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Allow iteration over the 'arguments' object even if it escapes and ca…
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…nnot be detected. Note that this causes some incorrect code to "work" when transpiled.

let obj = {
  0: 'x',
  1: 'y',
  length: 2,
};
for (let x of obj) {}

should throw a TypeError, but will not when transpiled. However, if typechecking is enabled there will be a compiler error.

Fixes #1303
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=116058485
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@blickly
tbreisacher authored and blickly committed Mar 2, 2016
1 parent 0affbf5 commit 6a40212
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Showing 8 changed files with 111 additions and 112 deletions.
2 changes: 1 addition & 1 deletion externs/es6.js
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Expand Up @@ -142,7 +142,7 @@ Generator.prototype.return = function(value) {};
Generator.prototype.throw = function(exception) {}; Generator.prototype.throw = function(exception) {};




// TODO(johnlenz): Array should be Iterable. // TODO(johnlenz): Array and Arguments should be Iterable.






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2 changes: 1 addition & 1 deletion src/com/google/javascript/jscomp/Es6RewriteDestructuring.java
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Expand Up @@ -294,7 +294,7 @@ private void visitArrayPattern(NodeTraversal t, Node arrayPattern, Node parent)
String tempVarName = DESTRUCTURING_TEMP_VAR + (destructuringVarCounter++); String tempVarName = DESTRUCTURING_TEMP_VAR + (destructuringVarCounter++);
Node tempDecl = IR.var( Node tempDecl = IR.var(
IR.name(tempVarName), IR.name(tempVarName),
makeIterator(t, compiler, rhs.detachFromParent())); makeIterator(compiler, rhs.detachFromParent()));
tempDecl.useSourceInfoIfMissingFromForTree(arrayPattern); tempDecl.useSourceInfoIfMissingFromForTree(arrayPattern);
nodeToDetach.getParent().addChildBefore(tempDecl, nodeToDetach); nodeToDetach.getParent().addChildBefore(tempDecl, nodeToDetach);


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2 changes: 1 addition & 1 deletion src/com/google/javascript/jscomp/Es6RewriteGenerators.java
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Expand Up @@ -179,7 +179,7 @@ private void visitYieldFor(NodeTraversal t, Node n, Node parent) {
Node enclosingStatement = NodeUtil.getEnclosingStatement(n); Node enclosingStatement = NodeUtil.getEnclosingStatement(n);
Node generator = IR.var( Node generator = IR.var(
IR.name(GENERATOR_YIELD_ALL_NAME), IR.name(GENERATOR_YIELD_ALL_NAME),
makeIterator(t, compiler, n.removeFirstChild())); makeIterator(compiler, n.removeFirstChild()));
Node entryDecl = IR.var(IR.name(GENERATOR_YIELD_ALL_ENTRY)); Node entryDecl = IR.var(IR.name(GENERATOR_YIELD_ALL_ENTRY));
Node assignIterResult = Node assignIterResult =
IR.assign( IR.assign(
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33 changes: 7 additions & 26 deletions src/com/google/javascript/jscomp/Es6ToEs3Converter.java
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Expand Up @@ -259,7 +259,7 @@ private void visitForOf(NodeTraversal t, Node node, Node parent) {
Node iterResult = IR.name(ITER_RESULT + variableName); Node iterResult = IR.name(ITER_RESULT + variableName);
iterResult.makeNonIndexable(); iterResult.makeNonIndexable();


Node init = IR.var(iterName.cloneTree(), makeIterator(t, compiler, iterable)); Node init = IR.var(iterName.cloneTree(), makeIterator(compiler, iterable));
Node initIterResult = iterResult.cloneTree(); Node initIterResult = iterResult.cloneTree();
initIterResult.addChildToFront(getNext.cloneTree()); initIterResult.addChildToFront(getNext.cloneTree());
init.addChildToBack(initIterResult); init.addChildToBack(initIterResult);
Expand Down Expand Up @@ -397,7 +397,7 @@ private void visitArrayLitOrCallWithSpread(NodeTraversal t, Node node, Node pare
currGroup = null; currGroup = null;
} }
compiler.needsEs6Runtime = true; compiler.needsEs6Runtime = true;
groups.add(arrayFromIterable(t, compiler, currElement.removeFirstChild())); groups.add(arrayFromIterable(compiler, currElement.removeFirstChild()));
} else { } else {
if (currGroup == null) { if (currGroup == null) {
currGroup = IR.arraylit(); currGroup = IR.arraylit();
Expand Down Expand Up @@ -937,36 +937,17 @@ private void cannotConvertYet(Node n, String feature) {
} }


