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 tests whether a property on a node is equal to a property on another node. A node-tuple satisfies the
32 * constraint only if:
33 * <ul>
34 * <li>the {@code selector1Name} node has a property named {@code property1Name}, and</li>
35 * <li>the {@code selector2Name} node has a property named {@code property2Name}, and</li>
36 * <li>the value of property {@code property1Name} is equal to the value of property {@code property2Name}</li>
37 * </ul>
38 */
39 @Immutable
40 public class EquiJoinCondition implements JoinCondition {
41 private static final long serialVersionUID = 1L;
42
43 private final SelectorName selector1Name;
44 private final String property1Name;
45 private final SelectorName selector2Name;
46 private final String property2Name;
47 private final int hc;
48
49 /**
50 * Create an equi-join condition, given the names of the selector and property for the left- and right-hand-side of the join.
51 *
52 * @param selector1Name the selector name appearing on the left-side of the join; never null
53 * @param property1Name the property name for the left-side of the join; never null
54 * @param selector2Name the selector name appearing on the right-side of the join; never null
55 * @param property2Name the property name for the right-side of the join; never null
56 */
57 public EquiJoinCondition( SelectorName selector1Name,
58 String property1Name,
59 SelectorName selector2Name,
60 String property2Name ) {
61 CheckArg.isNotNull(selector1Name, "selector1Name");
62 CheckArg.isNotNull(property1Name, "property1Name");
63 CheckArg.isNotNull(selector2Name, "selector2Name");
64 CheckArg.isNotNull(property2Name, "property2Name");
65 this.selector1Name = selector1Name;
66 this.property1Name = property1Name;
67 this.selector2Name = selector2Name;
68 this.property2Name = property2Name;
69 this.hc = HashCode.compute(this.selector1Name, this.property1Name, this.selector2Name, this.property2Name);
70 }
71
72 /**
73 * Create an equi-join condition, given the columns.
74 *
75 * @param column1 the column for the left-side of the join; never null
76 * @param column2 the column for the right-side of the join; never null
77 */
78 public EquiJoinCondition( Column column1,
79 Column column2 ) {
80 this(column1.selectorName(), column1.propertyName(), column2.selectorName(), column2.propertyName());
81 }
82
83 /**
84 * Get the name of the selector that appears on the left-side of the join.
85 *
86 * @return the selector name appearing on the left-side of the join; never null
87 */
88 public final SelectorName selector1Name() {
89 return selector1Name;
90 }
91
92 /**
93 * Get the name of the property that appears on the left-side of the join.
94 *
95 * @return the property name for the left-side of the join; never null
96 */
97 public final String property1Name() {
98 return property1Name;
99 }
100
101 /**
102 * Get the name of the selector that appears on the right-side of the join.
103 *
104 * @return the selector name appearing on the right-side of the join; never null
105 */
106 public final SelectorName selector2Name() {
107 return selector2Name;
108 }
109
110 /**
111 * Get the name of the property that appears on the left-side of the join.
112 *
113 * @return the property name for the left-side of the join; never null
114 */
115 public final String property2Name() {
116 return property2Name;
117 }
118
119 /**
120 * {@inheritDoc}
121 *
122 * @see java.lang.Object#toString()
123 */
124 @Override
125 public String toString() {
126 return Visitors.readable(this);
127 }
128
129 /**
130 * {@inheritDoc}
131 *
132 * @see java.lang.Object#hashCode()
133 */
134 @Override
135 public int hashCode() {
136 return hc;
137 }
138
139 /**
140 * {@inheritDoc}
141 *
142 * @see java.lang.Object#equals(java.lang.Object)
143 */
144 @Override
145 public boolean equals( Object obj ) {
146 if (obj == this) return true;
147 if (obj instanceof EquiJoinCondition) {
148 EquiJoinCondition that = (EquiJoinCondition)obj;
149 if (this.hc != that.hc) return false;
150 if (!this.selector1Name.equals(that.selector1Name)) return false;
151 if (!this.selector2Name.equals(that.selector2Name)) return false;
152 if (!this.property1Name.equals(that.property1Name)) return false;
153 if (!this.property2Name.equals(that.property2Name)) return false;
154 return true;
155 }
156 return false;
157 }
158
159 /**
160 * {@inheritDoc}
161 *
162 * @see org.modeshape.graph.query.model.Visitable#accept(org.modeshape.graph.query.model.Visitor)
163 */
164 public void accept( Visitor visitor ) {
165 visitor.visit(this);
166 }
167 }