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 EXTENSIONS_RENDERER_OBJECT_BACKED_NATIVE_HANDLER_H_
6#define EXTENSIONS_RENDERER_OBJECT_BACKED_NATIVE_HANDLER_H_
7
8#include <string>
9#include <vector>
10
11#include "base/bind.h"
12#include "base/memory/linked_ptr.h"
13#include "extensions/renderer/native_handler.h"
14#include "extensions/renderer/scoped_persistent.h"
15#include "v8/include/v8-util.h"
16#include "v8/include/v8.h"
17
18namespace extensions {
19class ScriptContext;
20
21// An ObjectBackedNativeHandler is a factory for JS objects with functions on
22// them that map to native C++ functions. Subclasses should call RouteFunction()
23// in their constructor to define functions on the created JS objects.
24class ObjectBackedNativeHandler : public NativeHandler {
25 public:
26  explicit ObjectBackedNativeHandler(ScriptContext* context);
27  virtual ~ObjectBackedNativeHandler();
28
29  // Create an object with bindings to the native functions defined through
30  // RouteFunction().
31  virtual v8::Handle<v8::Object> NewInstance() OVERRIDE;
32
33  v8::Isolate* GetIsolate() const;
34
35 protected:
36  typedef base::Callback<void(const v8::FunctionCallbackInfo<v8::Value>&)>
37      HandlerFunction;
38
39  // Installs a new 'route' from |name| to |handler_function|. This means that
40  // NewInstance()s of this ObjectBackedNativeHandler will have a property
41  // |name| which will be handled by |handler_function|.
42  void RouteFunction(const std::string& name,
43                     const HandlerFunction& handler_function);
44
45  ScriptContext* context() const { return context_; }
46
47  virtual void Invalidate() OVERRIDE;
48
49 private:
50  // Callback for RouteFunction which routes the V8 call to the correct
51  // base::Bound callback.
52  static void Router(const v8::FunctionCallbackInfo<v8::Value>& args);
53
54  // When RouteFunction is called we create a v8::Object to hold the data we
55  // need when handling it in Router() - this is the base::Bound function to
56  // route to.
57  //
58  // We need a v8::Object because it's possible for v8 to outlive the
59  // base::Bound function; the lifetime of an ObjectBackedNativeHandler is the
60  // lifetime of webkit's involvement with it, not the life of the v8 context.
61  // A scenario when v8 will outlive us is if a frame holds onto the
62  // contentWindow of an iframe after it's removed.
63  //
64  // So, we use v8::Objects here to hold that data, effectively refcounting
65  // the data. When |this| is destroyed we remove the base::Bound function from
66  // the object to indicate that it shoudn't be called.
67  typedef v8::PersistentValueVector<v8::Object> RouterData;
68  RouterData router_data_;
69
70  ScriptContext* context_;
71
72  ScopedPersistent<v8::ObjectTemplate> object_template_;
73
74  DISALLOW_COPY_AND_ASSIGN(ObjectBackedNativeHandler);
75};
76
77}  // namespace extensions
78
79#endif  // EXTENSIONS_RENDERER_OBJECT_BACKED_NATIVE_HANDLER_H_
80