/** /**
* Returns a call to {@code $jscomp.makeIterator} with {@code iterable} as its argument, unless * Returns a call to {@code $jscomp.makeIterator} with {@code iterable} as its argument.
* {@code iterable} is the special {@code arguments} variable, in which case the returned Node is:
* {@code $jscomp.makeIterator($jscomp.arrayFromArguments(iterable))}.
*/ */
static Node makeIterator(NodeTraversal t, AbstractCompiler compiler, Node iterable) { static Node makeIterator(AbstractCompiler compiler, Node iterable) {
if (iterable.isName()) {
Var var = t.getScope().getVar(iterable.getString());
if (var != null && var.isArguments()) {
iterable = IR.call(
NodeUtil.newQName(compiler, "$jscomp.arrayFromArguments"),
iterable);
}
}
return callEs6RuntimeFunction(compiler, iterable, "makeIterator"); return callEs6RuntimeFunction(compiler, iterable, "makeIterator");
} }


/** /**
* Returns a call to $jscomp.arrayFromIterable with {@code iterable} as its argument, unless * Returns a call to $jscomp.arrayFromIterable with {@code iterable} as its argument.
* {@code iterable} is the special {@code arguments} variable, in which case
* {@code $jscomp.arrayFromArguments} is called instead.
*/ */
private static Node arrayFromIterable(NodeTraversal t, AbstractCompiler compiler, Node iterable) { private static Node arrayFromIterable(AbstractCompiler compiler, Node iterable) {
String fnName = "arrayFromIterable"; return callEs6RuntimeFunction(compiler, iterable, "arrayFromIterable");
if (iterable.isName()) {
Var var = t.getScope().getVar(iterable.getString());
if (var != null && var.isArguments()) {
fnName = "arrayFromArguments";
}
}
return callEs6RuntimeFunction(compiler, iterable, fnName);
} }


private static Node callEs6RuntimeFunction( private static Node callEs6RuntimeFunction(
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23 changes: 3 additions & 20 deletions src/com/google/javascript/jscomp/js/es6/runtime.js
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Expand Up @@ -90,7 +90,7 @@ $jscomp.initSymbolIterator = function() {
/** /**
* Creates an iterator for the given iterable. * Creates an iterator for the given iterable.
* *
* @param {string|!Array<T>|!Iterable<T>|!Iterator<T>} iterable * @param {string|!Array<T>|!Iterable<T>|!Iterator<T>|!Arguments<T>} iterable
* @return {!Iterator<T>} * @return {!Iterator<T>}
* @template T * @template T
* @suppress {reportUnknownTypes} * @suppress {reportUnknownTypes}
Expand All @@ -101,10 +101,7 @@ $jscomp.makeIterator = function(iterable) {
if (iterable[$jscomp.global.Symbol.iterator]) { if (iterable[$jscomp.global.Symbol.iterator]) {
return iterable[$jscomp.global.Symbol.iterator](); return iterable[$jscomp.global.Symbol.iterator]();
} }
if (!(iterable instanceof Array) && typeof iterable != 'string' &&
!(iterable instanceof String)) {
throw new TypeError(iterable + ' is not iterable');
}
let index = 0; let index = 0;
return /** @type {!Iterator} */ ({ return /** @type {!Iterator} */ ({
next() { next() {
Expand Down Expand Up @@ -142,7 +139,7 @@ $jscomp.arrayFromIterator = function(iterator) {


