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


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 package org.apache.commons.jexl.parser;
17
18 import java.lang.reflect.Array JavaDoc;
19 import java.util.Collection JavaDoc;
20 import java.util.Map JavaDoc;
21
22 import org.apache.commons.jexl.JexlContext;
23 import org.apache.commons.jexl.util.Introspector;
24 import org.apache.commons.jexl.util.introspection.Info;
25 import org.apache.commons.jexl.util.introspection.VelMethod;
26
27 /**
28  * generalized size() function for all classes we can think of.
29  *
30  * @author <a HREF="mailto:geirm@apache.org">Geir Magnusson Jr.</a>
31  * @author <a HREF="hw@kremvax.net">Mark H. Wilkinson</a>
32  * @version $Id: ASTSizeFunction.java 398324 2006-04-30 12:20:24Z dion $
33  */
34 public class ASTSizeFunction extends SimpleNode {
35     /**
36      * Create the node given an id.
37      *
38      * @param id node id.
39      */
40     public ASTSizeFunction(int id) {
41         super(id);
42     }
43
44     /**
45      * Create a node with the given parser and id.
46      *
47      * @param p a parser.
48      * @param id node id.
49      */
50     public ASTSizeFunction(Parser p, int id) {
51         super(p, id);
52     }
53
54     /** {@inheritDoc} */
55     public Object JavaDoc jjtAccept(ParserVisitor visitor, Object JavaDoc data) {
56         return visitor.visit(this, data);
57     }
58
59     /** {@inheritDoc} */
60     public Object JavaDoc value(JexlContext jc) throws Exception JavaDoc {
61         SimpleNode arg = (SimpleNode) jjtGetChild(0);
62
63         Object JavaDoc val = arg.value(jc);
64
65         if (val == null) {
66             throw new Exception JavaDoc("size() : null arg");
67         }
68
69         return new Integer JavaDoc(ASTSizeFunction.sizeOf(val));
70     }
71
72     /**
73      * Calculate the <code>size</code> of various types: Collection, Array, Map, String,
74      * and anything that has a int size() method.
75      *
76      * @param val the object to get the size of.
77      * @return the size of val
78      * @throws Exception if the size cannot be determined.
79      */
80     public static int sizeOf(Object JavaDoc val) throws Exception JavaDoc {
81         if (val instanceof Collection JavaDoc) {
82             return ((Collection JavaDoc) val).size();
83         } else if (val.getClass().isArray()) {
84             return Array.getLength(val);
85         } else if (val instanceof Map JavaDoc) {
86             return ((Map JavaDoc) val).size();
87         } else if (val instanceof String JavaDoc) {
88             return ((String JavaDoc) val).length();
89         } else {
90             // check if there is a size method on the object that returns an
91 // integer
92 // and if so, just use it
93 Object JavaDoc[] params = new Object JavaDoc[0];
94             Info velInfo = new Info("", 1, 1);
95             VelMethod vm = Introspector.getUberspect().getMethod(val, "size", params, velInfo);
96             if (vm != null && vm.getReturnType() == Integer.TYPE) {
97                 Integer JavaDoc result = (Integer JavaDoc) vm.invoke(val, params);
98                 return result.intValue();
99             }
100             throw new Exception JavaDoc("size() : unknown type : " + val.getClass());
101         }
102     }
103
104 }
105
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