Source code
Revision control
Copy as Markdown
Other Tools
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* 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
/* JavaScript iterators. */
#include "vm/Iteration.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/Likely.h"
#include "mozilla/Maybe.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/PodOperations.h"
#include <algorithm>
#include <new>
#include "jsapi.h"
#include "jstypes.h"
#include "builtin/Array.h"
#include "builtin/SelfHostingDefines.h"
#include "ds/Sort.h"
#include "gc/GC.h"
#include "gc/GCContext.h"
#include "js/ForOfIterator.h" // JS::ForOfIterator
#include "js/friend/ErrorMessages.h" // js::GetErrorMessage, JSMSG_*
#include "js/PropertySpec.h"
#include "util/DifferentialTesting.h"
#include "util/Poison.h"
#include "vm/GlobalObject.h"
#include "vm/Interpreter.h"
#include "vm/JSContext.h"
#include "vm/JSObject.h"
#include "vm/NativeObject.h" // js::PlainObject
#include "vm/Shape.h"
#include "vm/StringType.h"
#include "vm/TypedArrayObject.h"
#ifdef ENABLE_RECORD_TUPLE
# include "builtin/RecordObject.h"
# include "builtin/TupleObject.h"
#endif
#include "vm/NativeObject-inl.h"
#include "vm/PlainObject-inl.h" // js::PlainObject::createWithTemplate
using namespace js;
using mozilla::ArrayEqual;
using mozilla::DebugOnly;
using mozilla::Maybe;
using mozilla::PodCopy;
using RootedPropertyIteratorObject = Rooted<PropertyIteratorObject*>;
static const gc::AllocKind ITERATOR_FINALIZE_KIND =
gc::AllocKind::OBJECT2_BACKGROUND;
// Beware! This function may have to trace incompletely-initialized
// |NativeIterator| allocations if the |IdToString| in that constructor recurs
// into this code.
void NativeIterator::trace(JSTracer* trc) {
TraceNullableEdge(trc, &objectBeingIterated_, "objectBeingIterated_");
TraceNullableEdge(trc, &iterObj_, "iterObj");
// The limits below are correct at every instant of |NativeIterator|
// initialization, with the end-pointer incremented as each new shape is
// created, so they're safe to use here.
std::for_each(shapesBegin(), shapesEnd(), [trc](GCPtr<Shape*>& shape) {
TraceEdge(trc, &shape, "iterator_shape");
});
// But as properties must be created *before* shapes, |propertiesBegin()|
// that depends on |shapesEnd()| having its final value can't safely be
// used. Until this is fully initialized, use |propertyCursor_| instead,
// which points at the start of properties even in partially initialized
// |NativeIterator|s. (|propertiesEnd()| is safe at all times with respect
// to the properly-chosen beginning.)
//
// Note that we must trace all properties (not just those not yet visited,
// or just visited, due to |NativeIterator::previousPropertyWas|) for
// |NativeIterator|s to be reusable.
GCPtr<JSLinearString*>* begin =
MOZ_LIKELY(isInitialized()) ? propertiesBegin() : propertyCursor_;
std::for_each(begin, propertiesEnd(), [trc](GCPtr<JSLinearString*>& prop) {
// Properties begin life non-null and never *become*
// null. (Deletion-suppression will shift trailing
// properties over a deleted property in the properties
// array, but it doesn't null them out.)
TraceEdge(trc, &prop, "prop");
});
}
using PropertyKeySet = GCHashSet<PropertyKey, DefaultHasher<PropertyKey>>;
class PropertyEnumerator {
RootedObject obj_;
MutableHandleIdVector props_;
PropertyIndexVector* indices_;
uint32_t flags_;
Rooted<PropertyKeySet> visited_;
bool enumeratingProtoChain_ = false;
enum class IndicesState {
// Every property that has been enumerated so far can be represented as a
// PropertyIndex, but we are not currently producing a list of indices. If
// the state is Valid when we are done enumerating, then the resulting
// iterator can be marked as NativeIteratorIndices::AvailableOnRequest.
Valid,
// Every property that has been enumerated so far can be represented as a
// PropertyIndex, and |indices_| points to a PropertyIndexVector containing
// those indices. This is used when we want to create a NativeIterator with
// valid indices.
Allocating,
// It is not possible to represent every property of the object being
// enumerated as a PropertyIndex. For example, enumerated properties on the
// prototype chain are unsupported. We can transition to this state from
// either of the other two.
Unsupported
};
IndicesState indicesState_;
public:
PropertyEnumerator(JSContext* cx, JSObject* obj, uint32_t flags,
MutableHandleIdVector props,
PropertyIndexVector* indices = nullptr)
: obj_(cx, obj),
props_(props),
indices_(indices),
flags_(flags),
visited_(cx, PropertyKeySet(cx)),
indicesState_(indices ? IndicesState::Allocating
: IndicesState::Valid) {}
bool snapshot(JSContext* cx);
void markIndicesUnsupported() { indicesState_ = IndicesState::Unsupported; }
bool supportsIndices() const {
return indicesState_ != IndicesState::Unsupported;
}
bool allocatingIndices() const {
return indicesState_ == IndicesState::Allocating;
}
private:
template <bool CheckForDuplicates>
bool enumerate(JSContext* cx, jsid id, bool enumerable,
PropertyIndex index = PropertyIndex::Invalid());
bool enumerateExtraProperties(JSContext* cx);
template <bool CheckForDuplicates>
bool enumerateNativeProperties(JSContext* cx);
bool enumerateNativeProperties(JSContext* cx, bool checkForDuplicates) {
if (checkForDuplicates) {
return enumerateNativeProperties<true>(cx);
}
return enumerateNativeProperties<false>(cx);
}
template <bool CheckForDuplicates>
bool enumerateProxyProperties(JSContext* cx);
void reversePropsAndIndicesAfter(size_t initialLength) {
// We iterate through prop maps in descending order of property creation,
// but we need our return value to be in ascending order. If we are tracking
// property indices, make sure to keep them in sync.
MOZ_ASSERT(props_.begin() + initialLength <= props_.end());
MOZ_ASSERT_IF(allocatingIndices(), props_.length() == indices_->length());
std::reverse(props_.begin() + initialLength, props_.end());
if (allocatingIndices()) {
std::reverse(indices_->begin() + initialLength, indices_->end());
}
}
};
template <bool CheckForDuplicates>
bool PropertyEnumerator::enumerate(JSContext* cx, jsid id, bool enumerable,
PropertyIndex index) {
if (CheckForDuplicates) {
// If we've already seen this, we definitely won't add it.
PropertyKeySet::AddPtr p = visited_.lookupForAdd(id);
if (MOZ_UNLIKELY(!!p)) {
return true;
}
// It's not necessary to add properties to the hash set at the end of
// the prototype chain, but custom enumeration behaviors might return
// duplicated properties, so always add in such cases.
if (obj_->is<ProxyObject>() || obj_->staticPrototype() ||
obj_->getClass()->getNewEnumerate()) {
if (!visited_.add(p, id)) {
return false;
}
}
}
if (!enumerable && !(flags_ & JSITER_HIDDEN)) {
return true;
}
// Symbol-keyed properties and nonenumerable properties are skipped unless
// the caller specifically asks for them. A caller can also filter out
// non-symbols by asking for JSITER_SYMBOLSONLY. PrivateName symbols are
// skipped unless JSITER_PRIVATE is passed.
if (id.isSymbol()) {
if (!(flags_ & JSITER_SYMBOLS)) {
return true;
}
if (!(flags_ & JSITER_PRIVATE) && id.isPrivateName()) {
return true;
}
} else {
if ((flags_ & JSITER_SYMBOLSONLY)) {
return true;
}
}
MOZ_ASSERT_IF(allocatingIndices(), indices_->length() == props_.length());
if (!props_.append(id)) {
return false;
}
if (!supportsIndices()) {
return true;
}
if (index.kind() == PropertyIndex::Kind::Invalid || enumeratingProtoChain_) {
markIndicesUnsupported();
return true;
}
if (allocatingIndices() && !indices_->append(index)) {
return false;
}
return true;
}
bool PropertyEnumerator::enumerateExtraProperties(JSContext* cx) {
MOZ_ASSERT(obj_->getClass()->getNewEnumerate());
RootedIdVector properties(cx);
bool enumerableOnly = !(flags_ & JSITER_HIDDEN);
if (!obj_->getClass()->getNewEnumerate()(cx, obj_, &properties,
enumerableOnly)) {
return false;
}
RootedId id(cx);
for (size_t n = 0; n < properties.length(); n++) {
id = properties[n];
// The enumerate hook does not indicate whether the properties
// it returns are enumerable or not. Since we already passed
// `enumerableOnly` to the hook to filter out non-enumerable
// properties, it doesn't really matter what we pass here.
bool enumerable = true;
if (!enumerate<true>(cx, id, enumerable)) {
return false;
}
}
return true;
}
static bool SortComparatorIntegerIds(jsid a, jsid b, bool* lessOrEqualp) {
uint32_t indexA, indexB;
MOZ_ALWAYS_TRUE(IdIsIndex(a, &indexA));
MOZ_ALWAYS_TRUE(IdIsIndex(b, &indexB));
*lessOrEqualp = (indexA <= indexB);
return true;
}
template <bool CheckForDuplicates>
bool PropertyEnumerator::enumerateNativeProperties(JSContext* cx) {
Handle<NativeObject*> pobj = obj_.as<NativeObject>();
// We don't need to iterate over the shape's properties if we're only
// interested in enumerable properties and the object is known to have no
// enumerable properties.
