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 }