Retro68/gcc/libjava/classpath/javax/swing/undo/UndoableEdit.java

/* UndoableEdit.java --
   Copyright (C) 2002, 2006, Free Software Foundation, Inc.

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package javax.swing.undo;

/**
 * An editing operation that supports undo/redoability.
 *
 * @author Andrew Selkirk
 */
public interface UndoableEdit
{

  /**
   * Incorporates another editing action into this one, thus forming a
   * combined action.
   *
   * @param edit the editing action to be incorporated.
   *
   * @return <code>true</code> if the edit was combined successfully, and
   *         <code>false</code> if it could not be combined.
   */
  boolean addEdit(UndoableEdit edit);

  /**
   * Determines whether it would be possible to redo this editing
   * action.
   *
   * @return <code>true</code> to indicate that this action can be
   * redone, <code>false</code> otherwise.
   *
   * @see #redo()
   * @see #canUndo()
   */
  boolean canRedo();

  /**
   * Determines whether it would be possible to undo this editing
   * action.
   *
   * @return <code>true</code> to indicate that this action can be
   * undone, <code>false</code> otherwise.
   *
   * @see #undo()
   * @see #canRedo()
   */
  boolean canUndo();

  /**
   * Informs this edit action that it will no longer be used. Some
   * actions might use this information to release resources, for
   * example open files.  Called by {@link UndoManager} before this
   * action is removed from the edit queue.
   */
  void die();

  /**
   * Returns a human-readable, localized name that describes this
   * editing action and can be displayed to the user.
   *
   * @return The presentation name.
   */
  String getPresentationName();

  /**
   * Returns the redo presentation name.
   *
   * @return The redo presentation name.
   */
  String getRedoPresentationName();

  /**
   * Returns the undo presentation name.
   *
   * @return The undo presentation name.
   */
  String getUndoPresentationName();

  /**
   * Determines whether this editing action is significant enough for
   * being seperately undoable by the user. A typical significant
   * action would be the resizing of an object. However, changing the
   * selection in a text document would usually not be considered
   * significant.
   *
   * @return <code>true</code> to indicate that the action is
   * significant enough for being separately undoable, or
   * <code>false</code> otherwise.
   */
  boolean isSignificant();

  /**
   * Redoes this editing action.
   *
   * @throws CannotRedoException if the edit cannot be undone.
   *
   * @see #canRedo()
   * @see #undo()
   */
  void redo() throws CannotRedoException;

  /**
   * Incorporates another editing action into this one, thus forming a
   * combined action that replaces the argument action.
   *
   * @param edit the editing action to be replaced.
   *
   * @return <code>true</code> if the edit is successfully replaced, and
   *         <code>false</code> otherwise.
   */
  boolean replaceEdit(UndoableEdit edit);

  /**
   * Undoes this editing action.
   *
   * @throws CannotUndoException if the edit cannot be undone.
   *
   * @see #canUndo()
   * @see #redo()
   */
  void undo() throws CannotUndoException;

}