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Groovy: A powerful, dynamic language for the JVM
/*
* Copyright 2003-2007 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.codehaus.groovy.ast.expr;
import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.GroovyCodeVisitor;
/**
* Represents a constant expression such as null, true, false
*
* @author James Strachan
* @version $Revision: 12194 $
*/
public class ConstantExpression extends Expression {
// The following fields are only used internally; every occurrence of a user-defined expression of the same kind
// has its own instance so as to preserve line information. Consequently, to test for such an expression, don't
// compare against the field but call isXXXExpression() instead.
public static final ConstantExpression NULL = new ConstantExpression(null);
public static final ConstantExpression TRUE = new ConstantExpression(Boolean.TRUE);
public static final ConstantExpression FALSE = new ConstantExpression(Boolean.FALSE);
public static final ConstantExpression EMPTY_STRING = new ConstantExpression("");
//public static final Expression EMPTY_ARRAY = new PropertyExpression(new ClassExpression(ArgumentListExpression.class.getName()), "EMPTY_ARRAY");
// the following fields are only used internally; there are no user-defined expressions of the same kind
public static final ConstantExpression VOID = new ConstantExpression(Void.class);
public static final ConstantExpression EMTPY_EXPRESSION = new ConstantExpression(null);
private Object value;
private String constantName;
public ConstantExpression(Object value) {
this.value = value;
if (this.value != null)
setType(ClassHelper.make(value.getClass()));
}
public String toString() {
return "ConstantExpression[" + value + "]";
}
public void visit(GroovyCodeVisitor visitor) {
visitor.visitConstantExpression(this);
}
public Expression transformExpression(ExpressionTransformer transformer) {
return this;
}
/**
* @return the value of this constant expression
*/
public Object getValue() {
return value;
}
public String getText() {
return (value == null) ? "null" : value.toString();
}
public String getConstantName() {
return constantName;
}
public void setConstantName(String constantName) {
this.constantName = constantName;
}
public boolean isNullExpression() {
return value == null;
}
public boolean isTrueExpression() {
return Boolean.TRUE.equals(value);
}
public boolean isFalseExpression() {
return Boolean.FALSE.equals(value);
}
public boolean isEmptyStringExpression() {
return "".equals(value);
}
}