//
// Don't optimize if CheckForDuplicates is true, because non-enumerable
// properties still have to participate in duplicate-property checking.
const bool iterShapeProperties = CheckForDuplicates ||
(flags_ & JSITER_HIDDEN) ||
pobj->hasEnumerableProperty();
bool enumerateSymbols;
if (flags_ & JSITER_SYMBOLSONLY) {
if (!iterShapeProperties) {
return true;
}
enumerateSymbols = true;
} else {
// Collect any dense elements from this object.
size_t firstElemIndex = props_.length();
size_t initlen = pobj->getDenseInitializedLength();
const Value* elements = pobj->getDenseElements();
bool hasHoles = false;
for (uint32_t i = 0; i < initlen; ++i) {
if (elements[i].isMagic(JS_ELEMENTS_HOLE)) {
hasHoles = true;
} else {
// Dense arrays never get so large that i would not fit into an
// integer id.
if (!enumerate<CheckForDuplicates>(cx, PropertyKey::Int(i),
/* enumerable = */ true,
PropertyIndex::ForElement(i))) {
return false;
}
}
}
// Collect any typed array or shared typed array elements from this
// object.
if (pobj->is<TypedArrayObject>()) {
size_t len = pobj->as<TypedArrayObject>().length().valueOr(0);
// Fail early if the typed array is enormous, because this will be very
// slow and will likely report OOM. This also means we don't need to
// handle indices greater than PropertyKey::IntMax in the loop below.
static_assert(PropertyKey::IntMax == INT32_MAX);
if (len > INT32_MAX) {
ReportOutOfMemory(cx);
return false;
}
for (uint32_t i = 0; i < len; i++) {
if (!enumerate<CheckForDuplicates>(cx, PropertyKey::Int(i),
/* enumerable = */ true)) {
return false;
}
}
}
#ifdef ENABLE_RECORD_TUPLE
else {
Rooted<RecordType*> rec(cx);
if (RecordObject::maybeUnbox(pobj, &rec)) {
Rooted<ArrayObject*> keys(cx, rec->keys());
for (size_t i = 0; i < keys->length(); i++) {
JSAtom* key = &keys->getDenseElement(i).toString()->asAtom();
PropertyKey id = AtomToId(key);
if (!enumerate<CheckForDuplicates>(cx, id,
/* enumerable = */ true)) {
return false;
}
}
return true;
} else {
mozilla::Maybe<TupleType&> tup = TupleObject::maybeUnbox(pobj);
if (tup) {
uint32_t len = tup->length();
for (size_t i = 0; i < len; i++) {
// We expect tuple indices not to get so large that `i` won't
// fit into an `int32_t`.
MOZ_ASSERT(PropertyKey::fitsInInt(i));
PropertyKey id = PropertyKey::Int(i);
if (!enumerate<CheckForDuplicates>(cx, id,
/* enumerable = */ true)) {
return false;
}
}
return true;
}
}
}
#endif
// The code below enumerates shape properties (including sparse elements) so
// if we can ignore those we're done.
if (!iterShapeProperties) {
return true;
}
// Collect any sparse elements from this object.
bool isIndexed = pobj->isIndexed();
if (isIndexed) {
// If the dense elements didn't have holes, we don't need to include
// them in the sort.
if (!hasHoles) {
firstElemIndex = props_.length();
}
for (ShapePropertyIter<NoGC> iter(pobj->shape()); !iter.done(); iter++) {
jsid id = iter->key();
uint32_t dummy;
if (IdIsIndex(id, &dummy)) {
if (!enumerate<CheckForDuplicates>(cx, id, iter->enumerable())) {
return false;
}
}
}
MOZ_ASSERT(firstElemIndex <= props_.length());
jsid* ids = props_.begin() + firstElemIndex;
size_t n = props_.length() - firstElemIndex;
RootedIdVector tmp(cx);
if (!tmp.resize(n)) {
return false;
}
PodCopy(tmp.begin(), ids, n);
if (!MergeSort(ids, n, tmp.begin(), SortComparatorIntegerIds)) {
return false;
}
}
size_t initialLength = props_.length();
/* Collect all unique property names from this object's shape. */
bool symbolsFound = false;
for (ShapePropertyIter<NoGC> iter(pobj->shape()); !iter.done(); iter++) {
jsid id = iter->key();
if (id.isSymbol()) {
symbolsFound = true;
continue;
}
uint32_t dummy;
if (isIndexed && IdIsIndex(id, &dummy)) {
continue;
}
PropertyIndex index = iter->isDataProperty()
? PropertyIndex::ForSlot(pobj, iter->slot())
: PropertyIndex::Invalid();
if (!enumerate<CheckForDuplicates>(cx, id, iter->enumerable(), index)) {
return false;
}
}
reversePropsAndIndicesAfter(initialLength);
enumerateSymbols = symbolsFound && (flags_ & JSITER_SYMBOLS);
}
if (enumerateSymbols) {
MOZ_ASSERT(iterShapeProperties);
MOZ_ASSERT(!allocatingIndices());
// Do a second pass to collect symbols. The spec requires that all symbols
// appear after all strings in [[OwnPropertyKeys]] for ordinary objects:
size_t initialLength = props_.length();
for (ShapePropertyIter<NoGC> iter(pobj->shape()); !iter.done(); iter++) {
jsid id = iter->key();
if (id.isSymbol()) {
if (!enumerate<CheckForDuplicates>(cx, id, iter->enumerable())) {
return false;
}
}
}
reversePropsAndIndicesAfter(initialLength);
}
return true;
}
template <bool CheckForDuplicates>
bool PropertyEnumerator::enumerateProxyProperties(JSContext* cx) {
MOZ_ASSERT(obj_->is<ProxyObject>());
RootedIdVector proxyProps(cx);
if (flags_ & JSITER_HIDDEN || flags_ & JSITER_SYMBOLS) {
// This gets all property keys, both strings and symbols. The call to
// enumerate in the loop below will filter out unwanted keys, per the
// flags.
if (!Proxy::ownPropertyKeys(cx, obj_, &proxyProps)) {
return false;
}
Rooted<mozilla::Maybe<PropertyDescriptor>> desc(cx);
for (size_t n = 0, len = proxyProps.length(); n < len; n++) {
bool enumerable = false;
// We need to filter, if the caller just wants enumerable symbols.
if (!(flags_ & JSITER_HIDDEN)) {
if (!Proxy::getOwnPropertyDescriptor(cx, obj_, proxyProps[n], &desc)) {
return false;
}
enumerable = desc.isSome() && desc->enumerable();
}
if (!enumerate<CheckForDuplicates>(cx, proxyProps[n], enumerable)) {
return false;
}
}
return true;
}
// Returns enumerable property names (no symbols).
if (!Proxy::getOwnEnumerablePropertyKeys(cx, obj_, &proxyProps)) {
return false;
}
for (size_t n = 0, len = proxyProps.length(); n < len; n++) {
if (!enumerate<CheckForDuplicates>(cx, proxyProps[n], true)) {
return false;
}
}
return true;
}
#ifdef DEBUG
struct SortComparatorIds {
JSContext* const cx;
explicit SortComparatorIds(JSContext* cx) : cx(cx) {}
bool operator()(jsid aArg, jsid bArg, bool* lessOrEqualp) {
RootedId a(cx, aArg);
RootedId b(cx, bArg);
// Pick an arbitrary order on jsids that is as stable as possible
// across executions.
if (a == b) {
*lessOrEqualp = true;
return true;
}
enum class KeyType { Void, Int, String, Symbol };
auto keyType = [](PropertyKey key) {
if (key.isString()) {
return KeyType::String;
}
if (key.isInt()) {
return KeyType::Int;
}
if (key.isSymbol()) {
return KeyType::Symbol;
}
MOZ_ASSERT(key.isVoid());
return KeyType::Void;
};
if (keyType(a) != keyType(b)) {
*lessOrEqualp = (keyType(a) <= keyType(b));
return true;
}
if (a.isInt()) {
*lessOrEqualp = (a.toInt() <= b.toInt());
return true;
}
RootedString astr(cx), bstr(cx);
if (a.isSymbol()) {
MOZ_ASSERT(b.isSymbol());
JS::SymbolCode ca = a.toSymbol()->code();
JS::SymbolCode cb = b.toSymbol()->code();
if (ca != cb) {
*lessOrEqualp = uint32_t(ca) <= uint32_t(cb);
return true;
}
MOZ_ASSERT(ca == JS::SymbolCode::PrivateNameSymbol ||
ca == JS::SymbolCode::InSymbolRegistry ||
ca == JS::SymbolCode::UniqueSymbol);
astr = a.toSymbol()->description();
bstr = b.toSymbol()->description();
if (!astr || !bstr) {
*lessOrEqualp = !astr;
return true;
}
// Fall through to string comparison on the descriptions. The sort
// order is nondeterministic if two different unique symbols have
// the same description.
