01: /*
02: * Copyright 2002-2006 The Apache Software Foundation.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
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;
22: import java.util.Map;
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 jjtAccept(ParserVisitor visitor, Object data) {
53: return visitor.visit(this , data);
54: }
55:
56: /** {@inheritDoc} */
57: public Object value(JexlContext jc) throws Exception {
58: SimpleNode sn = (SimpleNode) jjtGetChild(0);
59:
60: /*
61: * I can't believe this
62: */
63:
64: Object o = sn.value(jc);
65:
66: if (o == null) {
67: return Boolean.TRUE;
68: }
69:
70: if (o instanceof String && "".equals(o)) {
71: return Boolean.TRUE;
72: }
73:
74: if (o.getClass().isArray() && ((Object[]) o).length == 0) {
75: return Boolean.TRUE;
76: }
77:
78: if (o instanceof Collection && ((Collection) o).isEmpty()) {
79: return Boolean.TRUE;
80: }
81:
82: /*
83: * Map isn't a collection
84: */
85: if (o instanceof Map && ((Map) o).isEmpty()) {
86: return Boolean.TRUE;
87: }
88:
89: return Boolean.FALSE;
90: }
91: }
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