Implement message cascade

README.md

@@ -44,8 +44,6 @@ the specifications are as follows:
 
  - local variables in methods do not yet support the full slotDeclartion style
 
- - as in SOM method chains are not supported
-
  - as in SOM, blocks can only have 3 arguments (counting `self`)
 
 Obtaining and Running SOMns

core-lib/TestSuite/LanguageTests.som

@@ -739,4 +739,61 @@ class LanguageTests usingPlatform: platform testFramework: minitest = Value (
       assert: o is: self.
     )
   ) : ( TEST_CONTEXT = () )
+
+  public class MessageCascades = TestContext ()(
+    class Cnt = (| public v ::= 0. |)(
+      public inc = ( v:: v + 1 )
+    )
+
+    class Setters = (|
+      public slot1
+      public slot2
+    |)(
+	    public runCascadeForEffect = (
+        self slot1: 23;
+             slot2: 42
+      )
+
+      public runCascadeForValue = (
+        ^ self slot1;
+               slot2
+      )
+    )
+
+    public testCascadeOnFieldRead = (
+      | c = Cnt new. |
+      assert: c v equals: 0.
+      c inc; inc; inc.
+      assert: c v equals: 3.
+    )
+
+    public testCascadeOnMultipleSends = (
+      | c = Cnt new. |
+      assert: c v equals: 0.
+      c inc inc inc;
+        inc;
+        inc;
+        inc.
+      assert: c v equals: 6.
+    )
+
+    public testKeywordCascade = (
+      | arr = Array new: 3. |
+
+      arr at: 1 put: 2;
+          at: 2 put: 3;
+          at: 3 put: 4.
+      assert: (arr at: 1) equals: 2.
+      assert: (arr at: 2) equals: 3.
+      assert: (arr at: 3) equals: 4.
+    )
+
+    public testSetter = (
+      | setter = Setters new. |
+      setter runCascadeForEffect.
+      assert: setter slot1 equals: 23.
+      assert: setter slot2 equals: 42.
+      assert: setter runCascadeForValue equals: 42.
+    )
+  ) : ( TEST_CONTEXT = () )
 )

src/som/compiler/Lexer.java

@@ -182,6 +182,8 @@ private Symbol doSym() {
     } else if (currentChar() == '*' && nextChar() == ')') {
       state.incPtr(2);
       state.set(Symbol.EndComment, '\0', "*)");
+    } else if (currentChar() == ';') {
+      match(Symbol.Semicolon);
     } else if (currentChar() == ')') {
       match(Symbol.EndTerm);
     } else if (currentChar() == '#') {

src/som/compiler/MethodBuilder.java

@@ -85,6 +85,8 @@ public final class MethodBuilder {
 
   private final List<SInvokable> embeddedBlockMethods;
 
+  private int cascadeId;
+
 
   public MethodBuilder(final MixinBuilder holder, final MixinScope clsScope) {
     this(holder, clsScope, null, false, holder.getLanguage());
@@ -339,6 +341,11 @@ public void addArgument(final String arg, final SourceSection source) {
     arguments.put(arg, argument);
   }
 
+  public Local addMessageCascadeTemp(final SourceSection source) throws MethodDefinitionError {
+    cascadeId += 1;
+    return addLocal("$cascadeTmp" + cascadeId, true, source);
+  }
+
   public Local addLocal(final String name, final boolean immutable,
       final SourceSection source) throws MethodDefinitionError {
     if (arguments.containsKey(name)) {

src/som/compiler/Parser.java

@@ -59,6 +59,7 @@
 import static som.compiler.Symbol.Pound;
 import static som.compiler.Symbol.RCurly;
 import static som.compiler.Symbol.STString;
+import static som.compiler.Symbol.Semicolon;
 import static som.compiler.Symbol.SlotMutableAssign;
 import static som.compiler.Symbol.Star;
 import static som.interpreter.SNodeFactory.createImplicitReceiverSend;
@@ -408,7 +409,7 @@ private void mixinApplication(final MixinBuilder mxnBuilder, final int mixinId)
     if (sym != NewTerm && sym != MixinOperator && sym != Period) {
       mixinFactorySend = (AbstractUninitializedMessageSendNode) messages(
           mxnBuilder.getInitializerMethodBuilder(),
-          mxnBuilder.getInitializerMethodBuilder().getSelfRead(getSource(coord)));
+          new ExpressionNode[] {mxnBuilder.getInitializerMethodBuilder().getSelfRead(getSource(coord))});
 
       uniqueInitName = MixinBuilder.getInitializerName(
           mixinFactorySend.getSelector(), mixinId);
@@ -439,7 +440,7 @@ private void inheritanceClause(final MixinBuilder mxnBuilder)
       // used to create the proper initialize method, on which we rely here.
       ExpressionNode superFactorySend = messages(
           mxnBuilder.getInitializerMethodBuilder(),
-          mxnBuilder.getInitializerMethodBuilder().getSuperReadNode(getEmptySource()));
+          new ExpressionNode[] {mxnBuilder.getInitializerMethodBuilder().getSuperReadNode(getEmptySource())});
 
