chrome/browser/command_updater.h

   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
  12 class CommandObserver;
  13 class 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 //
  23 class 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_