} else {
astr = IdToString(cx, a);
if (!astr) {
return false;
}
bstr = IdToString(cx, b);
if (!bstr) {
return false;
}
}
int32_t result;
if (!CompareStrings(cx, astr, bstr, &result)) {
return false;
}
*lessOrEqualp = (result <= 0);
return true;
}
};
#endif /* DEBUG */
static void AssertNoEnumerableProperties(NativeObject* obj) {
#ifdef DEBUG
// Verify the object has no enumerable properties if the HasEnumerable
// ObjectFlag is not set.
MOZ_ASSERT(!obj->hasEnumerableProperty());
static constexpr size_t MaxPropsToCheck = 5;
size_t count = 0;
for (ShapePropertyIter<NoGC> iter(obj->shape()); !iter.done(); iter++) {
MOZ_ASSERT(!iter->enumerable());
if (++count > MaxPropsToCheck) {
break;
}
}
#endif // DEBUG
}
static bool ProtoMayHaveEnumerableProperties(JSObject* obj) {
if (!obj->is<NativeObject>()) {
return true;
}
JSObject* proto = obj->as<NativeObject>().staticPrototype();
while (proto) {
if (!proto->is<NativeObject>()) {
return true;
}
NativeObject* nproto = &proto->as<NativeObject>();
if (nproto->hasEnumerableProperty() ||
nproto->getDenseInitializedLength() > 0 ||
ClassCanHaveExtraEnumeratedProperties(nproto->getClass())) {
return true;
}
AssertNoEnumerableProperties(nproto);
proto = nproto->staticPrototype();
}
return false;
}
bool PropertyEnumerator::snapshot(JSContext* cx) {
// If we're only interested in enumerable properties and the proto chain has
// no enumerable properties (the common case), we can optimize this to ignore
// the proto chain. This also lets us take advantage of the no-duplicate-check
// optimization below.
if (!(flags_ & JSITER_HIDDEN) && !(flags_ & JSITER_OWNONLY) &&
!ProtoMayHaveEnumerableProperties(obj_)) {
flags_ |= JSITER_OWNONLY;
}
// Don't check for duplicates if we're only interested in own properties.
// This does the right thing for most objects: native objects don't have
// duplicate property ids and we allow the [[OwnPropertyKeys]] proxy trap to
// return duplicates.
//
// The only special case is when the object has a newEnumerate hook: it
// can return duplicate properties and we have to filter them. This is
// handled below.
bool checkForDuplicates = !(flags_ & JSITER_OWNONLY);
do {
if (obj_->getClass()->getNewEnumerate()) {
markIndicesUnsupported();
if (!enumerateExtraProperties(cx)) {
return false;
}
if (obj_->is<NativeObject>()) {
if (!enumerateNativeProperties(cx, /*checkForDuplicates*/ true)) {
return false;
}
}
} else if (obj_->is<NativeObject>()) {
// Give the object a chance to resolve all lazy properties
if (JSEnumerateOp enumerateOp = obj_->getClass()->getEnumerate()) {
markIndicesUnsupported();
if (!enumerateOp(cx, obj_.as<NativeObject>())) {
return false;
}
}
if (!enumerateNativeProperties(cx, checkForDuplicates)) {
return false;
}
} else if (obj_->is<ProxyObject>()) {
markIndicesUnsupported();
if (checkForDuplicates) {
if (!enumerateProxyProperties<true>(cx)) {
return false;
}
} else {
if (!enumerateProxyProperties<false>(cx)) {
return false;
}
}
} else {
MOZ_CRASH("non-native objects must have an enumerate op");
}
if (flags_ & JSITER_OWNONLY) {
break;
}
if (!GetPrototype(cx, obj_, &obj_)) {
return false;
}
enumeratingProtoChain_ = true;
// The [[Prototype]] chain might be cyclic.
if (!CheckForInterrupt(cx)) {
return false;
}
} while (obj_ != nullptr);
#ifdef DEBUG
if (js::SupportDifferentialTesting() && !supportsIndices()) {
/*
* 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();
RootedIdVector tmp(cx);
if (!tmp.resize(n)) {
return false;
}
PodCopy(tmp.begin(), ids, n);
if (!MergeSort(ids, n, tmp.begin(), SortComparatorIds(cx))) {
return false;
}
}
#endif
return true;
}
JS_PUBLIC_API bool js::GetPropertyKeys(JSContext* cx, HandleObject obj,
unsigned flags,
MutableHandleIdVector props) {
uint32_t validFlags =
flags & (JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS |
JSITER_SYMBOLSONLY | JSITER_PRIVATE);
PropertyEnumerator enumerator(cx, obj, validFlags, props);
return enumerator.snapshot(cx);
}
static inline void RegisterEnumerator(JSContext* cx, NativeIterator* ni) {
MOZ_ASSERT(ni->objectBeingIterated());
// Register non-escaping native enumerators (for-in) with the current
// context.
ni->link(cx->compartment()->enumeratorsAddr());
MOZ_ASSERT(!ni->isActive());
ni->markActive();
}
static PropertyIteratorObject* NewPropertyIteratorObject(JSContext* cx) {
const JSClass* clasp = &PropertyIteratorObject::class_;
Rooted<SharedShape*> shape(
cx,
SharedShape::getInitialShape(cx, clasp, cx->realm(), TaggedProto(nullptr),
ITERATOR_FINALIZE_KIND));
if (!shape) {
return nullptr;
}
auto* res = NativeObject::create<PropertyIteratorObject>(
cx, ITERATOR_FINALIZE_KIND, GetInitialHeap(GenericObject, clasp), shape);
if (!res) {
return nullptr;
}
// CodeGenerator::visitIteratorStartO assumes the iterator object is not
// inside the nursery when deciding whether a barrier is necessary.
MOZ_ASSERT(!js::gc::IsInsideNursery(res));
return res;
}
static inline size_t NumTrailingBytes(size_t propertyCount, size_t shapeCount,
bool hasIndices) {
static_assert(alignof(GCPtr<JSLinearString*>) <= alignof(NativeIterator));
static_assert(alignof(GCPtr<Shape*>) <= alignof(GCPtr<JSLinearString*>));
static_assert(alignof(PropertyIndex) <= alignof(GCPtr<Shape*>));
size_t result = propertyCount * sizeof(GCPtr<JSLinearString*>) +
shapeCount * sizeof(GCPtr<Shape*>);
if (hasIndices) {
result += propertyCount * sizeof(PropertyIndex);
}
return result;
}
static inline size_t AllocationSize(size_t propertyCount, size_t shapeCount,
bool hasIndices) {
return sizeof(NativeIterator) +
NumTrailingBytes(propertyCount, shapeCount, hasIndices);
}
static PropertyIteratorObject* CreatePropertyIterator(
JSContext* cx, Handle<JSObject*> objBeingIterated, HandleIdVector props,
bool supportsIndices, PropertyIndexVector* indices,
uint32_t cacheableProtoChainLength) {
MOZ_ASSERT_IF(indices, supportsIndices);
if (props.length() >= NativeIterator::PropCountLimit) {
ReportAllocationOverflow(cx);
return nullptr;
}
bool hasIndices = !!indices;
// If the iterator is cacheable, we store the shape of each object
// along the proto chain in the iterator. If the iterator is not
// cacheable, but has indices, then we store one shape (the shape of
// the object being iterated.)
uint32_t numShapes = cacheableProtoChainLength;
if (numShapes == 0 && hasIndices) {
numShapes = 1;
}
Rooted<PropertyIteratorObject*> propIter(cx, NewPropertyIteratorObject(cx));
if (!propIter) {
return nullptr;
}
void* mem = cx->pod_malloc_with_extra<NativeIterator, uint8_t>(
NumTrailingBytes(props.length(), numShapes, hasIndices));
if (!mem) {
return nullptr;
}
// This also registers |ni| with |propIter|.
bool hadError = false;
new (mem) NativeIterator(cx, propIter, objBeingIterated, props,
supportsIndices, indices, numShapes, &hadError);
if (hadError) {
return nullptr;
}
return propIter;
}
static HashNumber HashIteratorShape(Shape* shape) {
return DefaultHasher<Shape*>::hash(shape);
}
/**
* Initialize a fresh NativeIterator.
*
* This definition is a bit tricky: some parts of initializing are fallible, so
* as we initialize, we must carefully keep this in GC-safe state (see
* NativeIterator::trace).
*/
NativeIterator::NativeIterator(JSContext* cx,
Handle<PropertyIteratorObject*> propIter,
Handle<JSObject*> objBeingIterated,
HandleIdVector props, bool supportsIndices,
PropertyIndexVector* indices, uint32_t numShapes,
bool* hadError)
: objectBeingIterated_(objBeingIterated),
iterObj_(propIter),
// NativeIterator initially acts (before full initialization) as if it
// contains no shapes...
shapesEnd_(shapesBegin()),
// ...and no properties.
propertyCursor_(
reinterpret_cast<GCPtr<JSLinearString*>*>(shapesBegin() + numShapes)),
propertiesEnd_(propertyCursor_),
shapesHash_(0),
flagsAndCount_(
initialFlagsAndCount(props.length())) // note: no Flags::Initialized
{
// If there are shapes, the object and all objects on its prototype chain must
// be native objects. See CanCompareIterableObjectToCache.
