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


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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
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