The Tor Browser: js/src/jsiter.cpp@6474c204b198 (annotated)

js/src/jsiter.cpp@6474c204b198 (annotated)

js/src/jsiter.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- 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/. */
 /* JavaScript iterators. */
 #include "jsiter.h"
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/PodOperations.h"
 #include "jsarray.h"
 #include "jsatom.h"
 #include "jscntxt.h"
 #include "jsgc.h"
 #include "jsobj.h"
 #include "jsopcode.h"
 #include "jsproxy.h"
 #include "jsscript.h"
 #include "jstypes.h"
 #include "jsutil.h"
 #include "ds/Sort.h"
 #include "gc/Marking.h"
 #include "vm/GeneratorObject.h"
 #include "vm/GlobalObject.h"
 #include "vm/Interpreter.h"
 #include "vm/Shape.h"
 #include "vm/StopIterationObject.h"
 #include "jsinferinlines.h"
 #include "jsobjinlines.h"
 #include "jsscriptinlines.h"
 #include "vm/Stack-inl.h"
 #include "vm/String-inl.h"
 using namespace js;
 using namespace js::gc;
 using JS::ForOfIterator;
 using mozilla::ArrayLength;
 #ifdef JS_MORE_DETERMINISTIC
 using mozilla::PodCopy;
 #endif
 using mozilla::PodZero;
 typedef Rooted<PropertyIteratorObject*> RootedPropertyIteratorObject;
 static const gc::AllocKind ITERATOR_FINALIZE_KIND = gc::FINALIZE_OBJECT2_BACKGROUND;
 void
 NativeIterator::mark(JSTracer *trc)
 {
     for (HeapPtr<JSFlatString> *str = begin(); str < end(); str++)
         MarkString(trc, str, "prop");
     if (obj)
         MarkObject(trc, &obj, "obj");
     // The SuppressDeletedPropertyHelper loop can GC, so make sure that if the
     // GC removes any elements from the list, it won't remove this one.
     if (iterObj_)
         MarkObjectUnbarriered(trc, &iterObj_, "iterObj");
 }
 struct IdHashPolicy {
     typedef jsid Lookup;
     static HashNumber hash(jsid id) {
         return JSID_BITS(id);
     }
     static bool match(jsid id1, jsid id2) {
         return id1 == id2;
     }
 };
 typedef HashSet<jsid, IdHashPolicy> IdSet;
 static inline bool
 NewKeyValuePair(JSContext *cx, jsid id, const Value &val, MutableHandleValue rval)
 {
     JS::AutoValueArray<2> vec(cx);
     vec[0].set(IdToValue(id));
     vec[1].set(val);
     JSObject *aobj = NewDenseCopiedArray(cx, 2, vec.begin());
     if (!aobj)
         return false;
     rval.setObject(*aobj);
     return true;
 }
 static inline bool
 Enumerate(JSContext *cx, HandleObject pobj, jsid id,
           bool enumerable, unsigned flags, IdSet& ht, AutoIdVector *props)
 {
     /*
      * We implement __proto__ using a property on |Object.prototype|, but
      * because __proto__ is highly deserving of removal, we don't want it to
      * show up in property enumeration, even if only for |Object.prototype|
      * (think introspection by Prototype-like frameworks that add methods to
      * the built-in prototypes).  So exclude __proto__ if the object where the
      * property was found has no [[Prototype]] and might be |Object.prototype|.
      */
     if (MOZ_UNLIKELY(!pobj->getTaggedProto().isObject() && JSID_IS_ATOM(id, cx->names().proto)))
         return true;
     if (!(flags & JSITER_OWNONLY) || pobj->is<ProxyObject>() || pobj->getOps()->enumerate) {
         /* If we've already seen this, we definitely won't add it. */
         IdSet::AddPtr p = ht.lookupForAdd(id);
         if (MOZ_UNLIKELY(!!p))
             return true;
         /*
          * It's not necessary to add properties to the hash table at the end of
          * the prototype chain, but custom enumeration behaviors might return
          * duplicated properties, so always add in such cases.
          */
         if ((pobj->is<ProxyObject>() || pobj->getProto() || pobj->getOps()->enumerate) && !ht.add(p, id))
             return false;
     }
     if (enumerable || (flags & JSITER_HIDDEN))
         return props->append(id);
     return true;
 }
 static bool
 EnumerateNativeProperties(JSContext *cx, HandleObject pobj, unsigned flags, IdSet &ht,
                           AutoIdVector *props)
 {
     /* Collect any dense elements from this object. */
     size_t initlen = pobj->getDenseInitializedLength();
     const Value *vp = pobj->getDenseElements();
     for (size_t i = 0; i < initlen; ++i, ++vp) {
         if (!vp->isMagic(JS_ELEMENTS_HOLE)) {
             /* Dense arrays never get so large that i would not fit into an integer id. */
             if (!Enumerate(cx, pobj, INT_TO_JSID(i), /* enumerable = */ true, flags, ht, props))
                 return false;
         }
     }
     /* Collect any typed array elements from this object. */
     if (pobj->is<TypedArrayObject>()) {
         size_t len = pobj->as<TypedArrayObject>().length();
         for (size_t i = 0; i < len; i++) {
             if (!Enumerate(cx, pobj, INT_TO_JSID(i), /* enumerable = */ true, flags, ht, props))
                 return false;
         }
     }
     size_t initialLength = props->length();
     /* Collect all unique properties from this object's scope. */
     Shape::Range<NoGC> r(pobj->lastProperty());
     for (; !r.empty(); r.popFront()) {
         Shape &shape = r.front();
         if (!Enumerate(cx, pobj, shape.propid(), shape.enumerable(), flags, ht, props))
             return false;
     }
     ::Reverse(props->begin() + initialLength, props->end());
     return true;
 }
 #ifdef JS_MORE_DETERMINISTIC
 struct SortComparatorIds
 {
     JSContext   *const cx;
     SortComparatorIds(JSContext *cx)
       : cx(cx) {}
     bool operator()(jsid a, jsid b, bool *lessOrEqualp)
     {
         /* Pick an arbitrary total order on jsids that is stable across executions. */
         RootedString astr(cx, IdToString(cx, a));
 	if (!astr)
 	    return false;
         RootedString bstr(cx, IdToString(cx, b));
         if (!bstr)
             return false;
         int32_t result;
         if (!CompareStrings(cx, astr, bstr, &result))
             return false;
         *lessOrEqualp = (result <= 0);
         return true;
     }
 };
 #endif /* JS_MORE_DETERMINISTIC */
 static bool
 Snapshot(JSContext *cx, JSObject *pobj_, unsigned flags, AutoIdVector *props)
 {
     IdSet ht(cx);
     if (!ht.init(32))
         return false;
     RootedObject pobj(cx, pobj_);
     do {
         const Class *clasp = pobj->getClass();
         if (pobj->isNative() &&
             !pobj->getOps()->enumerate &&
             !(clasp->flags & JSCLASS_NEW_ENUMERATE)) {
             if (!clasp->enumerate(cx, pobj))
                 return false;
             if (!EnumerateNativeProperties(cx, pobj, flags, ht, props))
                 return false;
         } else {
             if (pobj->is<ProxyObject>()) {
                 AutoIdVector proxyProps(cx);
                 if (flags & JSITER_OWNONLY) {
                     if (flags & JSITER_HIDDEN) {
                         if (!Proxy::getOwnPropertyNames(cx, pobj, proxyProps))
                             return false;
                     } else {
                         if (!Proxy::keys(cx, pobj, proxyProps))
                             return false;
                     }
                 } else {
                     if (!Proxy::enumerate(cx, pobj, proxyProps))
                         return false;
                 }
                 for (size_t n = 0, len = proxyProps.length(); n < len; n++) {
                     if (!Enumerate(cx, pobj, proxyProps[n], true, flags, ht, props))
                         return false;
                 }
                 /* Proxy objects enumerate the prototype on their own, so we are done here. */
                 break;
             }
             RootedValue state(cx);
             RootedId id(cx);
             JSIterateOp op = (flags & JSITER_HIDDEN) ? JSENUMERATE_INIT_ALL : JSENUMERATE_INIT;
             if (!JSObject::enumerate(cx, pobj, op, &state, &id))
                 return false;
             if (state.isMagic(JS_NATIVE_ENUMERATE)) {
                 if (!EnumerateNativeProperties(cx, pobj, flags, ht, props))
                     return false;
             } else {
                 while (true) {
                     RootedId id(cx);
                     if (!JSObject::enumerate(cx, pobj, JSENUMERATE_NEXT, &state, &id))
                         return false;
                     if (state.isNull())
                         break;
                     if (!Enumerate(cx, pobj, id, true, flags, ht, props))
                         return false;
                 }
             }
         }
         if (flags & JSITER_OWNONLY)
             break;
     } while ((pobj = pobj->getProto()) != nullptr);
 #ifdef JS_MORE_DETERMINISTIC
     /*
      * In some cases the enumeration order for an object depends on the
      * execution mode (interpreter vs. JIT), especially for native objects
      * with a class enumerate hook (where resolving a property changes the
      * resulting enumeration order). These aren't really bugs, but the
      * differences can change the generated output and confuse correctness
      * fuzzers, so we sort the ids if such a fuzzer is running.
