Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

feat(cdk): allow Tokens to be encoded as lists #1144

Merged
merged 2 commits into from
Nov 12, 2018
Merged

feat(cdk): allow Tokens to be encoded as lists #1144

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
4ad13e0
feat(cdk): allow Tokens to be encoded as lists
rix0rrr Nov 12, 2018
0e97f45
Update some docs
rix0rrr Nov 12, 2018
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
13 changes: 11 additions & 2 deletions packages/@aws-cdk/cdk/lib/cloudformation/fn.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -87,6 +87,7 @@ export class FnJoin extends Fn {
private readonly listOfValues: any[];
// Cache for the result of resolveValues() - since it otherwise would be computed several times
private _resolvedValues?: any[];
private canOptimize: boolean;

/**
* Creates an ``Fn::Join`` function.
Expand All @@ -103,11 +104,13 @@ export class FnJoin extends Fn {
super('Fn::Join', [ delimiter, new Token(() => this.resolveValues()) ]);
this.delimiter = delimiter;
this.listOfValues = listOfValues;
this.canOptimize = true;
}

public resolve(): any {
if (this.resolveValues().length === 1) {
return this.resolveValues()[0];
const resolved = this.resolveValues();
if (this.canOptimize && resolved.length === 1) {
return resolved[0];
}
return super.resolve();
}
Expand All @@ -120,6 +123,12 @@ export class FnJoin extends Fn {
private resolveValues() {
if (this._resolvedValues) { return this._resolvedValues; }

if (unresolved(this.listOfValues)) {
// This is a list token, don't resolve and also don't optimize.
this.canOptimize = false;
return this._resolvedValues = this.listOfValues;
}

const resolvedValues = [...this.listOfValues.map(e => resolve(e))];
let i = 0;
while (i < resolvedValues.length) {
Expand Down
145 changes: 112 additions & 33 deletions packages/@aws-cdk/cdk/lib/core/tokens.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,8 @@ export const RESOLVE_METHOD = 'resolve';
* semantics.
*/
export class Token {
private tokenKey?: string;
private tokenStringification?: string;
private tokenListification?: string[];

/**
* Creates a token that resolves to `value`.
Expand Down Expand Up @@ -72,10 +73,10 @@ export class Token {
return this.valueOrFunction.toString();
}

if (this.tokenKey === undefined) {
this.tokenKey = TOKEN_STRING_MAP.register(this, this.displayName);
if (this.tokenStringification === undefined) {
this.tokenStringification = TOKEN_MAP.registerString(this, this.displayName);
}
return this.tokenKey;
return this.tokenStringification;
}

/**
Expand All @@ -89,6 +90,30 @@ export class Token {
throw new Error('JSON.stringify() cannot be applied to structure with a Token in it. Use a document-specific stringification method instead.');
}

/**
* Return a string list representation of this token
*
* Call this if the Token intrinsically evaluates to a list of strings.
* If so, you can represent the Token in a similar way in the type
* system.
*
* Note that even though the Token is represented as a list of strings, you
* still cannot do any operations on it such as concatenation, indexing,
* or taking its length. The only useful operations you can do to these lists
* is constructing a `FnJoin` or a `FnSelect` on it.
*/
public toList(): string[] {
const valueType = typeof this.valueOrFunction;
if (valueType === 'string' || valueType === 'number' || valueType === 'boolean') {
throw new Error('Got a literal Token value; cannot be encoded as a list.');
}

if (this.tokenListification === undefined) {
this.tokenListification = TOKEN_MAP.registerList(this, this.displayName);
}
return this.tokenListification;
}

/**
* Return a concated version of this Token in a string context
*
Expand All @@ -103,12 +128,15 @@ export class Token {

/**
* Returns true if obj is a token (i.e. has the resolve() method or is a string
* that includes token markers).
* that includes token markers), or it's a listifictaion of a Token string.
*
* @param obj The object to test.
*/
export function unresolved(obj: any): boolean {
if (typeof(obj) === 'string') {
return TOKEN_STRING_MAP.createTokenString(obj).test();
return TOKEN_MAP.createStringTokenString(obj).test();
} else if (Array.isArray(obj) && obj.length === 1) {
return isListToken(obj[0]);
} else {
return typeof(obj[RESOLVE_METHOD]) === 'function';
}
Expand Down Expand Up @@ -158,7 +186,7 @@ export function resolve(obj: any, prefix?: string[]): any {
// string - potentially replace all stringified Tokens
//
if (typeof(obj) === 'string') {
return TOKEN_STRING_MAP.resolveMarkers(obj as string);
return TOKEN_MAP.resolveStringTokens(obj as string);
}

//
Expand All @@ -169,27 +197,31 @@ export function resolve(obj: any, prefix?: string[]): any {
return obj;
}

//
// tokens - invoke 'resolve' and continue to resolve recursively
//

if (unresolved(obj)) {
const value = obj[RESOLVE_METHOD]();
return resolve(value, path);
}

//
// arrays - resolve all values, remove undefined and remove empty arrays
//

if (Array.isArray(obj)) {
if (containsListToken(obj)) {
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Something is odd here... Isn't a list token always size=1? Why are we checking if the array "contains a list token"? Is this for the use case where an array contains other arrays as elements (that is solved in the recursion).