       SSymbol initializerName = MixinBuilder.getInitializerName(
           ((AbstractUninitializedMessageSendNode) superFactorySend).getSelector());
@@ -1044,12 +1045,59 @@ private ExpressionNode evaluation(final MethodBuilder builder)
     } else {
       exp = primary(builder);
     }
+
     if (symIsMessageSend()) {
-      exp = messages(builder, exp);
+      SourceCoordinate coord = getCoordinate();
+      ExpressionNode[] lastReceiver = new ExpressionNode[] {exp};
+
+      exp = messages(builder, lastReceiver);
+
+      if (sym == Semicolon) {
+        exp = msgCascade(exp, lastReceiver[0], builder, coord);
+      }
     }
     return exp;
   }
 
+  private ExpressionNode msgCascade(final ExpressionNode nonEmptyMessage,
+      final ExpressionNode lastReceiver, final MethodBuilder builder,
+      final SourceCoordinate coord) throws ProgramDefinitionError {
+    List<ExpressionNode> cascade = new ArrayList<>();
+    SourceSection tmpSource = getSource(coord);
+
+    nonEmptyMessage.adoptChildren();
+
+    // first, create a temp variable, to which the result of the receiver is
+    // written, and then replace receiver use with reads from temp
+    Local tmp = builder.addMessageCascadeTemp(tmpSource);
+
+    // evaluate last receiver, and write value to temp
+    cascade.add(tmp.getWriteNode(0, lastReceiver, tmpSource));
+
+    // replace receiver with read from temp
+    lastReceiver.replace(tmp.getReadNode(0, tmpSource));
+
+    // add the initial message of the cascade, it is now send to the temp read
+    cascade.add(nonEmptyMessage);
+
+    while (sym == Semicolon) {
+      expect(Semicolon, KeywordTag.class);
+
+      ExpressionNode exp;
+      if (sym == Keyword) {
+        exp = keywordMessage(builder, tmp.getReadNode(0, tmpSource), false, false, null);
+      } else if (sym == OperatorSequence || symIn(binaryOpSyms)) {
+        exp = binaryMessage(builder, tmp.getReadNode(0, tmpSource), false, null);
+      } else {
+        assert sym == Identifier;
+        exp = unaryMessage(tmp.getReadNode(0, tmpSource), false, null);
+      }
+      cascade.add(exp);
+    }
+
+    return createSequence(cascade, getSource(coord));
+  }
+
   private boolean symIsMessageSend() {
     return sym == Identifier || sym == Keyword || sym == OperatorSequence
         || symIn(binaryOpSyms) || sym == EventualSend;
@@ -1148,8 +1196,9 @@ protected ExpressionNode binaryConsecutiveMessages(
   }
 
   private ExpressionNode messages(final MethodBuilder builder,
-      final ExpressionNode receiver) throws ProgramDefinitionError {
-    ExpressionNode msg = receiver;
+      final ExpressionNode[] lastReceiver) throws ProgramDefinitionError {
+    ExpressionNode msg = lastReceiver[0];
+
     SourceCoordinate coord = getCoordinate();
     boolean eventualSend = accept(EventualSend, KeywordTag.class);
 
@@ -1159,6 +1208,7 @@ private ExpressionNode messages(final MethodBuilder builder,
     }
 
     while (sym == Identifier) {
+      lastReceiver[0] = msg;
       msg = unaryMessage(msg, eventualSend, sendOp);
       eventualSend = accept(EventualSend, KeywordTag.class);
       if (eventualSend) {
@@ -1167,6 +1217,7 @@ private ExpressionNode messages(final MethodBuilder builder,
     }
 
     if (sym == OperatorSequence || symIn(binaryOpSyms)) {
+      lastReceiver[0] = msg;
       msg = binaryConsecutiveMessages(builder, msg, eventualSend, sendOp);
       eventualSend = accept(EventualSend, KeywordTag.class);
       if (eventualSend) {
@@ -1175,6 +1226,7 @@ private ExpressionNode messages(final MethodBuilder builder,
     }
 
     if (sym == Keyword) {
+      lastReceiver[0] = msg;
       msg = keywordMessage(builder, msg, true, eventualSend, sendOp);
     }
 

src/som/compiler/Symbol.java

@@ -26,7 +26,7 @@
 
 enum Symbol {
   NONE, Numeral, Not, And, Or, Star, Div, Mod, Plus, Minus, Equal, More, Less,
-  Comma, At, Per, NewBlock, EndBlock, LCurly, RCurly, Colon, Period, Exit, NewTerm,
+  Comma, At, Per, NewBlock, EndBlock, LCurly, RCurly, Colon, Semicolon, Period, Exit, NewTerm,
   EndTerm, Pound, STString,
   BeginComment, EndComment, SlotMutableAssign, EventualSend, MixinOperator,
   Identifier, Keyword, SetterKeyword,