001: /* ====================================================================
002: * Tea - Copyright (c) 1997-2000 Walt Disney Internet Group
003: * ====================================================================
004: * The Tea Software License, Version 1.1
005: *
006: * Copyright (c) 2000 Walt Disney Internet Group. All rights reserved.
007: *
008: * Redistribution and use in source and binary forms, with or without
009: * modification, are permitted provided that the following conditions
010: * are met:
011: *
012: * 1. Redistributions of source code must retain the above copyright
013: * notice, this list of conditions and the following disclaimer.
014: *
015: * 2. Redistributions in binary form must reproduce the above copyright
016: * notice, this list of conditions and the following disclaimer in
017: * the documentation and/or other materials provided with the
018: * distribution.
019: *
020: * 3. The end-user documentation included with the redistribution,
021: * if any, must include the following acknowledgment:
022: * "This product includes software developed by the
023: * Walt Disney Internet Group (http://opensource.go.com/)."
024: * Alternately, this acknowledgment may appear in the software itself,
025: * if and wherever such third-party acknowledgments normally appear.
026: *
027: * 4. The names "Tea", "TeaServlet", "Kettle", "Trove" and "BeanDoc" must
028: * not be used to endorse or promote products derived from this
029: * software without prior written permission. For written
030: * permission, please contact opensource@dig.com.
031: *
032: * 5. Products derived from this software may not be called "Tea",
033: * "TeaServlet", "Kettle" or "Trove", nor may "Tea", "TeaServlet",
034: * "Kettle", "Trove" or "BeanDoc" appear in their name, without prior
035: * written permission of the Walt Disney Internet Group.
036: *
037: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
038: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
039: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
040: * DISCLAIMED. IN NO EVENT SHALL THE WALT DISNEY INTERNET GROUP OR ITS
041: * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
042: * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
043: * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
044: * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
045: * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
046: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
047: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
048: * ====================================================================
049: *
050: * For more information about Tea, please see http://opensource.go.com/.
051: */
052:
053: package com.go.tea.parsetree;
054:
055: import com.go.tea.compiler.SourceInfo;
056: import com.go.tea.compiler.Type;
057:
058: /******************************************************************************
059: * NegateExpression is a simple unary expression that calculates the negative
060: * value of an expression. The expression it operates on must return a
061: * Number type.
062: *
063: * @author Brian S O'Neill
064: * @version
065: * <!--$$Revision:--> 19 <!-- $-->, <!--$$JustDate:--> 9/07/00 <!-- $-->
066: */
067: public class NegateExpression extends Expression {
068: private Expression mExpr;
069:
070: public NegateExpression(SourceInfo info, Expression expr) {
071: super (info);
072: mExpr = expr;
073: }
074:
075: public Object accept(NodeVisitor visitor) {
076: return visitor.visit(this );
077: }
078:
079: public Object clone() {
080: NegateExpression ne = (NegateExpression) super .clone();
081: ne.mExpr = (Expression) mExpr.clone();
082: return ne;
083: }
084:
085: public boolean isExceptionPossible() {
086: if (mExpr != null) {
087: if (mExpr.isExceptionPossible()) {
088: return true;
089: }
090: Type type = mExpr.getType();
091: if (type != null && type.isNullable()) {
092: return true;
093: }
094: }
095: return false;
096: }
097:
098: public void setType(Type type) {
099: // NegateExpressions never evaluate to null.
100: super .setType(type.toNonNull());
101: }
102:
103: public Expression getExpression() {
104: return mExpr;
105: }
106:
107: public void setExpression(Expression expr) {
108: mExpr = expr;
109: }
110: }
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