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 | |
| 31 | PrototypeIterator(Isolate* isolate, Handle<Object> receiver, |
| 32 | WhereToStart where_to_start = START_AT_PROTOTYPE) |
| 33 | : did_jump_to_prototype_chain_(false), |
| 34 | object_(NULL), |
| 35 | handle_(receiver), |
| 36 | isolate_(isolate) { |
| 37 | CHECK(!handle_.is_null()); |
| 38 | if (where_to_start == START_AT_PROTOTYPE) { |
| 39 | Advance(); |
| 40 | } |
| 41 | } |
| 42 | PrototypeIterator(Isolate* isolate, Object* receiver, |
| 43 | WhereToStart where_to_start = START_AT_PROTOTYPE) |
| 44 | : did_jump_to_prototype_chain_(false), |
| 45 | object_(receiver), |
| 46 | isolate_(isolate) { |
| 47 | if (where_to_start == START_AT_PROTOTYPE) { |
| 48 | Advance(); |
| 49 | } |
| 50 | } |
| 51 | explicit PrototypeIterator(Map* receiver_map) |
| 52 | : did_jump_to_prototype_chain_(true), |
| 53 | object_(receiver_map->prototype()), |
| 54 | isolate_(receiver_map->GetIsolate()) {} |
| 55 | explicit PrototypeIterator(Handle<Map> receiver_map) |
| 56 | : did_jump_to_prototype_chain_(true), |
| 57 | object_(NULL), |
| 58 | handle_(handle(receiver_map->prototype(), receiver_map->GetIsolate())), |
| 59 | isolate_(receiver_map->GetIsolate()) {} |
| 60 | ~PrototypeIterator() {} |
| 61 | |
| 62 | Object* GetCurrent() const { |
| 63 | DCHECK(handle_.is_null()); |
| 64 | return object_; |
| 65 | } |
| 66 | static Handle<Object> GetCurrent(const PrototypeIterator& iterator) { |
| 67 | DCHECK(!iterator.handle_.is_null()); |
| 68 | return iterator.handle_; |
| 69 | } |
| 70 | void Advance() { |
| 71 | if (handle_.is_null() && object_->IsJSProxy()) { |
| 72 | did_jump_to_prototype_chain_ = true; |
| 73 | object_ = isolate_->heap()->null_value(); |
| 74 | return; |
| 75 | } else if (!handle_.is_null() && handle_->IsJSProxy()) { |
| 76 | did_jump_to_prototype_chain_ = true; |
| 77 | handle_ = handle(isolate_->heap()->null_value(), isolate_); |
| 78 | return; |
| 79 | } |
| 80 | AdvanceIgnoringProxies(); |
| 81 | } |
| 82 | void AdvanceIgnoringProxies() { |
| 83 | if (!did_jump_to_prototype_chain_) { |
| 84 | did_jump_to_prototype_chain_ = true; |
| 85 | if (handle_.is_null()) { |
| 86 | object_ = object_->GetRootMap(isolate_)->prototype(); |
| 87 | } else { |
| 88 | handle_ = handle(handle_->GetRootMap(isolate_)->prototype(), isolate_); |
| 89 | } |
| 90 | } else { |
| 91 | if (handle_.is_null()) { |
| 92 | object_ = HeapObject::cast(object_)->map()->prototype(); |
| 93 | } else { |
| 94 | handle_ = |
| 95 | handle(HeapObject::cast(*handle_)->map()->prototype(), isolate_); |
| 96 | } |
| 97 | } |
| 98 | } |
| 99 | bool IsAtEnd(WhereToEnd where_to_end = END_AT_NULL) const { |
| 100 | if (handle_.is_null()) { |
| 101 | return object_->IsNull() || |
| 102 | (did_jump_to_prototype_chain_ && |
| 103 | where_to_end == END_AT_NON_HIDDEN && |
| 104 | !HeapObject::cast(object_)->map()->is_hidden_prototype()); |
| 105 | } else { |
| 106 | return handle_->IsNull() || |
| 107 | (did_jump_to_prototype_chain_ && |
| 108 | where_to_end == END_AT_NON_HIDDEN && |
| 109 | !Handle<HeapObject>::cast(handle_)->map()->is_hidden_prototype()); |
| 110 | } |
| 111 | } |
| 112 | bool IsAtEnd(Object* final_object) { |
| 113 | DCHECK(handle_.is_null()); |
| 114 | return object_->IsNull() || object_ == final_object; |
| 115 | } |
| 116 | bool IsAtEnd(Handle<Object> final_object) { |
| 117 | DCHECK(!handle_.is_null()); |
| 118 | return handle_->IsNull() || *handle_ == *final_object; |
| 119 | } |
| 120 | |
| 121 | private: |
| 122 | bool did_jump_to_prototype_chain_; |
| 123 | Object* object_; |
| 124 | Handle<Object> handle_; |
| 125 | Isolate* isolate_; |
| 126 | |
| 127 | DISALLOW_COPY_AND_ASSIGN(PrototypeIterator); |
| 128 | }; |
| 129 | |
| 130 | |
| 131 | } // namespace internal |
| 132 | |
| 133 | } // namespace v8 |
| 134 | |
| 135 | #endif // V8_PROTOTYPE_H_ |