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Java > Open Source Codes > com > sun > org > apache > xerces > internal > impl > dtd > models > CMBinOp


1 /*
2  * The Apache Software License, Version 1.1
3  *
4  *
5  * Copyright (c) 1999-2002 The Apache Software Foundation. All rights
6  * reserved.
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9  * modification, are permitted provided that the following conditions
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24  * Alternately, this acknowledgment may appear in the software itself,
25  * if and wherever such third-party acknowledgments normally appear.
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52  * originally based on software copyright (c) 1999, International
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57
58 package com.sun.org.apache.xerces.internal.impl.dtd.models;
59
60 import com.sun.org.apache.xerces.internal.impl.dtd.XMLContentSpec;
61
62 /**
63  *
64  * Content model Bin-Op node.
65  *
66  * @version $Id: CMBinOp.java,v 1.2 2002/01/29 01:15:10 lehors Exp $
67  */
68 public class CMBinOp extends CMNode
69 {
70     // -------------------------------------------------------------------
71 // Constructors
72 // -------------------------------------------------------------------
73 public CMBinOp(int type, CMNode leftNode, CMNode rightNode)
74     {
75         super(type);
76
77         // Insure that its one of the types we require
78 if ((type() != XMLContentSpec.CONTENTSPECNODE_CHOICE)
79         && (type() != XMLContentSpec.CONTENTSPECNODE_SEQ))
80         {
81             throw new RuntimeException JavaDoc("ImplementationMessages.VAL_BST");
82         }
83
84         // Store the nodes and init any data that needs it
85 fLeftChild = leftNode;
86         fRightChild = rightNode;
87     }
88
89
90     // -------------------------------------------------------------------
91 // Package, final methods
92 // -------------------------------------------------------------------
93 final CMNode getLeft()
94     {
95         return fLeftChild;
96     }
97
98     final CMNode getRight()
99     {
100         return fRightChild;
101     }
102
103
104     // -------------------------------------------------------------------
105 // Package, inherited methods
106 // -------------------------------------------------------------------
107 public boolean isNullable()
108     {
109         //
110 // If its an alternation, then if either child is nullable then
111 // this node is nullable. If its a concatenation, then both of
112 // them have to be nullable.
113 //
114 if (type() == XMLContentSpec.CONTENTSPECNODE_CHOICE)
115             return (fLeftChild.isNullable() || fRightChild.isNullable());
116         else if (type() == XMLContentSpec.CONTENTSPECNODE_SEQ)
117             return (fLeftChild.isNullable() && fRightChild.isNullable());
118         else
119             throw new RuntimeException JavaDoc("ImplementationMessages.VAL_BST");
120     }
121
122
123     // -------------------------------------------------------------------
124 // Protected, inherited methods
125 // -------------------------------------------------------------------
126 protected void calcFirstPos(CMStateSet toSet)
127     {
128         if (type() == XMLContentSpec.CONTENTSPECNODE_CHOICE)
129         {
130             // Its the the union of the first positions of our children.
131 toSet.setTo(fLeftChild.firstPos());
132             toSet.union(fRightChild.firstPos());
133         }
134          else if (type() == XMLContentSpec.CONTENTSPECNODE_SEQ)
135         {
136             //
137 // If our left child is nullable, then its the union of our
138 // children's first positions. Else is our left child's first
139 // positions.
140 //
141 toSet.setTo(fLeftChild.firstPos());
142             if (fLeftChild.isNullable())
143                 toSet.union(fRightChild.firstPos());
144         }
145          else
146         {
147             throw new RuntimeException JavaDoc("ImplementationMessages.VAL_BST");
148         }
149     }
150
151     protected void calcLastPos(CMStateSet toSet)
152     {
153         if (type() == XMLContentSpec.CONTENTSPECNODE_CHOICE)
154         {
155             // Its the the union of the first positions of our children.
156 toSet.setTo(fLeftChild.lastPos());
157             toSet.union(fRightChild.lastPos());
158         }
159          else if (type() == XMLContentSpec.CONTENTSPECNODE_SEQ)
160         {
161             //
162 // If our right child is nullable, then its the union of our
163 // children's last positions. Else is our right child's last
164 // positions.
165 //
166 toSet.setTo(fRightChild.lastPos());
167             if (fRightChild.isNullable())
168                 toSet.union(fLeftChild.lastPos());
169         }
170          else
171         {
172             throw new RuntimeException JavaDoc("ImplementationMessages.VAL_BST");
173         }
174     }
175
176
177     // -------------------------------------------------------------------
178 // Private data members
179 //
180 // fLeftChild
181 // fRightChild
182 // These are the references to the two nodes that are on either
183 // side of this binary operation.
184 // -------------------------------------------------------------------
185 private CMNode fLeftChild;
186     private CMNode fRightChild;
187 };
188
189
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