001    /*
002     $Id: ConstantExpression.java,v 1.8 2005/02/01 10:46:54 russel Exp $
003    
004     Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved.
005    
006     Redistribution and use of this software and associated documentation
007     ("Software"), with or without modification, are permitted provided
008     that the following conditions are met:
009    
010     1. Redistributions of source code must retain copyright
011        statements and notices.  Redistributions must also contain a
012        copy of this document.
013    
014     2. Redistributions in binary form must reproduce the
015        above copyright notice, this list of conditions and the
016        following disclaimer in the documentation and/or other
017        materials provided with the distribution.
018    
019     3. The name "groovy" must not be used to endorse or promote
020        products derived from this Software without prior written
021        permission of The Codehaus.  For written permission,
022        please contact info@codehaus.org.
023    
024     4. Products derived from this Software may not be called "groovy"
025        nor may "groovy" appear in their names without prior written
026        permission of The Codehaus. "groovy" is a registered
027        trademark of The Codehaus.
028    
029     5. Due credit should be given to The Codehaus -
030        http://groovy.codehaus.org/
031    
032     THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
033     ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
034     NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
035     FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
036     THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
037     INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
038     (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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042     ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
043     OF THE POSSIBILITY OF SUCH DAMAGE.
044    
045     */
046    package org.codehaus.groovy.ast.expr;
047    
048    import org.codehaus.groovy.ast.GroovyCodeVisitor;
049    import org.codehaus.groovy.classgen.AsmClassGenerator;
050    
051    /**
052     * Represents a constant expression such as null, true, false
053     * 
054     * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
055     * @version $Revision: 1.8 $
056     */
057    public class ConstantExpression extends Expression {
058        public static final ConstantExpression VOID = new ConstantExpression(Void.class);
059        public static final ConstantExpression NULL = new ConstantExpression(null);
060        public static final ConstantExpression TRUE = new ConstantExpression(Boolean.TRUE);
061        public static final ConstantExpression FALSE = new ConstantExpression(Boolean.FALSE);
062        public static final ConstantExpression EMPTY_STRING = new ConstantExpression("");
063        //public static final Expression EMPTY_ARRAY = new PropertyExpression(new ClassExpression(ArgumentListExpression.class.getName()), "EMPTY_ARRAY");
064    
065        private Object value;
066        
067        public ConstantExpression(Object value) {
068            this.value = value;
069            if (this.value != null)
070                setTypeClass(value.getClass());
071        }
072    
073        public String toString() {
074            return super.toString() +"[value=" + value + "]";
075        }
076    
077        public void visit(GroovyCodeVisitor visitor) {
078            visitor.visitConstantExpression(this);
079        }
080    
081    
082        public Expression transformExpression(ExpressionTransformer transformer) {
083            return this;
084        }
085    
086        protected void resolveType(AsmClassGenerator resolver) {
087            //
088        }
089    
090        /**
091         * @return the value of this constant expression
092         */    
093        public Object getValue() {
094            return value;
095        }
096    
097        public String getText() {
098            return (value == null) ? "null" : value.toString();
099        }
100    }