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// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_OBJECTS_PROTOTYPE_INL_H_
#define V8_OBJECTS_PROTOTYPE_INL_H_
#include "src/objects/prototype.h"
#include "src/handles/handles-inl.h"
#include "src/objects/js-proxy.h"
#include "src/objects/map-inl.h"
namespace v8 {
namespace internal {
PrototypeIterator::PrototypeIterator(Isolate* isolate,
Handle<JSReceiver> receiver,
WhereToStart where_to_start,
WhereToEnd where_to_end)
: isolate_(isolate),
handle_(receiver),
where_to_end_(where_to_end),
is_at_end_(false),
seen_proxies_(0) {
CHECK(!handle_.is_null());
if (where_to_start == kStartAtPrototype) Advance();
}
PrototypeIterator::PrototypeIterator(Isolate* isolate, JSReceiver receiver,
WhereToStart where_to_start,
WhereToEnd where_to_end)
: isolate_(isolate),
object_(receiver),
where_to_end_(where_to_end),
is_at_end_(false),
seen_proxies_(0) {
if (where_to_start == kStartAtPrototype) Advance();
}
PrototypeIterator::PrototypeIterator(Isolate* isolate, Map receiver_map,
WhereToEnd where_to_end)
: isolate_(isolate),
object_(receiver_map.GetPrototypeChainRootMap(isolate_).prototype()),
where_to_end_(where_to_end),
is_at_end_(object_.IsNull(isolate_)),
seen_proxies_(0) {
if (!is_at_end_ && where_to_end_ == END_AT_NON_HIDDEN) {
DCHECK(object_.IsJSReceiver());
Map map = JSReceiver::cast(object_).map();
is_at_end_ = !map.has_hidden_prototype();
}
}
PrototypeIterator::PrototypeIterator(Isolate* isolate, Handle<Map> receiver_map,
WhereToEnd where_to_end)
: isolate_(isolate),
handle_(receiver_map->GetPrototypeChainRootMap(isolate_).prototype(),
isolate_),
where_to_end_(where_to_end),
is_at_end_(handle_->IsNull(isolate_)),
seen_proxies_(0) {
if (!is_at_end_ && where_to_end_ == END_AT_NON_HIDDEN) {
DCHECK(handle_->IsJSReceiver());
Map map = JSReceiver::cast(*handle_).map();
is_at_end_ = !map.has_hidden_prototype();
}
}
bool PrototypeIterator::HasAccess() const {
// We can only perform access check in the handlified version of the
// PrototypeIterator.
DCHECK(!handle_.is_null());
if (handle_->IsAccessCheckNeeded()) {
return isolate_->MayAccess(handle(isolate_->context(), isolate_),
Handle<JSObject>::cast(handle_));
}
return true;
}
void PrototypeIterator::Advance() {
if (handle_.is_null() && object_.IsJSProxy()) {
is_at_end_ = true;
object_ = ReadOnlyRoots(isolate_).null_value();
return;
} else if (!handle_.is_null() && handle_->IsJSProxy()) {
is_at_end_ = true;
handle_ = isolate_->factory()->null_value();
return;
}
AdvanceIgnoringProxies();
}
void PrototypeIterator::AdvanceIgnoringProxies() {
Object object = handle_.is_null() ? object_ : *handle_;
Map map = HeapObject::cast(object).map();
HeapObject prototype = map.prototype();
is_at_end_ = where_to_end_ == END_AT_NON_HIDDEN ? !map.has_hidden_prototype()
: prototype.IsNull(isolate_);
if (handle_.is_null()) {
object_ = prototype;
} else {
handle_ = handle(prototype, isolate_);
}
}
V8_WARN_UNUSED_RESULT bool PrototypeIterator::AdvanceFollowingProxies() {
DCHECK(!(handle_.is_null() && object_.IsJSProxy()));
if (!HasAccess()) {
// Abort the lookup if we do not have access to the current object.
handle_ = isolate_->factory()->null_value();
is_at_end_ = true;
return true;
}
return AdvanceFollowingProxiesIgnoringAccessChecks();
}
V8_WARN_UNUSED_RESULT bool
PrototypeIterator::AdvanceFollowingProxiesIgnoringAccessChecks() {
if (handle_.is_null() || !handle_->IsJSProxy()) {
AdvanceIgnoringProxies();
return true;
}
// Due to possible __proto__ recursion limit the number of Proxies
// we visit to an arbitrarily chosen large number.
seen_proxies_++;
if (seen_proxies_ > JSProxy::kMaxIterationLimit) {
isolate_->StackOverflow();
return false;
}
MaybeHandle<HeapObject> proto =
JSProxy::GetPrototype(Handle<JSProxy>::cast(handle_));
if (!proto.ToHandle(&handle_)) return false;
is_at_end_ = where_to_end_ == END_AT_NON_HIDDEN || handle_->IsNull(isolate_);
return true;
}
} // namespace internal
} // namespace v8
#endif // V8_OBJECTS_PROTOTYPE_INL_H_