com.dlsc.flexgantt.command
Class DefaultCommandStack

java.lang.Object
  com.dlsc.flexgantt.command.DefaultCommandStack

All Implemented Interfaces:

ICommandStack

public class DefaultCommandStack
extends java.lang.Object
implements ICommandStack

The default command stack implementation manages a list of executed and undone commands. The stack has a default size of 20, which means that the last 20 commands can be undone. The stack size can be passed to the stack's constructor. Commands will be removed from the stack once the stack's limit is reached.

Since:

1.0

Author:

Dirk Lemmermann

See Also:

ICommand, ICommandStackListener

Constructor Summary

DefaultCommandStack()
Creates a new command stack with a default size (number of undoable commands).

DefaultCommandStack(int size)
Creates a new command stack.

Method Summary

void	addCommandStackListener(ICommandStackListener l) Adds a listener to the command stack.
void	clear() Clears the command stack, which means that the list of executed and undone commands will be cleared and no further commands can be undone or redone.
void	execute(ICommand cmd, IProgressMonitor monitor) Executes the given command.
protected void	fireCommandStackChanged(CommandStackEvent event) Used internally to inform stack listeners about executed, undone or redone commands.
ICommandStackListener[]	getCommandStackListeners() Returns all command stack listeners.
java.util.List<ICommand>	getExecutedCommands() Returns a copy of the list of executed commands.
ICommand	getRedoableCommand() Returns the command, which would be redone if the application called the redo operation on the stack.
int	getSize() Returns the stack size as defined via the constructor or default stack size value.
ICommand	getUndoableCommand() Returns the command, which would be undone if the application called the undo operation on the stack.
java.util.List<ICommand>	getUndoneCommands() Returns a copy of the list of undone commands.
boolean	isRedoable() Determines whether the command stack currently supports the redo operation.
boolean	isUndoable() Determines whether the command stack currently supports the undo operation.
void	redo(IProgressMonitor monitor) If it is redoable then the last undone command can be redone by calling this method.
void	removeCommandStackListener(ICommandStackListener l) Removes a listener from the command stack.
void	undo(IProgressMonitor monitor) If it is undoable then the last executed command can be undone by calling this method.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DefaultCommandStack

public DefaultCommandStack(int size)

Creates a new command stack.

Parameters:

size - the maximum stack size and number of undoable commands

Since:

1.0

DefaultCommandStack

public DefaultCommandStack()

Creates a new command stack with a default size (number of undoable commands).

Since:

1.0

Method Detail

getSize

public int getSize()

Returns the stack size as defined via the constructor or default stack size value.

Returns:

the command stack's size

Since:

1.0

execute

public void execute(ICommand cmd,
                    IProgressMonitor monitor)

Executes the given command. If undoable the command will be added to the list of undoable commands. This list will be cleared if the command is not undoable. If the number of undoable commands exceeds the stack size then the oldest undoable command will be removed from the stack. A command stack event will be fired upon completion of the command execution.

Specified by:

execute in interface ICommandStack

Parameters:

cmd - the command to execute

monitor - a monitor to report the command's progress to

Since:

1.0

See Also:

CommandStackEvent

undo

public void undo(IProgressMonitor monitor)

If it is undoable then the last executed command can be undone by calling this method. The command will be stored in the list of undone commands and an event will be fired, which informs the listeners of the stack that the command was undone.

Specified by:

undo in interface ICommandStack

Parameters:

monitor - a monitor for reporting progress of the undo operation

Since:

1.0

See Also:

ICommandStack.undo(IProgressMonitor), CommandStackEvent

redo

public void redo(IProgressMonitor monitor)

If it is redoable then the last undone command can be redone by calling this method. The command will be put back on the list of executed commands and an event will be fired, which informs the listeners of the stack that the command was redone.

Specified by:

redo in interface ICommandStack

Parameters:

monitor - a monitor for reporting the progress of the redo operation

Since:

1.0

See Also:

ICommandStack.redo(IProgressMonitor), CommandStackEvent

clear

public void clear()

Clears the command stack, which means that the list of executed and undone commands will be cleared and no further commands can be undone or redone.

Specified by:

clear in interface ICommandStack

Since:

1.0

See Also:

ICommandStack.clear()

isUndoable

public boolean isUndoable()

Determines whether the command stack currently supports the undo operation. This depends on the last executed command. If the command can be undone then the stack can be undone.

Specified by:

isUndoable in interface ICommandStack

Returns:

boolean

Since:

1.0

See Also:

ICommandStack.isUndoable()

isRedoable

public boolean isRedoable()

Determines whether the command stack currently supports the redo operation. This depends on the last undone command. If the command can be redone then the stack can be redone.

Specified by:

isRedoable in interface ICommandStack

Returns:

boolean

Since:

1.0

See Also:

ICommandStack.isRedoable()

addCommandStackListener

public void addCommandStackListener(ICommandStackListener l)

Adds a listener to the command stack. The listener will receive command stack events informing it which command was executed, undone or redone.

Specified by:

addCommandStackListener in interface ICommandStack

Parameters:

l - the listener to add

Since:

1.0

See Also:

ICommandStack.addCommandStackListener(ICommandStackListener)

removeCommandStackListener

public void removeCommandStackListener(ICommandStackListener l)

Removes a listener from the command stack.

Specified by:

removeCommandStackListener in interface ICommandStack

Parameters:

l - the listener to remove

Since:

1.0

See Also:

ICommandStack.removeCommandStackListener(ICommandStackListener)

getCommandStackListeners

public ICommandStackListener[] getCommandStackListeners()

Returns all command stack listeners.

Returns:

an array of all command stack listeners

Since:

1.0

fireCommandStackChanged

protected void fireCommandStackChanged(CommandStackEvent event)

Used internally to inform stack listeners about executed, undone or redone commands.

Parameters:

event - the event to send to the listeners

Since:

1.0

getUndoableCommand

public ICommand getUndoableCommand()

Returns the command, which would be undone if the application called the undo operation on the stack. This method is useful for displaying the command's name in an undo button or menu item.

Specified by:

getUndoableCommand in interface ICommandStack

Returns:

the next undoable command or NULL if the last command that was executed can not be undone

Since:

1.0

See Also:

ICommandStack.getUndoableCommand()

getRedoableCommand

public ICommand getRedoableCommand()

Returns the command, which would be redone if the application called the redo operation on the stack. This method is useful for displaying the command's name in a redo button or menu item.

Specified by:

getRedoableCommand in interface ICommandStack

Returns:

the next redoable command or NULL if the last command that was undone can not be redone

Since:

1.0

See Also:

ICommandStack.getRedoableCommand()

getExecutedCommands

public java.util.List<ICommand> getExecutedCommands()

Returns a copy of the list of executed commands. The next undo operation will be performed on the last command in this list.

Returns:

a list of executed commands that can be undone

Since:

1.0

getUndoneCommands

public java.util.List<ICommand> getUndoneCommands()

Returns a copy of the list of undone commands. The next redo operation will be performed on the last command in this list.

Returns:

a list of undone commands that can be redone

Since:

1.0