KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > apache > commons > el > BinaryOperatorExpression


1 /*
2  * The Apache Software License, Version 1.1
3  *
4  * Copyright (c) 1999 The Apache Software Foundation. All rights
5  * reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  * notice, this list of conditions and the following disclaimer.
13  *
14  * 2. Redistributions in binary form must reproduce the above copyright
15  * notice, this list of conditions and the following disclaimer in
16  * the documentation and/or other materials provided with the
17  * distribution.
18  *
19  * 3. The end-user documentation included with the redistribution, if
20  * any, must include the following acknowlegement:
21  * "This product includes software developed by the
22  * Apache Software Foundation (http://www.apache.org/)."
23  * Alternately, this acknowlegement may appear in the software itself,
24  * if and wherever such third-party acknowlegements normally appear.
25  *
26  * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
27  * Foundation" must not be used to endorse or promote products derived
28  * from this software without prior written permission. For written
29  * permission, please contact apache@apache.org.
30  *
31  * 5. Products derived from this software may not be called "Apache"
32  * nor may "Apache" appear in their names without prior written
33  * permission of the Apache Group.
34  *
35  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
36  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
37  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
38  * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
39  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
41  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
42  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
43  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
44  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
45  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
46  * SUCH DAMAGE.
47  * ====================================================================
48  *
49  * This software consists of voluntary contributions made by many
50  * individuals on behalf of the Apache Software Foundation. For more
51  * information on the Apache Software Foundation, please see
52  * <http://www.apache.org/>.
53  *
54  */

55
56 package org.apache.commons.el;
57
58 import java.util.List JavaDoc;
59 import java.util.Map JavaDoc;
60 import javax.servlet.jsp.el.ELException JavaDoc;
61 import javax.servlet.jsp.el.VariableResolver JavaDoc;
62 import javax.servlet.jsp.el.FunctionMapper JavaDoc;
63
64 /**
65  *
66  * <p>An expression representing a binary operator on a value
67  *
68  * @author Nathan Abramson - Art Technology Group
69  * @author Shawn Bayern
70  * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: luehe $
71  **/

72
73 public class BinaryOperatorExpression
74   extends Expression
75 {
76   //-------------------------------------
77
// Properties
78
//-------------------------------------
79
// property expression
80

81   Expression mExpression;
82   public Expression getExpression ()
83   { return mExpression; }
84   public void setExpression (Expression pExpression)
85   { mExpression = pExpression; }
86
87   //-------------------------------------
88
// property operators
89

90   List JavaDoc mOperators;
91   public List JavaDoc getOperators ()
92   { return mOperators; }
93   public void setOperators (List JavaDoc pOperators)
94   { mOperators = pOperators; }
95
96   //-------------------------------------
97
// property expressions
98

99   List JavaDoc mExpressions;
100   public List JavaDoc getExpressions ()
101   { return mExpressions; }
102   public void setExpressions (List JavaDoc pExpressions)
103   { mExpressions = pExpressions; }
104
105   //-------------------------------------
106
/**
107    *
108    * Constructor
109    **/

110   public BinaryOperatorExpression (Expression pExpression,
111                    List JavaDoc pOperators,
112                    List JavaDoc pExpressions)
113   {
114     mExpression = pExpression;
115     mOperators = pOperators;
116     mExpressions = pExpressions;
117   }
118
119   //-------------------------------------
120
// Expression methods
121
//-------------------------------------
122
/**
123    *
124    * Returns the expression in the expression language syntax
125    **/

126   public String JavaDoc getExpressionString ()
127   {
128     StringBuffer JavaDoc buf = new StringBuffer JavaDoc ();
129     buf.append ("(");
130     buf.append (mExpression.getExpressionString ());
131     for (int i = 0; i < mOperators.size (); i++) {
132       BinaryOperator operator = (BinaryOperator) mOperators.get (i);
133       Expression expression = (Expression) mExpressions.get (i);
134       buf.append (" ");
135       buf.append (operator.getOperatorSymbol ());
136       buf.append (" ");
137       buf.append (expression.getExpressionString ());
138     }
139     buf.append (")");
140
141     return buf.toString ();
142   }
143
144   //-------------------------------------
145
/**
146    *
147    * Evaluates to the literal value
148    **/

149   public Object JavaDoc evaluate (VariableResolver JavaDoc pResolver,
150               FunctionMapper JavaDoc functions,
151               Logger pLogger)
152     throws ELException JavaDoc
153   {
154     Object JavaDoc value = mExpression.evaluate (pResolver, functions, pLogger);
155     for (int i = 0; i < mOperators.size (); i++) {
156       BinaryOperator operator = (BinaryOperator) mOperators.get (i);
157
158       // For the And/Or operators, we need to coerce to a boolean
159
// before testing if we shouldEvaluate
160
if (operator.shouldCoerceToBoolean ()) {
161     value = Coercions.coerceToBoolean (value, pLogger);
162       }
163
164       if (operator.shouldEvaluate (value)) {
165     Expression expression = (Expression) mExpressions.get (i);
166     Object JavaDoc nextValue = expression.evaluate (pResolver,
167                         functions,
168                         pLogger);
169
170     value = operator.apply (value, nextValue, pLogger);
171       }
172     }
173     return value;
174   }
175
176   //-------------------------------------
177
}
178
Popular Tags