/**
* Copyright 2010 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.waveprotocol.wave.model.document.operation.algorithm;
/**
* A tracker that tracks the positions of two cursors relative to each other.
*
* @author Alexandre Mah
*/
final class PositionTracker {
/**
* The relative position of a cursor relative to another cursor.
*/
interface RelativePosition {
/**
* Increases the relative position of the cursor.
*
* @param amount the amount by which to increase the relative position
*/
void increase(int amount);
/**
* @return the relative position
*/
int get();
}
int position = 0;
/**
* @return a RelativePosition representing the first cursor's position
* relative to the second cursor
*/
RelativePosition getPosition1() {
return new RelativePosition() {
public void increase(int amount) {
position += amount;
}
public int get() {
return position;
}
};
}
/**
* @return a RelativePosition representing the second cursor's position
* relative to the first cursor
*/
RelativePosition getPosition2() {
return new RelativePosition() {
public void increase(int amount) {
position -= amount;
}
public int get() {
return -position;
}
};
}
}