gcc/libjava/javax/swing/undo/AbstractUndoableEdit.java

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package javax.swing.undo;

// Imports
import java.io.Serializable;

/**
 * AbstractUndoableEdit
 * @author Andrew Selkirk
 */
public class AbstractUndoableEdit implements UndoableEdit, Serializable
{
  static final long serialVersionUID = 580150227676302096L;

  //-------------------------------------------------------------
  // Constants --------------------------------------------------
  //-------------------------------------------------------------

  /**
   * String returned by getRedoPresentationName()
   */
  protected static final String RedoName = "Redo";

  /**
   * String returned by getUndoPresentationName()
   */
  protected static final String UndoName = "Undo";


  //-------------------------------------------------------------
  // Variables --------------------------------------------------
  //-------------------------------------------------------------

  /**
   * TODO
   */
  private boolean hasBeenDone = false;

  /**
   * The edit is alive
   */
  private boolean alive = true;


  //-------------------------------------------------------------
  // Initialization ---------------------------------------------
  //-------------------------------------------------------------

  /**
   * Create new AbstractUndoableEdit
   */
  public AbstractUndoableEdit()
  {
  } // AbstractUndoableEdit()


  //-------------------------------------------------------------
  // Interface: UndoableEdit ------------------------------------
  //-------------------------------------------------------------

  /**
   * addEdit
   * @param anEdit TODO
   * @returns TODO
   */
  public boolean addEdit(UndoableEdit anEdit)
  {
    return false;
  } // addEdit()

  /**
   * canRedo()
   * @returns true if redoable, false otherwise
   */
  public boolean canRedo()
  {
    if (alive == true && hasBeenDone == false)
      return true;
    return false;
  } // canRedo()

  /**
   * canUndo()
   * @returns true if undoable, false otherwise
   */
  public boolean canUndo()
  {
    if (alive == true && hasBeenDone == true)
      return true;
    return false;
  } // canUndo()

  /**
   * die
   */
  public void die()
  {
    alive = false;
  } // die()

  /**
   * getPresentation
   * @returns TODO
   */
  public String getPresentationName()
  {
    return "";
  } // getPresentationName()

  /**
   * getRedoPresentationName
   * @returns TODO
   */
  public String getRedoPresentationName()
  {
    if (getPresentationName().equals(""))
      return RedoName;
    return RedoName + " " + getPresentationName();
  } // getRedoPresentationName()

  /**
   * getUndoPresentationName
   * @returns TODO
   */
  public String getUndoPresentationName()
  {
    if (getPresentationName().equals(""))
      return UndoName;
    return UndoName + " " + getPresentationName();
  } // getUndoPresentationName()

  /**
   * isSignificant
   * @returns true
   */
  public boolean isSignificant()
  {
    return true;
  } // isSignificant()

  /**
   * redo
   * @throws CannotRedoException TODO
   */
  public void redo() throws CannotRedoException
  {
    if (! canRedo())
      throw new CannotRedoException();
    hasBeenDone = true;
  } // redo()

  /**
   * replaceEdit
   * @param anEdit TODO
   * @returns TODO
   */
  public boolean replaceEdit(UndoableEdit anEdit)
  {
    return false;
  } // replaceEdit()

  /**
   * String representation
   * @returns String representation
   */
  public String toString()
  {
    return (super.toString() + " hasBeenDone: " + hasBeenDone
	    + " alive: " + alive);
  }

  /**
   * undo
   * @throws CannotUndoException TODO
   */
  public void undo() throws CannotUndoException
  {
    if (! canUndo())
      throw new CannotUndoException();
    hasBeenDone = false;
  } // undo()
} // AbstractUndoableEdit