MOZ_ASSERT_IF(numShapes > 0,
objBeingIterated && objBeingIterated->is<NativeObject>());
MOZ_ASSERT(!*hadError);
bool hasActualIndices = !!indices;
MOZ_ASSERT_IF(hasActualIndices, indices->length() == props.length());
// NOTE: This must be done first thing: The caller can't free `this` on error
// because it has GCPtr fields whose barriers have already fired; the
// store buffer has pointers to them. Only the GC can free `this` (via
// PropertyIteratorObject::finalize).
propIter->initNativeIterator(this);
// The GC asserts on finalization that `this->allocationSize()` matches the
// `nbytes` passed to `AddCellMemory`. So once these lines run, we must make
// `this->allocationSize()` correct. That means infallibly initializing the
// shapes, and ensuring that indicesState_.allocated() is true if we've
// allocated space for indices. It's OK for the constructor to fail after
// that.
size_t nbytes = AllocationSize(props.length(), numShapes, hasActualIndices);
AddCellMemory(propIter, nbytes, MemoryUse::NativeIterator);
if (supportsIndices) {
if (hasActualIndices) {
// If the string allocation fails, indicesAllocated() must be true
// so that this->allocationSize() is correct. Set it to Disabled. It will
// be updated below.
setIndicesState(NativeIteratorIndices::Disabled);
} else {
// This object supports indices (ie it only has own enumerable
// properties), but we didn't allocate them because we haven't seen a
// consumer yet. We mark the iterator so that potential consumers know to
// request a fresh iterator with indices.
setIndicesState(NativeIteratorIndices::AvailableOnRequest);
}
}
if (numShapes > 0) {
// Construct shapes into the shapes array. Also compute the shapesHash,
// which incorporates Shape* addresses that could have changed during a GC
// triggered in (among other places) |IdToString| above.
JSObject* pobj = objBeingIterated;
HashNumber shapesHash = 0;
for (uint32_t i = 0; i < numShapes; i++) {
MOZ_ASSERT(pobj->is<NativeObject>());
Shape* shape = pobj->shape();
new (shapesEnd_) GCPtr<Shape*>(shape);
shapesEnd_++;
shapesHash = mozilla::AddToHash(shapesHash, HashIteratorShape(shape));
pobj = pobj->staticPrototype();
}
shapesHash_ = shapesHash;
// There are two cases in which we need to store shapes. If this
// iterator is cacheable, we store the shapes for the entire proto
// chain so we can check that the cached iterator is still valid
// (see MacroAssembler::maybeLoadIteratorFromShape). If this iterator
// has indices, then even if it isn't cacheable we need to store the
// shape of the iterated object itself (see IteratorHasIndicesAndBranch).
// In the former case, assert that we're storing the entire proto chain.
MOZ_ASSERT_IF(numShapes > 1, pobj == nullptr);
}
MOZ_ASSERT(static_cast<void*>(shapesEnd_) == propertyCursor_);
// Allocate any strings in the nursery until the first minor GC. After this
// point they will end up getting tenured anyway because they are reachable
// from |propIter| which will be tenured.
AutoSelectGCHeap gcHeap(cx);
size_t numProps = props.length();
for (size_t i = 0; i < numProps; i++) {
JSLinearString* str = IdToString(cx, props[i], gcHeap);
if (!str) {
*hadError = true;
return;
}
new (propertiesEnd_) GCPtr<JSLinearString*>(str);
propertiesEnd_++;
}
if (hasActualIndices) {
PropertyIndex* cursor = indicesBegin();
for (size_t i = 0; i < numProps; i++) {
*cursor++ = (*indices)[i];
}
MOZ_ASSERT(uintptr_t(cursor) == uintptr_t(this) + nbytes);
setIndicesState(NativeIteratorIndices::Valid);
}
markInitialized();
MOZ_ASSERT(!*hadError);
}
inline size_t NativeIterator::allocationSize() const {
size_t numShapes = shapesEnd() - shapesBegin();
return AllocationSize(initialPropertyCount(), numShapes, indicesAllocated());
}
/* static */
bool IteratorHashPolicy::match(PropertyIteratorObject* obj,
const Lookup& lookup) {
NativeIterator* ni = obj->getNativeIterator();
if (ni->shapesHash() != lookup.shapesHash ||
ni->shapeCount() != lookup.numShapes) {
return false;
}
return ArrayEqual(reinterpret_cast<Shape**>(ni->shapesBegin()), lookup.shapes,
ni->shapeCount());
}
static inline bool CanCompareIterableObjectToCache(JSObject* obj) {
if (obj->is<NativeObject>()) {
return obj->as<NativeObject>().getDenseInitializedLength() == 0;
}
return false;
}
static bool CanStoreInIteratorCache(JSObject* obj) {
do {
MOZ_ASSERT(obj->as<NativeObject>().getDenseInitializedLength() == 0);
// Typed arrays have indexed properties not captured by the Shape guard.
// Enumerate hooks may add extra properties.
if (MOZ_UNLIKELY(ClassCanHaveExtraEnumeratedProperties(obj->getClass()))) {
return false;
}
obj = obj->staticPrototype();
} while (obj);
return true;
}
static MOZ_ALWAYS_INLINE PropertyIteratorObject* LookupInShapeIteratorCache(
JSContext* cx, JSObject* obj, uint32_t* cacheableProtoChainLength) {
if (!obj->shape()->cache().isIterator() ||
!CanCompareIterableObjectToCache(obj)) {
return nullptr;
}
PropertyIteratorObject* iterobj = obj->shape()->cache().toIterator();
NativeIterator* ni = iterobj->getNativeIterator();
MOZ_ASSERT(*ni->shapesBegin() == obj->shape());
if (!ni->isReusable()) {
return nullptr;
}
// Verify shapes of proto chain.
JSObject* pobj = obj;
for (GCPtr<Shape*>* s = ni->shapesBegin() + 1; s != ni->shapesEnd(); s++) {
Shape* shape = *s;
pobj = pobj->staticPrototype();
if (pobj->shape() != shape) {
return nullptr;
}
if (!CanCompareIterableObjectToCache(pobj)) {
return nullptr;
}
}
MOZ_ASSERT(CanStoreInIteratorCache(obj));
*cacheableProtoChainLength = ni->shapeCount();
return iterobj;
}
static MOZ_ALWAYS_INLINE PropertyIteratorObject* LookupInIteratorCache(
JSContext* cx, JSObject* obj, uint32_t* cacheableProtoChainLength) {
MOZ_ASSERT(*cacheableProtoChainLength == 0);
if (PropertyIteratorObject* shapeCached =
LookupInShapeIteratorCache(cx, obj, cacheableProtoChainLength)) {
return shapeCached;
}
Vector<Shape*, 8> shapes(cx);
HashNumber shapesHash = 0;
JSObject* pobj = obj;
do {
if (!CanCompareIterableObjectToCache(pobj)) {
return nullptr;
}
MOZ_ASSERT(pobj->is<NativeObject>());
Shape* shape = pobj->shape();
shapesHash = mozilla::AddToHash(shapesHash, HashIteratorShape(shape));
if (MOZ_UNLIKELY(!shapes.append(shape))) {
cx->recoverFromOutOfMemory();
return nullptr;
}
pobj = pobj->staticPrototype();
} while (pobj);
MOZ_ASSERT(!shapes.empty());
*cacheableProtoChainLength = shapes.length();
IteratorHashPolicy::Lookup lookup(shapes.begin(), shapes.length(),
shapesHash);
auto p = ObjectRealm::get(obj).iteratorCache.lookup(lookup);
if (!p) {
return nullptr;
}
PropertyIteratorObject* iterobj = *p;
MOZ_ASSERT(iterobj->compartment() == cx->compartment());
NativeIterator* ni = iterobj->getNativeIterator();
if (!ni->isReusable()) {
return nullptr;
}
return iterobj;
}
[[nodiscard]] static bool StoreInIteratorCache(
JSContext* cx, JSObject* obj, PropertyIteratorObject* iterobj) {
MOZ_ASSERT(CanStoreInIteratorCache(obj));
NativeIterator* ni = iterobj->getNativeIterator();
MOZ_ASSERT(ni->shapeCount() > 0);
obj->shape()->maybeCacheIterator(cx, iterobj);
IteratorHashPolicy::Lookup lookup(
reinterpret_cast<Shape**>(ni->shapesBegin()), ni->shapeCount(),
ni->shapesHash());
ObjectRealm::IteratorCache& cache = ObjectRealm::get(obj).iteratorCache;
bool ok;
auto p = cache.lookupForAdd(lookup);
if (MOZ_LIKELY(!p)) {
ok = cache.add(p, iterobj);
} else {
// If we weren't able to use an existing cached iterator, just
// replace it.
cache.remove(p);
ok = cache.relookupOrAdd(p, lookup, iterobj);
}
if (!ok) {
ReportOutOfMemory(cx);
return false;
}
return true;
}
bool js::EnumerateProperties(JSContext* cx, HandleObject obj,
MutableHandleIdVector props) {
MOZ_ASSERT(props.empty());
if (MOZ_UNLIKELY(obj->is<ProxyObject>())) {
return Proxy::enumerate(cx, obj, props);
}
uint32_t flags = 0;
PropertyEnumerator enumerator(cx, obj, flags, props);
return enumerator.snapshot(cx);
}
#ifdef DEBUG
static bool IndicesAreValid(NativeObject* obj, NativeIterator* ni) {
MOZ_ASSERT(ni->hasValidIndices());
size_t numDenseElements = obj->getDenseInitializedLength();
size_t numFixedSlots = obj->numFixedSlots();
const Value* elements = obj->getDenseElements();
GCPtr<JSLinearString*>* keys = ni->propertiesBegin();
PropertyIndex* indices = ni->indicesBegin();
for (uint32_t i = 0; i < ni->numKeys(); i++) {
PropertyIndex index = indices[i];
switch (index.kind()) {
case PropertyIndex::Kind::Element:
// Verify that the dense element exists and is not a hole.
if (index.index() >= numDenseElements ||
elements[index.index()].isMagic(JS_ELEMENTS_HOLE)) {
return false;
}
break;
case PropertyIndex::Kind::FixedSlot: {
// Verify that the slot exists and is an enumerable data property with
// the expected key.