      *
      * We don't do this in the general case because (a) doing so is slow,
      * and (b) it also breaks the web, which expects enumeration order to
      * follow the order in which properties are added, in certain cases.
      * Since ECMA does not specify an enumeration order for objects, both
      * behaviors are technically correct to do.
      */
     jsid *ids = props->begin();
     size_t n = props->length();
     AutoIdVector tmp(cx);
     if (!tmp.resize(n))
         return false;
     PodCopy(tmp.begin(), ids, n);
     if (!MergeSort(ids, n, tmp.begin(), SortComparatorIds(cx)))
         return false;
 #endif /* JS_MORE_DETERMINISTIC */
     return true;
 }
 bool
 js::VectorToIdArray(JSContext *cx, AutoIdVector &props, JSIdArray **idap)
 {
     JS_STATIC_ASSERT(sizeof(JSIdArray) > sizeof(jsid));
     size_t len = props.length();
     size_t idsz = len * sizeof(jsid);
     size_t sz = (sizeof(JSIdArray) - sizeof(jsid)) + idsz;
     JSIdArray *ida = static_cast<JSIdArray *>(cx->malloc_(sz));
     if (!ida)
         return false;
     ida->length = static_cast<int>(len);
     jsid *v = props.begin();
     for (int i = 0; i < ida->length; i++)
         ida->vector[i].init(v[i]);
     *idap = ida;
     return true;
 }
 JS_FRIEND_API(bool)
 js::GetPropertyNames(JSContext *cx, JSObject *obj, unsigned flags, AutoIdVector *props)
 {
     return Snapshot(cx, obj, flags & (JSITER_OWNONLY | JSITER_HIDDEN), props);
 }
 size_t sCustomIteratorCount = 0;
 static inline bool
 GetCustomIterator(JSContext *cx, HandleObject obj, unsigned flags, MutableHandleValue vp)
 {
     JS_CHECK_RECURSION(cx, return false);
     /* Check whether we have a valid __iterator__ method. */
     HandlePropertyName name = cx->names().iteratorIntrinsic;
     if (!JSObject::getProperty(cx, obj, obj, name, vp))
         return false;
     /* If there is no custom __iterator__ method, we are done here. */
     if (!vp.isObject()) {
         vp.setUndefined();
         return true;
     }
     if (!cx->runningWithTrustedPrincipals())
         ++sCustomIteratorCount;
     /* Otherwise call it and return that object. */
     Value arg = BooleanValue((flags & JSITER_FOREACH) == 0);
     if (!Invoke(cx, ObjectValue(*obj), vp, 1, &arg, vp))
         return false;
     if (vp.isPrimitive()) {
         /*
          * We are always coming from js::ValueToIterator, and we are no longer on
          * trace, so the object we are iterating over is on top of the stack (-1).
          */
         JSAutoByteString bytes;
         if (!AtomToPrintableString(cx, name, &bytes))
             return false;
         RootedValue val(cx, ObjectValue(*obj));
         js_ReportValueError2(cx, JSMSG_BAD_TRAP_RETURN_VALUE,
                              -1, val, js::NullPtr(), bytes.ptr());
         return false;
     }
     return true;
 }
 template <typename T>
 static inline bool
 Compare(T *a, T *b, size_t c)
 {
     size_t n = (c + size_t(7)) / size_t(8);
     switch (c % 8) {
       case 0: do { if (*a++ != *b++) return false;
       case 7:      if (*a++ != *b++) return false;
       case 6:      if (*a++ != *b++) return false;
       case 5:      if (*a++ != *b++) return false;
       case 4:      if (*a++ != *b++) return false;
       case 3:      if (*a++ != *b++) return false;
       case 2:      if (*a++ != *b++) return false;
       case 1:      if (*a++ != *b++) return false;
               } while (--n > 0);
     }
     return true;
 }
 static inline PropertyIteratorObject *
 NewPropertyIteratorObject(JSContext *cx, unsigned flags)
 {
     if (flags & JSITER_ENUMERATE) {
         RootedTypeObject type(cx, cx->getNewType(&PropertyIteratorObject::class_, nullptr));
         if (!type)
             return nullptr;
         JSObject *metadata = nullptr;
         if (!NewObjectMetadata(cx, &metadata))
             return nullptr;
         const Class *clasp = &PropertyIteratorObject::class_;
         RootedShape shape(cx, EmptyShape::getInitialShape(cx, clasp, nullptr, nullptr, metadata,
                                                           ITERATOR_FINALIZE_KIND));
         if (!shape)
             return nullptr;
         JSObject *obj = JSObject::create(cx, ITERATOR_FINALIZE_KIND,
                                          GetInitialHeap(GenericObject, clasp), shape, type);
         if (!obj)
             return nullptr;
         JS_ASSERT(obj->numFixedSlots() == JSObject::ITER_CLASS_NFIXED_SLOTS);
         return &obj->as<PropertyIteratorObject>();
     }
     JSObject *obj = NewBuiltinClassInstance(cx, &PropertyIteratorObject::class_);
     if (!obj)
         return nullptr;
     return &obj->as<PropertyIteratorObject>();
 }
 NativeIterator *
 NativeIterator::allocateIterator(JSContext *cx, uint32_t slength, const AutoIdVector &props)
 {
     size_t plength = props.length();
     NativeIterator *ni = (NativeIterator *)
         cx->malloc_(sizeof(NativeIterator)
                     + plength * sizeof(JSString *)
                     + slength * sizeof(Shape *));
     if (!ni)
         return nullptr;
     AutoValueVector strings(cx);
     ni->props_array = ni->props_cursor = (HeapPtr<JSFlatString> *) (ni + 1);
     ni->props_end = ni->props_array + plength;
     if (plength) {
         for (size_t i = 0; i < plength; i++) {
             JSFlatString *str = IdToString(cx, props[i]);
             if (!str || !strings.append(StringValue(str)))
                 return nullptr;
             ni->props_array[i].init(str);
         }
     }
     ni->next_ = nullptr;
     ni->prev_ = nullptr;
     return ni;
 }
 NativeIterator *
 NativeIterator::allocateSentinel(JSContext *cx)
 {
     NativeIterator *ni = (NativeIterator *)js_malloc(sizeof(NativeIterator));
     if (!ni)
         return nullptr;
     PodZero(ni);
     ni->next_ = ni;
     ni->prev_ = ni;
     return ni;
 }
 inline void
 NativeIterator::init(JSObject *obj, JSObject *iterObj, unsigned flags, uint32_t slength, uint32_t key)
 {
     this->obj.init(obj);
     this->iterObj_ = iterObj;
     this->flags = flags;
     this->shapes_array = (Shape **) this->props_end;
     this->shapes_length = slength;
     this->shapes_key = key;
 }
 static inline void
 RegisterEnumerator(JSContext *cx, PropertyIteratorObject *iterobj, NativeIterator *ni)
 {
     /* Register non-escaping native enumerators (for-in) with the current context. */
     if (ni->flags & JSITER_ENUMERATE) {
         ni->link(cx->compartment()->enumerators);
         JS_ASSERT(!(ni->flags & JSITER_ACTIVE));
         ni->flags |= JSITER_ACTIVE;
     }
 }
 static inline bool
 VectorToKeyIterator(JSContext *cx, HandleObject obj, unsigned flags, AutoIdVector &keys,
                     uint32_t slength, uint32_t key, MutableHandleValue vp)
 {
     JS_ASSERT(!(flags & JSITER_FOREACH));
     if (obj) {
         if (obj->hasSingletonType() && !obj->setIteratedSingleton(cx))
             return false;
         types::MarkTypeObjectFlags(cx, obj, types::OBJECT_FLAG_ITERATED);
     }
     Rooted<PropertyIteratorObject *> iterobj(cx, NewPropertyIteratorObject(cx, flags));
     if (!iterobj)
         return false;
     NativeIterator *ni = NativeIterator::allocateIterator(cx, slength, keys);
     if (!ni)
         return false;
     ni->init(obj, iterobj, flags, slength, key);
     if (slength) {
         /*
          * Fill in the shape array from scratch.  We can't use the array that was
          * computed for the cache lookup earlier, as constructing iterobj could
          * have triggered a shape-regenerating GC.  Don't bother with regenerating
          * the shape key; if such a GC *does* occur, we can only get hits through
          * the one-slot lastNativeIterator cache.
