Bug 1147371: Implement calling IteratorClose and "return" on iterators in yield*

Issue #74

3 files changed, 141 insertions, 13 deletions

diff --git a/js/src/tests/ecma_6/Generators/delegating-yield-2.js b/js/src/tests/ecma_6/Generators/delegating-yield-2.js
index 918fb33e11..34cb3f4a9f 100644
--- a/js/src/tests/ecma_6/Generators/delegating-yield-2.js
+++ b/js/src/tests/ecma_6/Generators/delegating-yield-2.js
@@ -25,8 +25,8 @@ assertThrowsValue(function () { outer.throw(42) }, 42);
 inner = g1();
 outer = delegate(inner);
 assertIteratorNext(outer, 1);
-inner.throw = function(e) { return e*2; };
-assertEq(84, outer.throw(42));
+inner.throw = function(e) { return { value: e*2 }; };
+assertEq(84, outer.throw(42).value);
 assertIteratorDone(outer, undefined);
 
 // Monkeypatching inner.next.
@@ -41,7 +41,9 @@ outer = delegate(inner);
 assertIteratorNext(outer, 1);
 delete GeneratorObjectPrototype.throw;
 var outer_throw_42 = GeneratorObjectPrototype_throw.bind(outer, 42);
-assertThrowsValue(outer_throw_42, 42);
+// yield* protocol violation: no 'throw' method
+assertThrowsInstanceOf(outer_throw_42, TypeError);
+// Now done, so just throws.
 assertThrowsValue(outer_throw_42, 42);
 
 // Monkeypunch a different throw handler.
@@ -49,11 +51,11 @@ inner = g2();
 outer = delegate(inner);
 outer_throw_42 = GeneratorObjectPrototype_throw.bind(outer, 42);
 assertIteratorNext(outer, 1);
-GeneratorObjectPrototype.throw = function(e) { return e*2; }
-assertEq(84, outer_throw_42());
-assertEq(84, outer_throw_42());
+GeneratorObjectPrototype.throw = function(e) { return { value: e*2 }; }
+assertEq(84, outer_throw_42().value);
+assertEq(84, outer_throw_42().value);
 // This continues indefinitely.
-assertEq(84, outer_throw_42());
+assertEq(84, outer_throw_42().value);
 assertIteratorDone(outer, undefined);
 
