Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 1 | // Copyright 2014 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef V8_PROTOTYPE_H_ |
| 6 | #define V8_PROTOTYPE_H_ |
| 7 | |
| 8 | #include "src/isolate.h" |
| 9 | #include "src/objects.h" |
| 10 | |
| 11 | namespace v8 { |
| 12 | namespace internal { |
| 13 | |
| 14 | /** |
| 15 | * A class to uniformly access the prototype of any Object and walk its |
| 16 | * prototype chain. |
| 17 | * |
| 18 | * The PrototypeIterator can either start at the prototype (default), or |
| 19 | * include the receiver itself. If a PrototypeIterator is constructed for a |
| 20 | * Map, it will always start at the prototype. |
| 21 | * |
| 22 | * The PrototypeIterator can either run to the null_value(), the first |
| 23 | * non-hidden prototype, or a given object. |
| 24 | */ |
| 25 | class PrototypeIterator { |
| 26 | public: |
| 27 | enum WhereToStart { START_AT_RECEIVER, START_AT_PROTOTYPE }; |
| 28 | |
| 29 | enum WhereToEnd { END_AT_NULL, END_AT_NON_HIDDEN }; |
| 30 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 31 | const int kProxyPrototypeLimit = 100 * 1000; |
| 32 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 33 | PrototypeIterator(Isolate* isolate, Handle<Object> receiver, |
| 34 | WhereToStart where_to_start = START_AT_PROTOTYPE) |
| 35 | : did_jump_to_prototype_chain_(false), |
| 36 | object_(NULL), |
| 37 | handle_(receiver), |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 38 | isolate_(isolate), |
| 39 | seen_proxies_(0) { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 40 | CHECK(!handle_.is_null()); |
| 41 | if (where_to_start == START_AT_PROTOTYPE) { |
| 42 | Advance(); |
| 43 | } |
| 44 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 45 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 46 | PrototypeIterator(Isolate* isolate, Object* receiver, |
| 47 | WhereToStart where_to_start = START_AT_PROTOTYPE) |
| 48 | : did_jump_to_prototype_chain_(false), |
| 49 | object_(receiver), |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 50 | isolate_(isolate), |
| 51 | seen_proxies_(0) { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 52 | if (where_to_start == START_AT_PROTOTYPE) { |
| 53 | Advance(); |
| 54 | } |
| 55 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 56 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 57 | explicit PrototypeIterator(Map* receiver_map) |
| 58 | : did_jump_to_prototype_chain_(true), |
| 59 | object_(receiver_map->prototype()), |
| 60 | isolate_(receiver_map->GetIsolate()) {} |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 61 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 62 | explicit PrototypeIterator(Handle<Map> receiver_map) |
| 63 | : did_jump_to_prototype_chain_(true), |
| 64 | object_(NULL), |
| 65 | handle_(handle(receiver_map->prototype(), receiver_map->GetIsolate())), |
| 66 | isolate_(receiver_map->GetIsolate()) {} |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 67 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 68 | ~PrototypeIterator() {} |
| 69 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 70 | bool HasAccess() const { |
| 71 | // We can only perform access check in the handlified version of the |
| 72 | // PrototypeIterator. |
| 73 | DCHECK(!handle_.is_null()); |
| 74 | if (handle_->IsAccessCheckNeeded()) { |
| 75 | return isolate_->MayAccess(handle(isolate_->context()), |
| 76 | Handle<JSObject>::cast(handle_)); |
| 77 | } |
| 78 | return true; |
| 79 | } |
| 80 | |
| 81 | template <typename T = Object> |
| 82 | T* GetCurrent() const { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 83 | DCHECK(handle_.is_null()); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 84 | return T::cast(object_); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 85 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 86 | |
| 87 | template <typename T = Object> |
| 88 | static Handle<T> GetCurrent(const PrototypeIterator& iterator) { |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 89 | DCHECK(!iterator.handle_.is_null()); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 90 | DCHECK(iterator.object_ == NULL); |
