Add a helper for implementing Promise-valued properties.

Source/bindings/core/v8/ScriptPromisePropertyBase.cpp

Index: Source/bindings/core/v8/ScriptPromisePropertyBase.cpp
diff --git a/Source/bindings/core/v8/ScriptPromisePropertyBase.cpp b/Source/bindings/core/v8/ScriptPromisePropertyBase.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..c423c5e53c006d98b2447f087508f24bb578883d
--- /dev/null
+++ b/Source/bindings/core/v8/ScriptPromisePropertyBase.cpp
@@ -0,0 +1,156 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "bindings/core/v8/ScriptPromisePropertyBase.h"
+
+#include "bindings/core/v8/V8Binding.h"
+#include "bindings/core/v8/V8HiddenValue.h"
+#include "core/dom/ExecutionContext.h"
+
+namespace WebCore {
+
+ScriptPromisePropertyBase::ScriptPromisePropertyBase(ExecutionContext* executionContext, Name name)
+    : ContextLifecycleObserver(executionContext)
+    , m_isolate(toIsolate(executionContext))
+    , m_name(name)
+    , m_state(Pending)
+{
+}
+
+ScriptPromisePropertyBase::~ScriptPromisePropertyBase()
+{
+    v8::HandleScope handleScope(m_isolate);
+    v8::Handle<v8::Object> wrapper = m_mainWorldWrapper.newLocal(m_isolate);
+    if (!wrapper.IsEmpty()) {
+        wrapper->DeleteHiddenValue(resolverName());
+        wrapper->DeleteHiddenValue(promiseName());
+    }
+}
+
+static void clearHandle(const v8::WeakCallbackData<v8::Object, ScopedPersistent<v8::Object> >& data)
+{
+    data.GetParameter()->clear();
+}
+
+ScriptPromise ScriptPromisePropertyBase::promise(DOMWrapperWorld& world)
+{
+    if (!executionContext())
+        return ScriptPromise();
+
+    if (!world.isMainWorld()) {
+        // FIXME: Support isolated worlds.
+        return ScriptPromise();
+    }
+
+    v8::HandleScope handleScope(m_isolate);
+    v8::Handle<v8::Context> context = toV8Context(executionContext(), world);
+    if (context.IsEmpty())
+        return ScriptPromise();
+    ScriptState* scriptState = ScriptState::from(context);
+    ScriptState::Scope scope(scriptState);
+
+    v8::Handle<v8::Object> wrapper = m_mainWorldWrapper.newLocal(m_isolate);
+    if (wrapper.IsEmpty()) {
+        wrapper = holder(context->Global(), m_isolate);
+        ASSERT(!wrapper.IsEmpty());
+        ASSERT(V8HiddenValue::getHiddenValue(m_isolate, wrapper, resolverName()).IsEmpty());
+        ASSERT(V8HiddenValue::getHiddenValue(m_isolate, wrapper, promiseName()).IsEmpty());
+        m_mainWorldWrapper.set(m_isolate, wrapper);
+        m_mainWorldWrapper.setWeak(&m_mainWorldWrapper, &clearHandle);
+    }
+    ASSERT(wrapper->CreationContext() == context);
+
+    v8::Handle<v8::Promise> promise = V8HiddenValue::getHiddenValue(m_isolate, wrapper, promiseName()).As<v8::Promise>();
+    if (!promise.IsEmpty()) {
+        // Return cached Promise
+        return ScriptPromise(scriptState, promise);
+    }
+
+    // Create and cache the Promise
+    v8::Handle<v8::Promise::Resolver> resolver = v8::Promise::Resolver::New(m_isolate);
+    promise = resolver->GetPromise();
+    V8HiddenValue::setHiddenValue(m_isolate, wrapper, promiseName(), promise);
+    V8HiddenValue::setHiddenValue(m_isolate, promise, promiseName(), wrapper);

[haraken, 2014/07/03 02:43:20]

Just help me understand: Why do you need the reference from the promise back to
the wrapper?

Don't we need to delete the reference in ~ScriptPromisePropertyBase().

+
+    switch (m_state) {
+    case Pending:
+        // Cache the resolver too
+        V8HiddenValue::setHiddenValue(m_isolate, wrapper, resolverName(), resolver);
+        break;
+    case Resolved:
+    case Rejected:
+        resolveOrRejectInternal(resolver);
+        break;
+    }
+
+    return ScriptPromise(scriptState, promise);
+}
+
+void ScriptPromisePropertyBase::resolveOrReject(State targetState)
+{
+    ASSERT(executionContext());
+    ASSERT(m_state == Pending);
+    ASSERT(targetState == Resolved || targetState == Rejected);
+
+    m_state = targetState;
+
+    v8::HandleScope handleScope(m_isolate);
+    v8::Handle<v8::Object> wrapper = m_mainWorldWrapper.newLocal(m_isolate);
+    if (wrapper.IsEmpty())
+        return; // wrapper has died or was never populated
+    ScriptState::Scope scope(ScriptState::from(wrapper->CreationContext()));
+
+    v8::Handle<v8::Promise::Resolver> resolver = V8HiddenValue::getHiddenValue(m_isolate, wrapper, resolverName()).As<v8::Promise::Resolver>();
+
+    V8HiddenValue::deleteHiddenValue(m_isolate, wrapper, resolverName());
+    resolveOrRejectInternal(resolver);
+}
+
+void ScriptPromisePropertyBase::resolveOrRejectInternal(v8::Handle<v8::Promise::Resolver> resolver)
+{
+    switch (m_state) {
+    case Pending:
+        ASSERT_NOT_REACHED();
+        break;
+    case Resolved:
+        resolver->Resolve(resolvedValue(resolver->CreationContext()->Global(), m_isolate));
+        break;
+    case Rejected:
+        resolver->Reject(rejectedValue(resolver->CreationContext()->Global(), m_isolate));
+        break;
+    }
+}
+
+v8::Handle<v8::String> ScriptPromisePropertyBase::promiseName()

[haraken, 2014/07/03 02:43:20]

I'd move this to V8HiddenValue.cpp.

+{
+    switch (m_name) {
+#define P(Name)                                           \
+    case Name:                                            \
+        return V8HiddenValue::Name ## Promise(m_isolate);
+
+        SCRIPT_PROMISE_PROPERTIES(P)
+
+#undef P
+    }
+    ASSERT_NOT_REACHED();
+    return v8::Handle<v8::String>();
+}
+
+v8::Handle<v8::String> ScriptPromisePropertyBase::resolverName()
+{
+    switch (m_name) {
+#define P(Name)                                            \
+    case Name:                                             \
+        return V8HiddenValue::Name ## Resolver(m_isolate);
+
+        SCRIPT_PROMISE_PROPERTIES(P)
+
+#undef P
+    }
+    ASSERT_NOT_REACHED();
+    return v8::Handle<v8::String>();
+}
+
+} // namespace WebCore