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/*
 * This file is part of the DiffX library.
 *
 * For licensing information please see the file license.txt included in the release.
 * A copy of this licence can also be found at
 *   http://www.opensource.org/licenses/artistic-license-2.0.php
 */
package com.topologi.diffx.algorithm;

/**
 * A matrix implementation which backbone is a matrix of short numbers.
 * 
 * @author Christophe Lauret (Allette Systems)
 * @version 7 April 2005
 */
public final class MatrixShort implements Matrix {
  // TODO: this class should probably not be public

  /**
   * The actual matrix storing the values.
   */
  private short[][] matrix;

  /**
   * @see com.topologi.diffx.algorithm.Matrix#setup(int, int)
   */
  public void setup(int width, int height) {
    this.matrix = new short[width][height];
  }

  /**
   * @see com.topologi.diffx.algorithm.Matrix#set(int, int, int)
   */
  public void set(int i, int j, int x) {
    this.matrix[i][j] = (short)x;
  }

  /**
   * @see com.topologi.diffx.algorithm.Matrix#get(int, int)
   */
  public int get(int i, int j) {
    return this.matrix[i][j];
  }

  /**
   * @see com.topologi.diffx.algorithm.Matrix#incrementPathBy(int, int, int)
   */
  public void incrementPathBy(int i, int j, int n) {
    this.matrix[i][j] = (short)(this.matrix[i+1][j+1] + n);
  }

  /**
   * @see com.topologi.diffx.algorithm.Matrix#incrementByMaxPath(int, int)
   */
  public void incrementByMaxPath(int i, int j) {
    this.matrix[i][j] = max(this.matrix[i+1][j], this.matrix[i][j+1]);
  }

  /**
   * @see com.topologi.diffx.algorithm.Matrix#isGreaterX(int, int)
   */
  public boolean isGreaterX(int i, int j) {
    return this.matrix[i+1][j] > this.matrix[i][j+1];
  }

  /**
   * @see com.topologi.diffx.algorithm.Matrix#isGreaterY(int, int)
   */
  public boolean isGreaterY(int i, int j) {
    return this.matrix[i+1][j] < this.matrix[i][j+1];
  }

  /**
   * @see com.topologi.diffx.algorithm.Matrix#isSameXY(int, int)
   */
  public boolean isSameXY(int i, int j) {
    return this.matrix[i+1][j] == this.matrix[i][j+1];
  }

  /**
   * Returns the maximum of the two values.
   * 
   * @param a The first value to compare.
   * @param b The second value to compare.
   * 
   * @return The maximum of the two values.
   */
  private static short max(short a, short b) {
    return a >= b? a : b;
  }


  /**
   * @see java.lang.Object#toString()
   */
  @Override
  public String toString() {
    StringBuffer out = new StringBuffer();
    for (int j = 0; j < this.matrix[0].length; j++) {
      for (short[] element : this.matrix) {
        out.append(element[j]+"\t");
      }
      out.append('\n');
    }
    return out.toString();
  }

  /**
   * Gets rid of the underlying matrix so that garbage collector can do its work.
   * 
   * @see Matrix#release()
   */
  public void release() {
    this.matrix = null;
  }

}