Maybe<PropertyInfo> prop =
obj->lookupPure(AtomToId(&keys[i]->asAtom()));
if (!prop.isSome() || !prop->hasSlot() || !prop->enumerable() ||
!prop->isDataProperty() || prop->slot() != index.index()) {
return false;
}
break;
}
case PropertyIndex::Kind::DynamicSlot: {
// Verify that the slot exists and is an enumerable data property with
// the expected key.
Maybe<PropertyInfo> prop =
obj->lookupPure(AtomToId(&keys[i]->asAtom()));
if (!prop.isSome() || !prop->hasSlot() || !prop->enumerable() ||
!prop->isDataProperty() ||
prop->slot() - numFixedSlots != index.index()) {
return false;
}
break;
}
case PropertyIndex::Kind::Invalid:
return false;
}
}
return true;
}
#endif
template <bool WantIndices>
static PropertyIteratorObject* GetIteratorImpl(JSContext* cx,
HandleObject obj) {
MOZ_ASSERT(!obj->is<PropertyIteratorObject>());
MOZ_ASSERT(cx->compartment() == obj->compartment(),
"We may end up allocating shapes in the wrong zone!");
uint32_t cacheableProtoChainLength = 0;
if (PropertyIteratorObject* iterobj =
LookupInIteratorCache(cx, obj, &cacheableProtoChainLength)) {
NativeIterator* ni = iterobj->getNativeIterator();
bool recreateWithIndices = WantIndices && ni->indicesAvailableOnRequest();
if (!recreateWithIndices) {
MOZ_ASSERT_IF(WantIndices && ni->hasValidIndices(),
IndicesAreValid(&obj->as<NativeObject>(), ni));
ni->initObjectBeingIterated(*obj);
RegisterEnumerator(cx, ni);
return iterobj;
}
}
if (cacheableProtoChainLength > 0 && !CanStoreInIteratorCache(obj)) {
cacheableProtoChainLength = 0;
}
RootedIdVector keys(cx);
PropertyIndexVector indices(cx);
bool supportsIndices = false;
if (MOZ_UNLIKELY(obj->is<ProxyObject>())) {
if (!Proxy::enumerate(cx, obj, &keys)) {
return nullptr;
}
} else {
uint32_t flags = 0;
PropertyEnumerator enumerator(cx, obj, flags, &keys, &indices);
if (!enumerator.snapshot(cx)) {
return nullptr;
}
supportsIndices = enumerator.supportsIndices();
MOZ_ASSERT_IF(WantIndices && supportsIndices,
keys.length() == indices.length());
}
// If the object has dense elements, mark the dense elements as
// maybe-in-iteration.
//
// The iterator is a snapshot so if indexed properties are added after this
// point we don't need to do anything. However, the object might have sparse
// elements now that can be densified later. To account for this, we set the
// maybe-in-iteration flag also in NativeObject::maybeDensifySparseElements.
//
// In debug builds, AssertDenseElementsNotIterated is used to check the flag
// is set correctly.
if (obj->is<NativeObject>() &&
obj->as<NativeObject>().getDenseInitializedLength() > 0) {
obj->as<NativeObject>().markDenseElementsMaybeInIteration();
}
PropertyIndexVector* indicesPtr =
WantIndices && supportsIndices ? &indices : nullptr;
PropertyIteratorObject* iterobj = CreatePropertyIterator(
cx, obj, keys, supportsIndices, indicesPtr, cacheableProtoChainLength);
if (!iterobj) {
return nullptr;
}
RegisterEnumerator(cx, iterobj->getNativeIterator());
cx->check(iterobj);
MOZ_ASSERT_IF(
WantIndices && supportsIndices,
IndicesAreValid(&obj->as<NativeObject>(), iterobj->getNativeIterator()));
#ifdef DEBUG
if (obj->is<NativeObject>()) {
if (PrototypeMayHaveIndexedProperties(&obj->as<NativeObject>())) {
iterobj->getNativeIterator()->setMaybeHasIndexedPropertiesFromProto();
}
}
#endif
// Cache the iterator object.
if (cacheableProtoChainLength > 0) {
if (!StoreInIteratorCache(cx, obj, iterobj)) {
return nullptr;
}
}
return iterobj;
}
PropertyIteratorObject* js::GetIterator(JSContext* cx, HandleObject obj) {
return GetIteratorImpl<false>(cx, obj);
}
PropertyIteratorObject* js::GetIteratorWithIndices(JSContext* cx,
HandleObject obj) {
return GetIteratorImpl<true>(cx, obj);
}
PropertyIteratorObject* js::LookupInIteratorCache(JSContext* cx,
HandleObject obj) {
uint32_t dummy = 0;
return LookupInIteratorCache(cx, obj, &dummy);
}
PropertyIteratorObject* js::LookupInShapeIteratorCache(JSContext* cx,
HandleObject obj) {
uint32_t dummy = 0;
return LookupInShapeIteratorCache(cx, obj, &dummy);
}
// ES 2017 draft 7.4.7.
PlainObject* js::CreateIterResultObject(JSContext* cx, HandleValue value,
bool done) {
// Step 1 (implicit).
// Step 2.
Rooted<PlainObject*> templateObject(
cx, GlobalObject::getOrCreateIterResultTemplateObject(cx));
if (!templateObject) {
return nullptr;
}
PlainObject* resultObj = PlainObject::createWithTemplate(cx, templateObject);
if (!resultObj) {
return nullptr;
}
// Step 3.
resultObj->setSlot(GlobalObject::IterResultObjectValueSlot, value);
// Step 4.
resultObj->setSlot(GlobalObject::IterResultObjectDoneSlot,
done ? TrueHandleValue : FalseHandleValue);
// Step 5.
return resultObj;
}
PlainObject* GlobalObject::getOrCreateIterResultTemplateObject(JSContext* cx) {
HeapPtr<PlainObject*>& obj = cx->global()->data().iterResultTemplate;
if (obj) {
return obj;
}
PlainObject* templateObj =
createIterResultTemplateObject(cx, WithObjectPrototype::Yes);
obj.init(templateObj);
return obj;
}
/* static */
PlainObject* GlobalObject::getOrCreateIterResultWithoutPrototypeTemplateObject(
JSContext* cx) {
HeapPtr<PlainObject*>& obj =
cx->global()->data().iterResultWithoutPrototypeTemplate;
if (obj) {
return obj;
}
PlainObject* templateObj =
createIterResultTemplateObject(cx, WithObjectPrototype::No);
obj.init(templateObj);
return obj;
}
/* static */
PlainObject* GlobalObject::createIterResultTemplateObject(
JSContext* cx, WithObjectPrototype withProto) {
// Create template plain object
Rooted<PlainObject*> templateObject(
cx, withProto == WithObjectPrototype::Yes
? NewPlainObject(cx, TenuredObject)
: NewPlainObjectWithProto(cx, nullptr));
if (!templateObject) {
return nullptr;
}
// Set dummy `value` property
if (!NativeDefineDataProperty(cx, templateObject, cx->names().value,
UndefinedHandleValue, JSPROP_ENUMERATE)) {
return nullptr;
}
// Set dummy `done` property
if (!NativeDefineDataProperty(cx, templateObject, cx->names().done,
TrueHandleValue, JSPROP_ENUMERATE)) {
return nullptr;
}
#ifdef DEBUG
// Make sure that the properties are in the right slots.
