;
  return lval_eval(e, x);
}

lval* builtin_join(lenv* e, lval* a) {
  
  for (int i = 0; i < a->count; i++) {
    LASSERT_TYPE("join", a, i, LVAL_QEXPR);
  }
  
  lval* x = lval_pop(a, 0);
  
  while (a->count) {
    lval* y = lval_pop(a, 0);
    x = lval_join(x, y);
  }
  
  lval_del(a);
  return x;
}

lval* builtin_op(lenv* e, lval* a, char* op) {
  
  for (int i = 0; i < a->count; i++) {
    LASSERT_TYPE(op, a, i, LVAL_NUM);
  }
  
  lval* x = lval_pop(a, 0);
  
  if ((strcmp(op, "-") == 0) && a->count == 0) {
    x->num = -x->num;
  }
  
  while (a->count > 0) {  
    lval* y = lval_pop(a, 0);
    
    if (strcmp(op, "+") == 0) { x->num += y->num; }
    if (strcmp(op, "-") == 0) { x->num -= y->num; }
    if (strcmp(op, "*") == 0) { x->num *= y->num; }
    if (strcmp(op, "/") == 0) {
      if (y->num == 0) {
        lval_del(x); lval_del(y);
        x = lval_err("Division By Zero.");
        break;
      }
      x->num /= y->num;
    }
    
    lval_del(y);
  }
  
  lval_del(a);
  return x;
}

lval* builtin_add(lenv* e, lval* a) {
  return builtin_op(e, a, "+");
}

lval* builtin_sub(lenv* e, lval* a) {
  return builtin_op(e, a, "-");
}

lval* builtin_mul(lenv* e, lval* a) {
  return builtin_op(e, a, "*");
}

lval* builtin_div(lenv* e, lval* a) {
  return builtin_op(e, a, "/");
}

lval* builtin_def(lenv* e, lval* a) {

  LASSERT_TYPE("def", a, 0, LVAL_QEXPR);
  
  /* First argument is symbol list */
  lval* syms = a->cell[0];
  
  /* Ensure all elements of first list are symbols */
  for (int i = 0; i < syms->count; i++) {
    LASSERT(a, (syms->cell[i]->type == LVAL_SYM),
      "Function 'def' cannot define non-symbol. "
      "Got %s, Expected %s.",
      ltype_name(syms->cell[i]->type), ltype_name(LVAL_SYM));
  }
  
  /* Check correct number of symbols and values */
  LASSERT(a, (syms->count == a->count-1),
    "Function 'def' passed too many arguments for symbols. "
    "Got %i, Expected %i.",
    syms->count, a->count-1);
  
  /* Assign copies of values to symbols */
  for (int i = 0; i < syms->count; i++) {
    lenv_put(e, syms->cell[i], a->cell[i+1]);
  }
  
  lval_del(a);
  return lval_sexpr();
}

void lenv_add_builtin(lenv* e, char* name, lbuiltin func) {
  lval* k = lval_sym(name);
  lval* v = lval_fun(func);
  lenv_put(e, k, v);
  lval_del(k); lval_del(v);
}

void lenv_add_builtins(lenv* e) {
  /* Variable Functions */
  lenv_add_builtin(e, "def", builtin_def);
  
  /* List Functions */
  lenv_add_builtin(e, "list", builtin_list);
  lenv_add_builtin(e, "head", builtin_head);
  lenv_add_builtin(e, "tail", builtin_tail);
  lenv_add_builtin(e, "eval", builtin_eval);
  lenv_add_builtin(e, "join", builtin_join);
  
  /* Mathematical Functions */
  lenv_add_builtin(e, "+", builtin_add);
  lenv_add_builtin(e, "-", builtin_sub);
  lenv_add_builtin(e, "*", builtin_mul);
  lenv_add_builtin(e, "/", builtin_div);
}

/* Evaluation */

lval* lval_eval_sexpr(lenv* e, lval* v) {
  
  for (int i = 0; i < v->count; i++) {
    v->cell[i] = lval_eval(e, v->cell[i]);
  }
  
  for (int i = 0; i < v->count; i++) {
    if (v->cell[i]->type == LVAL_ERR) { return lval_take(v, i); }
  }
  
  if (v->count == 0) { return v; }  
  if (v->count == 1) { return lval_take(v, 0); }
  
