1 /*
2 * $Header: /home/cvs/jakarta-commons-sandbox/jelly/src/java/org/apache/commons/jelly/expression/jexl/JexlExpressionFactory.java,v 1.9 2002/08/12 10:28:51 jstrachan Exp $
3 * $Revision: 1.9 $
4 * $Date: 2002/08/12 10:28:51 $
5 *
6 * ====================================================================
7 *
8 * The Apache Software License, Version 1.1
9 *
10 * Copyright (c) 1999-2002 The Apache Software Foundation. All rights
11 * reserved.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 *
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 *
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in
22 * the documentation and/or other materials provided with the
23 * distribution.
24 *
25 * 3. The end-user documentation included with the redistribution, if
26 * any, must include the following acknowlegement:
27 * "This product includes software developed by the
28 * Apache Software Foundation (http://www.apache.org/)."
29 * Alternately, this acknowlegement may appear in the software itself,
30 * if and wherever such third-party acknowlegements normally appear.
31 *
32 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
33 * Foundation" must not be used to endorse or promote products derived
34 * from this software without prior written permission. For written
35 * permission, please contact apache@apache.org.
36 *
37 * 5. Products derived from this software may not be called "Apache"
38 * nor may "Apache" appear in their names without prior written
39 * permission of the Apache Group.
40 *
41 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
42 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
43 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
44 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
45 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
46 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
47 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
48 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
49 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
50 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
51 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * SUCH DAMAGE.
53 * ====================================================================
54 *
55 * This software consists of voluntary contributions made by many
56 * individuals on behalf of the Apache Software Foundation. For more
57 * information on the Apache Software Foundation, please see
58 * <http://www.apache.org/>.
59 *
60 * $Id: JexlExpressionFactory.java,v 1.9 2002/08/12 10:28:51 jstrachan Exp $
61 */
62
63 package org.apache.commons.jelly.expression.jexl;
64
65 import org.apache.commons.jelly.JellyContext;
66 import org.apache.commons.jelly.expression.Expression;
67 import org.apache.commons.jelly.expression.ExpressionSupport;
68 import org.apache.commons.jelly.expression.ExpressionFactory;
69
70 //import org.apache.commons.jexl.resolver.FlatResolver;
71
72 /***
73 * Represents a factory of <a href="http://jakarta.apache.org/commons/jexl.html">Jexl</a>
74 * expression which fully supports the Expression Language in JSTL and JSP.
75 * In addition this ExpressionFactory can also support Ant style variable
76 * names, where '.' is used inside variable names.
77 *
78 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
79 * @version $Revision: 1.9 $
80 */
81
82 public class JexlExpressionFactory implements ExpressionFactory {
83
84 /*** whether we should allow Ant-style expresssions, using dots as part of variable name */
85 private boolean supportAntVariables = true;
86
87 // ExpressionFactory interface
88 //-------------------------------------------------------------------------
89 public Expression createExpression(final String text) throws Exception {
90 /*
91
92 org.apache.commons.jexl.Expression expr =
93 org.apache.commons.jexl.ExpressionFactory.createExpression(text);
94
95 if ( isSupportAntVariables() ) {
96 expr.addPostResolver(new FlatResolver());
97 }
98
99 return new JexlExpression( expr );
100 */
101
102 final Expression jexlExpression = new JexlExpression(
103 org.apache.commons.jexl.ExpressionFactory.createExpression(text)
104 );
105
106 if ( isSupportAntVariables() && isValidAntVariableName(text) ) {
107 ExpressionSupport expr = new ExpressionSupport() {
108 public Object evaluate(JellyContext context) {
109 Object answer = jexlExpression.evaluate(context);
110
111 if ( answer == null ) {
112 answer = context.getVariable(text);
113 }
114
115 return answer;
116 }
117 };
118
119 return expr;
120 }
121 return jexlExpression;
122 }
123
124 // Properties
125 //-------------------------------------------------------------------------
126
127 /***
128 * @return whether we should allow Ant-style expresssions, using dots as
129 * part of variable name
130 */
131 public boolean isSupportAntVariables() {
132 return supportAntVariables;
133 }
134
135 /***
136 * Sets whether we should allow Ant-style expresssions, using dots as
137 * part of variable name
138 */
139 public void setSupportAntVariables(boolean supportAntVariables) {
140 this.supportAntVariables = supportAntVariables;
141 }
142
143 // Implementation methods
144 //-------------------------------------------------------------------------
145
146 /***
147 * @return true if the given string is a valid Ant variable name,
148 * typically thats alphanumeric text with '.' etc.
149 */
150 protected boolean isValidAntVariableName(String text) {
151 char[] chars = text.toCharArray();
152 for (int i = 0, size = chars.length; i < size; i++ ) {
153 char ch = chars[i];
154 // could maybe be a bit more restrictive...
155 if ( Character.isWhitespace(ch) || ch == '[' ) {
156 return false;
157 }
158 }
159 return true;
160 }
161
162 }
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