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


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 java.util.Iterator JavaDoc;
20
21 import org.apache.commons.jexl.JexlContext;
22 import org.apache.commons.jexl.util.Introspector;
23 import org.apache.commons.jexl.util.introspection.Info;
24
25 /**
26  * ForEach statement. Syntax: foreach (var in iterable) Statement()
27  *
28  * @author Dion Gillard
29  * @since 1.1
30  */
31 public class ASTForeachStatement extends SimpleNode {
32     /** dummy velocity info. */
33     private static final Info DUMMY = new Info("", 1, 1);
34     /** index of the loop variable. */
35     private static final int VAR_INDEX = 0;
36     /** index of the items. */
37     private static final int ITEMS_INDEX = 1;
38     /** index of the code to execute. */
39     private static final int STATEMENT_INDEX = 2;
40
41
42     /**
43      * Create the node given an id.
44      *
45      * @param id node id.
46      */
47     public ASTForeachStatement(int id) {
48         super(id);
49     }
50
51     /**
52      * Create a node with the given parser and id.
53      *
54      * @param p a parser.
55      * @param id node id.
56      */
57     public ASTForeachStatement(Parser p, int id) {
58         super(p, id);
59     }
60
61     /** {@inheritDoc} */
62     public Object JavaDoc jjtAccept(ParserVisitor visitor, Object JavaDoc data) {
63         return visitor.visit(this, data);
64     }
65
66     /** {@inheritDoc} */
67     public Object JavaDoc value(JexlContext jc) throws Exception JavaDoc {
68         Object JavaDoc result = null;
69         /* first child is the loop variable */
70         ASTReference loopVariable = (ASTReference) jjtGetChild(VAR_INDEX);
71         /* second child is the variable to iterate */
72         SimpleNode iterable = (SimpleNode) jjtGetChild(ITEMS_INDEX);
73         Object JavaDoc iterableValue = iterable.value(jc);
74         // make sure there is a value to iterate on and a statement to execute
75 if (iterableValue != null && jjtGetNumChildren() >= (STATEMENT_INDEX + 1)) {
76             /* third child is the statement to execute */
77             SimpleNode statement = (SimpleNode) jjtGetChild(2);
78             // get an iterator for the collection/array etc via the
79 // introspector.
80 Iterator JavaDoc itemsIterator = Introspector.getUberspect().getIterator(
81                     iterableValue, DUMMY);
82             while (itemsIterator.hasNext()) {
83                 // set loopVariable to value of iterator
84 Object JavaDoc value = itemsIterator.next();
85                 jc.getVars().put(loopVariable.getRootString(), value);
86                 // execute statement
87 result = statement.value(jc);
88             }
89         }
90         return result;
91     }
92 }
93
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