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// 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.
#ifndef EXTENSIONS_RENDERER_OBJECT_BACKED_NATIVE_HANDLER_H_
#define EXTENSIONS_RENDERER_OBJECT_BACKED_NATIVE_HANDLER_H_
#include <string>
#include <vector>
#include "base/bind.h"
#include "base/macros.h"
#include "extensions/renderer/native_handler.h"
#include "v8/include/v8-util.h"
#include "v8/include/v8.h"
namespace extensions {
class ScriptContext;
// 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(ScriptContext* context);
~ObjectBackedNativeHandler() override;
// Create an object with bindings to the native functions defined through
// RouteFunction().
v8::Local<v8::Object> NewInstance() override;
v8::Isolate* GetIsolate() const;
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|.
//
// Routed functions are destroyed along with the destruction of this class,
// and are never called back into, therefore it's safe for |handler_function|
// to bind to base::Unretained.
//
// |feature_name| corresponds to the api feature the native handler is used
// for. If the associated ScriptContext does not have access to that feature,
// the |handler_function| is not invoked.
// TODO(devlin): Deprecate the version that doesn't take a |feature_name|.
void RouteFunction(const std::string& name,
const HandlerFunction& handler_function);
void RouteFunction(const std::string& name,
const std::string& feature_name,
const HandlerFunction& handler_function);
ScriptContext* context() const { return context_; }
void Invalidate() override;
// Returns true if the given |context| is allowed to access the given
// |object|. This should be checked before returning any objects from another
// context.
// |allow_null_context| indicates that if there is no ScriptContext associated
// with the |object|, it should be allowed.
// TODO(devlin): It'd be nice to track down when when there's no ScriptContext
// and remove |allow_null_context|.
static bool ContextCanAccessObject(const v8::Local<v8::Context>& context,
const v8::Local<v8::Object>& object,
bool allow_null_context);
// The following methods are convenience wrappers for methods on v8::Object
// with the corresponding names.
void SetPrivate(v8::Local<v8::Object> obj,
const char* key,
v8::Local<v8::Value> value);
static void SetPrivate(v8::Local<v8::Context> context,
v8::Local<v8::Object> obj,
const char* key,
v8::Local<v8::Value> value);
bool GetPrivate(v8::Local<v8::Object> obj,
const char* key,
v8::Local<v8::Value>* result);
static bool GetPrivate(v8::Local<v8::Context> context,
v8::Local<v8::Object> obj,
const char* key,
v8::Local<v8::Value>* result);
void DeletePrivate(v8::Local<v8::Object> obj, const char* key);
static void DeletePrivate(v8::Local<v8::Context> context,
v8::Local<v8::Object> obj,
const char* key);
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.
typedef v8::PersistentValueVector<v8::Object> RouterData;
RouterData router_data_;
ScriptContext* context_;
v8::Global<v8::ObjectTemplate> object_template_;
DISALLOW_COPY_AND_ASSIGN(ObjectBackedNativeHandler);
};
} // namespace extensions
#endif // EXTENSIONS_RENDERER_OBJECT_BACKED_NATIVE_HANDLER_H_
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