  /* Ensure first element is a function after evaluation */
  lval* f = lval_pop(v, 0);
  if (f->type != LVAL_FUN) {
    lval* err = lval_err(
      "S-Expression starts with incorrect type. "
      "Got %s, Expected %s.",
      ltype_name(f->type), ltype_name(LVAL_FUN));
    lval_del(f); lval_del(v);
    return err;
  }
  
  /* If so call function to get result */
  lval* result = f->fun(e, v);
  lval_del(f);
  return result;
}

lval* lval_eval(lenv* e, lval* v) {
  if (v->type == LVAL_SYM) {
    lval* x = lenv_get(e, v);
    lval_del(v);
    return x;
  }
  if (v->type == LVAL_SEXPR) { return lval_eval_sexpr(e, v); }
  return v;
}

/* Reading */

lval* lval_read_num(mpc_ast_t* t) {
  errno = 0;
  long x = strtol(t->contents, NULL, 10);
  return errno != ERANGE ? lval_num(x) : lval_err("Invalid Number.");
}

lval* lval_read(mpc_ast_t* t) {
  
  if (strstr(t->tag, "number")) { return lval_read_num(t); }
  if (strstr(t->tag, "symbol")) { return lval_sym(t->contents); }
  
  lval* x = NULL;
  if (strcmp(t->tag, ">") == 0) { x = lval_sexpr(); } 
  if (strstr(t->tag, "sexpr"))  { x = lval_sexpr(); }
  if (strstr(t->tag, "qexpr"))  { x = lval_qexpr(); }
  
  for (int i = 0; i < t->children_num; i++) {
    if (strcmp(t->children[i]->contents, "(") == 0) { continue; }
    if (strcmp(t->children[i]->contents, ")") == 0) { continue; }
    if (strcmp(t->children[i]->contents, "}") == 0) { continue; }
    if (strcmp(t->children[i]->contents, "{") == 0) { continue; }
    if (strcmp(t->children[i]->tag,  "regex") == 0) { continue; }
    x = lval_add(x, lval_read(t->children[i]));
  }
  
  return x;
}

/* Main */

int main(int argc, char** argv) {
  
  mpc_parser_t* Number = mpc_new("number");
  mpc_parser_t* Symbol = mpc_new("symbol");
  mpc_parser_t* Sexpr  = mpc_new("sexpr");
  mpc_parser_t* Qexpr  = mpc_new("qexpr");
  mpc_parser_t* Expr   = mpc_new("expr");
  mpc_parser_t* Lispy  = mpc_new("lispy");
  
  mpca_lang(MPCA_LANG_DEFAULT,
    "                                                     \
      number : /-?[0-9]+/ ;                               \
      symbol : /[a-zA-Z0-9_+\\-*\\/\\\\=<>!&]+/ ;         \
      sexpr  : '(' <expr>* ')' ;                          \
      qexpr  : '{' <expr>* '}' ;                          \
      expr   : <number> | <symbol> | <sexpr> | <qexpr> ;  \
      lispy  : /^/ <expr>* /$/ ;                          \
    ",
    Number, Symbol, Sexpr, Qexpr, Expr, Lispy);
  
  puts("Lispy Version 0.0.0.0.7");
  puts("Press Ctrl+c to Exit\n");
  
  lenv* e = lenv_new();
  lenv_add_builtins(e);
  
  while (1) {
  
    char* input = readline("lispy> ");
    add_history(input);
    
    mpc_result_t r;
    if (mpc_parse("<stdin>", input, Lispy, &r)) {
      lval* x = lval_eval(e, lval_read(r.output));
      lval_println(x);
      lval_del(x);
      mpc_ast_delete(r.output);
    } else {    
      mpc_err_print(r.error);
      mpc_err_delete(r.error);
    }
    
    free(input);
    
  }
  
  lenv_del(e);
  
  mpc_cleanup(6, Number, Symbol, Sexpr, Qexpr, Expr, Lispy);
  
  return 0;
}