| /* |
| * Copyright (C) 2007-2010 JĂșlio Vilmar Gesser. |
| * Copyright (C) 2011, 2013-2016 The JavaParser Team. |
| * |
| * This file is part of JavaParser. |
| * |
| * JavaParser can be used either under the terms of |
| * a) the GNU Lesser General Public License as published by |
| * the Free Software Foundation, either version 3 of the License, or |
| * (at your option) any later version. |
| * b) the terms of the Apache License |
| * |
| * You should have received a copy of both licenses in LICENCE.LGPL and |
| * LICENCE.APACHE. Please refer to those files for details. |
| * |
| * JavaParser is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU Lesser General Public License for more details. |
| */ |
| |
| package com.github.javaparser.ast; |
| |
| /** |
| * A key to a piece of data associated with a {@link Node} at runtime. |
| * The key contains type information that can be used to check the |
| * type of any user data value for the key when the value is set. DataKey is abstract in order to |
| * force the creation of a subtype. That subtype is used to test for identity when looking for the |
| * user data because actual object identity would suffer from problems under serialization. |
| * So, the correct way to declare a DataKey is like this: |
| * <p> |
| * <pre> |
| * <code> |
| * public static final DataKey<Role> ROLE = new DataKey<Role>() { }; |
| * </code> |
| * </pre> |
| * <p> |
| * This code was taken from the <a href="http://wicket.apache.org/">Wicket project</a>. |
| * |
| * @param <T> The type of the object which is stored |
| * @see Node#getData(DataKey) |
| */ |
| public abstract class DataKey<T> { |
| @Override |
| public int hashCode() { |
| return getClass().hashCode(); |
| } |
| |
| /** |
| * @see java.lang.Object#equals(java.lang.Object) |
| */ |
| @Override |
| public boolean equals(Object obj) { |
| return obj != null && getClass().equals(obj.getClass()); |
| } |
| } |