1 /* 2 * Grapht, an open source dependency injector. 3 * Copyright 2014-2015 various contributors (see CONTRIBUTORS.txt) 4 * Copyright 2010-2014 Regents of the University of Minnesota 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU Lesser General Public License as 8 * published by the Free Software Foundation; either version 2.1 of the 9 * License, or (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 13 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more 14 * details. 15 * 16 * You should have received a copy of the GNU General Public License along with 17 * this program; if not, write to the Free Software Foundation, Inc., 51 18 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. 19 */ 20 package org.grouplens.grapht.reflect; 21 22 import javax.inject.Provider; 23 24 /** 25 * Abstract implementation of {@link SatisfactionVisitor}. All methods delegate to 26 * {@link #visitDefault()}, which in turn returns a default value. 27 * 28 * @author <a href="http://grouplens.org">GroupLens Research</a> 29 * @since 0.5 30 */ 31 public abstract class AbstractSatisfactionVisitor<T> implements SatisfactionVisitor<T> { 32 protected final T defaultValue; 33 34 /** 35 * Construct a visitor with a null default. 36 */ 37 public AbstractSatisfactionVisitor() { 38 this(null); 39 } 40 41 /** 42 * Construct a visitor with the specified default value. 43 * 44 * @param dft The default value to be returned by {@link #visitDefault()}. 45 */ 46 public AbstractSatisfactionVisitor(T dft) { 47 defaultValue = dft; 48 } 49 50 /** 51 * Default method called when other methods are not overridden. The default implementation 52 * returns the default value provided to {@link #AbstractSatisfactionVisitor(Object)}. 53 * @return The return value. 54 */ 55 public T visitDefault() { 56 return defaultValue; 57 } 58 59 @Override 60 public T visitNull() { 61 return visitDefault(); 62 } 63 64 @Override 65 public T visitClass(Class<?> clazz) { 66 return visitDefault(); 67 } 68 69 @Override 70 public T visitInstance(Object instance) { 71 return visitDefault(); 72 } 73 74 @Override 75 public T visitProviderClass(Class<? extends Provider<?>> pclass) { 76 return visitDefault(); 77 } 78 79 @Override 80 public T visitProviderInstance(Provider<?> provider) { 81 return visitDefault(); 82 } 83 }