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// Copyright (c) 2012 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.
#ifndef CHROME_RENDERER_EXTENSIONS_OBJECT_BACKED_NATIVE_HANDLER_H_
#define CHROME_RENDERER_EXTENSIONS_OBJECT_BACKED_NATIVE_HANDLER_H_
#include <string>
#include <vector>
#include "base/bind.h"
#include "base/memory/linked_ptr.h"
#include "chrome/renderer/extensions/native_handler.h"
#include "chrome/renderer/extensions/scoped_persistent.h"
#include "chrome/renderer/extensions/unsafe_persistent.h"
#include "v8/include/v8.h"
namespace extensions {
class ChromeV8Context;
// An ObjectBackedNativeHandler is a factory for JS objects with functions on
// them that map to native C++ functions. Subclasses should call RouteFunction()
// in their constructor to define functions on the created JS objects.
class ObjectBackedNativeHandler : public NativeHandler {
public:
explicit ObjectBackedNativeHandler(ChromeV8Context* context);
virtual ~ObjectBackedNativeHandler();
// Create an object with bindings to the native functions defined through
// RouteFunction().
virtual v8::Handle<v8::Object> NewInstance() OVERRIDE;
protected:
typedef base::Callback<void(const v8::FunctionCallbackInfo<v8::Value>&)>
HandlerFunction;
// Installs a new 'route' from |name| to |handler_function|. This means that
// NewInstance()s of this ObjectBackedNativeHandler will have a property
// |name| which will be handled by |handler_function|.
void RouteFunction(const std::string& name,
const HandlerFunction& handler_function);
ChromeV8Context* context() const { return context_; }
virtual void Invalidate() OVERRIDE;
private:
// Callback for RouteFunction which routes the V8 call to the correct
// base::Bound callback.
static void Router(const v8::FunctionCallbackInfo<v8::Value>& args);
// When RouteFunction is called we create a v8::Object to hold the data we
// need when handling it in Router() - this is the base::Bound function to
// route to.
//
// We need a v8::Object because it's possible for v8 to outlive the
// base::Bound function; the lifetime of an ObjectBackedNativeHandler is the
// lifetime of webkit's involvement with it, not the life of the v8 context.
// A scenario when v8 will outlive us is if a frame holds onto the
// contentWindow of an iframe after it's removed.
//
// So, we use v8::Objects here to hold that data, effectively refcounting
// the data. When |this| is destroyed we remove the base::Bound function from
// the object to indicate that it shoudn't be called.
//
// Storing UnsafePersistents is safe here, because the corresponding
// Persistent handle is created in RouteFunction(), and it keeps the data
// pointed by the UnsafePersistent alive. It's not made weak or disposed, and
// nobody else has access to it. The Persistent is then disposed in
// Invalidate().
typedef std::vector<UnsafePersistent<v8::Object> > RouterData;
RouterData router_data_;
ChromeV8Context* context_;
ScopedPersistent<v8::ObjectTemplate> object_template_;
DISALLOW_COPY_AND_ASSIGN(ObjectBackedNativeHandler);
};
} // namespace extensions
#endif // CHROME_RENDERER_EXTENSIONS_OBJECT_BACKED_NATIVE_HANDLER_H_
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