ShapePropertyIter<NoGC> iter(templateObject->shape());
MOZ_ASSERT(iter->slot() == GlobalObject::IterResultObjectDoneSlot &&
iter->key() == NameToId(cx->names().done));
iter++;
MOZ_ASSERT(iter->slot() == GlobalObject::IterResultObjectValueSlot &&
iter->key() == NameToId(cx->names().value));
#endif
return templateObject;
}
/*** Iterator objects *******************************************************/
size_t PropertyIteratorObject::sizeOfMisc(
mozilla::MallocSizeOf mallocSizeOf) const {
return mallocSizeOf(getNativeIterator());
}
void PropertyIteratorObject::trace(JSTracer* trc, JSObject* obj) {
if (NativeIterator* ni =
obj->as<PropertyIteratorObject>().getNativeIterator()) {
ni->trace(trc);
}
}
void PropertyIteratorObject::finalize(JS::GCContext* gcx, JSObject* obj) {
if (NativeIterator* ni =
obj->as<PropertyIteratorObject>().getNativeIterator()) {
gcx->free_(obj, ni, ni->allocationSize(), MemoryUse::NativeIterator);
}
}
const JSClassOps PropertyIteratorObject::classOps_ = {
nullptr, // addProperty
nullptr, // delProperty
nullptr, // enumerate
nullptr, // newEnumerate
nullptr, // resolve
nullptr, // mayResolve
finalize, // finalize
nullptr, // call
nullptr, // construct
trace, // trace
};
const JSClass PropertyIteratorObject::class_ = {
"Iterator",
JSCLASS_HAS_RESERVED_SLOTS(SlotCount) | JSCLASS_BACKGROUND_FINALIZE,
&PropertyIteratorObject::classOps_};
static const JSClass ArrayIteratorPrototypeClass = {"Array Iterator", 0};
enum {
ArrayIteratorSlotIteratedObject,
ArrayIteratorSlotNextIndex,
ArrayIteratorSlotItemKind,
ArrayIteratorSlotCount
};
const JSClass ArrayIteratorObject::class_ = {
"Array Iterator", JSCLASS_HAS_RESERVED_SLOTS(ArrayIteratorSlotCount)};
ArrayIteratorObject* js::NewArrayIteratorTemplate(JSContext* cx) {
RootedObject proto(
cx, GlobalObject::getOrCreateArrayIteratorPrototype(cx, cx->global()));
if (!proto) {
return nullptr;
}
return NewTenuredObjectWithGivenProto<ArrayIteratorObject>(cx, proto);
}
ArrayIteratorObject* js::NewArrayIterator(JSContext* cx) {
RootedObject proto(
cx, GlobalObject::getOrCreateArrayIteratorPrototype(cx, cx->global()));
if (!proto) {
return nullptr;
}
return NewObjectWithGivenProto<ArrayIteratorObject>(cx, proto);
}
static const JSFunctionSpec array_iterator_methods[] = {
JS_SELF_HOSTED_FN("next", "ArrayIteratorNext", 0, 0), JS_FS_END};
static const JSClass StringIteratorPrototypeClass = {"String Iterator", 0};
enum {
StringIteratorSlotIteratedObject,
StringIteratorSlotNextIndex,
StringIteratorSlotCount
};
const JSClass StringIteratorObject::class_ = {
"String Iterator", JSCLASS_HAS_RESERVED_SLOTS(StringIteratorSlotCount)};
static const JSFunctionSpec string_iterator_methods[] = {
JS_SELF_HOSTED_FN("next", "StringIteratorNext", 0, 0), JS_FS_END};
StringIteratorObject* js::NewStringIteratorTemplate(JSContext* cx) {
RootedObject proto(
cx, GlobalObject::getOrCreateStringIteratorPrototype(cx, cx->global()));
if (!proto) {
return nullptr;
}
return NewTenuredObjectWithGivenProto<StringIteratorObject>(cx, proto);
}
StringIteratorObject* js::NewStringIterator(JSContext* cx) {
RootedObject proto(
cx, GlobalObject::getOrCreateStringIteratorPrototype(cx, cx->global()));
if (!proto) {
return nullptr;
}
return NewObjectWithGivenProto<StringIteratorObject>(cx, proto);
}
static const JSClass RegExpStringIteratorPrototypeClass = {
"RegExp String Iterator", 0};
enum {
// The regular expression used for iteration. May hold the original RegExp
// object when it is reused instead of a new RegExp object.
RegExpStringIteratorSlotRegExp,
// The String value being iterated upon.
RegExpStringIteratorSlotString,
// The source string of the original RegExp object. Used to validate we can
// reuse the original RegExp object for matching.
RegExpStringIteratorSlotSource,
// The flags of the original RegExp object.
RegExpStringIteratorSlotFlags,
// When non-negative, this slot holds the current lastIndex position when
// reusing the original RegExp object for matching. When set to |-1|, the
// iterator has finished. When set to any other negative value, the
// iterator is not yet exhausted and we're not on the fast path and we're
// not reusing the input RegExp object.
RegExpStringIteratorSlotLastIndex,
RegExpStringIteratorSlotCount
};
static_assert(RegExpStringIteratorSlotRegExp ==
REGEXP_STRING_ITERATOR_REGEXP_SLOT,
"RegExpStringIteratorSlotRegExp must match self-hosting define "
"for regexp slot.");
static_assert(RegExpStringIteratorSlotString ==
REGEXP_STRING_ITERATOR_STRING_SLOT,
"RegExpStringIteratorSlotString must match self-hosting define "
"for string slot.");
static_assert(RegExpStringIteratorSlotSource ==
REGEXP_STRING_ITERATOR_SOURCE_SLOT,
"RegExpStringIteratorSlotString must match self-hosting define "
"for source slot.");
static_assert(RegExpStringIteratorSlotFlags ==
REGEXP_STRING_ITERATOR_FLAGS_SLOT,
"RegExpStringIteratorSlotFlags must match self-hosting define "
"for flags slot.");
static_assert(RegExpStringIteratorSlotLastIndex ==
REGEXP_STRING_ITERATOR_LASTINDEX_SLOT,
"RegExpStringIteratorSlotLastIndex must match self-hosting "
"define for lastIndex slot.");
const JSClass RegExpStringIteratorObject::class_ = {
"RegExp String Iterator",
JSCLASS_HAS_RESERVED_SLOTS(RegExpStringIteratorSlotCount)};
static const JSFunctionSpec regexp_string_iterator_methods[] = {
JS_SELF_HOSTED_FN("next", "RegExpStringIteratorNext", 0, 0),
JS_FS_END};
RegExpStringIteratorObject* js::NewRegExpStringIteratorTemplate(JSContext* cx) {
RootedObject proto(cx, GlobalObject::getOrCreateRegExpStringIteratorPrototype(
cx, cx->global()));
if (!proto) {
return nullptr;
}
return NewTenuredObjectWithGivenProto<RegExpStringIteratorObject>(cx, proto);
}
RegExpStringIteratorObject* js::NewRegExpStringIterator(JSContext* cx) {
RootedObject proto(cx, GlobalObject::getOrCreateRegExpStringIteratorPrototype(
cx, cx->global()));
if (!proto) {
return nullptr;
}
return NewObjectWithGivenProto<RegExpStringIteratorObject>(cx, proto);
}
// static
PropertyIteratorObject* GlobalObject::getOrCreateEmptyIterator(JSContext* cx) {
if (!cx->global()->data().emptyIterator) {
RootedIdVector props(cx); // Empty
PropertyIteratorObject* iter =
CreatePropertyIterator(cx, nullptr, props, false, nullptr, 0);
if (!iter) {
return nullptr;
}
iter->getNativeIterator()->markEmptyIteratorSingleton();
cx->global()->data().emptyIterator.init(iter);
}
return cx->global()->data().emptyIterator;
}
PropertyIteratorObject* js::ValueToIterator(JSContext* cx, HandleValue vp) {
RootedObject obj(cx);
if (vp.isObject()) {
/* Common case. */
obj = &vp.toObject();
} else if (vp.isNullOrUndefined()) {
/*
* 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.
*/
return GlobalObject::getOrCreateEmptyIterator(cx);
} else {
obj = ToObject(cx, vp);
if (!obj) {
return nullptr;
}
}
return GetIterator(cx, obj);
}
void js::CloseIterator(JSObject* obj) {
if (!obj->is<PropertyIteratorObject>()) {
return;
}
// Remove iterator from the active list, which is a stack. The shared iterator
// used for for-in with null/undefined is immutable and unlinked.
NativeIterator* ni = obj->as<PropertyIteratorObject>().getNativeIterator();
if (ni->isEmptyIteratorSingleton()) {
return;
}
ni->unlink();
MOZ_ASSERT(ni->isActive());
ni->markInactive();
ni->clearObjectBeingIterated();
// Reset the enumerator; it may still be in the cached iterators for
// this thread and can be reused.
ni->resetPropertyCursorForReuse();
}
bool js::IteratorCloseForException(JSContext* cx, HandleObject obj) {
MOZ_ASSERT(cx->isExceptionPending());
bool isClosingGenerator = cx->isClosingGenerator();
JS::AutoSaveExceptionState savedExc(cx);
// Implements IteratorClose (ES 7.4.6) for exception unwinding. See
// also the bytecode generated by BytecodeEmitter::emitIteratorClose.
// Step 3.
//
// Get the "return" method.
RootedValue returnMethod(cx);
if (!GetProperty(cx, obj, obj, cx->names().return_, &returnMethod)) {
return false;
}
// Step 4.
//
// Do nothing if "return" is null or undefined. Throw a TypeError if the
// method is not IsCallable.
if (returnMethod.isNullOrUndefined()) {
return true;
}
if (!IsCallable(returnMethod)) {
return ReportIsNotFunction(cx, returnMethod);
}
// Step 5, 6, 8.
//
// Call "return" if it is not null or undefined.