          */
         JSObject *pobj = obj;
         size_t ind = 0;
         do {
             ni->shapes_array[ind++] = pobj->lastProperty();
             pobj = pobj->getProto();
         } while (pobj);
         JS_ASSERT(ind == slength);
     }
     iterobj->setNativeIterator(ni);
     vp.setObject(*iterobj);
     RegisterEnumerator(cx, iterobj, ni);
     return true;
 }
 bool
 js::VectorToKeyIterator(JSContext *cx, HandleObject obj, unsigned flags, AutoIdVector &props,
                         MutableHandleValue vp)
 {
     return VectorToKeyIterator(cx, obj, flags, props, 0, 0, vp);
 }
 bool
 js::VectorToValueIterator(JSContext *cx, HandleObject obj, unsigned flags, AutoIdVector &keys,
                           MutableHandleValue vp)
 {
     JS_ASSERT(flags & JSITER_FOREACH);
     if (obj) {
         if (obj->hasSingletonType() && !obj->setIteratedSingleton(cx))
             return false;
         types::MarkTypeObjectFlags(cx, obj, types::OBJECT_FLAG_ITERATED);
     }
     Rooted<PropertyIteratorObject*> iterobj(cx, NewPropertyIteratorObject(cx, flags));
     if (!iterobj)
         return false;
     NativeIterator *ni = NativeIterator::allocateIterator(cx, 0, keys);
     if (!ni)
         return false;
     ni->init(obj, iterobj, flags, 0, 0);
     iterobj->setNativeIterator(ni);
     vp.setObject(*iterobj);
     RegisterEnumerator(cx, iterobj, ni);
     return true;
 }
 bool
 js::EnumeratedIdVectorToIterator(JSContext *cx, HandleObject obj, unsigned flags,
                                  AutoIdVector &props, MutableHandleValue vp)
 {
     if (!(flags & JSITER_FOREACH))
         return VectorToKeyIterator(cx, obj, flags, props, vp);
     return VectorToValueIterator(cx, obj, flags, props, vp);
 }
 static inline void
 UpdateNativeIterator(NativeIterator *ni, JSObject *obj)
 {
     // Update the object for which the native iterator is associated, so
     // SuppressDeletedPropertyHelper will recognize the iterator as a match.
     ni->obj = obj;
 }
 bool
 js::GetIterator(JSContext *cx, HandleObject obj, unsigned flags, MutableHandleValue vp)
 {
     Vector<Shape *, 8> shapes(cx);
     uint32_t key = 0;
     bool keysOnly = (flags == JSITER_ENUMERATE);
     if (obj) {
         if (JSIteratorOp op = obj->getClass()->ext.iteratorObject) {
             JSObject *iterobj = op(cx, obj, !(flags & JSITER_FOREACH));
             if (!iterobj)
                 return false;
             vp.setObject(*iterobj);
             return true;
         }
         if (keysOnly) {
             /*
              * Check to see if this is the same as the most recent object which
              * was iterated over.  We don't explicitly check for shapeless
              * objects here, as they are not inserted into the cache and
              * will result in a miss.
              */
             PropertyIteratorObject *last = cx->runtime()->nativeIterCache.last;
             if (last) {
                 NativeIterator *lastni = last->getNativeIterator();
                 if (!(lastni->flags & (JSITER_ACTIVE|JSITER_UNREUSABLE)) &&
                     obj->isNative() &&
                     obj->hasEmptyElements() &&
                     obj->lastProperty() == lastni->shapes_array[0])
                 {
                     JSObject *proto = obj->getProto();
                     if (proto->isNative() &&
                         proto->hasEmptyElements() &&
                         proto->lastProperty() == lastni->shapes_array[1] &&
                         !proto->getProto())
                     {
                         vp.setObject(*last);
                         UpdateNativeIterator(lastni, obj);
                         RegisterEnumerator(cx, last, lastni);
                         return true;
                     }
                 }
             }
             /*
              * The iterator object for JSITER_ENUMERATE never escapes, so we
              * don't care for the proper parent/proto to be set. This also
              * allows us to re-use a previous iterator object that is not
              * currently active.
              */
             {
                 JSObject *pobj = obj;
                 do {
                     if (!pobj->isNative() ||
                         !pobj->hasEmptyElements() ||
                         pobj->is<TypedArrayObject>() ||
                         pobj->hasUncacheableProto() ||
                         pobj->getOps()->enumerate ||
                         pobj->getClass()->enumerate != JS_EnumerateStub ||
                         pobj->nativeContainsPure(cx->names().iteratorIntrinsic))
                     {
                         shapes.clear();
                         goto miss;
                     }
                     Shape *shape = pobj->lastProperty();
                     key = (key + (key << 16)) ^ (uintptr_t(shape) >> 3);
                     if (!shapes.append(shape))
                         return false;
                     pobj = pobj->getProto();
                 } while (pobj);
             }
             PropertyIteratorObject *iterobj = cx->runtime()->nativeIterCache.get(key);
             if (iterobj) {
                 NativeIterator *ni = iterobj->getNativeIterator();
                 if (!(ni->flags & (JSITER_ACTIVE|JSITER_UNREUSABLE)) &&
                     ni->shapes_key == key &&
                     ni->shapes_length == shapes.length() &&
                     Compare(ni->shapes_array, shapes.begin(), ni->shapes_length)) {
                     vp.setObject(*iterobj);
                     UpdateNativeIterator(ni, obj);
                     RegisterEnumerator(cx, iterobj, ni);
                     if (shapes.length() == 2)
                         cx->runtime()->nativeIterCache.last = iterobj;
                     return true;
                 }
             }
         }
       miss:
         if (obj->is<ProxyObject>())
             return Proxy::iterate(cx, obj, flags, vp);
         if (!GetCustomIterator(cx, obj, flags, vp))
             return false;
         if (!vp.isUndefined())
             return true;
     }
     /* NB: for (var p in null) succeeds by iterating over no properties. */
     AutoIdVector keys(cx);
     if (flags & JSITER_FOREACH) {
         if (MOZ_LIKELY(obj != nullptr) && !Snapshot(cx, obj, flags, &keys))
             return false;
         JS_ASSERT(shapes.empty());
         if (!VectorToValueIterator(cx, obj, flags, keys, vp))
             return false;
     } else {
         if (MOZ_LIKELY(obj != nullptr) && !Snapshot(cx, obj, flags, &keys))
             return false;
         if (!VectorToKeyIterator(cx, obj, flags, keys, shapes.length(), key, vp))
             return false;
     }
     PropertyIteratorObject *iterobj = &vp.toObject().as<PropertyIteratorObject>();
     /* Cache the iterator object if possible. */
     if (shapes.length())
         cx->runtime()->nativeIterCache.set(key, iterobj);
     if (shapes.length() == 2)
         cx->runtime()->nativeIterCache.last = iterobj;
     return true;
 }
 JSObject *
 js::GetIteratorObject(JSContext *cx, HandleObject obj, uint32_t flags)
 {
     RootedValue value(cx);
     if (!GetIterator(cx, obj, flags, &value))
         return nullptr;
     return &value.toObject();
 }
 JSObject *
 js::CreateItrResultObject(JSContext *cx, HandleValue value, bool done)
 {
     // FIXME: We can cache the iterator result object shape somewhere.
     AssertHeapIsIdle(cx);
     RootedObject proto(cx, cx->global()->getOrCreateObjectPrototype(cx));
     if (!proto)
         return nullptr;
     RootedObject obj(cx, NewObjectWithGivenProto(cx, &JSObject::class_, proto, cx->global()));
     if (!obj)
         return nullptr;
     if (!JSObject::defineProperty(cx, obj, cx->names().value, value))
         return nullptr;
     RootedValue doneBool(cx, BooleanValue(done));
     if (!JSObject::defineProperty(cx, obj, cx->names().done, doneBool))
         return nullptr;
     return obj;
 }
 bool
 js_ThrowStopIteration(JSContext *cx)
 {
     JS_ASSERT(!JS_IsExceptionPending(cx));
     // StopIteration isn't a constructor, but it's stored in GlobalObject
     // as one, out of laziness. Hence the GetBuiltinConstructor call here.
