1// Copyright (c) 2012 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 CHROME_BROWSER_COMMAND_UPDATER_H_
6#define CHROME_BROWSER_COMMAND_UPDATER_H_
7
8#include "base/basictypes.h"
9#include "base/containers/hash_tables.h"
10#include "ui/base/window_open_disposition.h"
11
12class CommandObserver;
13class CommandUpdaterDelegate;
14
15////////////////////////////////////////////////////////////////////////////////
16//
17// CommandUpdater class
18//
19//   This object manages the enabled state of a set of commands. Observers
20//   register to listen to changes in this state so they can update their
21//   presentation.
22//
23class CommandUpdater {
24 public:
25  // Create a CommandUpdater with |delegate| to handle the execution of specific
26  // commands.
27  explicit CommandUpdater(CommandUpdaterDelegate* delegate);
28  ~CommandUpdater();
29
30  // Returns true if the specified command ID is supported.
31  bool SupportsCommand(int id) const;
32
33  // Returns true if the specified command ID is enabled. The command ID must be
34  // supported by this updater.
35  bool IsCommandEnabled(int id) const;
36
37  // Performs the action associated with this command ID using CURRENT_TAB
38  // disposition.
39  // Returns true if the command was executed (i.e. it is supported and is
40  // enabled).
41  bool ExecuteCommand(int id);
42
43  // Performs the action associated with this command ID using the given
44  // disposition.
45  // Returns true if the command was executed (i.e. it is supported and is
46  // enabled).
47  bool ExecuteCommandWithDisposition(int id, WindowOpenDisposition disposition);
48
49  // Adds an observer to the state of a particular command. If the command does
50  // not exist, it is created, initialized to false.
51  void AddCommandObserver(int id, CommandObserver* observer);
52
53  // Removes an observer to the state of a particular command.
54  void RemoveCommandObserver(int id, CommandObserver* observer);
55
56  // Removes |observer| for all commands on which it's registered.
57  void RemoveCommandObserver(CommandObserver* observer);
58
59  // Notify all observers of a particular command that the command has been
60  // enabled or disabled. If the command does not exist, it is created and
61  // initialized to |state|. This function is very lightweight if the command
62  // state has not changed.
63  void UpdateCommandEnabled(int id, bool state);
64
65 private:
66  // A piece of data about a command - whether or not it is enabled, and a list
67  // of objects that observe the enabled state of this command.
68  class Command;
69
70  // Get a Command node for a given command ID, creating an entry if it doesn't
71  // exist if desired.
72  Command* GetCommand(int id, bool create);
73
74  // The delegate is responsible for executing commands.
75  CommandUpdaterDelegate* delegate_;
76
77  // This is a map of command IDs to states and observer lists
78  typedef base::hash_map<int, Command*> CommandMap;
79  CommandMap commands_;
80
81  DISALLOW_COPY_AND_ASSIGN(CommandUpdater);
82};
83
84#endif  // CHROME_BROWSER_COMMAND_UPDATER_H_
85