001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.hivemind.methodmatch;
016    
017    import java.util.ArrayList;
018    import java.util.Iterator;
019    import java.util.List;
020    
021    import org.apache.hivemind.ApplicationRuntimeException;
022    import org.apache.hivemind.HiveMind;
023    import org.apache.hivemind.Location;
024    import org.apache.hivemind.service.MethodSignature;
025    
026    /**
027     * A utility class used for matching a {@link org.apache.hivemind.service.MethodSignature} against a
028     * method pattern (this is primarily used by {@link org.apache.hivemind.ServiceInterceptorFactory
029     * interceptor factories}). A method pattern consists of a <em>name pattern</em> and an optional
030     * <em>parameters pattern</em>.
031     * <p>
032     * The name pattern matches against the method name, and can be one of the following:
033     * <ul>
034     * <li>A single name - which requires an exact match. Example: <code>perform</code>
035     * <li>A name suffix, indicated with a leading '*'. Example: <code>*form</code>
036     * <li>A name prefix, indicated with a trailing '*'. Example: <code>per*</code>
037     * <li>A name substring, indicated with leading and trailing '*'s. Example: <code>*erfo*</code>.
038     * <li>A match any, indicated with a single '*'. Example: <code>*</code>
039     * </ul>
040     * <p>
041     * The parameters pattern follows the name pattern and is optional. It is used to check the number
042     * of parameters, or their types. When the parameters pattern is omitted, then the number and types
043     * of parameters are not considred when matching methods.
044     * <p>
045     * The parameters pattern, when present, is contained within open and closed parenthis after the
046     * method pattern. Inside the parenthesis may be a number, indicating the exact number of method
047     * parameters to match against. Alternately, a comma-seperated list of Java types is used, which
048     * matches against a method that takes the exact set of parameters. Examples:
049     * <ul>
050     * <li><code>perform()</code>-- method with no parameters
051     * <li><code>perform(2)</code>-- method with two parameters
052     * <li><code>perform(java.util.List, int)</code>- method taking a List and an int parameter
053     * </ul>
054     * 
055     * @author Howard Lewis Ship
056     */
057    public class MethodMatcher
058    {
059        private class StoredPattern
060        {
061            String _methodPattern;
062    
063            MethodFilter _filter;
064    
065            Object _patternValue;
066    
067            StoredPattern(String pattern, Object value)
068            {
069                _methodPattern = pattern;
070                _patternValue = value;
071            }
072    
073            boolean match(MethodSignature sig)
074            {
075                if (_filter == null)
076                {
077    
078                    try
079                    {
080                        _filter = parseMethodPattern(_methodPattern);
081                    }
082                    catch (RuntimeException ex)
083                    {
084                        Location l = HiveMind.findLocation(new Object[]
085                        { _patternValue, ex });
086    
087                        if (l == null)
088                            throw ex;
089    
090                        throw new ApplicationRuntimeException(MethodMatchMessages.exceptionAtLocation(
091                                l,
092                                ex), ex);
093                    }
094                }
095    
096                return _filter.matchMethod(sig);
097            }
098        }
099    
100        private MethodPatternParser _parser = new MethodPatternParser();
101    
102        private List _methodInfos;
103    
104        private Object _defaultValue;
105    
106        /**
107         * Constructor that takes a default value returned when no stored method pattern matches the
108         * input to {@link #get(MethodSignature)}.
109         * 
110         * @since 1.1
111         */
112        public MethodMatcher(Object defaultValue)
113        {
114            _defaultValue = defaultValue;
115        }
116    
117        public MethodMatcher()
118        {
119            this(null);
120        }
121    
122        private MethodFilter parseMethodPattern(String pattern)
123        {
124            return _parser.parseMethodPattern(pattern);
125        }
126    
127        /**
128         * Stores a pattern and an associated value. Values can later be accessed via
129         * {@link #get(MethodSignature)}.
130         * 
131         * @param methodPattern
132         *            a pattern that is used to recognize methods
133         * @param patternValue
134         *            a value associated with the pattern
135         */
136        public synchronized void put(String methodPattern, Object patternValue)
137        {
138            if (_methodInfos == null)
139                _methodInfos = new ArrayList();
140    
141            StoredPattern sp = new StoredPattern(methodPattern, patternValue);
142    
143            _methodInfos.add(sp);
144        }
145    
146        /**
147         * Returns a pattern value prevoiusly stored via {@link #put(String, Object)}. Iterates over
148         * the patterns stored, in the order in which they were stored, until a match is found.
149         * 
150         * @param sig
151         *            the MethodSignature to find a matching pattern for
152         * @return the pattern value for the matching pattern, or the default value if not found (the
153         *         default value may be set in the constructor)
154         */
155        public synchronized Object get(MethodSignature sig)
156        {
157            if (_methodInfos == null)
158                return _defaultValue;
159    
160            Iterator i = _methodInfos.iterator();
161            while (i.hasNext())
162            {
163                StoredPattern sp = (StoredPattern) i.next();
164    
165                if (sp.match(sig))
166                    return sp._patternValue;
167            }
168    
169            // Not found.
170    
171            return _defaultValue;
172        }
173    }