/**
 * ===========================================
 * LibLayout : a free Java layouting library
 * ===========================================
 *
 * Project Info:  http://reporting.pentaho.org/liblayout/
 *
 * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors.
 *
 * This library is free software; you can redistribute it and/or modify it under the terms
 * of the GNU Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * ------------
 * $Id: CSSStyleRuleComparator.java 6653 2008-12-02 14:53:40Z tmorgner $
 * ------------
 * (C) Copyright 2006-2007, by Pentaho Corporation.
 */
package org.jfree.layouting.layouter.style;

import java.util.Comparator;

import org.jfree.layouting.input.style.CSSStyleRule;
import org.jfree.layouting.input.style.selectors.CSSSelector;
import org.jfree.layouting.input.style.selectors.SelectorWeight;

/**
 * Creation-Date: 08.12.2005, 21:31:51
 *
 * @author Thomas Morgner
 */
public class CSSStyleRuleComparator implements Comparator
{
  public CSSStyleRuleComparator()
  {
  }

  /**
   * Compares its two arguments for order.  Returns a negative integer, zero, or
   * a positive integer as the first argument is less than, equal to, or greater
   * than the second.<p>
   * <p/>
   * The implementor must ensure that <tt>sgn(compare(x, y)) == -sgn(compare(y,
   * x))</tt> for all <tt>x</tt> and <tt>y</tt>.  (This implies that
   * <tt>compare(x, y)</tt> must throw an exception if and only if
   * <tt>compare(y, x)</tt> throws an exception.)<p>
   * <p/>
   * The implementor must also ensure that the relation is transitive:
   * <tt>((compare(x, y)&gt;0) &amp;&amp; (compare(y, z)&gt;0))</tt> implies
   * <tt>compare(x, z)&gt;0</tt>.<p>
   * <p/>
   * Finally, the implementer must ensure that <tt>compare(x, y)==0</tt> implies
   * that <tt>sgn(compare(x, z))==sgn(compare(y, z))</tt> for all
   * <tt>z</tt>.<p>
   * <p/>
   * It is generally the case, but <i>not</i> strictly required that
   * <tt>(compare(x, y)==0) == (x.equals(y))</tt>.  Generally speaking, any
   * comparator that violates this condition should clearly indicate this fact.
   * The recommended language is "Note: this comparator imposes orderings that
   * are inconsistent with equals."
   *
   * @param o1 the first object to be compared.
   * @param o2 the second object to be compared.
   * @return a negative integer, zero, or a positive integer as the first
   *         argument is less than, equal to, or greater than the second.
   * @throws ClassCastException if the arguments' types prevent them from being
   *                            compared by this Comparator.
   */
  public int compare(final Object o1, final Object o2)
  {
    final CSSStyleRule r1 = (CSSStyleRule) o1;
    final CSSStyleRule r2 = (CSSStyleRule) o2;

    final CSSSelector selector1 = r1.getSelector();
    final CSSSelector selector2 = r2.getSelector();

    final SelectorWeight weight1 = selector1.getWeight();
    final SelectorWeight weight2 = selector2.getWeight();

    return weight1.compareTo(weight2);
  }
}