     RootedObject ctor(cx);
     if (GetBuiltinConstructor(cx, JSProto_StopIteration, &ctor))
         cx->setPendingException(ObjectValue(*ctor));
     return false;
 }
 /*** Iterator objects ****************************************************************************/
 bool
 js::IteratorConstructor(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         js_ReportMissingArg(cx, args.calleev(), 0);
         return false;
     }
     bool keyonly = false;
     if (args.length() >= 2)
         keyonly = ToBoolean(args[1]);
     unsigned flags = JSITER_OWNONLY | (keyonly ? 0 : (JSITER_FOREACH | JSITER_KEYVALUE));
     if (!ValueToIterator(cx, flags, args[0]))
         return false;
     args.rval().set(args[0]);
     return true;
 }
 MOZ_ALWAYS_INLINE bool
 IsIterator(HandleValue v)
 {
     return v.isObject() && v.toObject().hasClass(&PropertyIteratorObject::class_);
 }
 MOZ_ALWAYS_INLINE bool
 iterator_next_impl(JSContext *cx, CallArgs args)
 {
     JS_ASSERT(IsIterator(args.thisv()));
     RootedObject thisObj(cx, &args.thisv().toObject());
     if (!js_IteratorMore(cx, thisObj, args.rval()))
         return false;
     if (!args.rval().toBoolean()) {
         js_ThrowStopIteration(cx);
         return false;
     }
     return js_IteratorNext(cx, thisObj, args.rval());
 }
 static bool
 iterator_next(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     return CallNonGenericMethod<IsIterator, iterator_next_impl>(cx, args);
 }
 static const JSFunctionSpec iterator_methods[] = {
     JS_SELF_HOSTED_FN("@@iterator", "LegacyIteratorShim", 0, 0),
     JS_FN("next",      iterator_next,       0, 0),
     JS_FS_END
 };
 static JSObject *
 iterator_iteratorObject(JSContext *cx, HandleObject obj, bool keysonly)
 {
     return obj;
 }
 size_t
 PropertyIteratorObject::sizeOfMisc(mozilla::MallocSizeOf mallocSizeOf) const
 {
     return mallocSizeOf(getPrivate());
 }
 void
 PropertyIteratorObject::trace(JSTracer *trc, JSObject *obj)
 {
     if (NativeIterator *ni = obj->as<PropertyIteratorObject>().getNativeIterator())
         ni->mark(trc);
 }
 void
 PropertyIteratorObject::finalize(FreeOp *fop, JSObject *obj)
 {
     if (NativeIterator *ni = obj->as<PropertyIteratorObject>().getNativeIterator())
         fop->free_(ni);
 }
 const Class PropertyIteratorObject::class_ = {
     "Iterator",
     JSCLASS_IMPLEMENTS_BARRIERS |
     JSCLASS_HAS_CACHED_PROTO(JSProto_Iterator) |
     JSCLASS_HAS_PRIVATE |
     JSCLASS_BACKGROUND_FINALIZE,
     JS_PropertyStub,         /* addProperty */
     JS_DeletePropertyStub,   /* delProperty */
     JS_PropertyStub,         /* getProperty */
     JS_StrictPropertyStub,   /* setProperty */
     JS_EnumerateStub,
     JS_ResolveStub,
     JS_ConvertStub,
     finalize,
     nullptr,                 /* call        */
     nullptr,                 /* hasInstance */
     nullptr,                 /* construct   */
     trace,
     JS_NULL_CLASS_SPEC,
     {
         nullptr,             /* outerObject    */
         nullptr,             /* innerObject    */
         iterator_iteratorObject,
     }
 };
 enum {
     ArrayIteratorSlotIteratedObject,
     ArrayIteratorSlotNextIndex,
     ArrayIteratorSlotItemKind,
     ArrayIteratorSlotCount
 };
 const Class ArrayIteratorObject::class_ = {
     "Array Iterator",
     JSCLASS_IMPLEMENTS_BARRIERS |
     JSCLASS_HAS_RESERVED_SLOTS(ArrayIteratorSlotCount),
     JS_PropertyStub,         /* addProperty */
     JS_DeletePropertyStub,   /* delProperty */
     JS_PropertyStub,         /* getProperty */
     JS_StrictPropertyStub,   /* setProperty */
     JS_EnumerateStub,
     JS_ResolveStub,
     JS_ConvertStub,
     nullptr                  /* finalize    */
 };
 static const JSFunctionSpec array_iterator_methods[] = {
     JS_SELF_HOSTED_FN("@@iterator", "ArrayIteratorIdentity", 0, 0),
     JS_SELF_HOSTED_FN("next", "ArrayIteratorNext", 0, 0),
     JS_FS_END
 };
 static const Class StringIteratorPrototypeClass = {
     "String Iterator",
     JSCLASS_IMPLEMENTS_BARRIERS,
     JS_PropertyStub,         /* addProperty */
     JS_DeletePropertyStub,   /* delProperty */
     JS_PropertyStub,         /* getProperty */
     JS_StrictPropertyStub,   /* setProperty */
     JS_EnumerateStub,
     JS_ResolveStub,
     JS_ConvertStub,
     nullptr                  /* finalize    */
 };
 enum {
     StringIteratorSlotIteratedObject,
     StringIteratorSlotNextIndex,
     StringIteratorSlotCount
 };
 const Class StringIteratorObject::class_ = {
     "String Iterator",
     JSCLASS_IMPLEMENTS_BARRIERS |
     JSCLASS_HAS_RESERVED_SLOTS(StringIteratorSlotCount),
     JS_PropertyStub,         /* addProperty */
     JS_DeletePropertyStub,   /* delProperty */
     JS_PropertyStub,         /* getProperty */
     JS_StrictPropertyStub,   /* setProperty */
     JS_EnumerateStub,
     JS_ResolveStub,
     JS_ConvertStub,
     nullptr                  /* finalize    */
 };
 static const JSFunctionSpec string_iterator_methods[] = {
     JS_SELF_HOSTED_FN("@@iterator", "StringIteratorIdentity", 0, 0),
     JS_SELF_HOSTED_FN("next", "StringIteratorNext", 0, 0),
     JS_FS_END
 };
 static bool
 CloseLegacyGenerator(JSContext *cx, HandleObject genobj);
 bool
 js::ValueToIterator(JSContext *cx, unsigned flags, MutableHandleValue vp)
 {
     /* JSITER_KEYVALUE must always come with JSITER_FOREACH */
     JS_ASSERT_IF(flags & JSITER_KEYVALUE, flags & JSITER_FOREACH);
     /*
      * Make sure the more/next state machine doesn't get stuck. A value might
      * be left in iterValue when a trace is left due to an interrupt after
      * JSOP_MOREITER but before the value is picked up by FOR*.
      */
     cx->iterValue.setMagic(JS_NO_ITER_VALUE);
     RootedObject obj(cx);
     if (vp.isObject()) {
         /* Common case. */
         obj = &vp.toObject();
     } else {
         /*
          * Enumerating over null and undefined gives an empty enumerator, so
          * that |for (var p in <null or undefined>) <loop>;| never executes
          * <loop>, per ES5 12.6.4.
          */
         if (!(flags & JSITER_ENUMERATE) || !vp.isNullOrUndefined()) {
             obj = ToObject(cx, vp);
             if (!obj)
                 return false;
         }
     }
     return GetIterator(cx, obj, flags, vp);
 }
 bool
 js::CloseIterator(JSContext *cx, HandleObject obj)
 {
     cx->iterValue.setMagic(JS_NO_ITER_VALUE);
     if (obj->is<PropertyIteratorObject>()) {
         /* Remove enumerators from the active list, which is a stack. */
         NativeIterator *ni = obj->as<PropertyIteratorObject>().getNativeIterator();
         if (ni->flags & JSITER_ENUMERATE) {
             ni->unlink();
             JS_ASSERT(ni->flags & JSITER_ACTIVE);
             ni->flags &= ~JSITER_ACTIVE;
             /*
              * Reset the enumerator; it may still be in the cached iterators
              * for this thread, and can be reused.
              */
             ni->props_cursor = ni->props_array;
         }
     } else if (obj->is<LegacyGeneratorObject>()) {
         return CloseLegacyGenerator(cx, obj);
     }
     return true;
 }
 bool
 js::UnwindIteratorForException(JSContext *cx, HandleObject obj)
 {
     RootedValue v(cx);
     bool getOk = cx->getPendingException(&v);
     cx->clearPendingException();
     if (!CloseIterator(cx, obj))
         return false;
     if (!getOk)
         return false;
     cx->setPendingException(v);
     return true;
 }
 void
 js::UnwindIteratorForUncatchableException(JSContext *cx, JSObject *obj)
 {
     if (obj->is<PropertyIteratorObject>()) {
         NativeIterator *ni = obj->as<PropertyIteratorObject>().getNativeIterator();
         if (ni->flags & JSITER_ENUMERATE)
             ni->unlink();
     }
 }
 /*
  * Suppress enumeration of deleted properties. This function must be called
  * when a property is deleted and there might be active enumerators.
  *
  * We maintain a list of active non-escaping for-in enumerators. To suppress
  * a property, we check whether each active enumerator contains the (obj, id)
  * pair and has not yet enumerated |id|. If so, and |id| is the next property,
  * we simply advance the cursor. Otherwise, we delete |id| from the list.
  *
  * We do not suppress enumeration of a property deleted along an object's
  * prototype chain. Only direct deletions on the object are handled.
  *
  * This function can suppress multiple properties at once. The |predicate|
  * argument is an object which can be called on an id and returns true or
  * false. It also must have a method |matchesAtMostOne| which allows us to
  * stop searching after the first deletion if true.
  */
 template<typename StringPredicate>
 static bool
 SuppressDeletedPropertyHelper(JSContext *cx, HandleObject obj, StringPredicate predicate)
 {
     NativeIterator *enumeratorList = cx->compartment()->enumerators;
     NativeIterator *ni = enumeratorList->next();
     while (ni != enumeratorList) {
       again:
         /* This only works for identified suppressed keys, not values. */
         if (ni->isKeyIter() && ni->obj == obj && ni->props_cursor < ni->props_end) {
             /* Check whether id is still to come. */
             HeapPtr<JSFlatString> *props_cursor = ni->current();
             HeapPtr<JSFlatString> *props_end = ni->end();
             for (HeapPtr<JSFlatString> *idp = props_cursor; idp < props_end; ++idp) {
                 if (predicate(*idp)) {
                     /*
                      * Check whether another property along the prototype chain
                      * became visible as a result of this deletion.
