001: /*
002: * The Apache Software License, Version 1.1
003: *
004: * Copyright (c) 1999 The Apache Software Foundation. All rights
005: * reserved.
006: *
007: * Redistribution and use in source and binary forms, with or without
008: * modification, are permitted provided that the following conditions
009: * are met:
010: *
011: * 1. Redistributions of source code must retain the above copyright
012: * notice, this list of conditions and the following disclaimer.
013: *
014: * 2. Redistributions in binary form must reproduce the above copyright
015: * notice, this list of conditions and the following disclaimer in
016: * the documentation and/or other materials provided with the
017: * distribution.
018: *
019: * 3. The end-user documentation included with the redistribution, if
020: * any, must include the following acknowlegement:
021: * "This product includes software developed by the
022: * Apache Software Foundation (http://www.apache.org/)."
023: * Alternately, this acknowlegement may appear in the software itself,
024: * if and wherever such third-party acknowlegements normally appear.
025: *
026: * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
027: * Foundation" must not be used to endorse or promote products derived
028: * from this software without prior written permission. For written
029: * permission, please contact apache@apache.org.
030: *
031: * 5. Products derived from this software may not be called "Apache"
032: * nor may "Apache" appear in their names without prior written
033: * permission of the Apache Group.
034: *
035: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
036: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
037: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
038: * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
039: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
040: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
041: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
042: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
043: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
044: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
045: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
046: * SUCH DAMAGE.
047: * ====================================================================
048: *
049: * This software consists of voluntary contributions made by many
050: * individuals on behalf of the Apache Software Foundation. For more
051: * information on the Apache Software Foundation, please see
052: * <http://www.apache.org/>.
053: *
054: */
055:
056: package org.apache.commons.el;
057:
058: import java.util.List;
059: import java.util.Map;
060: import javax.servlet.jsp.el.ELException;
061: import javax.servlet.jsp.el.VariableResolver;
062: import javax.servlet.jsp.el.FunctionMapper;
063:
064: /**
065: *
066: * <p>Represents a conditional expression. I've decided not to produce an
067: * abstract base "TernaryOperatorExpression" class since (a) future ternary
068: * operators are unlikely and (b) it's not clear that there would be a
069: * meaningful way to abstract them. (For instance, would they all be right-
070: * associative? Would they all have two fixed operator symbols?)
071: *
072: * @author Shawn Bayern
073: **/
074:
075: public class ConditionalExpression extends Expression {
076: //-------------------------------------
077: // Properties
078: //-------------------------------------
079: // property condition
080:
081: Expression mCondition;
082:
083: public Expression getCondition() {
084: return mCondition;
085: }
086:
087: public void setCondition(Expression pCondition) {
088: mCondition = pCondition;
089: }
090:
091: //-------------------------------------
092: // property trueBranch
093:
094: Expression mTrueBranch;
095:
096: public Expression getTrueBranch() {
097: return mTrueBranch;
098: }
099:
100: public void setTrueBranch(Expression pTrueBranch) {
101: mTrueBranch = pTrueBranch;
102: }
103:
104: //-------------------------------------
105: // property falseBranch
106:
107: Expression mFalseBranch;
108:
109: public Expression getFalseBranch() {
110: return mFalseBranch;
111: }
112:
113: public void setFalseBranch(Expression pFalseBranch) {
114: mFalseBranch = pFalseBranch;
115: }
116:
117: //-------------------------------------
118: /**
119: *
120: * Constructor
121: **/
122: public ConditionalExpression(Expression pCondition,
123: Expression pTrueBranch, Expression pFalseBranch) {
124: mCondition = pCondition;
125: mTrueBranch = pTrueBranch;
126: mFalseBranch = pFalseBranch;
127: }
128:
129: //-------------------------------------
130: // Expression methods
131: //-------------------------------------
132: /**
133: *
134: * Returns the expression in the expression language syntax
135: **/
136: public String getExpressionString() {
137: return "( " + mCondition.getExpressionString() + " ? "
138: + mTrueBranch.getExpressionString() + " : "
139: + mFalseBranch.getExpressionString() + " )";
140: }
141:
142: //-------------------------------------
143: /**
144: *
145: * Evaluates the conditional expression and returns the literal result
146: **/
147: public Object evaluate(VariableResolver vr, FunctionMapper f,
148: Logger l) throws ELException {
149: // first, evaluate the condition (and coerce the result to a boolean value)
150: boolean condition = Coercions.coerceToBoolean(
151: mCondition.evaluate(vr, f, l), l).booleanValue();
152:
153: // then, use this boolean to branch appropriately
154: if (condition)
155: return mTrueBranch.evaluate(vr, f, l);
156: else
157: return mFalseBranch.evaluate(vr, f, l);
158: }
159:
160: //-------------------------------------
161: }
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