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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 constraint that evaluates to true when either of the other constraints evaluates to true.
32   */
33  @Immutable
34  public class Or implements Constraint {
35      private static final long serialVersionUID = 1L;
36  
37      private final Constraint left;
38      private final Constraint right;
39      private final int hc;
40  
41      /**
42       * Create a constraint that evaluates to true if either of the two supplied constraints evaluates to true.
43       * 
44       * @param left the left constraint
45       * @param right the right constraint
46       * @throws IllegalArgumentException if the left or right constraints are null
47       */
48      public Or( Constraint left,
49                 Constraint right ) {
50          CheckArg.isNotNull(left, "left");
51          CheckArg.isNotNull(right, "right");
52          this.left = left;
53          this.right = right;
54          this.hc = HashCode.compute(this.left, this.right);
55      }
56  
57      /**
58       * Get the left-hand constraint.
59       * 
60       * @return the left-hand constraint; never null
61       */
62      public Constraint left() {
63          return left;
64      }
65  
66      /**
67       * Get the right-hand constraint.
68       * 
69       * @return the right-hand constraint; never null
70       */
71      public Constraint right() {
72          return right;
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 Or) {
104             Or that = (Or)obj;
105             if (this.hc != that.hc) return false;
106             return this.left.equals(that.left) && this.right.equals(that.right);
107         }
108         return false;
109     }
110 
111     /**
112      * {@inheritDoc}
113      * 
114      * @see org.modeshape.graph.query.model.Visitable#accept(org.modeshape.graph.query.model.Visitor)
115      */
116     public void accept( Visitor visitor ) {
117         visitor.visit(this);
118     }
119 }