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Java > Open Source Codes > com > sun > org > apache > xerces > internal > impl > xs > models > XSCMBinOp


1 /*
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57
58 package com.sun.org.apache.xerces.internal.impl.xs.models;
59
60 import com.sun.org.apache.xerces.internal.impl.dtd.models.CMNode;
61 import com.sun.org.apache.xerces.internal.impl.dtd.models.CMStateSet;
62 import com.sun.org.apache.xerces.internal.impl.xs.XSModelGroupImpl;
63
64 /**
65  *
66  * Content model Bin-Op node.
67  *
68  * @author Neil Graham, IBM
69  * @version $$
70  */
71 public class XSCMBinOp extends CMNode {
72     // -------------------------------------------------------------------
73 // Constructors
74 // -------------------------------------------------------------------
75 public XSCMBinOp(int type, CMNode leftNode, CMNode rightNode)
76     {
77         super(type);
78
79         // Insure that its one of the types we require
80 if ((type() != XSModelGroupImpl.MODELGROUP_CHOICE)
81         && (type() != XSModelGroupImpl.MODELGROUP_SEQUENCE)) {
82             throw new RuntimeException JavaDoc("ImplementationMessages.VAL_BST");
83         }
84
85         // Store the nodes and init any data that needs it
86 fLeftChild = leftNode;
87         fRightChild = rightNode;
88     }
89
90
91     // -------------------------------------------------------------------
92 // Package, final methods
93 // -------------------------------------------------------------------
94 final CMNode getLeft() {
95         return fLeftChild;
96     }
97
98     final CMNode getRight() {
99         return fRightChild;
100     }
101
102
103     // -------------------------------------------------------------------
104 // Package, inherited methods
105 // -------------------------------------------------------------------
106 public boolean isNullable() {
107         //
108 // If its an alternation, then if either child is nullable then
109 // this node is nullable. If its a concatenation, then both of
110 // them have to be nullable.
111 //
112 if (type() == XSModelGroupImpl.MODELGROUP_CHOICE)
113             return (fLeftChild.isNullable() || fRightChild.isNullable());
114         else if (type() == XSModelGroupImpl.MODELGROUP_SEQUENCE)
115             return (fLeftChild.isNullable() && fRightChild.isNullable());
116         else
117             throw new RuntimeException JavaDoc("ImplementationMessages.VAL_BST");
118     }
119
120
121     // -------------------------------------------------------------------
122 // Protected, inherited methods
123 // -------------------------------------------------------------------
124 protected void calcFirstPos(CMStateSet toSet) {
125         if (type() == XSModelGroupImpl.MODELGROUP_CHOICE) {
126             // Its the the union of the first positions of our children.
127 toSet.setTo(fLeftChild.firstPos());
128             toSet.union(fRightChild.firstPos());
129         }
130          else if (type() == XSModelGroupImpl.MODELGROUP_SEQUENCE) {
131             //
132 // If our left child is nullable, then its the union of our
133 // children's first positions. Else is our left child's first
134 // positions.
135 //
136 toSet.setTo(fLeftChild.firstPos());
137             if (fLeftChild.isNullable())
138                 toSet.union(fRightChild.firstPos());
139         }
140          else {
141             throw new RuntimeException JavaDoc("ImplementationMessages.VAL_BST");
142         }
143     }
144
145     protected void calcLastPos(CMStateSet toSet) {
146         if (type() == XSModelGroupImpl.MODELGROUP_CHOICE) {
147             // Its the the union of the first positions of our children.
148 toSet.setTo(fLeftChild.lastPos());
149             toSet.union(fRightChild.lastPos());
150         }
151         else if (type() == XSModelGroupImpl.MODELGROUP_SEQUENCE) {
152             //
153 // If our right child is nullable, then its the union of our
154 // children's last positions. Else is our right child's last
155 // positions.
156 //
157 toSet.setTo(fRightChild.lastPos());
158             if (fRightChild.isNullable())
159                 toSet.union(fLeftChild.lastPos());
160         }
161         else {
162             throw new RuntimeException JavaDoc("ImplementationMessages.VAL_BST");
163         }
164     }
165
166
167     // -------------------------------------------------------------------
168 // Private data members
169 //
170 // fLeftChild
171 // fRightChild
172 // These are the references to the two nodes that are on either
173 // side of this binary operation.
174 // -------------------------------------------------------------------
175 private CMNode fLeftChild;
176     private CMNode fRightChild;
177 } // XSCMBinOp
178
179
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