001    /*
002     * $Id: MethodKey.java 4189 2006-11-02 11:44:45Z blackdrag $
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 that the
008     * following conditions are met:
009     *  1. Redistributions of source code must retain copyright statements and
010     * notices. Redistributions must also contain a copy of this document.
011     *  2. Redistributions in binary form must reproduce the above copyright
012     * notice, this list of conditions and the following disclaimer in the
013     * documentation and/or other materials provided with the distribution.
014     *  3. The name "groovy" must not be used to endorse or promote products
015     * derived from this Software without prior written permission of The Codehaus.
016     * For written permission, please contact info@codehaus.org.
017     *  4. Products derived from this Software may not be called "groovy" nor may
018     * "groovy" appear in their names without prior written permission of The
019     * Codehaus. "groovy" is a registered trademark of The Codehaus.
020     *  5. Due credit should be given to The Codehaus - http://groovy.codehaus.org/
021     *
022     * THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS ``AS IS'' AND ANY
023     * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
024     * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
025     * DISCLAIMED. IN NO EVENT SHALL THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR
026     * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
027     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
028     * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
029     * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
030     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
031     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
032     * DAMAGE.
033     *
034     */
035    package org.codehaus.groovy.runtime;
036    
037    import java.util.ArrayList;
038    import java.util.Collections;
039    import java.util.List;
040    
041    /**
042     * An abstract base class for a key used for comparators and Map keys to lookup a method by
043     * name and parameter types
044     * 
045     * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
046     * @version $Revision: 4189 $
047     */
048    public abstract class MethodKey {
049    
050        private int hash;
051        private String name;
052        private Class sender;
053        
054        public MethodKey(Class sender, String name) {
055            this.sender = sender;
056            this.name = name;
057        }
058    
059        /**
060         * Creates an immutable copy that we can cache. 
061         */
062        public MethodKey createCopy() {
063            int size = getParameterCount();
064            Class[] paramTypes = new Class[size];
065            for (int i = 0; i < size; i++) {
066                paramTypes[i] = getParameterType(i);
067            }
068            return new DefaultMethodKey(sender, name, paramTypes);
069        }
070    
071        public boolean equals(Object that) {
072            if (this == that) {
073                return true;
074            }
075            else if (hashCode() == that.hashCode() && that instanceof MethodKey) {
076                return equals((MethodKey) that);
077            }
078            return false;
079        }
080    
081        public boolean equals(MethodKey that) {
082            int size = getParameterCount();
083            if (sender!=that.sender) return false;
084            if (name.equals(that.name) && size == that.getParameterCount()) {
085                for (int i = 0; i < size; i++) {
086                    if (!getParameterType(i).equals(that.getParameterType(i))) {
087                        return false;
088                    }
089                }
090                return true;
091            }
092            return false;
093        }
094    
095        public int hashCode() {
096            if (hash == 0) {
097                hash = createHashCode();
098                if (hash == 0) {
099                    hash = 0xcafebabe;
100                }
101            }
102            return hash;
103        }
104    
105        public String toString() {
106            return super.toString() + "[name:" + name + "; params:" + getParamterTypes();
107        }
108    
109        public String getName() {
110            return name;
111        }
112    
113        public List getParamterTypes() {
114            int size = getParameterCount();
115            if (size <= 0) {
116                return Collections.EMPTY_LIST;
117            }
118            List params = new ArrayList(size);
119            for (int i = 0; i < size; i++) {
120                params.add(getParameterType(i));
121            }
122            return params;
123        }
124    
125        public abstract int getParameterCount();
126        public abstract Class getParameterType(int index);
127    
128        protected int createHashCode() {
129            int answer = name.hashCode();
130            int size = getParameterCount();
131    
132            /** @todo we should use the real Josh Bloch algorithm here */
133    
134            // can't remember the exact Josh Bloch algorithm and I've not got the book handy
135            // but its something like this IIRC
136            for (int i = 0; i < size; i++) {
137                answer *= 37;
138                answer += 1 + getParameterType(i).hashCode();
139            }
140            answer *= 37;
141            answer += 1 + sender.hashCode();
142            return answer;
143        }
144    }