001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.el;
018
019 import java.util.List;
020 import java.util.Iterator;
021 import java.util.ArrayList;
022
023 import javax.servlet.jsp.el.ELException;
024 import javax.servlet.jsp.el.FunctionMapper;
025 import javax.servlet.jsp.el.VariableResolver;
026
027 /**
028 *
029 * <p>An expression representing a binary operator on a value
030 *
031 * @author Nathan Abramson - Art Technology Group
032 * @author Shawn Bayern
033 * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: bayard $
034 **/
035
036 public class BinaryOperatorExpression
037 extends Expression
038 {
039 //-------------------------------------
040 // Properties
041 //-------------------------------------
042 // property expression
043
044 Expression mExpression;
045 public Expression getExpression ()
046 { return mExpression; }
047 public void setExpression (Expression pExpression)
048 { mExpression = pExpression; }
049
050 //-------------------------------------
051 // property operators
052
053 List mOperators;
054 public List getOperators ()
055 { return mOperators; }
056 public void setOperators (List pOperators)
057 { mOperators = pOperators; }
058
059 //-------------------------------------
060 // property expressions
061
062 List mExpressions;
063 public List getExpressions ()
064 { return mExpressions; }
065 public void setExpressions (List pExpressions)
066 { mExpressions = pExpressions; }
067
068 //-------------------------------------
069 /**
070 *
071 * Constructor
072 **/
073 public BinaryOperatorExpression (Expression pExpression,
074 List pOperators,
075 List pExpressions)
076 {
077 mExpression = pExpression;
078 mOperators = pOperators;
079 mExpressions = pExpressions;
080 }
081
082 //-------------------------------------
083 // Expression methods
084 //-------------------------------------
085 /**
086 *
087 * Returns the expression in the expression language syntax
088 **/
089 public String getExpressionString ()
090 {
091 StringBuffer buf = new StringBuffer ();
092 buf.append ("(");
093 buf.append (mExpression.getExpressionString ());
094 for (int i = 0, size = mOperators.size(); i < size; i++) {
095 BinaryOperator operator = (BinaryOperator) mOperators.get (i);
096 Expression expression = (Expression) mExpressions.get (i);
097 buf.append (" ");
098 buf.append (operator.getOperatorSymbol ());
099 buf.append (" ");
100 buf.append (expression.getExpressionString ());
101 }
102 buf.append (")");
103
104 return buf.toString ();
105 }
106
107 //-------------------------------------
108 /**
109 *
110 * Evaluates to the literal value
111 **/
112 public Object evaluate (VariableResolver pResolver,
113 FunctionMapper functions)
114 throws ELException
115 {
116 Object value = mExpression.evaluate (pResolver, functions);
117 for (int i = 0, size = mOperators.size(); i < size; i++) {
118 BinaryOperator operator = (BinaryOperator) mOperators.get (i);
119
120 // For the And/Or operators, we need to coerce to a boolean
121 // before testing if we shouldEvaluate
122 if (operator.shouldCoerceToBoolean ()) {
123 value = Coercions.coerceToBoolean (value);
124 }
125
126 if (operator.shouldEvaluate (value)) {
127 Expression expression = (Expression) mExpressions.get (i);
128 Object nextValue = expression.evaluate (pResolver,
129 functions);
130
131 value = operator.apply (value, nextValue);
132 }
133 }
134 return value;
135 }
136
137 public Expression bindFunctions(final FunctionMapper functions) throws ELException {
138 final List args = new ArrayList(mExpressions.size());
139 for (Iterator argIter = mExpressions.iterator(); argIter.hasNext();) {
140 args.add(((Expression)argIter.next()).bindFunctions(functions));
141 }
142 // it would be nice if we knew for sure that the operators list
143 // was immutable, but we'll just assume so for now.
144 return new BinaryOperatorExpression(
145 mExpression.bindFunctions(functions),
146 mOperators,
147 args);
148 }
149
150 //-------------------------------------
151 }