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 MOJO_PUBLIC_CPP_BINDINGS_LIB_FILTER_CHAIN_H_
6#define MOJO_PUBLIC_CPP_BINDINGS_LIB_FILTER_CHAIN_H_
7
8#include <utility>
9#include <vector>
10
11#include "base/macros.h"
12#include "mojo/public/cpp/bindings/message.h"
13#include "mojo/public/cpp/bindings/message_filter.h"
14
15namespace mojo {
16namespace internal {
17
18class FilterChain {
19 public:
20  // Doesn't take ownership of |sink|. Therefore |sink| has to stay alive while
21  // this object is alive.
22  explicit FilterChain(MessageReceiver* sink = nullptr);
23
24  FilterChain(FilterChain&& other);
25  FilterChain& operator=(FilterChain&& other);
26  ~FilterChain();
27
28  template <typename FilterType, typename... Args>
29  inline void Append(Args&&... args);
30
31  // Doesn't take ownership of |sink|. Therefore |sink| has to stay alive while
32  // this object is alive.
33  void SetSink(MessageReceiver* sink);
34
35  // Returns a receiver to accept messages. Messages flow through all filters in
36  // the same order as they were appended to the chain. If all filters allow a
37  // message to pass, it will be forwarded to |sink_|.
38  // The returned value is invalidated when this object goes away.
39  MessageReceiver* GetHead();
40
41 private:
42  // Owned by this object.
43  // TODO(dcheng): Use unique_ptr.
44  std::vector<MessageFilter*> filters_;
45
46  MessageReceiver* sink_;
47
48  DISALLOW_COPY_AND_ASSIGN(FilterChain);
49};
50
51template <typename FilterType, typename... Args>
52inline void FilterChain::Append(Args&&... args) {
53  FilterType* filter = new FilterType(std::forward<Args>(args)..., sink_);
54  if (!filters_.empty())
55    filters_.back()->set_sink(filter);
56  filters_.push_back(filter);
57}
58
59template <>
60inline void FilterChain::Append<PassThroughFilter>() {
61}
62
63}  // namespace internal
64}  // namespace mojo
65
66#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_FILTER_CHAIN_H_
67