 // The same, but restoring the original pre-monkey throw.
@@ -61,8 +63,8 @@ inner = g2();
 outer = delegate(inner);
 outer_throw_42 = GeneratorObjectPrototype_throw.bind(outer, 42);
 assertIteratorNext(outer, 1);
-assertEq(84, outer_throw_42());
-assertEq(84, outer_throw_42());
+assertEq(84, outer_throw_42().value);
+assertEq(84, outer_throw_42().value);
 GeneratorObjectPrototype.throw = GeneratorObjectPrototype_throw;
 assertIteratorResult(outer_throw_42(), 42, false);
 assertIteratorDone(outer, undefined);
diff --git a/js/src/tests/ecma_6/Generators/yield-star-iterator-close.js b/js/src/tests/ecma_6/Generators/yield-star-iterator-close.js
new file mode 100644
index 0000000000..ec62dd86de
--- /dev/null
+++ b/js/src/tests/ecma_6/Generators/yield-star-iterator-close.js
@@ -0,0 +1,123 @@
+// Tests that the "return" method on iterators is called in yield*
+// expressions.
+
+function test() {
+    var returnCalled = 0;
+    var returnCalledExpected = 0;
+    var nextCalled = 0;
+    var nextCalledExpected = 0;
+    var iterable = {};
+    iterable[Symbol.iterator] = makeIterator({
+        next: function() {
+            nextCalled++;
+            return { done: false };
+        },
+        ret: function() {
+            returnCalled++;
+            return { done: true, value: "iter.return" };
+        }
+    });
+
+    function* y() {
+        yield* iterable;
+    }
+
+    // G.p.throw on an iterator without "throw" calls IteratorClose.
+    var g1 = y();
+    g1.next();
+    assertThrowsValue(function() {
+        g1.throw("foo");
+    }, "foo");
+    assertEq(returnCalled, ++returnCalledExpected);
+    assertEq(nextCalled, ++nextCalledExpected);
+    g1.next();
+    assertEq(nextCalled, nextCalledExpected);
+
+    // G.p.return calls "return", and if the result.done is true, return the
+    // result.
+    var g2 = y();
+    g2.next();
+    var v2 = g2.return("test return");
+    assertEq(v2.done, true);
+    assertEq(v2.value, "iter.return");
+    assertEq(returnCalled, ++returnCalledExpected);
+    assertEq(nextCalled, ++nextCalledExpected);
+    g2.next();
+    assertEq(nextCalled, nextCalledExpected);
+
+    // G.p.return calls "return", and if the result.done is false, continue
+    // yielding.
+    iterable[Symbol.iterator] = makeIterator({
+        next: function() {
+            nextCalled++;
+            return { done: false };
+        },
+        ret: function() {
+            returnCalled++;
+            return { done: false, value: "iter.return" };
+        }
+    });
+    var g3 = y();
+    g3.next();
+    var v3 = g3.return("test return");
+    assertEq(v3.done, false);
+    assertEq(v3.value, "iter.return");
+    assertEq(returnCalled, ++returnCalledExpected);
+    assertEq(nextCalled, ++nextCalledExpected);
+    g3.next();
+    assertEq(nextCalled, ++nextCalledExpected);
+
+    // G.p.return throwing does not re-call iter.return.
+    iterable[Symbol.iterator] = makeIterator({
+        ret: function() {
+            returnCalled++;
+            throw "in iter.return";
+        }
+    });
+    var g4 = y();
+    g4.next();
+    assertThrowsValue(function() {
+        g4.return("in test");
+    }, "in iter.return");
+    assertEq(returnCalled, ++returnCalledExpected);
+
+    // G.p.return expects iter.return to return an Object.
+    iterable[Symbol.iterator] = makeIterator({
+        ret: function() {
+            returnCalled++;
+            return 42;
+        }
+    });
+    var g5 = y();
+    g5.next();
+    assertThrowsInstanceOf(function() {
+        g5.return("foo");
+    }, TypeError);
+    assertEq(returnCalled, ++returnCalledExpected);
+
+    // IteratorClose expects iter.return to return an Object.
+    var g6 = y();
+    g6.next();
+    assertThrowsInstanceOf(function() {
+        g6.throw("foo");
+    }, TypeError);
+    assertEq(returnCalled, ++returnCalledExpected);
+
+    // G.p.return passes its argument to "return".
+    iterable[Symbol.iterator] = makeIterator({
+        ret: function(x) {
+            assertEq(x, "in test");
+            returnCalled++;
+            return { done: true };
+        }
+    });
+    var g7 = y();
+    g7.next();
+    g7.return("in test");
+    assertEq(returnCalled, ++returnCalledExpected);
+}
+
+test();
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0);
diff --git a/js/src/tests/ecma_6/shell.js b/js/src/tests/ecma_6/shell.js
index 1d067a282d..4da9221d6d 100644
--- a/js/src/tests/ecma_6/shell.js
+++ b/js/src/tests/ecma_6/shell.js
@@ -22,14 +22,17 @@
     /** Make an iterator with a return method. */
     global.makeIterator = function makeIterator(overrides) {
         var iterator = {
-            next: function() {
+            throw: function(e) {
+                throw e;
+            },
+            next: function(x) {
                 if (overrides && overrides.next)
-                    return overrides.next();
+                    return overrides.next(x);
                 return { done: false };
             },
-            return: function() {
+            return: function(x) {
                 if (overrides && overrides.ret)
-                    return overrides.ret();
+                    return overrides.ret(x);
                 return { done: true };
             }
         };