1 /* 2 * Copyright (C) 2007-2010 Jlio Vilmar Gesser. 3 * Copyright (C) 2011, 2013-2016 The JavaParser Team. 4 * 5 * This file is part of JavaParser. 6 * 7 * JavaParser can be used either under the terms of 8 * a) the GNU Lesser General Public License as published by 9 * the Free Software Foundation, either version 3 of the License, or 10 * (at your option) any later version. 11 * b) the terms of the Apache License 12 * 13 * You should have received a copy of both licenses in LICENCE.LGPL and 14 * LICENCE.APACHE. Please refer to those files for details. 15 * 16 * JavaParser is distributed in the hope that it will be useful, 17 * but WITHOUT ANY WARRANTY; without even the implied warranty of 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19 * GNU Lesser General Public License for more details. 20 */ 21 22 package com.github.javaparser.ast; 23 24 /** 25 * A key to a piece of data associated with a {@link Node} at runtime. 26 * The key contains type information that can be used to check the 27 * type of any user data value for the key when the value is set. DataKey is abstract in order to 28 * force the creation of a subtype. That subtype is used to test for identity when looking for the 29 * user data because actual object identity would suffer from problems under serialization. 30 * So, the correct way to declare a DataKey is like this: 31 * <p> 32 * <pre> 33 * <code> 34 * public static final DataKey<Role> ROLE = new DataKey<Role>() { }; 35 * </code> 36 * </pre> 37 * <p> 38 * This code was taken from the <a href="http://wicket.apache.org/">Wicket project</a>. 39 * 40 * @param <T> The type of the object which is stored 41 * @see Node#getData(DataKey) 42 */ 43 public abstract class DataKey<T> { 44 @Override 45 public int hashCode() { 46 return getClass().hashCode(); 47 } 48 49 /** 50 * @see java.lang.Object#equals(java.lang.Object) 51 */ 52 @Override 53 public boolean equals(Object obj) { 54 return obj != null && getClass().equals(obj.getClass()); 55 } 56 } 57