                      */
                     RootedObject proto(cx);
                     if (!JSObject::getProto(cx, obj, &proto))
                         return false;
                     if (proto) {
                         RootedObject obj2(cx);
                         RootedShape prop(cx);
                         RootedId id(cx);
                         RootedValue idv(cx, StringValue(*idp));
                         if (!ValueToId<CanGC>(cx, idv, &id))
                             return false;
                         if (!JSObject::lookupGeneric(cx, proto, id, &obj2, &prop))
                             return false;
                         if (prop) {
                             unsigned attrs;
                             if (obj2->isNative())
                                 attrs = GetShapeAttributes(obj2, prop);
                             else if (!JSObject::getGenericAttributes(cx, obj2, id, &attrs))
                                 return false;
                             if (attrs & JSPROP_ENUMERATE)
                                 continue;
                         }
                     }
                     /*
                      * If lookupProperty or getAttributes above removed a property from
                      * ni, start over.
                      */
                     if (props_end != ni->props_end || props_cursor != ni->props_cursor)
                         goto again;
                     /*
                      * No property along the prototype chain stepped in to take the
                      * property's place, so go ahead and delete id from the list.
                      * If it is the next property to be enumerated, just skip it.
                      */
                     if (idp == props_cursor) {
                         ni->incCursor();
                     } else {
                         for (HeapPtr<JSFlatString> *p = idp; p + 1 != props_end; p++)
                             *p = *(p + 1);
                         ni->props_end = ni->end() - 1;
                         /*
                          * This invokes the pre barrier on this element, since
                          * it's no longer going to be marked, and ensures that
                          * any existing remembered set entry will be dropped.
                          */
                         *ni->props_end = nullptr;
                     }
                     /* Don't reuse modified native iterators. */
                     ni->flags |= JSITER_UNREUSABLE;
                     if (predicate.matchesAtMostOne())
                         break;
                 }
             }
         }
         ni = ni->next();
     }
     return true;
 }
 namespace {
 class SingleStringPredicate {
     Handle<JSFlatString*> str;
 public:
     SingleStringPredicate(Handle<JSFlatString*> str) : str(str) {}
     bool operator()(JSFlatString *str) { return EqualStrings(str, this->str); }
     bool matchesAtMostOne() { return true; }
 };
 } /* anonymous namespace */
 bool
 js_SuppressDeletedProperty(JSContext *cx, HandleObject obj, jsid id)
 {
     Rooted<JSFlatString*> str(cx, IdToString(cx, id));
     if (!str)
         return false;
     return SuppressDeletedPropertyHelper(cx, obj, SingleStringPredicate(str));
 }
 bool
 js_SuppressDeletedElement(JSContext *cx, HandleObject obj, uint32_t index)
 {
     RootedId id(cx);
     if (!IndexToId(cx, index, &id))
         return false;
     return js_SuppressDeletedProperty(cx, obj, id);
 }
 namespace {
 class IndexRangePredicate {
     uint32_t begin, end;
   public:
     IndexRangePredicate(uint32_t begin, uint32_t end) : begin(begin), end(end) {}
     bool operator()(JSFlatString *str) {
         uint32_t index;
         return str->isIndex(&index) && begin <= index && index < end;
     }
     bool matchesAtMostOne() { return false; }
 };
 } /* anonymous namespace */
 bool
 js_SuppressDeletedElements(JSContext *cx, HandleObject obj, uint32_t begin, uint32_t end)
 {
     return SuppressDeletedPropertyHelper(cx, obj, IndexRangePredicate(begin, end));
 }
 bool
 js_IteratorMore(JSContext *cx, HandleObject iterobj, MutableHandleValue rval)
 {
     /* Fast path for native iterators */
     NativeIterator *ni = nullptr;
     if (iterobj->is<PropertyIteratorObject>()) {
         /* Key iterators are handled by fast-paths. */
         ni = iterobj->as<PropertyIteratorObject>().getNativeIterator();
         bool more = ni->props_cursor < ni->props_end;
         if (ni->isKeyIter() || !more) {
             rval.setBoolean(more);
             return true;
         }
     }
     /* We might still have a pending value. */
     if (!cx->iterValue.isMagic(JS_NO_ITER_VALUE)) {
         rval.setBoolean(true);
         return true;
     }
     /* We're reentering below and can call anything. */
     JS_CHECK_RECURSION(cx, return false);
     /* Fetch and cache the next value from the iterator. */
     if (ni) {
         JS_ASSERT(!ni->isKeyIter());
         RootedId id(cx);
         RootedValue current(cx, StringValue(*ni->current()));
         if (!ValueToId<CanGC>(cx, current, &id))
             return false;
         ni->incCursor();
         RootedObject obj(cx, ni->obj);
         if (!JSObject::getGeneric(cx, obj, obj, id, rval))
             return false;
         if ((ni->flags & JSITER_KEYVALUE) && !NewKeyValuePair(cx, id, rval, rval))
             return false;
     } else {
         /* Call the iterator object's .next method. */
         if (!JSObject::getProperty(cx, iterobj, iterobj, cx->names().next, rval))
             return false;
         if (!Invoke(cx, ObjectValue(*iterobj), rval, 0, nullptr, rval)) {
             /* Check for StopIteration. */
             if (!cx->isExceptionPending())
                 return false;
             RootedValue exception(cx);
             if (!cx->getPendingException(&exception))
                 return false;
             if (!JS_IsStopIteration(exception))
                 return false;
             cx->clearPendingException();
             cx->iterValue.setMagic(JS_NO_ITER_VALUE);
             rval.setBoolean(false);
             return true;
         }
     }
     /* Cache the value returned by iterobj.next() so js_IteratorNext() can find it. */
     JS_ASSERT(!rval.isMagic(JS_NO_ITER_VALUE));
     cx->iterValue = rval;
     rval.setBoolean(true);
     return true;
 }
 bool
 js_IteratorNext(JSContext *cx, HandleObject iterobj, MutableHandleValue rval)
 {
     /* Fast path for native iterators */
     if (iterobj->is<PropertyIteratorObject>()) {
         /*
          * Implement next directly as all the methods of the native iterator are
          * read-only and permanent.
          */
         NativeIterator *ni = iterobj->as<PropertyIteratorObject>().getNativeIterator();
         if (ni->isKeyIter()) {
             JS_ASSERT(ni->props_cursor < ni->props_end);
             rval.setString(*ni->current());
             ni->incCursor();
             return true;
         }
     }
     JS_ASSERT(!cx->iterValue.isMagic(JS_NO_ITER_VALUE));
     rval.set(cx->iterValue);
     cx->iterValue.setMagic(JS_NO_ITER_VALUE);
     return true;
 }
 static bool
 stopiter_hasInstance(JSContext *cx, HandleObject obj, MutableHandleValue v, bool *bp)
 {
     *bp = JS_IsStopIteration(v);
     return true;
 }
 const Class StopIterationObject::class_ = {
     "StopIteration",
     JSCLASS_HAS_CACHED_PROTO(JSProto_StopIteration),
     JS_PropertyStub,         /* addProperty */
     JS_DeletePropertyStub,   /* delProperty */
     JS_PropertyStub,         /* getProperty */
     JS_StrictPropertyStub,   /* setProperty */
     JS_EnumerateStub,
     JS_ResolveStub,
     JS_ConvertStub,
     nullptr,                 /* finalize    */
     nullptr,                 /* call        */
     stopiter_hasInstance,
     nullptr                  /* construct   */
 };
 bool
 ForOfIterator::init(HandleValue iterable, NonIterableBehavior nonIterableBehavior)
 {
     JSContext *cx = cx_;
     RootedObject iterableObj(cx, ToObject(cx, iterable));
     if (!iterableObj)
         return false;
     JS_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, &optimized))
             return false;
         if (optimized) {
             // Got optimized stub.  Array is optimizable.
             index = 0;
             iterator = iterableObj;
             return true;
         }
     }
     JS_ASSERT(index == NOT_ARRAY);
     // The iterator is the result of calling obj[@@iterator]().
     InvokeArgs args(cx);
     if (!args.init(0))
         return false;
     args.setThis(ObjectValue(*iterableObj));
     RootedValue callee(cx);
     if (!JSObject::getProperty(cx, iterableObj, iterableObj, cx->names().std_iterator, &callee))
         return false;
     // Throw if obj[@@iterator] isn't callable if we were asked to do so.
