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Java > Open Source Codes > org > apache > commons > jexl > parser > SimpleNode


1 /*
2  * Copyright 2002-2006 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16
17 package org.apache.commons.jexl.parser;
18
19 import org.apache.commons.jexl.JexlContext;
20
21 /**
22  * A Useful implementation of {@link Node}. Mostly autogenerated by javacc
23  *
24  * @author <a HREF="mailto:geirm@apache.org">Geir Magnusson Jr.</a>
25  * @version $Id: SimpleNode.java 398328 2006-04-30 12:46:59Z dion $
26  */
27 public class SimpleNode implements Node {
28     /** parent node. */
29     protected Node parent;
30
31     /** children of this node. */
32     protected Node[] children;
33
34     /** id of the node. */
35     protected int id;
36
37     /** parser that created the node. */
38     protected Parser parser;
39
40     /**
41      * Create the node given an id.
42      *
43      * @param i node id.
44      */
45     public SimpleNode(int i) {
46         id = i;
47     }
48
49     /**
50      * Create a node with the given parser and id.
51      *
52      * @param p a parser.
53      * @param i node id.
54      */
55     public SimpleNode(Parser p, int i) {
56         this(i);
57         parser = p;
58     }
59
60     /**
61      * Start of the node.
62      */
63     public void jjtOpen() {
64     }
65
66     /**
67      * End of the node.
68      */
69     public void jjtClose() {
70     }
71
72     /** {@inheritDoc} */
73     public void jjtSetParent(Node n) {
74         parent = n;
75     }
76
77     /** {@inheritDoc} */
78     public Node jjtGetParent() {
79         return parent;
80     }
81
82     /** {@inheritDoc} */
83     public void jjtAddChild(Node n, int i) {
84         if (children == null) {
85             children = new Node[i + 1];
86         } else if (i >= children.length) {
87             Node[] c = new Node[i + 1];
88             System.arraycopy(children, 0, c, 0, children.length);
89             children = c;
90         }
91
92         children[i] = n;
93     }
94
95     /** {@inheritDoc} */
96     public Node jjtGetChild(int i) {
97         return children[i];
98     }
99
100     /** {@inheritDoc} */
101     public int jjtGetNumChildren() {
102         return (children == null) ? 0 : children.length;
103     }
104
105     /**
106      * Accept the visitor.
107      *
108      * @param visitor a {@link ParserVisitor}.
109      * @param data data to be passed along to the visitor.
110      * @return the value from visiting.
111      * @see ParserVisitor#visit
112      */
113     public Object JavaDoc jjtAccept(ParserVisitor visitor, Object JavaDoc data) {
114         return visitor.visit(this, data);
115     }
116
117     /**
118      * Visit all children.
119      *
120      * @param visitor a {@link ParserVisitor}.
121      * @param data data to be passed along to the visitor.
122      * @return the value from visiting.
123      * @see ParserVisitor#visit
124      */
125     public Object JavaDoc childrenAccept(ParserVisitor visitor, Object JavaDoc data) {
126         if (children != null) {
127             for (int i = 0; i < children.length; ++i) {
128                 children[i].jjtAccept(visitor, data);
129             }
130         }
131         return data;
132     }
133
134     /**
135      * Gets a string representation of the node.
136      * @return the node name.
137      */
138     public String JavaDoc toString() {
139         return ParserTreeConstants.jjtNodeName[id];
140     }
141
142     /**
143      * Used during dumping to output the node with a prefix.
144      * @param prefix text to prefix {@link #toString()}
145      * @return text.
146      */
147     public String JavaDoc toString(String JavaDoc prefix) {
148         return prefix + toString();
149     }
150
151     /**
152      * Dump the node and all children.
153      * @param prefix text to prefix the node output.
154      */
155     public void dump(String JavaDoc prefix) {
156         System.out.println(toString(prefix));
157
158         if (children != null) {
159             for (int i = 0; i < children.length; ++i) {
160                 SimpleNode n = (SimpleNode) children[i];
161
162                 if (n != null) {
163                     n.dump(prefix + " ");
164                 }
165             }
166         }
167     }
168
169     /**
170      * basic interpret - just invoke interpret on all children.
171      * @param pc the {@link JexlContext context} to interpret against.
172      * @return true if interpretation worked.
173      * @throws Exception on any error.
174      */
175     public boolean interpret(JexlContext pc) throws Exception JavaDoc {
176         for (int i = 0; i < jjtGetNumChildren(); i++) {
177             SimpleNode node = (SimpleNode) jjtGetChild(i);
178             if (!node.interpret(pc)) {
179                 return false;
180             }
181         }
182
183         return true;
184     }
185
186     /**
187      * Gets the value of this node.
188      *
189      * @param context the context to retrieve values from.
190      * @return the value of the node.
191      * @throws Exception when evaluating the operands fails.
192      */
193     public Object JavaDoc value(JexlContext context) throws Exception JavaDoc {
194         return null;
195     }
196
197     /**
198      * Sets the value for the node - again, only makes sense for some nodes but
199      * lazyness tempts me to put it here. Keeps things simple.
200      *
201      * @param context the context to retrieve values from.
202      * @param value the value.
203      * @return the result.
204      * @throws Exception when evaluating the operands fails.
205      */
206     public Object JavaDoc setValue(JexlContext context, Object JavaDoc value) throws Exception JavaDoc {
207         return null;
208     }
209
210     /**
211      * Used to let a node calcuate it's value..
212      * @param o the object to calculate with.
213      * @param ctx the context to retrieve values from.
214      * @throws Exception when calculating the value fails.
215      * @return the result of the calculation.
216      */
217     public Object JavaDoc execute(Object JavaDoc o, JexlContext ctx) throws Exception JavaDoc {
218         return null;
219     }
220 }
221
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