001: /*
002: $Id: OrderBy.java 206 2003-10-09 17:24:20Z jstrachan $
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: 206 $
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: }
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