     // 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()) {
         if (nonIterableBehavior == AllowNonIterable)
             return true;
         char *bytes = DecompileValueGenerator(cx, JSDVG_SEARCH_STACK, iterable, NullPtr());
         if (!bytes)
             return false;
         JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_NOT_ITERABLE, bytes);
         js_free(bytes);
         return false;
     }
     args.setCallee(callee);
     if (!Invoke(cx, args))
         return false;
     iterator = ToObject(cx, args.rval());
     if (!iterator)
         return false;
     return true;
 }
 inline bool
 ForOfIterator::nextFromOptimizedArray(MutableHandleValue vp, bool *done)
 {
     JS_ASSERT(index != NOT_ARRAY);
     if (!CheckForInterrupt(cx_))
         return false;
     JS_ASSERT(iterator->isNative());
     JS_ASSERT(iterator->is<ArrayObject>());
     if (index >= iterator->as<ArrayObject>().length()) {
         vp.setUndefined();
         *done = true;
         return true;
     }
     *done = false;
     // Try to get array element via direct access.
     if (index < iterator->getDenseInitializedLength()) {
         vp.set(iterator->getDenseElement(index));
         if (!vp.isMagic(JS_ELEMENTS_HOLE)) {
             ++index;
             return true;
         }
     }
     return JSObject::getElement(cx_, iterator, iterator, index++, vp);
 }
 bool
 ForOfIterator::next(MutableHandleValue vp, bool *done)
 {
     JS_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 method(cx_);
     if (!JSObject::getProperty(cx_, iterator, iterator, cx_->names().next, &method))
         return false;
     InvokeArgs args(cx_);
     if (!args.init(1))
         return false;
     args.setCallee(method);
     args.setThis(ObjectValue(*iterator));
     args[0].setUndefined();
     if (!Invoke(cx_, args))
         return false;
     RootedObject resultObj(cx_, ToObject(cx_, args.rval()));
     if (!resultObj)
         return false;
     RootedValue doneVal(cx_);
     if (!JSObject::getProperty(cx_, resultObj, resultObj, cx_->names().done, &doneVal))
         return false;
     *done = ToBoolean(doneVal);
     if (*done) {
         vp.setUndefined();
         return true;
     }
     return JSObject::getProperty(cx_, resultObj, resultObj, cx_->names().value, vp);
 }
 bool
 ForOfIterator::materializeArrayIterator()
 {
     JS_ASSERT(index != NOT_ARRAY);
     const char *nameString = "ArrayValuesAt";
     RootedAtom name(cx_, Atomize(cx_, nameString, strlen(nameString)));
     if (!name)
         return false;
     RootedValue val(cx_);
     if (!cx_->global()->getSelfHostedFunction(cx_, name, name, 1, &val))
         return false;
     InvokeArgs args(cx_);
     if (!args.init(1))
         return false;
     args.setCallee(val);
     args.setThis(ObjectValue(*iterator));
     args[0].set(Int32Value(index));
     if (!Invoke(cx_, args))
         return false;
     index = NOT_ARRAY;
     // Result of call to ArrayValuesAt must be an object.
     iterator = &args.rval().toObject();
     return true;
 }
 /*** Generators **********************************************************************************/
 template<typename T>
 static void
 FinalizeGenerator(FreeOp *fop, JSObject *obj)
 {
     JS_ASSERT(obj->is<T>());
     JSGenerator *gen = obj->as<T>().getGenerator();
     JS_ASSERT(gen);
     // gen is open when a script has not called its close method while
     // explicitly manipulating it.
     JS_ASSERT(gen->state == JSGEN_NEWBORN ||
               gen->state == JSGEN_CLOSED ||
               gen->state == JSGEN_OPEN);
     // If gen->state is JSGEN_CLOSED, gen->fp may be nullptr.
     if (gen->fp)
         JS_POISON(gen->fp, JS_SWEPT_FRAME_PATTERN, sizeof(InterpreterFrame));
     JS_POISON(gen, JS_SWEPT_FRAME_PATTERN, sizeof(JSGenerator));
     fop->free_(gen);
 }
 static void
 MarkGeneratorFrame(JSTracer *trc, JSGenerator *gen)
 {
     MarkValueRange(trc,
                    HeapValueify(gen->fp->generatorArgsSnapshotBegin()),
                    HeapValueify(gen->fp->generatorArgsSnapshotEnd()),
                    "Generator Floating Args");
     gen->fp->mark(trc);
     MarkValueRange(trc,
                    HeapValueify(gen->fp->generatorSlotsSnapshotBegin()),
                    HeapValueify(gen->regs.sp),
                    "Generator Floating Stack");
 }
 static void
 GeneratorWriteBarrierPre(JSContext *cx, JSGenerator *gen)
 {
     JS::Zone *zone = cx->zone();
     if (zone->needsBarrier())
         MarkGeneratorFrame(zone->barrierTracer(), gen);
 }
 static void
 GeneratorWriteBarrierPost(JSContext *cx, JSGenerator *gen)
 {
 #ifdef JSGC_GENERATIONAL
     cx->runtime()->gcStoreBuffer.putWholeCell(gen->obj);
 #endif
 }
 /*
  * Only mark generator frames/slots when the generator is not active on the
  * stack or closed. Barriers when copying onto the stack or closing preserve
  * gc invariants.
  */
 static bool
 GeneratorHasMarkableFrame(JSGenerator *gen)
 {
     return gen->state == JSGEN_NEWBORN || gen->state == JSGEN_OPEN;
 }
 /*
  * When a generator is closed, the GC things reachable from the contained frame
  * and slots become unreachable and thus require a write barrier.
  */
 static void
 SetGeneratorClosed(JSContext *cx, JSGenerator *gen)
 {
     JS_ASSERT(gen->state != JSGEN_CLOSED);
     if (GeneratorHasMarkableFrame(gen))
         GeneratorWriteBarrierPre(cx, gen);
     gen->state = JSGEN_CLOSED;
 #ifdef DEBUG
     MakeRangeGCSafe(gen->fp->generatorArgsSnapshotBegin(),
                     gen->fp->generatorArgsSnapshotEnd());
     MakeRangeGCSafe(gen->fp->generatorSlotsSnapshotBegin(),
                     gen->regs.sp);
     PodZero(&gen->regs, 1);
     gen->fp = nullptr;
 #endif
 }
 template<typename T>
 static void
 TraceGenerator(JSTracer *trc, JSObject *obj)
 {
     JS_ASSERT(obj->is<T>());
     JSGenerator *gen = obj->as<T>().getGenerator();
     JS_ASSERT(gen);
     if (GeneratorHasMarkableFrame(gen))
         MarkGeneratorFrame(trc, gen);
 }
 GeneratorState::GeneratorState(JSContext *cx, JSGenerator *gen, JSGeneratorState futureState)
   : RunState(cx, Generator, gen->fp->script()),
     cx_(cx),
     gen_(gen),
     futureState_(futureState),
     entered_(false)
 { }
 GeneratorState::~GeneratorState()
 {
     gen_->fp->setSuspended();
     if (entered_)
         cx_->leaveGenerator(gen_);
 }
 InterpreterFrame *
 GeneratorState::pushInterpreterFrame(JSContext *cx)
 {
     /*
      * Write barrier is needed since the generator stack can be updated,
      * and it's not barriered in any other way. We need to do it before
      * gen->state changes, which can cause us to trace the generator
      * differently.
      *
      * We could optimize this by setting a bit on the generator to signify
      * that it has been marked. If this bit has already been set, there is no
      * need to mark again. The bit would have to be reset before the next GC,
      * or else some kind of epoch scheme would have to be used.
      */
     GeneratorWriteBarrierPre(cx, gen_);
     gen_->state = futureState_;
     gen_->fp->clearSuspended();
     cx->enterGenerator(gen_);   /* OOM check above. */
     entered_ = true;
     return gen_->fp;
 }
 const Class LegacyGeneratorObject::class_ = {
     "Generator",
     JSCLASS_HAS_PRIVATE | JSCLASS_IMPLEMENTS_BARRIERS,
     JS_PropertyStub,         /* addProperty */
     JS_DeletePropertyStub,   /* delProperty */
     JS_PropertyStub,         /* getProperty */
     JS_StrictPropertyStub,   /* setProperty */
     JS_EnumerateStub,
     JS_ResolveStub,
     JS_ConvertStub,
     FinalizeGenerator<LegacyGeneratorObject>,
     nullptr,                 /* call        */
     nullptr,                 /* hasInstance */
     nullptr,                 /* construct   */
     TraceGenerator<LegacyGeneratorObject>,
     JS_NULL_CLASS_SPEC,
     {
         nullptr,             /* outerObject    */
         nullptr,             /* innerObject    */
         iterator_iteratorObject,
     }
 };
 const Class StarGeneratorObject::class_ = {
     "Generator",
     JSCLASS_HAS_PRIVATE | JSCLASS_IMPLEMENTS_BARRIERS,
     JS_PropertyStub,         /* addProperty */
     JS_DeletePropertyStub,   /* delProperty */
     JS_PropertyStub,         /* getProperty */
     JS_StrictPropertyStub,   /* setProperty */
     JS_EnumerateStub,
     JS_ResolveStub,
     JS_ConvertStub,
     FinalizeGenerator<StarGeneratorObject>,
     nullptr,                 /* call        */
     nullptr,                 /* hasInstance */
     nullptr,                 /* construct   */
     TraceGenerator<StarGeneratorObject>,
     JS_NULL_CLASS_SPEC,
     {
         nullptr,             /* outerObject    */
         nullptr,             /* innerObject    */
         iterator_iteratorObject,
     }
 };
 /*
  * Called from the JSOP_GENERATOR case in the interpreter, with fp referring
  * to the frame by which the generator function was activated.  Create a new
  * JSGenerator object, which contains its own InterpreterFrame that we populate
  * from *fp.  We know that upon return, the JSOP_GENERATOR opcode will return
  * from the activation in fp, so we can steal away fp->callobj and fp->argsobj
  * if they are non-null.
