1 // Copyright (c) 2010 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 #pragma once 8 9 #include "base/basictypes.h" 10 #include "base/hash_tables.h" 11 12 //////////////////////////////////////////////////////////////////////////////// 13 // 14 // CommandUpdater class 15 // 16 // This object manages the enabled state of a set of commands. Observers 17 // register to listen to changes in this state so they can update their 18 // presentation. 19 // 20 class CommandUpdater { 21 public: 22 // A Delegate object implements this interface so that it can execute commands 23 // when needed. 24 class CommandUpdaterDelegate { 25 public: 26 // Perform the action associated with the command with the specified ID. 27 virtual void ExecuteCommand(int id) = 0; 28 29 protected: 30 virtual ~CommandUpdaterDelegate(); 31 }; 32 33 // Create a CommandUpdater with a CommandUpdaterDelegate to handle execution 34 // of specific commands. 35 explicit CommandUpdater(CommandUpdaterDelegate* handler); 36 virtual ~CommandUpdater(); 37 38 // Returns true if the specified command ID is supported. 39 bool SupportsCommand(int id) const; 40 41 // Returns true if the specified command ID is enabled. The command ID must be 42 // supported by this updater. 43 bool IsCommandEnabled(int id) const; 44 45 // Performs the action associated with this command ID. 46 // TODO(beng): get rid of this since it's effectively just a pass-thru and the 47 // call sites would be better off using more well defined delegate interfaces. 48 void ExecuteCommand(int id); 49 50 // An Observer interface implemented by objects that want to be informed when 51 // the state of a particular command ID is modified. 52 class CommandObserver { 53 public: 54 // Notifies the observer that the enabled state has changed for the 55 // specified command id. 56 virtual void EnabledStateChangedForCommand(int id, bool enabled) = 0; 57 58 protected: 59 virtual ~CommandObserver(); 60 }; 61 62 // Adds an observer to the state of a particular command. If the command does 63 // not exist, it is created, initialized to false. 64 void AddCommandObserver(int id, CommandObserver* observer); 65 66 // Removes an observer to the state of a particular command. 67 void RemoveCommandObserver(int id, CommandObserver* observer); 68 69 // Removes |observer| for all commands on which it's registered. 70 void RemoveCommandObserver(CommandObserver* observer); 71 72 // Notify all observers of a particular command that the command has been 73 // enabled or disabled. If the command does not exist, it is created and 74 // initialized to |state|. This function is very lightweight if the command 75 // state has not changed. 76 void UpdateCommandEnabled(int id, bool state); 77 78 private: 79 // A piece of data about a command - whether or not it is enabled, and a list 80 // of objects that observe the enabled state of this command. 81 class Command; 82 83 // Get a Command node for a given command ID, creating an entry if it doesn't 84 // exist if desired. 85 Command* GetCommand(int id, bool create); 86 87 // The delegate is responsible for executing commands. 88 CommandUpdaterDelegate* delegate_; 89 90 // This is a map of command IDs to states and observer lists 91 typedef base::hash_map<int, Command*> CommandMap; 92 CommandMap commands_; 93 94 CommandUpdater(); 95 DISALLOW_COPY_AND_ASSIGN(CommandUpdater); 96 }; 97 98 #endif // CHROME_BROWSER_COMMAND_UPDATER_H_ 99
