public class UndoManager

Object
UndoManager

A compact undo / redo stack for the pure editors. Every mutation is recorded as a replacement of the range [start, start + removed.length) with inserted; the inverse simply swaps removed and inserted. Consecutive single character insertions are coalesced into one undo unit so a burst of typing undoes as a word rather than a keystroke at a time.

Constructors

public UndoManager()

Methods

`public void record(int start,` `String removed, String inserted)`	Records a mutation for later undo.
`public void breakRun()`	Breaks the current coalescing run so the next recorded insert starts a fresh undo unit.
`public boolean canUndo()`	True when there is anything to undo.
`public boolean canRedo()`	True when there is anything to redo.
`public int undo(EditorDocument doc)`	Undoes the most recent mutation against the supplied document.
`public int redo(EditorDocument doc)`	Redoes the most recently undone mutation against the supplied document.
`public void clear()`	Clears all recorded history.

Inherited methods

From Object

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

Constructor details

UndoManager

public UndoManager()

Method details

record

public void record(int start, String removed, String inserted)

Records a mutation for later undo. Clears the redo stack.

Parameters

start int: the offset at which text was removed / inserted
removed String: the text that was removed (empty for a pure insert)
inserted String: the text that was inserted (empty for a pure delete)

breakRun

public void breakRun()

Breaks the current coalescing run so the next recorded insert starts a fresh undo unit. Called on caret jumps, selection changes and structural edits.

canUndo

public boolean canUndo()

True when there is anything to undo.

canRedo

public boolean canRedo()

True when there is anything to redo.

undo

public int undo(EditorDocument doc)

Undoes the most recent mutation against the supplied document.

Parameters

doc EditorDocument: the document to mutate

Returns

the caret offset after the undo, or -1 when there was nothing to undo

redo

public int redo(EditorDocument doc)

Redoes the most recently undone mutation against the supplied document.

Parameters

doc EditorDocument: the document to mutate

Returns

the caret offset after the redo, or -1 when there was nothing to redo

clear

public void clear()

Clears all recorded history.