| 91 | return Handle<T>::cast(iterator.handle_); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 92 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 93 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 94 | void Advance() { |
| 95 | if (handle_.is_null() && object_->IsJSProxy()) { |
| 96 | did_jump_to_prototype_chain_ = true; |
| 97 | object_ = isolate_->heap()->null_value(); |
| 98 | return; |
| 99 | } else if (!handle_.is_null() && handle_->IsJSProxy()) { |
| 100 | did_jump_to_prototype_chain_ = true; |
| 101 | handle_ = handle(isolate_->heap()->null_value(), isolate_); |
| 102 | return; |
| 103 | } |
| 104 | AdvanceIgnoringProxies(); |
| 105 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 106 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 107 | void AdvanceIgnoringProxies() { |
| 108 | if (!did_jump_to_prototype_chain_) { |
| 109 | did_jump_to_prototype_chain_ = true; |
| 110 | if (handle_.is_null()) { |
| 111 | object_ = object_->GetRootMap(isolate_)->prototype(); |
| 112 | } else { |
| 113 | handle_ = handle(handle_->GetRootMap(isolate_)->prototype(), isolate_); |
| 114 | } |
| 115 | } else { |
| 116 | if (handle_.is_null()) { |
| 117 | object_ = HeapObject::cast(object_)->map()->prototype(); |
| 118 | } else { |
| 119 | handle_ = |
| 120 | handle(HeapObject::cast(*handle_)->map()->prototype(), isolate_); |
| 121 | } |
| 122 | } |
| 123 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 124 | |
| 125 | // Returns false iff a call to JSProxy::GetPrototype throws. |
| 126 | // TODO(neis): This should probably replace Advance(). |
| 127 | bool AdvanceFollowingProxies() { |
| 128 | DCHECK(!(handle_.is_null() && object_->IsJSProxy())); |
| 129 | if (!HasAccess()) { |
| 130 | // Abort the lookup if we do not have access to the current object. |
| 131 | handle_ = isolate_->factory()->null_value(); |
| 132 | return true; |
| 133 | } |
| 134 | if (handle_.is_null() || !handle_->IsJSProxy()) { |
| 135 | AdvanceIgnoringProxies(); |
| 136 | return true; |
| 137 | } |
| 138 | // Due to possible __proto__ recursion limit the number of Proxies |
| 139 | // we visit to an arbitrarily chosen large number. |
| 140 | seen_proxies_++; |
| 141 | if (seen_proxies_ > kProxyPrototypeLimit) { |
| 142 | isolate_->Throw( |
| 143 | *isolate_->factory()->NewRangeError(MessageTemplate::kStackOverflow)); |
| 144 | return false; |
| 145 | } |
| 146 | did_jump_to_prototype_chain_ = true; |
| 147 | MaybeHandle<Object> proto = |
| 148 | JSProxy::GetPrototype(Handle<JSProxy>::cast(handle_)); |
| 149 | return proto.ToHandle(&handle_); |
| 150 | } |
| 151 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 152 | bool IsAtEnd(WhereToEnd where_to_end = END_AT_NULL) const { |
| 153 | if (handle_.is_null()) { |
| 154 | return object_->IsNull() || |
| 155 | (did_jump_to_prototype_chain_ && |
| 156 | where_to_end == END_AT_NON_HIDDEN && |
| 157 | !HeapObject::cast(object_)->map()->is_hidden_prototype()); |
| 158 | } else { |
| 159 | return handle_->IsNull() || |
| 160 | (did_jump_to_prototype_chain_ && |
| 161 | where_to_end == END_AT_NON_HIDDEN && |
| 162 | !Handle<HeapObject>::cast(handle_)->map()->is_hidden_prototype()); |
| 163 | } |
| 164 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 165 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 166 | bool IsAtEnd(Object* final_object) { |
| 167 | DCHECK(handle_.is_null()); |
| 168 | return object_->IsNull() || object_ == final_object; |
| 169 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 170 | |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 171 | bool IsAtEnd(Handle<Object> final_object) { |
| 172 | DCHECK(!handle_.is_null()); |
| 173 | return handle_->IsNull() || *handle_ == *final_object; |
| 174 | } |
| 175 | |
| 176 | private: |
| 177 | bool did_jump_to_prototype_chain_; |
| 178 | Object* object_; |
| 179 | Handle<Object> handle_; |
| 180 | Isolate* isolate_; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 181 | int seen_proxies_; |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 182 | |
| 183 | DISALLOW_COPY_AND_ASSIGN(PrototypeIterator); |
| 184 | }; |
| 185 | |
| 186 | |
| 187 | } // namespace internal |
| 188 | |
| 189 | } // namespace v8 |
| 190 | |
| 191 | #endif // V8_PROTOTYPE_H_ |