001 /*
002 $Id: OrderBy.java,v 1.1 2003/10/09 17:24:19 jstrachan Exp $
003
004 Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.
005
006 Redistribution and use of this software and associated documentation
007 ("Software"), with or without modification, are permitted provided
008 that the following conditions are met:
009
010 1. Redistributions of source code must retain copyright
011 statements and notices. Redistributions must also contain a
012 copy of this document.
013
014 2. Redistributions in binary form must reproduce the
015 above copyright notice, this list of conditions and the
016 following disclaimer in the documentation and/or other
017 materials provided with the distribution.
018
019 3. The name "groovy" must not be used to endorse or promote
020 products derived from this Software without prior written
021 permission of The Codehaus. For written permission,
022 please contact info@codehaus.org.
023
024 4. Products derived from this Software may not be called "groovy"
025 nor may "groovy" appear in their names without prior written
026 permission of The Codehaus. "groovy" is a registered
027 trademark of The Codehaus.
028
029 5. Due credit should be given to The Codehaus -
030 http://groovy.codehaus.org/
031
032 THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
033 ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
034 NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
035 FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
036 THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
037 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
038 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
039 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
040 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
041 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
042 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
043 OF THE POSSIBILITY OF SUCH DAMAGE.
044
045 */
046 package groovy.util;
047
048 import groovy.lang.Closure;
049
050 import java.util.ArrayList;
051 import java.util.Comparator;
052 import java.util.Iterator;
053 import java.util.List;
054
055 /**
056 * A helper class for sorting objects via a closure to return the field
057 * or operation on which to sort.
058 *
059 * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
060 * @version $Revision: 1.1 $
061 */
062 public class OrderBy implements Comparator {
063
064 List closures;
065
066 public OrderBy() {
067 this.closures = new ArrayList();
068 }
069
070 public OrderBy(Closure closure) {
071 this();
072 closures.add(closure);
073 }
074
075 public OrderBy(List closures) {
076 this.closures = closures;
077 }
078
079 public void add(Closure closure) {
080 closures.add(closure);
081 }
082
083 public int compare(Object object1, Object object2) {
084 for (Iterator iter = closures.iterator(); iter.hasNext();) {
085 Closure closure = (Closure) iter.next();
086 Object value1 = closure.call(object1);
087 Object value2 = closure.call(object2);
088
089 if (value1 == value2) {
090 continue;
091 }
092 if (value1 == null) {
093 return -1;
094 }
095 if (value1 instanceof Comparable) {
096 Comparable c1 = (Comparable) value1;
097 return c1.compareTo(value2);
098 }
099 if (value1.equals(value2)) {
100 continue;
101 }
102 return value1.hashCode() - value2.hashCode();
103 }
104 return 0;
105 }
106 }