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


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 import java.util.Collection JavaDoc;
22 import java.util.Map JavaDoc;
23
24 /**
25  * function to see if reference doesn't exist in context.
26  *
27  * @author <a HREF="mailto:geirm@apache.org">Geir Magnusson Jr.</a>
28  * @author <a HREF="mailto:tobrien@apache.org">Tim O'Brien</a>
29  * @version $Id: ASTEmptyFunction.java 398190 2006-04-29 16:04:10Z dion $
30  */
31 public class ASTEmptyFunction extends SimpleNode {
32     /**
33      * Create the node given an id.
34      *
35      * @param id node id.
36      */
37     public ASTEmptyFunction(int id) {
38         super(id);
39     }
40
41     /**
42      * Create a node with the given parser and id.
43      *
44      * @param p a parser.
45      * @param id node id.
46      */
47     public ASTEmptyFunction(Parser p, int id) {
48         super(p, id);
49     }
50
51     /** {@inheritDoc} */
52     public Object JavaDoc jjtAccept(ParserVisitor visitor, Object JavaDoc data) {
53         return visitor.visit(this, data);
54     }
55
56     /** {@inheritDoc} */
57     public Object JavaDoc value(JexlContext jc) throws Exception JavaDoc {
58         SimpleNode sn = (SimpleNode) jjtGetChild(0);
59
60         /*
61          * I can't believe this
62          */
63
64         Object JavaDoc o = sn.value(jc);
65
66         if (o == null) {
67             return Boolean.TRUE;
68         }
69
70         if (o instanceof String JavaDoc && "".equals(o)) {
71             return Boolean.TRUE;
72         }
73
74         if (o.getClass().isArray() && ((Object JavaDoc[]) o).length == 0) {
75             return Boolean.TRUE;
76         }
77
78         if (o instanceof Collection JavaDoc && ((Collection JavaDoc) o).isEmpty()) {
79             return Boolean.TRUE;
80         }
81
82         /*
83          * Map isn't a collection
84          */
85         if (o instanceof Map JavaDoc && ((Map JavaDoc) o).isEmpty()) {
86             return Boolean.TRUE;
87         }
88
89         return Boolean.FALSE;
90     }
91 }
92
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