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

No, the issue is to detect the case where someone has done:

const xs = token.toList();
xs.push('hello');

// Or
const xs = ['hello'].concat(token.toList());

In that case, we want to detect that the token as constructed was meant to be a Token but is now illegal because of the concatenation.

return TOKEN_MAP.resolveListTokens(obj);
}

const arr = obj
.map((x, i) => resolve(x, path.concat(i.toString())))
.filter(x => typeof(x) !== 'undefined');

return arr;
}

//
// tokens - invoke 'resolve' and continue to resolve recursively
//

if (unresolved(obj)) {
const value = obj[RESOLVE_METHOD]();
return resolve(value, path);
}

//
// objects - deep-resolve all values
//
Expand Down Expand Up @@ -221,6 +253,14 @@ export function resolve(obj: any, prefix?: string[]): any {
return result;
}

function isListToken(x: any) {
return typeof(x) === 'string' && TOKEN_MAP.createListTokenString(x).test();
}

function containsListToken(xs: any[]) {
return xs.some(isListToken);
}

/**
* Central place where we keep a mapping from Tokens to their String representation
*
Expand All @@ -230,7 +270,7 @@ export function resolve(obj: any, prefix?: string[]): any {
* All instances of TokenStringMap share the same storage, so that this process
* works even when different copies of the library are loaded.
*/
class TokenStringMap {
class TokenMap {
private readonly tokenMap: {[key: string]: Token};

constructor() {
Expand All @@ -239,7 +279,7 @@ class TokenStringMap {
}

/**
* Generating a unique string for this Token, returning a key
* Generate a unique string for this Token, returning a key
*
* Every call for the same Token will produce a new unique string, no
* attempt is made to deduplicate. Token objects should cache the
Expand All @@ -249,35 +289,56 @@ class TokenStringMap {
* hint. This may be used to produce aesthetically pleasing and
* recognizable token representations for humans.
*/
public register(token: Token, representationHint?: string): string {
const counter = Object.keys(this.tokenMap).length;
const representation = representationHint || `TOKEN`;
public registerString(token: Token, representationHint?: string): string {
const key = this.register(token, representationHint);
return `${BEGIN_STRING_TOKEN_MARKER}${key}${END_TOKEN_MARKER}`;
}

const key = `${representation}.${counter}`;
if (new RegExp(`[^${VALID_KEY_CHARS}]`).exec(key)) {
throw new Error(`Invalid characters in token representation: ${key}`);
}
/**
* Generate a unique string for this Token, returning a key
*/
public registerList(token: Token, representationHint?: string): string[] {
const key = this.register(token, representationHint);
return [`${BEGIN_LIST_TOKEN_MARKER}${key}${END_TOKEN_MARKER}`];
}

this.tokenMap[key] = token;
return `${BEGIN_TOKEN_MARKER}${key}${END_TOKEN_MARKER}`;
/**
* Returns a `TokenString` for this string.
*/
public createStringTokenString(s: string) {
return new TokenString(s, BEGIN_STRING_TOKEN_MARKER, `[${VALID_KEY_CHARS}]+`, END_TOKEN_MARKER);
}

/**
* Returns a `TokenString` for this string.
*/
public createTokenString(s: string) {
return new TokenString(s, BEGIN_TOKEN_MARKER, `[${VALID_KEY_CHARS}]+`, END_TOKEN_MARKER);
public createListTokenString(s: string) {
return new TokenString(s, BEGIN_LIST_TOKEN_MARKER, `[${VALID_KEY_CHARS}]+`, END_TOKEN_MARKER);
}

/**
* Replace any Token markers in this string with their resolved values
*/
public resolveMarkers(s: string): any {
const str = this.createTokenString(s);
public resolveStringTokens(s: string): any {
const str = this.createStringTokenString(s);
const fragments = str.split(this.lookupToken.bind(this));
return fragments.join();
}

public resolveListTokens(xs: string[]): any {
// Must be a singleton list token, because concatenation is not allowed.
if (xs.length !== 1) {
throw new Error(`Cannot add elements to list token, got: ${xs}`);
}

const str = this.createListTokenString(xs[0]);
const fragments = str.split(this.lookupToken.bind(this));
if (fragments.length !== 1) {
throw new Error(`Cannot concatenate strings in a tokenized string array, got: ${xs[0]}`);
}
return fragments.values()[0];
}

/**
* Find a Token by key
*/
Expand All @@ -288,16 +349,30 @@ class TokenStringMap {

return this.tokenMap[key];
}

private register(token: Token, representationHint?: string): string {
const counter = Object.keys(this.tokenMap).length;
const representation = representationHint || `TOKEN`;

const key = `${representation}.${counter}`;
if (new RegExp(`[^${VALID_KEY_CHARS}]`).exec(key)) {
throw new Error(`Invalid characters in token representation: ${key}`);
}

this.tokenMap[key] = token;
return key;
}
}

const BEGIN_TOKEN_MARKER = '${Token[';
const BEGIN_STRING_TOKEN_MARKER = '${Token[';
const BEGIN_LIST_TOKEN_MARKER = '#{Token[';
const END_TOKEN_MARKER = ']}';
const VALID_KEY_CHARS = 'a-zA-Z0-9:._-';

/**
* Singleton instance of the token string map
*/
const TOKEN_STRING_MAP = new TokenStringMap();
const TOKEN_MAP = new TokenMap();

/**
* Interface that Token joiners implement
Expand Down Expand Up @@ -382,6 +457,10 @@ type Fragment = StringFragment | TokenFragment;
class TokenStringFragments {
private readonly fragments = new Array<Fragment>();

public get length() {
return this.fragments.length;
}

public values(): any[] {
return this.fragments.map(f => f.type === 'token' ? resolve(f.token) : f.str);
}
Expand Down
Loading