Implement ScriptPromise and ScriptFunction

Source/bindings/v8/ScriptPromise.h

+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
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+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
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+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef ScriptPromise_h
+#define ScriptPromise_h
+
+#include "bindings/v8/ScopedPersistent.h"
+#include "bindings/v8/ScriptFunction.h"
+#include "bindings/v8/V8ScriptRunner.h"
+
+#include <v8.h>
+
+namespace WebCore {
+
+// ScriptPromise is a class for hooking into the then() chain for a
+// Promise from the C++ world.
+//
+// To use this, provide a subclass of ScriptFunction where the 'call'
+// method the function to pass to 'Promise.then'.
+//
+// class MyCallback : public ScriptFunction {
+// public:
+//   MyCallback(PassRefPtr<MyClass> reciever) : m_receiver(receiver) { }
+//   virtual ScriptValue call(ScriptValue scriptValue) {
+//     m_receiver->HaveValue(scriptValue.v8Value().As<v8::Integer>()->Value())

[abarth-chromium, 2013/08/15 00:35:15]

This example code is no good.  Why do you assume that the scriptValue actually
is an integer?  I'm worried that people will copy this code, but we have no way
to test it or even mark sure it compiles...

+//     return scriptValue;
+//   }
+//   int value() const { return m_value; }
+//
+// private:
+//   RefPtr<MyClass> m_receiver;
+// };
+//
+// void MyClass::saveValue(ScriptPromise* promise) {
+//   promise->then(adoptRef(new MyCallback(this)));

[abarth-chromium, 2013/08/15 00:35:15]

adoptRef(new MyCallback(this))  should be   MyCallback::create

+// }
+//
+// void MyClass::HaveValue(int value) {
+//   .. deal with the value here.
+// }
+class ScriptPromise {
+public:
+    explicit ScriptPromise(ScriptValue promise)
+        : m_promise(promise.v8Value()) { }
+
+    bool then(PassRefPtr<ScriptFunction> prpFunction)
+    {
+        if (m_promise.isEmpty())
+            return false;
+        v8::Isolate* isolate = v8::Isolate::GetCurrent();
+        v8::Handle<v8::Value> promise = m_promise.newLocal(isolate);
+        if (!promise->IsObject())
+            return false;
+
+        v8::Handle<v8::Object> promiseObject = promise.As<v8::Object>();
+        v8::Handle<v8::Value> then = promiseObject->Get(v8::String::NewSymbol("then"));
+        if (then.IsEmpty() || !then->IsFunction())
+            return false;
+
+        RefPtr<ScriptFunction> function(prpFunction);
+        v8::Handle<v8::Value> argv[] = {
+            function->toV8()
+        };
+        m_result.set(isolate, V8ScriptRunner::callFunction(then.As<v8::Function>(), getScriptExecutionContext(), promiseObject, WTF_ARRAY_LENGTH(argv), argv));
+        return true;
+    }
+
+    ScriptValue ResultPromise() { return ScriptValue(m_result.newLocal(v8::Isolate::GetCurrent())); }

[abarth-chromium, 2013/08/15 00:35:15]

ResultPromise -> resultPromise

+
+private:
+    ScopedPersistent<v8::Value> m_promise;
+    ScopedPersistent<v8::Value> m_result;

[abarth-chromium, 2013/08/15 00:35:15]

Rather than storing m_result as a member, why not make it an out parameter of
|then| ?

+};
+
+} // namespace WebCore
+
+
+#endif // ScriptPromise_h