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


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  * x = y, assigns a value to a variable in the context.
23  *
24  * @author Dion Gillard
25  *
26  */
27 public class ASTAssignment extends SimpleNode {
28     /**
29      * Create the node given an id.
30      *
31      * @param id node id.
32      */
33     public ASTAssignment(int id) {
34         super(id);
35     }
36
37     /**
38      * Create a node with the given parser and id.
39      *
40      * @param p a parser.
41      * @param id node id.
42      */
43     public ASTAssignment(Parser p, int id) {
44         super(p, id);
45     }
46
47     /** {@inheritDoc} */
48     public Object JavaDoc jjtAccept(ParserVisitor visitor, Object JavaDoc data) {
49         return visitor.visit(this, data);
50     }
51
52     /** {@inheritDoc} */
53     public Object JavaDoc value(JexlContext context) throws Exception JavaDoc {
54         // left should be the variable (reference) to assign to
55 SimpleNode left = (SimpleNode) jjtGetChild(0);
56         // right should be the expression to evaluate
57 Object JavaDoc right = ((SimpleNode) jjtGetChild(1)).value(context);
58         if (left instanceof ASTReference) {
59             ASTReference reference = (ASTReference) left;
60             left = (SimpleNode) reference.jjtGetChild(0);
61             if (left instanceof ASTIdentifier) {
62                 String JavaDoc identifier = ((ASTIdentifier) left)
63                         .getIdentifierString();
64                 context.getVars().put(identifier, right);
65             }
66         }
67         return right;
68     }
69 }
70
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