1 files changed, 172 insertions, 0 deletions
diff --git a/js/src/vm/ForOfIterator.cpp b/js/src/vm/ForOfIterator.cpp
new file mode 100644
index 000000000..7bd521a6a
--- /dev/null
+++ b/js/src/vm/ForOfIterator.cpp
@@ -0,0 +1,172 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jsapi.h"
+#include "jscntxt.h"
+#include "jscompartment.h"
+#include "jsobj.h"
+
+#include "vm/Interpreter.h"
+#include "vm/PIC.h"
+
+#include "jsobjinlines.h"
+
+using namespace js;
+using JS::ForOfIterator;
+
+bool
+ForOfIterator::init(HandleValue iterable, NonIterableBehavior nonIterableBehavior)
+{
+    JSContext* cx = cx_;
+    RootedObject iterableObj(cx, ToObject(cx, iterable));
+    if (!iterableObj)
+        return false;
+
+    MOZ_ASSERT(index == NOT_ARRAY);
+
+    // Check the PIC first for a match.
+    if (iterableObj->is<ArrayObject>()) {
+        ForOfPIC::Chain* stubChain = ForOfPIC::getOrCreate(cx);
+        if (!stubChain)
+            return false;
+
+        bool optimized;
+        if (!stubChain->tryOptimizeArray(cx, iterableObj.as<ArrayObject>(), &optimized))
+            return false;
+
+        if (optimized) {
+            // Got optimized stub.  Array is optimizable.
+            index = 0;
+            iterator = iterableObj;
+            return true;
+        }
+    }
+
+    MOZ_ASSERT(index == NOT_ARRAY);
+
+    RootedValue callee(cx);
+    RootedId iteratorId(cx, SYMBOL_TO_JSID(cx->wellKnownSymbols().iterator));
+    if (!GetProperty(cx, iterableObj, iterableObj, iteratorId, &callee))
+        return false;
+
+    // If obj[@@iterator] is undefined and we were asked to allow non-iterables,
+    // bail out now without setting iterator.  This will make valueIsIterable(),
+    // which our caller should check, return false.
+    if (nonIterableBehavior == AllowNonIterable && callee.isUndefined())
+        return true;
+
+    // Throw if obj[@@iterator] isn't callable.
+    // js::Invoke is about to check for this kind of error anyway, but it would
+    // throw an inscrutable error message about |method| rather than this nice
+    // one about |obj|.
+    if (!callee.isObject() || !callee.toObject().isCallable()) {
+        UniqueChars bytes = DecompileValueGenerator(cx, JSDVG_SEARCH_STACK, iterable, nullptr);
+        if (!bytes)
+            return false;
+        JS_ReportErrorNumberLatin1(cx, GetErrorMessage, nullptr, JSMSG_NOT_ITERABLE, bytes.get());
+        return false;
+    }
+
+    RootedValue res(cx);
+    if (!js::Call(cx, callee, iterable, &res))
+        return false;
+
+    if (!res.isObject())
+        return ThrowCheckIsObject(cx, CheckIsObjectKind::GetIterator);
+
+    iterator = &res.toObject();
+    return true;
+}
+
+inline bool
+ForOfIterator::nextFromOptimizedArray(MutableHandleValue vp, bool* done)
+{
+    MOZ_ASSERT(index != NOT_ARRAY);
+
+    if (!CheckForInterrupt(cx_))
+        return false;
+
+    ArrayObject* arr = &iterator->as<ArrayObject>();
+
+    if (index >= arr->length()) {
+        vp.setUndefined();
+        *done = true;
+        return true;
+    }
+    *done = false;
+
+    // Try to get array element via direct access.
+    if (index < arr->getDenseInitializedLength()) {
+        vp.set(arr->getDenseElement(index));
+        if (!vp.isMagic(JS_ELEMENTS_HOLE)) {
+            ++index;
+            return true;
+        }
+    }
+
+    return GetElement(cx_, iterator, iterator, index++, vp);
+}
+
+bool
+ForOfIterator::next(MutableHandleValue vp, bool* done)
+{
+    MOZ_ASSERT(iterator);
+    if (index != NOT_ARRAY) {
+        ForOfPIC::Chain* stubChain = ForOfPIC::getOrCreate(cx_);
+        if (!stubChain)
+            return false;
+
+        if (stubChain->isArrayNextStillSane())
+            return nextFromOptimizedArray(vp, done);
+
+        // ArrayIterator.prototype.next changed, materialize a proper
+        // ArrayIterator instance and fall through to slowpath case.
+        if (!materializeArrayIterator())
+            return false;
+    }
+
+    RootedValue v(cx_);
+    if (!GetProperty(cx_, iterator, iterator, cx_->names().next, &v))
+        return false;
+
+    if (!js::Call(cx_, v, iterator, &v))
+        return false;
+
+    if (!v.isObject())
+        return ThrowCheckIsObject(cx_, CheckIsObjectKind::IteratorNext);
+
+    RootedObject resultObj(cx_, &v.toObject());
+    if (!GetProperty(cx_, resultObj, resultObj, cx_->names().done, &v))
+        return false;
+
+    *done = ToBoolean(v);
+    if (*done) {
+        vp.setUndefined();
+        return true;
+    }
+
+    return GetProperty(cx_, resultObj, resultObj, cx_->names().value, vp);
+}
+
+bool
+ForOfIterator::materializeArrayIterator()
+{
+    MOZ_ASSERT(index != NOT_ARRAY);
+
+    HandlePropertyName name = cx_->names().ArrayValuesAt;
+    RootedValue val(cx_);
+    if (!GlobalObject::getSelfHostedFunction(cx_, cx_->global(), name, name, 1, &val))
+        return false;
+
+    RootedValue indexOrRval(cx_, Int32Value(index));
+    if (!js::Call(cx_, val, iterator, indexOrRval, &indexOrRval))
+        return false;
+
+    index = NOT_ARRAY;
+    // Result of call to ArrayValuesAt must be an object.
+    iterator = &indexOrRval.toObject();
+    return true;
+}