001: /*
002: * Copyright (c) 1998-2008 Caucho Technology -- all rights reserved
003: *
004: * This file is part of Resin(R) Open Source
005: *
006: * Each copy or derived work must preserve the copyright notice and this
007: * notice unmodified.
008: *
009: * Resin Open Source is free software; you can redistribute it and/or modify
010: * it under the terms of the GNU General Public License as published by
011: * the Free Software Foundation; either version 2 of the License, or
012: * (at your option) any later version.
013: *
014: * Resin Open Source is distributed in the hope that it will be useful,
015: * but WITHOUT ANY WARRANTY; without even the implied warranty of
016: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
017: * of NON-INFRINGEMENT. See the GNU General Public License for more
018: * details.
019: *
020: * You should have received a copy of the GNU General Public License
021: * along with Resin Open Source; if not, write to the
022: *
023: * Free SoftwareFoundation, Inc.
024: * 59 Temple Place, Suite 330
025: * Boston, MA 02111-1307 USA
026: *
027: * @author Scott Ferguson
028: */
029:
030: package com.caucho.el;
031:
032: import com.caucho.vfs.WriteStream;
033:
034: import javax.el.ELContext;
035: import javax.el.ELException;
036: import java.io.IOException;
037:
038: /**
039: * Represents a conditional expression
040: */
041: public class ConditionalExpr extends Expr {
042: private Expr _test;
043: private Expr _trueExpr;
044: private Expr _falseExpr;
045:
046: /**
047: * Creates the conditional expression.
048: *
049: * @param test the conditional expressions test.
050: * @param trueExpr the true subexpression
051: * @param falseExpr the false subexpression
052: */
053: public ConditionalExpr(Expr test, Expr trueExpr, Expr falseExpr) {
054: _test = test;
055: _trueExpr = trueExpr;
056: _falseExpr = falseExpr;
057: }
058:
059: /**
060: * Returns true if this is a constant expression.
061: */
062: @Override
063: public boolean isConstant() {
064: return (_test.isConstant() && _trueExpr.isConstant() && _falseExpr
065: .isConstant());
066: }
067:
068: /**
069: * Evaluate the expression as an object.
070: *
071: * @param env the variable environment
072: *
073: * @return the result as an object
074: */
075: @Override
076: public Object getValue(ELContext env) throws ELException {
077: if (_test.evalBoolean(env))
078: return _trueExpr.getValue(env);
079: else
080: return _falseExpr.getValue(env);
081: }
082:
083: /**
084: * Evaluate the expression as a long
085: *
086: * @param env the variable environment
087: *
088: * @return the result as an long
089: */
090: @Override
091: public long evalLong(ELContext env) throws ELException {
092: if (_test.evalBoolean(env))
093: return _trueExpr.evalLong(env);
094: else
095: return _falseExpr.evalLong(env);
096: }
097:
098: /**
099: * Evaluate the expression as a double
100: *
101: * @param env the variable environment
102: *
103: * @return the result as an double
104: */
105: @Override
106: public double evalDouble(ELContext env) throws ELException {
107: if (_test.evalBoolean(env))
108: return _trueExpr.evalDouble(env);
109: else
110: return _falseExpr.evalDouble(env);
111: }
112:
113: /**
114: * Evaluate the expression as a string
115: *
116: * @param env the variable environment
117: *
118: * @return the result as a string
119: */
120: @Override
121: public String evalString(ELContext env) throws ELException {
122: if (_test.evalBoolean(env))
123: return _trueExpr.evalString(env);
124: else
125: return _falseExpr.evalString(env);
126: }
127:
128: /**
129: * Evaluate the expression as a boolean
130: *
131: * @param env the variable environment
132: *
133: * @return the result as a boolean
134: */
135: @Override
136: public boolean evalBoolean(ELContext env) throws ELException {
137: if (_test.evalBoolean(env))
138: return _trueExpr.evalBoolean(env);
139: else
140: return _falseExpr.evalBoolean(env);
141: }
142:
143: /**
144: * Prints the Java code to recreate the expr
145: *
146: * @param os the output stream to the *.java file
147: */
148: @Override
149: public void printCreate(WriteStream os) throws IOException {
150: os.print("new com.caucho.el.ConditionalExpr(");
151: _test.printCreate(os);
152: os.print(", ");
153: _trueExpr.printCreate(os);
154: os.print(", ");
155: _falseExpr.printCreate(os);
156: os.print(")");
157: }
158:
159: /**
160: * Returns true for equal strings.
161: */
162: public boolean equals(Object o) {
163: if (!(o instanceof ConditionalExpr))
164: return false;
165:
166: ConditionalExpr expr = (ConditionalExpr) o;
167:
168: return (_test == expr._test && _trueExpr.equals(expr._trueExpr) && _falseExpr
169: .equals(expr._falseExpr));
170: }
171:
172: /**
173: * Returns a readable representation of the expr.
174: */
175: public String toString() {
176: return "(" + _test + " ? " + _trueExpr + " : " + _falseExpr
177: + ")";
178: }
179: }
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