RootedValue rval(cx);
bool ok = Call(cx, returnMethod, obj, &rval);
if (isClosingGenerator) {
// Closing an iterator is implemented as an exception, but in spec
// terms it is a Completion value with [[Type]] return. In this case
// we *do* care if the call threw and if it returned an object.
if (!ok) {
return false;
}
if (!rval.isObject()) {
return ThrowCheckIsObject(cx, CheckIsObjectKind::IteratorReturn);
}
} else {
// We don't care if the call threw or that it returned an Object, as
// Step 6 says if IteratorClose is being called during a throw, the
// original throw has primacy.
savedExc.restore();
}
return true;
}
void js::UnwindIteratorForUncatchableException(JSObject* obj) {
if (obj->is<PropertyIteratorObject>()) {
NativeIterator* ni = obj->as<PropertyIteratorObject>().getNativeIterator();
if (ni->isEmptyIteratorSingleton()) {
return;
}
ni->unlink();
}
}
static bool SuppressDeletedProperty(JSContext* cx, NativeIterator* ni,
HandleObject obj,
Handle<JSLinearString*> str) {
if (ni->objectBeingIterated() != obj) {
return true;
}
ni->disableIndices();
// Optimization for the following common case:
//
// for (var p in o) {
// delete o[p];
// }
//
// Note that usually both strings will be atoms so we only check for pointer
// equality here.
if (ni->previousPropertyWas(str)) {
return true;
}
while (true) {
bool restart = false;
// Check whether id is still to come.
GCPtr<JSLinearString*>* const cursor = ni->nextProperty();
GCPtr<JSLinearString*>* const end = ni->propertiesEnd();
for (GCPtr<JSLinearString*>* idp = cursor; idp < end; ++idp) {
// Common case: both strings are atoms.
if ((*idp)->isAtom() && str->isAtom()) {
if (*idp != str) {
continue;
}
} else {
if (!EqualStrings(*idp, str)) {
continue;
}
}
// Check whether another property along the prototype chain became
// visible as a result of this deletion.
RootedObject proto(cx);
if (!GetPrototype(cx, obj, &proto)) {
return false;
}
if (proto) {
RootedId id(cx);
RootedValue idv(cx, StringValue(*idp));
if (!PrimitiveValueToId<CanGC>(cx, idv, &id)) {
return false;
}
Rooted<mozilla::Maybe<PropertyDescriptor>> desc(cx);
RootedObject holder(cx);
if (!GetPropertyDescriptor(cx, proto, id, &desc, &holder)) {
return false;
}
if (desc.isSome() && desc->enumerable()) {
continue;
}
}
// If GetPropertyDescriptor above removed a property from ni, start
// over.
if (end != ni->propertiesEnd() || cursor != ni->nextProperty()) {
restart = true;
break;
}
// 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 == cursor) {
ni->incCursor();
} else {
for (GCPtr<JSLinearString*>* p = idp; p + 1 != end; p++) {
*p = *(p + 1);
}
ni->trimLastProperty();
}
ni->markHasUnvisitedPropertyDeletion();
return true;
}
if (!restart) {
return true;
}
}
}
/*
* 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.
*/
static bool SuppressDeletedPropertyHelper(JSContext* cx, HandleObject obj,
Handle<JSLinearString*> str) {
NativeIteratorListIter iter(obj->compartment()->enumeratorsAddr());
while (!iter.done()) {
NativeIterator* ni = iter.next();
if (!SuppressDeletedProperty(cx, ni, obj, str)) {
return false;
}
}
return true;
}
bool js::SuppressDeletedProperty(JSContext* cx, HandleObject obj, jsid id) {
if (MOZ_LIKELY(!obj->compartment()->objectMaybeInIteration(obj))) {
return true;
}
if (id.isSymbol()) {
return true;
}
Rooted<JSLinearString*> str(cx, IdToString(cx, id));
if (!str) {
return false;
}
return SuppressDeletedPropertyHelper(cx, obj, str);
}
bool js::SuppressDeletedElement(JSContext* cx, HandleObject obj,
uint32_t index) {
if (MOZ_LIKELY(!obj->compartment()->objectMaybeInIteration(obj))) {
return true;
}
RootedId id(cx);
if (!IndexToId(cx, index, &id)) {
return false;
}
Rooted<JSLinearString*> str(cx, IdToString(cx, id));
if (!str) {
return false;
}
return SuppressDeletedPropertyHelper(cx, obj, str);
}
#ifdef DEBUG
void js::AssertDenseElementsNotIterated(NativeObject* obj) {
// Search for active iterators for |obj| and assert they don't contain any
// property keys that are dense elements. This is used to check correctness
// of the MAYBE_IN_ITERATION flag on ObjectElements.
//
// Ignore iterators that may contain indexed properties from objects on the
// Limit the number of properties we check to avoid slowing down debug builds
// too much.
static constexpr uint32_t MaxPropsToCheck = 10;
uint32_t propsChecked = 0;
NativeIteratorListIter iter(obj->compartment()->enumeratorsAddr());
while (!iter.done()) {
NativeIterator* ni = iter.next();
if (ni->objectBeingIterated() == obj &&
!ni->maybeHasIndexedPropertiesFromProto()) {
for (GCPtr<JSLinearString*>* idp = ni->nextProperty();
idp < ni->propertiesEnd(); ++idp) {
uint32_t index;
if (idp->get()->isIndex(&index)) {
MOZ_ASSERT(!obj->containsDenseElement(index));
}
if (++propsChecked > MaxPropsToCheck) {
return;
}
}
}
}
}
#endif
static const JSFunctionSpec iterator_methods[] = {
JS_SELF_HOSTED_SYM_FN(iterator, "IteratorIdentity", 0, 0),
JS_FS_END,
};
static const JSFunctionSpec iterator_static_methods[] = {
JS_SELF_HOSTED_FN("from", "IteratorFrom", 1, 0),
JS_FS_END,
};
// These methods are only attached to Iterator.prototype when the
// Iterator Helpers feature is enabled.
static const JSFunctionSpec iterator_methods_with_helpers[] = {
JS_SELF_HOSTED_FN("map", "IteratorMap", 1, 0),
JS_SELF_HOSTED_FN("filter", "IteratorFilter", 1, 0),
JS_SELF_HOSTED_FN("take", "IteratorTake", 1, 0),
JS_SELF_HOSTED_FN("drop", "IteratorDrop", 1, 0),
JS_SELF_HOSTED_FN("flatMap", "IteratorFlatMap", 1, 0),
JS_SELF_HOSTED_FN("reduce", "IteratorReduce", 1, 0),
JS_SELF_HOSTED_FN("toArray", "IteratorToArray", 0, 0),
JS_SELF_HOSTED_FN("forEach", "IteratorForEach", 1, 0),
JS_SELF_HOSTED_FN("some", "IteratorSome", 1, 0),
JS_SELF_HOSTED_FN("every", "IteratorEvery", 1, 0),
JS_SELF_HOSTED_FN("find", "IteratorFind", 1, 0),
JS_SELF_HOSTED_SYM_FN(iterator, "IteratorIdentity", 0, 0),
JS_FS_END,
};
static bool SetterThatIgnoresPrototypeProperties(JSContext* cx,
Handle<Value> thisv,
Handle<PropertyKey> prop,
Handle<Value> value) {
// Step 1.
Rooted<JSObject*> thisObj(cx,
RequireObject(cx, JSMSG_OBJECT_REQUIRED, thisv));
if (!thisObj) {
return false;
}
// Step 2.
Rooted<JSObject*> home(
cx, GlobalObject::getOrCreateIteratorPrototype(cx, cx->global()));
if (!home) {
return false;
}
if (thisObj == home) {
UniqueChars propName =
IdToPrintableUTF8(cx, prop, IdToPrintableBehavior::IdIsPropertyKey);
if (!propName) {
return false;
}
// Step 2.b.
JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_READ_ONLY,
propName.get());
return false;
}
// Step 3.
Rooted<Maybe<PropertyDescriptor>> desc(cx);
if (!GetOwnPropertyDescriptor(cx, thisObj, prop, &desc)) {
return false;
}
// Step 4.
if (desc.isNothing()) {
// Step 4.a.
return DefineDataProperty(cx, thisObj, prop, value, JSPROP_ENUMERATE);
}
// Step 5.
return SetProperty(cx, thisObj, prop, value);
}
static bool toStringTagGetter(JSContext* cx, unsigned argc, Value* vp) {
CallArgs args = CallArgsFromVp(argc, vp);
// Step 1.
args.rval().setString(cx->names().Iterator);
return true;
}
static bool toStringTagSetter(JSContext* cx, unsigned argc, Value* vp) {
CallArgs args = CallArgsFromVp(argc, vp);
// Step 1.
Rooted<PropertyKey> prop(
cx, PropertyKey::Symbol(cx->wellKnownSymbols().toStringTag));
if (!SetterThatIgnoresPrototypeProperties(cx, args.thisv(), prop,
args.get(0))) {
return false;
}
// Step 2.
args.rval().setUndefined();
return true;
}
static bool constructorGetter(JSContext* cx, unsigned argc, Value* vp) {
CallArgs args = CallArgsFromVp(argc, vp);
// Step 1.
Rooted<JSObject*> constructor(
cx, GlobalObject::getOrCreateConstructor(cx, JSProto_Iterator));
if (!constructor) {
return false;
}
args.rval().setObject(*constructor);
return true;
}
static bool constructorSetter(JSContext* cx, unsigned argc, Value* vp) {
CallArgs args = CallArgsFromVp(argc, vp);
// Step 1.
