source: trunk/gcc/libjava/javax/swing/undo/AbstractUndoableEdit.java

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   Copyright (C) 2002 Free Software Foundation, Inc.

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package javax.swing.undo;

// Imports
import java.io.Serializable;

/**
 * AbstractUndoableEdit
 * @author Andrew Selkirk
 */
public class AbstractUndoableEdit       extends         Object
                                                                        implements      UndoableEdit,
                                                                                                Serializable {

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

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

        /**
         * String returned by getUndoPresentationName()
         */
        protected static        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;
                } // if
                return false;
        } // canRedo()

        /**
         * canUndo()
         * @returns true if undoable, false otherwise
         */
        public boolean canUndo() {
                if (alive == true && hasBeenDone == true) {
                        return true;
                } // if
                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("") == true) {
                        return RedoName;
                } else {
                        return RedoName + " " + getPresentationName();
                }
        } // getRedoPresentationName()

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

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

        /**
         * redo
         * @throws CannotRedoException TODO
         */
        public void redo() throws CannotRedoException {
                if (canRedo() == false) {
                        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 null; // TODO
        } // toString()

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


} // AbstractUndoableEdit