  */
 JSObject *
 js_NewGenerator(JSContext *cx, const InterpreterRegs &stackRegs)
 {
     JS_ASSERT(stackRegs.stackDepth() == 0);
     InterpreterFrame *stackfp = stackRegs.fp();
     JS_ASSERT(stackfp->script()->isGenerator());
     Rooted<GlobalObject*> global(cx, &stackfp->global());
     RootedObject obj(cx);
     if (stackfp->script()->isStarGenerator()) {
         RootedValue pval(cx);
         RootedObject fun(cx, stackfp->fun());
         // FIXME: This would be faster if we could avoid doing a lookup to get
         // the prototype for the instance.  Bug 906600.
         if (!JSObject::getProperty(cx, fun, fun, cx->names().prototype, &pval))
             return nullptr;
         JSObject *proto = pval.isObject() ? &pval.toObject() : nullptr;
         if (!proto) {
             proto = GlobalObject::getOrCreateStarGeneratorObjectPrototype(cx, global);
             if (!proto)
                 return nullptr;
         }
         obj = NewObjectWithGivenProto(cx, &StarGeneratorObject::class_, proto, global);
     } else {
         JS_ASSERT(stackfp->script()->isLegacyGenerator());
         JSObject *proto = GlobalObject::getOrCreateLegacyGeneratorObjectPrototype(cx, global);
         if (!proto)
             return nullptr;
         obj = NewObjectWithGivenProto(cx, &LegacyGeneratorObject::class_, proto, global);
     }
     if (!obj)
         return nullptr;
     /* Load and compute stack slot counts. */
     Value *stackvp = stackfp->generatorArgsSnapshotBegin();
     unsigned vplen = stackfp->generatorArgsSnapshotEnd() - stackvp;
     /* Compute JSGenerator size. */
     unsigned nbytes = sizeof(JSGenerator) +
                    (-1 + /* one Value included in JSGenerator */
                     vplen +
                     VALUES_PER_STACK_FRAME +
                     stackfp->script()->nslots()) * sizeof(HeapValue);
     JS_ASSERT(nbytes % sizeof(Value) == 0);
     JS_STATIC_ASSERT(sizeof(InterpreterFrame) % sizeof(HeapValue) == 0);
     JSGenerator *gen = (JSGenerator *) cx->calloc_(nbytes);
     if (!gen)
         return nullptr;
     /* Cut up floatingStack space. */
     HeapValue *genvp = gen->stackSnapshot;
     SetValueRangeToUndefined((Value *)genvp, vplen);
     InterpreterFrame *genfp = reinterpret_cast<InterpreterFrame *>(genvp + vplen);
     /* Initialize JSGenerator. */
     gen->obj.init(obj);
     gen->state = JSGEN_NEWBORN;
     gen->fp = genfp;
     gen->prevGenerator = nullptr;
     /* Copy from the stack to the generator's floating frame. */
     gen->regs.rebaseFromTo(stackRegs, *genfp);
     genfp->copyFrameAndValues<InterpreterFrame::DoPostBarrier>(cx, (Value *)genvp, stackfp,
                                                          stackvp, stackRegs.sp);
     genfp->setSuspended();
     obj->setPrivate(gen);
     return obj;
 }
 static void
 SetGeneratorClosed(JSContext *cx, JSGenerator *gen);
 typedef enum JSGeneratorOp {
     JSGENOP_NEXT,
     JSGENOP_SEND,
     JSGENOP_THROW,
     JSGENOP_CLOSE
 } JSGeneratorOp;
 /*
  * Start newborn or restart yielding generator and perform the requested
  * operation inside its frame.
  */
 static bool
 SendToGenerator(JSContext *cx, JSGeneratorOp op, HandleObject obj,
                 JSGenerator *gen, HandleValue arg, GeneratorKind generatorKind,
                 MutableHandleValue rval)
 {
     JS_ASSERT(generatorKind == LegacyGenerator || generatorKind == StarGenerator);
     if (gen->state == JSGEN_RUNNING || gen->state == JSGEN_CLOSING) {
         JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_NESTING_GENERATOR);
         return false;
     }
     JSGeneratorState futureState;
     JS_ASSERT(gen->state == JSGEN_NEWBORN || gen->state == JSGEN_OPEN);
     switch (op) {
       case JSGENOP_NEXT:
       case JSGENOP_SEND:
         if (gen->state == JSGEN_OPEN) {
             /*
              * Store the argument to send as the result of the yield
              * expression. The generator stack is not barriered, so we need
              * write barriers here.
              */
             HeapValue::writeBarrierPre(gen->regs.sp[-1]);
             gen->regs.sp[-1] = arg;
             HeapValue::writeBarrierPost(cx->runtime(), gen->regs.sp[-1], &gen->regs.sp[-1]);
         }
         futureState = JSGEN_RUNNING;
         break;
       case JSGENOP_THROW:
         cx->setPendingException(arg);
         futureState = JSGEN_RUNNING;
         break;
       default:
         JS_ASSERT(op == JSGENOP_CLOSE);
         JS_ASSERT(generatorKind == LegacyGenerator);
         cx->setPendingException(MagicValue(JS_GENERATOR_CLOSING));
         futureState = JSGEN_CLOSING;
         break;
     }
     bool ok;
     {
         GeneratorState state(cx, gen, futureState);
         ok = RunScript(cx, state);
         if (!ok && gen->state == JSGEN_CLOSED)
             return false;
     }
     if (gen->fp->isYielding()) {
         /*
          * Yield is ordinarily infallible, but ok can be false here if a
          * Debugger.Frame.onPop hook fails.
          */
         JS_ASSERT(gen->state == JSGEN_RUNNING);
         JS_ASSERT(op != JSGENOP_CLOSE);
         gen->fp->clearYielding();
         gen->state = JSGEN_OPEN;
         GeneratorWriteBarrierPost(cx, gen);
         rval.set(gen->fp->returnValue());
         return ok;
     }
     if (ok) {
         if (generatorKind == StarGenerator) {
             // Star generators return a {value:FOO, done:true} object.
             rval.set(gen->fp->returnValue());
         } else {
             JS_ASSERT(generatorKind == LegacyGenerator);
             // Otherwise we discard the return value and throw a StopIteration
             // if needed.
