001    /***
002     *
003     * Copyright (c) 2007 Paul Hammant
004     * All rights reserved.
005     *
006     * Redistribution and use in source and binary forms, with or without
007     * modification, are permitted provided that the following conditions
008     * are met:
009     * 1. Redistributions of source code must retain the above copyright
010     *    notice, this list of conditions and the following disclaimer.
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. Neither the name of the copyright holders nor the names of its
015     *    contributors may be used to endorse or promote products derived from
016     *    this software without specific prior written permission.
017     *
018     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
019     * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
020     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
021     * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
022     * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
023     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
024     * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
025     * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
026     * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
027     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
028     * THE POSSIBILITY OF SUCH DAMAGE.
029     */
030    
031    package com.thoughtworks.paranamer;
032    
033    import com.thoughtworks.paranamer.BytecodeReadingParanamer;
034    
035    import java.lang.reflect.AccessibleObject;
036    import java.lang.reflect.Method;
037    import java.lang.reflect.Constructor;
038    
039    /**
040     * Implementation of Paranamer which automatically chooses between two Paranamer implementations depending on which can supply data
041     *
042     * @author Paul Hammant
043     * @author Mauro Talevi
044     */
045    public class AdaptiveParanamer implements Paranamer {
046    
047        public static final String __PARANAMER_DATA = "v1.0 \n"
048            + "com.thoughtworks.paranamer.AdaptiveParanamer AdaptiveParanamer \n"
049            + "com.thoughtworks.paranamer.AdaptiveParanamer AdaptiveParanamer com.thoughtworks.paranamer.Paranamer,com.thoughtworks.paranamer.Paranamer delegate,fallback\n"
050            + "com.thoughtworks.paranamer.AdaptiveParanamer toString \n"
051            + "com.thoughtworks.paranamer.AdaptiveParanamer lookupParameterNames java.lang.AccessibleObject methodOrCtor \n";
052    
053        private Paranamer delegate;
054        private Paranamer fallback;
055    
056        /**
057         * Cache a DefaultParanamer's lookups.
058         */
059        public AdaptiveParanamer() {
060            this(new DefaultParanamer(), new BytecodeReadingParanamer());
061        }
062    
063    
064        /**
065         * Cache a primary and secondary Paranamer instance (the second is a fallback to the first)
066         * @param delegate first
067         * @param fallback second
068         */
069        public AdaptiveParanamer(Paranamer delegate, Paranamer fallback) {
070            this.delegate = delegate;
071            this.fallback = fallback;
072            if (delegate == null || fallback == null || delegate == fallback) {
073                throw new RuntimeException("must supply delegate and fallback (which must be different)");
074            }
075        }
076    
077        public String[] lookupParameterNames(AccessibleObject methodOrConstructor) {
078            return lookupParameterNames(methodOrConstructor, true);
079        }
080    
081        public String[] lookupParameterNames(AccessibleObject methodOrCtor, boolean throwExceptionIfMissing) {
082    
083            Class declaringClass = null;
084            String name = null;
085            if (methodOrCtor instanceof Method) {
086                Method method = (Method) methodOrCtor;
087                declaringClass = method.getDeclaringClass();
088                name = method.getName();
089            } else {
090                Constructor constructor = (Constructor) methodOrCtor;
091                declaringClass = constructor.getDeclaringClass();
092                name = constructor.getName();
093            }
094    
095            String[] names = delegate.lookupParameterNames(methodOrCtor, false);
096            if (names == Paranamer.EMPTY_NAMES) {
097                names = fallback.lookupParameterNames(methodOrCtor, throwExceptionIfMissing);
098            }
099            return names;
100    
101        }
102    
103        /**
104         * @Deperecated Use 'new CachingParanamer(new AdaptiveParanamer())' instead.
105         */
106        public int areParameterNamesAvailable(Class clazz, String ctorOrMethodName) {
107            int i = delegate.areParameterNamesAvailable(clazz, ctorOrMethodName);
108            if (i != Paranamer.PARAMETER_NAMES_FOUND) {
109                i = fallback.areParameterNamesAvailable(clazz, ctorOrMethodName);
110            }
111            return i;
112        }
113    
114        public String toString() {
115             return new StringBuffer("[AdaptiveParanamer delegate=")
116             .append(delegate).append(", fallback=").append(fallback).append("]").toString();
117         }
118    
119    }