Rooted<PropertyKey> prop(cx, NameToId(cx->names().constructor));
if (!SetterThatIgnoresPrototypeProperties(cx, args.thisv(), prop,
args.get(0))) {
return false;
}
// Step 2.
args.rval().setUndefined();
return true;
}
static const JSPropertySpec iterator_properties[] = {
// NOTE: Contrary to most other @@toStringTag properties, this property
// has a special setter (and a getter).
JS_SYM_GETSET(toStringTag, toStringTagGetter, toStringTagSetter, 0),
JS_PS_END,
};
/* static */
bool GlobalObject::initIteratorProto(JSContext* cx,
Handle<GlobalObject*> global) {
if (global->hasBuiltinProto(ProtoKind::IteratorProto)) {
return true;
}
RootedObject proto(
cx, GlobalObject::createBlankPrototype<PlainObject>(cx, global));
if (!proto) {
return false;
}
// %IteratorPrototype%.map.[[Prototype]] is %Generator% and
// %Generator%.prototype.[[Prototype]] is %IteratorPrototype%.
// Populate the slot early, to prevent runaway mutual recursion.
global->initBuiltinProto(ProtoKind::IteratorProto, proto);
if (!DefinePropertiesAndFunctions(cx, proto, nullptr, iterator_methods)) {
// In this case, we leave a partially initialized object in the
// slot. There's no obvious way to do better, since this object may already
// be in the prototype chain of %GeneratorPrototype%.
return false;
}
return true;
}
/* static */
template <GlobalObject::ProtoKind Kind, const JSClass* ProtoClass,
const JSFunctionSpec* Methods, const bool needsFuseProperty>
bool GlobalObject::initObjectIteratorProto(JSContext* cx,
Handle<GlobalObject*> global,
Handle<JSAtom*> tag) {
if (global->hasBuiltinProto(Kind)) {
return true;
}
RootedObject iteratorProto(
cx, GlobalObject::getOrCreateIteratorPrototype(cx, global));
if (!iteratorProto) {
return false;
}
RootedObject proto(cx, GlobalObject::createBlankPrototypeInheriting(
cx, ProtoClass, iteratorProto));
if (!proto || !DefinePropertiesAndFunctions(cx, proto, nullptr, Methods) ||
(tag && !DefineToStringTag(cx, proto, tag))) {
return false;
}
if constexpr (needsFuseProperty) {
if (!JSObject::setHasFuseProperty(cx, proto)) {
return false;
}
}
global->initBuiltinProto(Kind, proto);
return true;
}
/* static */
NativeObject* GlobalObject::getOrCreateArrayIteratorPrototype(
JSContext* cx, Handle<GlobalObject*> global) {
return MaybeNativeObject(getOrCreateBuiltinProto(
cx, global, ProtoKind::ArrayIteratorProto,
cx->names().Array_Iterator_.toHandle(),
initObjectIteratorProto<
ProtoKind::ArrayIteratorProto, &ArrayIteratorPrototypeClass,
array_iterator_methods, /* hasFuseProperty= */ true>));
}
/* static */
JSObject* GlobalObject::getOrCreateStringIteratorPrototype(
JSContext* cx, Handle<GlobalObject*> global) {
return getOrCreateBuiltinProto(
cx, global, ProtoKind::StringIteratorProto,
cx->names().String_Iterator_.toHandle(),
initObjectIteratorProto<ProtoKind::StringIteratorProto,
&StringIteratorPrototypeClass,
string_iterator_methods>);
}
/* static */
JSObject* GlobalObject::getOrCreateRegExpStringIteratorPrototype(
JSContext* cx, Handle<GlobalObject*> global) {
return getOrCreateBuiltinProto(
cx, global, ProtoKind::RegExpStringIteratorProto,
cx->names().RegExp_String_Iterator_.toHandle(),
initObjectIteratorProto<ProtoKind::RegExpStringIteratorProto,
&RegExpStringIteratorPrototypeClass,
regexp_string_iterator_methods>);
}
// Iterator Helper Proposal 2.1.3.1 Iterator()
// ed6e15a
static bool IteratorConstructor(JSContext* cx, unsigned argc, Value* vp) {
CallArgs args = CallArgsFromVp(argc, vp);
// Step 1.
if (!ThrowIfNotConstructing(cx, args, "Iterator")) {
return false;
}
// Throw TypeError if NewTarget is the active function object, preventing the
// Iterator constructor from being used directly.
if (args.callee() == args.newTarget().toObject()) {
JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
JSMSG_BOGUS_CONSTRUCTOR, "Iterator");
return false;
}
// Step 2.
RootedObject proto(cx);
if (!GetPrototypeFromBuiltinConstructor(cx, args, JSProto_Iterator, &proto)) {
return false;
}
JSObject* obj = NewObjectWithClassProto<IteratorObject>(cx, proto);
if (!obj) {
return false;
}
args.rval().setObject(*obj);
return true;
}
static const ClassSpec IteratorObjectClassSpec = {
GenericCreateConstructor<IteratorConstructor, 0, gc::AllocKind::FUNCTION>,
GenericCreatePrototype<IteratorObject>,
iterator_static_methods,
nullptr,
iterator_methods_with_helpers,
iterator_properties,
IteratorObject::finishInit,
};
const JSClass IteratorObject::class_ = {
"Iterator",
JSCLASS_HAS_CACHED_PROTO(JSProto_Iterator),
JS_NULL_CLASS_OPS,
&IteratorObjectClassSpec,
};
const JSClass IteratorObject::protoClass_ = {
"Iterator.prototype",
JSCLASS_HAS_CACHED_PROTO(JSProto_Iterator),
JS_NULL_CLASS_OPS,
&IteratorObjectClassSpec,
};
/* static */ bool IteratorObject::finishInit(JSContext* cx, HandleObject ctor,
HandleObject proto) {
Rooted<PropertyKey> id(cx, NameToId(cx->names().constructor));
return JS_DefinePropertyById(cx, proto, id, constructorGetter,
constructorSetter, 0);
}
// Set up WrapForValidIteratorObject class and its prototype.
static const JSFunctionSpec wrap_for_valid_iterator_methods[] = {
JS_SELF_HOSTED_FN("next", "WrapForValidIteratorNext", 0, 0),
JS_SELF_HOSTED_FN("return", "WrapForValidIteratorReturn", 0, 0),
JS_FS_END,
};
static const JSClass WrapForValidIteratorPrototypeClass = {
"Wrap For Valid Iterator", 0};
const JSClass WrapForValidIteratorObject::class_ = {
"Wrap For Valid Iterator",
JSCLASS_HAS_RESERVED_SLOTS(WrapForValidIteratorObject::SlotCount),
};
/* static */
NativeObject* GlobalObject::getOrCreateWrapForValidIteratorPrototype(
JSContext* cx, Handle<GlobalObject*> global) {
return MaybeNativeObject(getOrCreateBuiltinProto(
cx, global, ProtoKind::WrapForValidIteratorProto,
Handle<JSAtom*>(nullptr),
initObjectIteratorProto<ProtoKind::WrapForValidIteratorProto,
&WrapForValidIteratorPrototypeClass,
wrap_for_valid_iterator_methods>));
}
WrapForValidIteratorObject* js::NewWrapForValidIterator(JSContext* cx) {
RootedObject proto(cx, GlobalObject::getOrCreateWrapForValidIteratorPrototype(
cx, cx->global()));
if (!proto) {
return nullptr;
}
return NewObjectWithGivenProto<WrapForValidIteratorObject>(cx, proto);
}
// Common iterator object returned by Iterator Helper methods.
static const JSFunctionSpec iterator_helper_methods[] = {
JS_SELF_HOSTED_FN("next", "IteratorHelperNext", 0, 0),
JS_SELF_HOSTED_FN("return", "IteratorHelperReturn", 0, 0),
JS_FS_END,
};
static const JSClass IteratorHelperPrototypeClass = {"Iterator Helper", 0};
const JSClass IteratorHelperObject::class_ = {
"Iterator Helper",
JSCLASS_HAS_RESERVED_SLOTS(IteratorHelperObject::SlotCount),
};
/* static */
NativeObject* GlobalObject::getOrCreateIteratorHelperPrototype(
JSContext* cx, Handle<GlobalObject*> global) {
return MaybeNativeObject(getOrCreateBuiltinProto(
cx, global, ProtoKind::IteratorHelperProto,
cx->names().Iterator_Helper_.toHandle(),
initObjectIteratorProto<ProtoKind::IteratorHelperProto,
&IteratorHelperPrototypeClass,
iterator_helper_methods>));
}
IteratorHelperObject* js::NewIteratorHelper(JSContext* cx) {
RootedObject proto(
cx, GlobalObject::getOrCreateIteratorHelperPrototype(cx, cx->global()));
if (!proto) {
return nullptr;
}
return NewObjectWithGivenProto<IteratorHelperObject>(cx, proto);
}
bool js::IterableToArray(JSContext* cx, HandleValue iterable,
MutableHandle<ArrayObject*> array) {
JS::ForOfIterator iterator(cx);
if (!iterator.init(iterable, JS::ForOfIterator::ThrowOnNonIterable)) {
return false;
}
array.set(NewDenseEmptyArray(cx));
if (!array) {
return false;
}
RootedValue nextValue(cx);
while (true) {
bool done;
if (!iterator.next(&nextValue, &done)) {
return false;
}
if (done) {
break;
}
if (!NewbornArrayPush(cx, array, nextValue)) {
return false;
}
}
return true;
}