Bug 924040 - Update yield* to use @@iterator protocol. r=jwalden

js/src/frontend/BytecodeEmitter.cpp

@@ -5109,9 +5109,22 @@ EmitYieldStar(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *iter)
     JS_ASSERT(bce->sc->isFunctionBox());
     JS_ASSERT(bce->sc->asFunctionBox()->isStarGenerator());
 
-    if (!EmitTree(cx, bce, iter))                                // ITER
+    if (!EmitTree(cx, bce, iter))                                // ITERABLE
         return false;
 
+    // Convert iterable to iterator.
+    if (Emit1(cx, bce, JSOP_DUP) < 0)                            // ITERABLE ITERABLE
+        return false;
+    if (!EmitAtomOp(cx, cx->names().std_iterator, JSOP_CALLPROP, bce)) // ITERABLE @@ITERATOR
+        return false;
+    if (Emit1(cx, bce, JSOP_SWAP) < 0)                           // @@ITERATOR ITERABLE
+        return false;
+    if (Emit1(cx, bce, JSOP_NOTEARG) < 0)
+        return false;
+    if (EmitCall(cx, bce, JSOP_CALL, 0) < 0)                     // ITER
+        return false;
+    CheckTypeSet(cx, bce, JSOP_CALL);
+
     int depth = bce->stackDepth;
     JS_ASSERT(depth >= 1);
 

js/src/tests/ecma_6/Generators/delegating-yield-1.js

@@ -10,16 +10,20 @@ function results(results) {
     function next() {
         return results[i++];
     }
-    return { next: next }
+    var iter = { next: next }
+    var ret = {};
+    ret[std_iterator] = function () { return iter; }
+    return ret;
 }
 
 function* yield_results(expected) {
     return yield* results(expected);
 }
 
-function collect_results(iter) {
+function collect_results(iterable) {
     var ret = [];
     var result;
+    var iter = iterable[std_iterator]();
     do {
         result = iter.next();
         ret.push(result);

js/src/tests/ecma_6/Generators/delegating-yield-11.js

@@ -8,6 +8,7 @@ function Iter() {
     }
 
     this.next = next;
+    this[std_iterator] = function () { return this; }
 }
 
 function* delegate(iter) { return yield* iter; }

js/src/tests/ecma_6/Generators/delegating-yield-12.js

@@ -0,0 +1,49 @@
+// yield* calls @@iterator on the iterable to produce the iterator.
+
+var log = '';
+
+function IteratorWrapper(iterator) {
+    return {
+        next: function (val) {
+            log += 'n';
+            return iterator.next(val);
+        },
+
+        throw: function (exn) {
+            log += 't';
+            return iterator.throw(exn);
+        }
+    };
+}
+
+function IterableWrapper(iterable) {
+    var ret = {};
+
+    ret[std_iterator] = function () {
+        log += 'i';
+        return IteratorWrapper(iterable[std_iterator]());
+    }
+
+    return ret;
+}
+
+function* delegate(iter) { return yield* iter; }
+
+var iter = delegate(IterableWrapper([1, 2, 3]));
+assertIteratorResult(1, false, iter.next());
+assertIteratorResult(2, false, iter.next());
+assertIteratorResult(3, false, iter.next());
+assertIteratorResult(undefined, true, iter.next());
+
+assertEq(log, 'innnn');
+
+iter = delegate([1, 2, 3]);
+assertIteratorResult(1, false, iter.next());
+assertIteratorResult(2, false, iter.next());
+assertIteratorResult(3, false, iter.next());
+assertIteratorResult(undefined, true, iter.next());
+
+assertEq(log, 'innnn');
+
+if (typeof reportCompare == "function")
+    reportCompare(true, true);

js/src/tests/ecma_6/Generators/delegating-yield-5.js

@@ -6,16 +6,20 @@ function results(results) {
     function next() {
         return results[i++];
     }
-    return { next: next }
+    var iter = { next: next };
+    var ret = {};
+    ret[std_iterator] = function () { return iter; }
+    return ret;
 }
 
 function* yield_results(expected, n) {
     return yield* n ? yield_results(expected, n - 1) : results(expected);
 }
 
-function collect_results(iter) {
+function collect_results(iterable) {
     var ret = [];
     var result;
+    var iter = iterable[std_iterator]();
     do {
         result = iter.next();
         ret.push(result);

js/src/tests/ecma_6/Generators/delegating-yield-6.js

@@ -15,13 +15,20 @@ function collect_results(iter) {
 
 function Iter(val, count) {
     function next() {
+        log += 'n';
         return {
             get done() { log += "d"; return count-- == 0; },
             get value() { log += "v"; return val; }
         }
     }
 
+    function iterator() {
+        log += 'i';
+        return this;
+    }
+
     this.next = next;
+    this[std_iterator] = iterator;
 }
 
 function* delegate(iter) { return yield* iter; }
@@ -37,13 +44,13 @@ outer.next();
 outer.next();
 outer.next();
 
-assertEq(log, "ddddddv");
+assertEq(log, "indndndndndndv");
 
 // Outer's dead, man.  Outer's dead.
 assertThrowsInstanceOf(outer.next.bind(outer), TypeError);
 
 // No more checking the iterator.
-assertEq(log, "ddddddv");
+assertEq(log, "indndndndndndv");
 
 if (typeof reportCompare == "function")
     reportCompare(true, true);

js/src/tests/ecma_6/Generators/delegating-yield-7.js

@@ -2,10 +2,15 @@
 
 function results(results) {
     var i = 0;
+    function iterator() {
+        return this;
+    }
     function next() {
         return results[i++];
     }
-    return { next: next }
+    var ret = { next: next }
+    ret[std_iterator] = iterator;
+    return ret;
 }
 
 function* yield_results(expected) {

js/src/tests/ecma_6/Generators/shell.js

@@ -3,9 +3,20 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 
+var std_iterator = (function() {
+    try {
+        for (var _ of new Proxy({}, { get: function(_, name) { throw name; } }))
+            break;
+    } catch (name) {
+        return name;
+    }
+    throw 'wat';
+})();
+
 function assertFalse(a) { assertEq(a, false) }
 function assertTrue(a) { assertEq(a, true) }
 function assertNotEq(found, not_expected) { assertFalse(found === expected) }
 function assertIteratorResult(value, done, result) {
-    assertDeepEq(result, { value: value, done: done });
+    assertDeepEq(result.value, value);
+    assertEq(result.done, done);
 }