1 // Copyright 2014 The Chromium 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 ScriptPromiseProperty_h 6 #define ScriptPromiseProperty_h 7 8 #include "bindings/core/v8/ScriptPromise.h" 9 #include "bindings/core/v8/ScriptPromisePropertyBase.h" 10 #include "bindings/core/v8/V8Binding.h" 11 #include "wtf/Noncopyable.h" 12 #include "wtf/PassRefPtr.h" 13 14 namespace blink { 15 16 class ExecutionContext; 17 18 // ScriptPromiseProperty is a helper for implementing a DOM method or 19 // attribute whose value is a Promise, and the same Promise must be 20 // returned each time. 21 // 22 // ScriptPromiseProperty does not keep Promises or worlds alive to 23 // deliver Promise resolution/rejection to them; the Promise 24 // resolution/rejections are delivered if the holder's wrapper is 25 // alive. This is achieved by keeping a weak reference from 26 // ScriptPromiseProperty to the holder's wrapper, and references in 27 // hidden values from the wrapper to the promise and resolver 28 // (coincidentally the Resolver and Promise may be the same object, 29 // but that is an implementation detail of v8.) 30 // 31 // ----> Resolver 32 // / 33 // ScriptPromiseProperty - - -> Holder Wrapper ----> Promise 34 // 35 // To avoid exposing the action of the garbage collector to script, 36 // you should keep the wrapper alive as long as a promise may be 37 // settled. 38 // 39 // To avoid clobbering hidden values, a holder should only have one 40 // ScriptPromiseProperty object for a given name at a time. See reset. 41 template<typename HolderType, typename ResolvedType, typename RejectedType> 42 class ScriptPromiseProperty : public ScriptPromisePropertyBase { 43 WTF_MAKE_NONCOPYABLE(ScriptPromiseProperty); 44 public: 45 // Creates a ScriptPromiseProperty that will create Promises in 46 // the specified ExecutionContext for a property of 'holder' 47 // (typically ScriptPromiseProperty should be a member of the 48 // property holder). 49 // 50 // When implementing a ScriptPromiseProperty add the property name 51 // to ScriptPromiseProperties.h and pass 52 // ScriptPromiseProperty::Foo to create. The name must be unique 53 // per kind of holder. 54 template<typename PassHolderType> 55 ScriptPromiseProperty(ExecutionContext*, PassHolderType, Name); 56 57 virtual ~ScriptPromiseProperty() { } 58 59 template<typename PassResolvedType> 60 void resolve(PassResolvedType); 61 62 template<typename PassRejectedType> 63 void reject(PassRejectedType); 64 65 // Resets this property by unregistering the Promise property from the 66 // holder wrapper. Resets the internal state to Pending and clears the 67 // resolved and the rejected values. 68 // This method keeps the holder object and the property name. 69 void reset(); 70 71 virtual void trace(Visitor*) OVERRIDE; 72 73 private: 74 virtual v8::Handle<v8::Object> holder(v8::Handle<v8::Object> creationContext, v8::Isolate*) OVERRIDE; 75 virtual v8::Handle<v8::Value> resolvedValue(v8::Handle<v8::Object> creationContext, v8::Isolate*) OVERRIDE; 76 virtual v8::Handle<v8::Value> rejectedValue(v8::Handle<v8::Object> creationContext, v8::Isolate*) OVERRIDE; 77 78 HolderType m_holder; 79 ResolvedType m_resolved; 80 RejectedType m_rejected; 81 }; 82 83 template<typename HolderType, typename ResolvedType, typename RejectedType> 84 template<typename PassHolderType> 85 ScriptPromiseProperty<HolderType, ResolvedType, RejectedType>::ScriptPromiseProperty(ExecutionContext* executionContext, PassHolderType holder, Name name) 86 : ScriptPromisePropertyBase(executionContext, name) 87 , m_holder(holder) 88 { 89 } 90 91 template<typename HolderType, typename ResolvedType, typename RejectedType> 92 template<typename PassResolvedType> 93 void ScriptPromiseProperty<HolderType, ResolvedType, RejectedType>::resolve(PassResolvedType value) 94 { 95 if (state() != Pending) { 96 ASSERT_NOT_REACHED(); 97 return; 98 } 99 if (!executionContext() || executionContext()->activeDOMObjectsAreStopped()) 100 return; 101 m_resolved = value; 102 resolveOrReject(Resolved); 103 } 104 105 template<typename HolderType, typename ResolvedType, typename RejectedType> 106 template<typename PassRejectedType> 107 void ScriptPromiseProperty<HolderType, ResolvedType, RejectedType>::reject(PassRejectedType value) 108 { 109 if (state() != Pending) { 110 ASSERT_NOT_REACHED(); 111 return; 112 } 113 if (!executionContext() || executionContext()->activeDOMObjectsAreStopped()) 114 return; 115 m_rejected = value; 116 resolveOrReject(Rejected); 117 } 118 119 template<typename HolderType, typename ResolvedType, typename RejectedType> 120 v8::Handle<v8::Object> ScriptPromiseProperty<HolderType, ResolvedType, RejectedType>::holder(v8::Handle<v8::Object> creationContext, v8::Isolate* isolate) 121 { 122 v8::Handle<v8::Value> value = V8ValueTraits<HolderType>::toV8Value(m_holder, creationContext, isolate); 123 return value.As<v8::Object>(); 124 } 125 126 template<typename HolderType, typename ResolvedType, typename RejectedType> 127 v8::Handle<v8::Value> ScriptPromiseProperty<HolderType, ResolvedType, RejectedType>::resolvedValue(v8::Handle<v8::Object> creationContext, v8::Isolate* isolate) 128 { 129 ASSERT(state() == Resolved); 130 return V8ValueTraits<ResolvedType>::toV8Value(m_resolved, creationContext, isolate); 131 } 132 133 template<typename HolderType, typename ResolvedType, typename RejectedType> 134 v8::Handle<v8::Value> ScriptPromiseProperty<HolderType, ResolvedType, RejectedType>::rejectedValue(v8::Handle<v8::Object> creationContext, v8::Isolate* isolate) 135 { 136 ASSERT(state() == Rejected); 137 return V8ValueTraits<RejectedType>::toV8Value(m_rejected, creationContext, isolate); 138 } 139 140 template<typename HolderType, typename ResolvedType, typename RejectedType> 141 void ScriptPromiseProperty<HolderType, ResolvedType, RejectedType>::reset() 142 { 143 resetBase(); 144 m_resolved = ResolvedType(); 145 m_rejected = RejectedType(); 146 } 147 148 template<typename HolderType, typename ResolvedType, typename RejectedType> 149 void ScriptPromiseProperty<HolderType, ResolvedType, RejectedType>::trace(Visitor* visitor) 150 { 151 TraceIfNeeded<HolderType>::trace(visitor, &m_holder); 152 TraceIfNeeded<ResolvedType>::trace(visitor, &m_resolved); 153 TraceIfNeeded<RejectedType>::trace(visitor, &m_rejected); 154 ScriptPromisePropertyBase::trace(visitor); 155 } 156 157 } // namespace blink 158 159 #endif // ScriptPromiseProperty_h 160