1 /*
2 * ModeShape (http://www.modeshape.org)
3 * See the COPYRIGHT.txt file distributed with this work for information
4 * regarding copyright ownership. Some portions may be licensed
5 * to Red Hat, Inc. under one or more contributor license agreements.
6 * See the AUTHORS.txt file in the distribution for a full listing of
7 * individual contributors.
8 *
9 * ModeShape is free software. Unless otherwise indicated, all code in ModeShape
10 * is licensed to you under the terms of the GNU Lesser General Public License as
11 * published by the Free Software Foundation; either version 2.1 of
12 * the License, or (at your option) any later version.
13 *
14 * ModeShape is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this software; if not, write to the Free
21 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
23 */
24 package org.modeshape.graph.query.model;
25
26 import net.jcip.annotations.Immutable;
27 import org.modeshape.common.util.CheckArg;
28 import org.modeshape.common.util.HashCode;
29
30 /**
31 * A join condition that evaluates to true only when the named node is a descendant of another named node.
32 */
33 @Immutable
34 public class DescendantNodeJoinCondition implements JoinCondition {
35 private static final long serialVersionUID = 1L;
36
37 private final SelectorName descendantSelectorName;
38 private final SelectorName ancestorSelectorName;
39 private final int hc;
40
41 /**
42 * Create a join condition that determines whether the node identified by the descendant selector is indeed a descendant of
43 * the node identified by the ancestor selector.
44 *
45 * @param ancestorSelectorName the name of the ancestor selector
46 * @param descendantSelectorName the name of the descendant selector
47 */
48 public DescendantNodeJoinCondition( SelectorName ancestorSelectorName,
49 SelectorName descendantSelectorName ) {
50 CheckArg.isNotNull(descendantSelectorName, "descendantSelectorName");
51 CheckArg.isNotNull(ancestorSelectorName, "ancestorSelectorName");
52 this.descendantSelectorName = descendantSelectorName;
53 this.ancestorSelectorName = ancestorSelectorName;
54 this.hc = HashCode.compute(this.descendantSelectorName, this.ancestorSelectorName);
55 }
56
57 /**
58 * Get the name of the selector for the descedant node.
59 *
60 * @return the selector name of the descendant node; never null
61 */
62 public final SelectorName descendantSelectorName() {
63 return descendantSelectorName;
64 }
65
66 /**
67 * Get the name of the selector for the ancestor node.
68 *
69 * @return the selector name of the ancestor node; never null
70 */
71 public final SelectorName ancestorSelectorName() {
72 return ancestorSelectorName;
73 }
74
75 /**
76 * {@inheritDoc}
77 *
78 * @see java.lang.Object#toString()
79 */
80 @Override
81 public String toString() {
82 return Visitors.readable(this);
83 }
84
85 /**
86 * {@inheritDoc}
87 *
88 * @see java.lang.Object#hashCode()
89 */
90 @Override
91 public int hashCode() {
92 return hc;
93 }
94
95 /**
96 * {@inheritDoc}
97 *
98 * @see java.lang.Object#equals(java.lang.Object)
99 */
100 @Override
101 public boolean equals( Object obj ) {
102 if (obj == this) return true;
103 if (obj instanceof DescendantNodeJoinCondition) {
104 DescendantNodeJoinCondition that = (DescendantNodeJoinCondition)obj;
105 if (this.hc != that.hc) return false;
106 if (!this.descendantSelectorName.equals(that.descendantSelectorName)) return false;
107 if (!this.ancestorSelectorName.equals(that.ancestorSelectorName)) return false;
108 return true;
109 }
110 return false;
111 }
112
113 /**
114 * {@inheritDoc}
115 *
116 * @see org.modeshape.graph.query.model.Visitable#accept(org.modeshape.graph.query.model.Visitor)
117 */
118 public void accept( Visitor visitor ) {
119 visitor.visit(this);
120 }
121 }