             rval.setUndefined();
             if (op != JSGENOP_CLOSE)
                 ok = js_ThrowStopIteration(cx);
         }
     }
     SetGeneratorClosed(cx, gen);
     return ok;
 }
 MOZ_ALWAYS_INLINE bool
 star_generator_next(JSContext *cx, CallArgs args)
 {
     RootedObject thisObj(cx, &args.thisv().toObject());
     JSGenerator *gen = thisObj->as<StarGeneratorObject>().getGenerator();
     if (gen->state == JSGEN_CLOSED) {
         RootedObject obj(cx, CreateItrResultObject(cx, JS::UndefinedHandleValue, true));
         if (!obj)
             return false;
         args.rval().setObject(*obj);
         return true;
     }
     if (gen->state == JSGEN_NEWBORN && args.hasDefined(0)) {
         RootedValue val(cx, args[0]);
         js_ReportValueError(cx, JSMSG_BAD_GENERATOR_SEND,
                             JSDVG_SEARCH_STACK, val, js::NullPtr());
         return false;
     }
     return SendToGenerator(cx, JSGENOP_SEND, thisObj, gen, args.get(0), StarGenerator,
                            args.rval());
 }
 MOZ_ALWAYS_INLINE bool
 star_generator_throw(JSContext *cx, CallArgs args)
 {
     RootedObject thisObj(cx, &args.thisv().toObject());
     JSGenerator *gen = thisObj->as<StarGeneratorObject>().getGenerator();
     if (gen->state == JSGEN_CLOSED) {
         cx->setPendingException(args.get(0));
         return false;
     }
     return SendToGenerator(cx, JSGENOP_THROW, thisObj, gen, args.get(0), StarGenerator,
                            args.rval());
 }
 MOZ_ALWAYS_INLINE bool
 legacy_generator_next(JSContext *cx, CallArgs args)
 {
     RootedObject thisObj(cx, &args.thisv().toObject());
     JSGenerator *gen = thisObj->as<LegacyGeneratorObject>().getGenerator();
     if (gen->state == JSGEN_CLOSED)
         return js_ThrowStopIteration(cx);
     if (gen->state == JSGEN_NEWBORN && args.hasDefined(0)) {
         RootedValue val(cx, args[0]);
         js_ReportValueError(cx, JSMSG_BAD_GENERATOR_SEND,
                             JSDVG_SEARCH_STACK, val, js::NullPtr());
         return false;
     }
     return SendToGenerator(cx, JSGENOP_SEND, thisObj, gen, args.get(0), LegacyGenerator,
                            args.rval());
 }
 MOZ_ALWAYS_INLINE bool
 legacy_generator_throw(JSContext *cx, CallArgs args)
 {
     RootedObject thisObj(cx, &args.thisv().toObject());
     JSGenerator *gen = thisObj->as<LegacyGeneratorObject>().getGenerator();
     if (gen->state == JSGEN_CLOSED) {
         cx->setPendingException(args.length() >= 1 ? args[0] : UndefinedValue());
         return false;
     }
     return SendToGenerator(cx, JSGENOP_THROW, thisObj, gen, args.get(0), LegacyGenerator,
                            args.rval());
 }
 static bool
 CloseLegacyGenerator(JSContext *cx, HandleObject obj, MutableHandleValue rval)
 {
     JS_ASSERT(obj->is<LegacyGeneratorObject>());
     JSGenerator *gen = obj->as<LegacyGeneratorObject>().getGenerator();
     if (gen->state == JSGEN_CLOSED) {
         rval.setUndefined();
         return true;
     }
     if (gen->state == JSGEN_NEWBORN) {
         SetGeneratorClosed(cx, gen);
         rval.setUndefined();
         return true;
     }
     return SendToGenerator(cx, JSGENOP_CLOSE, obj, gen, JS::UndefinedHandleValue, LegacyGenerator,
                            rval);
 }
 static bool
 CloseLegacyGenerator(JSContext *cx, HandleObject obj)
 {
     RootedValue rval(cx);
     return CloseLegacyGenerator(cx, obj, &rval);
 }
 MOZ_ALWAYS_INLINE bool
 legacy_generator_close(JSContext *cx, CallArgs args)
 {
     RootedObject thisObj(cx, &args.thisv().toObject());
     return CloseLegacyGenerator(cx, thisObj, args.rval());
 }
 template<typename T>
 MOZ_ALWAYS_INLINE bool
 IsObjectOfType(HandleValue v)
 {
     return v.isObject() && v.toObject().is<T>();
 }
 template<typename T, NativeImpl Impl>
 static bool
 NativeMethod(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     return CallNonGenericMethod<IsObjectOfType<T>, Impl>(cx, args);
 }
 #define JSPROP_ROPERM   (JSPROP_READONLY | JSPROP_PERMANENT)
 #define JS_METHOD(name, T, impl, len, attrs) JS_FN(name, (NativeMethod<T,impl>), len, attrs)
 static const JSFunctionSpec star_generator_methods[] = {
     JS_SELF_HOSTED_FN("@@iterator", "IteratorIdentity", 0, 0),
     JS_METHOD("next", StarGeneratorObject, star_generator_next, 1, 0),
     JS_METHOD("throw", StarGeneratorObject, star_generator_throw, 1, 0),
     JS_FS_END
 };
 static const JSFunctionSpec legacy_generator_methods[] = {
     JS_SELF_HOSTED_FN("@@iterator", "LegacyGeneratorIteratorShim", 0, 0),
     // "send" is an alias for "next".
     JS_METHOD("next", LegacyGeneratorObject, legacy_generator_next, 1, JSPROP_ROPERM),
     JS_METHOD("send", LegacyGeneratorObject, legacy_generator_next, 1, JSPROP_ROPERM),
     JS_METHOD("throw", LegacyGeneratorObject, legacy_generator_throw, 1, JSPROP_ROPERM),
     JS_METHOD("close", LegacyGeneratorObject, legacy_generator_close, 0, JSPROP_ROPERM),
     JS_FS_END
 };
 static JSObject*
 NewSingletonObjectWithObjectPrototype(JSContext *cx, Handle<GlobalObject *> global)
 {
     JSObject *proto = global->getOrCreateObjectPrototype(cx);
     if (!proto)
         return nullptr;
     return NewObjectWithGivenProto(cx, &JSObject::class_, proto, global, SingletonObject);
 }
 static JSObject*
 NewSingletonObjectWithFunctionPrototype(JSContext *cx, Handle<GlobalObject *> global)
 {
     JSObject *proto = global->getOrCreateFunctionPrototype(cx);
     if (!proto)
         return nullptr;
     return NewObjectWithGivenProto(cx, &JSObject::class_, proto, global, SingletonObject);
 }
 /* static */ bool
 GlobalObject::initIteratorClasses(JSContext *cx, Handle<GlobalObject *> global)
 {
     RootedObject iteratorProto(cx);
     Value iteratorProtoVal = global->getPrototype(JSProto_Iterator);
     if (iteratorProtoVal.isObject()) {
         iteratorProto = &iteratorProtoVal.toObject();
     } else {
         iteratorProto = global->createBlankPrototype(cx, &PropertyIteratorObject::class_);
         if (!iteratorProto)
             return false;
         AutoIdVector blank(cx);
         NativeIterator *ni = NativeIterator::allocateIterator(cx, 0, blank);
         if (!ni)
             return false;
         ni->init(nullptr, nullptr, 0 /* flags */, 0, 0);
         iteratorProto->as<PropertyIteratorObject>().setNativeIterator(ni);
         Rooted<JSFunction*> ctor(cx);
         ctor = global->createConstructor(cx, IteratorConstructor, cx->names().Iterator, 2);
         if (!ctor)
             return false;
         if (!LinkConstructorAndPrototype(cx, ctor, iteratorProto))
             return false;
         if (!DefinePropertiesAndBrand(cx, iteratorProto, nullptr, iterator_methods))
             return false;
         if (!GlobalObject::initBuiltinConstructor(cx, global, JSProto_Iterator,
                                                   ctor, iteratorProto))
         {
             return false;
         }
     }
     RootedObject proto(cx);
     if (global->getSlot(ARRAY_ITERATOR_PROTO).isUndefined()) {
         const Class *cls = &ArrayIteratorObject::class_;
         proto = global->createBlankPrototypeInheriting(cx, cls, *iteratorProto);
         if (!proto || !DefinePropertiesAndBrand(cx, proto, nullptr, array_iterator_methods))
             return false;
         global->setReservedSlot(ARRAY_ITERATOR_PROTO, ObjectValue(*proto));
     }
     if (global->getSlot(STRING_ITERATOR_PROTO).isUndefined()) {
         const Class *cls = &StringIteratorPrototypeClass;
         proto = global->createBlankPrototype(cx, cls);
         if (!proto || !DefinePropertiesAndBrand(cx, proto, nullptr, string_iterator_methods))
             return false;
         global->setReservedSlot(STRING_ITERATOR_PROTO, ObjectValue(*proto));
     }
     if (global->getSlot(LEGACY_GENERATOR_OBJECT_PROTO).isUndefined()) {
         proto = NewSingletonObjectWithObjectPrototype(cx, global);
         if (!proto || !DefinePropertiesAndBrand(cx, proto, nullptr, legacy_generator_methods))
             return false;
         global->setReservedSlot(LEGACY_GENERATOR_OBJECT_PROTO, ObjectValue(*proto));
     }
     if (global->getSlot(STAR_GENERATOR_OBJECT_PROTO).isUndefined()) {
         RootedObject genObjectProto(cx, NewSingletonObjectWithObjectPrototype(cx, global));
         if (!genObjectProto)
             return false;
         if (!DefinePropertiesAndBrand(cx, genObjectProto, nullptr, star_generator_methods))
             return false;
         RootedObject genFunctionProto(cx, NewSingletonObjectWithFunctionPrototype(cx, global));
         if (!genFunctionProto)
             return false;
         if (!LinkConstructorAndPrototype(cx, genFunctionProto, genObjectProto))
             return false;
         RootedValue function(cx, global->getConstructor(JSProto_Function));
         if (!function.toObjectOrNull())
             return false;
         RootedAtom name(cx, cx->names().GeneratorFunction);
         RootedObject genFunction(cx, NewFunctionWithProto(cx, NullPtr(), Generator, 1,
                                                           JSFunction::NATIVE_CTOR, global, name,
                                                           &function.toObject()));
         if (!genFunction)
             return false;
         if (!LinkConstructorAndPrototype(cx, genFunction, genFunctionProto))
             return false;
         global->setSlot(STAR_GENERATOR_OBJECT_PROTO, ObjectValue(*genObjectProto));
         global->setConstructor(JSProto_GeneratorFunction, ObjectValue(*genFunction));
         global->setPrototype(JSProto_GeneratorFunction, ObjectValue(*genFunctionProto));
     }
     if (global->getPrototype(JSProto_StopIteration).isUndefined()) {
         proto = global->createBlankPrototype(cx, &StopIterationObject::class_);
         if (!proto || !JSObject::freeze(cx, proto))
             return false;
         // This should use a non-JSProtoKey'd slot, but this is easier for now.
         if (!GlobalObject::initBuiltinConstructor(cx, global, JSProto_StopIteration, proto, proto))
             return false;
         global->setConstructor(JSProto_StopIteration, ObjectValue(*proto));
     }
     return true;
 }
 JSObject *
 js_InitIteratorClasses(JSContext *cx, HandleObject obj)
 {
     Rooted<GlobalObject*> global(cx, &obj->as<GlobalObject>());
     if (!GlobalObject::initIteratorClasses(cx, global))
         return nullptr;
     return global->getIteratorPrototype();
 }

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js/src/jsiter.cpp