/** /**
* Copies the values from an Iterable into an Array. * Copies the values from an Iterable into an Array.
* @param {string|!Array<T>|!Iterable<T>} iterable * @param {string|!Array<T>|!Iterable<T>|!Arguments<T>} iterable
* @return {!Array<T>} * @return {!Array<T>}
* @template T * @template T
*/ */
Expand All @@ -155,20 +152,6 @@ $jscomp.arrayFromIterable = function(iterable) {
}; };




/**
* Copies the values from an Arguments object into an Array.
* @param {!Arguments} args
* @return {!Array}
*/
$jscomp.arrayFromArguments = function(args) {
const result = [];
for (let i = 0; i < args.length; i++) {
result.push(args[i]);
}
return result;
};


/** /**
* Inherit the prototype methods and static methods from one constructor * Inherit the prototype methods and static methods from one constructor
* into another. * into another.
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16 changes: 2 additions & 14 deletions src/com/google/javascript/jscomp/js/es6_runtime.js
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Expand Up @@ -50,15 +50,12 @@
/**@suppress {reportUnknownTypes} /**@suppress {reportUnknownTypes}
@template T @template T
@param {(string|!Array<T>|!Iterable<T>|!Iterator<T>)} iterable @param {(string|!Array<T>|!Iterable<T>|!Iterator<T>|!Arguments<T>)} iterable
@return {!Iterator<T>} */$jscomp.makeIterator = function(iterable) { @return {!Iterator<T>} */$jscomp.makeIterator = function(iterable) {
$jscomp.initSymbolIterator(); $jscomp.initSymbolIterator();
if (iterable[$jscomp.global.Symbol.iterator]) { if (iterable[$jscomp.global.Symbol.iterator]) {
return iterable[$jscomp.global.Symbol.iterator](); return iterable[$jscomp.global.Symbol.iterator]();
} }
if (!(iterable instanceof Array) && typeof iterable != "string" && !(iterable instanceof String)) {
throw new TypeError(iterable + " is not iterable");
}
var index = 0; var index = 0;
return /**@type {!Iterator} */({next:function() { return /**@type {!Iterator} */({next:function() {
if (index == iterable.length) { if (index == iterable.length) {
Expand All @@ -81,7 +78,7 @@
}; };
/**@template T /**@template T
@param {(string|!Array<T>|!Iterable<T>)} iterable @param {(string|!Array<T>|!Iterable<T>|!Arguments<T>)} iterable
@return {!Array<T>} */$jscomp.arrayFromIterable = function(iterable) { @return {!Array<T>} */$jscomp.arrayFromIterable = function(iterable) {
if (iterable instanceof Array) { if (iterable instanceof Array) {
return iterable; return iterable;
Expand All @@ -90,15 +87,6 @@
} }
}; };
/** /**
@param {!Arguments} args
@return {!Array} */$jscomp.arrayFromArguments = function(args) {
/**@const */var result = [];
for (var i = 0;i < args.length;i++) {
result.push(args[i]);
}
return result;
};
/**
@param {!Function} childCtor @param {!Function} childCtor
@param {!Function} parentCtor */$jscomp.inherits = function(childCtor, parentCtor) { @param {!Function} parentCtor */$jscomp.inherits = function(childCtor, parentCtor) {
/**@constructor */function tempCtor() { /**@constructor */function tempCtor() {
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3 changes: 1 addition & 2 deletions test/com/google/javascript/jscomp/Es6RewriteDestructuringTest.java
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Expand Up @@ -362,8 +362,7 @@ public void testArrayDestructuringArguments() {
"function f() { var [x, y] = arguments; }", "function f() { var [x, y] = arguments; }",
LINE_JOINER.join( LINE_JOINER.join(
"function f() {", "function f() {",
" var $jscomp$destructuring$var0 = $jscomp.makeIterator(", " var $jscomp$destructuring$var0 = $jscomp.makeIterator(arguments);",
" $jscomp.arrayFromArguments(arguments));",
" var x = $jscomp$destructuring$var0.next().value;", " var x = $jscomp$destructuring$var0.next().value;",
" var y = $jscomp$destructuring$var0.next().value;", " var y = $jscomp$destructuring$var0.next().value;",
"}")); "}"));
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