src/third_party/WebKit/Source/bindings/core/v8/ScriptPromiseProperty.h

   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