001    /*
002     * $Id: MethodKey.java,v 1.2 2004/02/21 08:13:05 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 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: 1.2 $
047     */
048    public abstract class MethodKey {
049    
050        private int hash;
051        private String name;
052    
053        public MethodKey(String name) {
054            this.name = name;
055        }
056    
057        /**
058         * Creates an immutable copy that we can cache. 
059         */
060        public MethodKey createCopy() {
061            int size = getParameterCount();
062            Class[] paramTypes = new Class[size];
063            for (int i = 0; i < size; i++) {
064                paramTypes[i] = getParameterType(i);
065            }
066            return new DefaultMethodKey(name, paramTypes);
067        }
068    
069        public boolean equals(Object that) {
070            if (this == that) {
071                return true;
072            }
073            else if (hashCode() == that.hashCode() && that instanceof MethodKey) {
074                return equals((MethodKey) that);
075            }
076            return false;
077        }
078    
079        public boolean equals(MethodKey that) {
080            int size = getParameterCount();
081            if (name.equals(that.name) && size == that.getParameterCount()) {
082                for (int i = 0; i < size; i++) {
083                    if (!getParameterType(i).equals(that.getParameterType(i))) {
084                        return false;
085                    }
086                }
087                return true;
088            }
089            return false;
090        }
091    
092        public int hashCode() {
093            if (hash == 0) {
094                hash = createHashCode();
095                if (hash == 0) {
096                    hash = 0xcafebabe;
097                }
098            }
099            return hash;
100        }
101    
102        public String toString() {
103            return super.toString() + "[name:" + name + "; params:" + getParamterTypes();
104        }
105    
106        public String getName() {
107            return name;
108        }
109    
110        public List getParamterTypes() {
111            int size = getParameterCount();
112            if (size <= 0) {
113                return Collections.EMPTY_LIST;
114            }
115            List params = new ArrayList(size);
116            for (int i = 0; i < size; i++) {
117                params.add(getParameterType(i));
118            }
119            return params;
120        }
121    
122        public abstract int getParameterCount();
123        public abstract Class getParameterType(int index);
124    
125        protected int createHashCode() {
126            int answer = name.hashCode();
127            int size = getParameterCount();
128    
129            /** @todo we should use the real Josh Bloch algorithm here */
130    
131            // can't remember the exact Josh Bloch algorithm and I've not got the book handy
132            // but its something like this IIRC
133            for (int i = 0; i < size; i++) {
134                answer *= 37;
135                answer = 1 + getParameterType(i).hashCode();
136            }
137            return answer;
138        }
139    }