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'rapiddweller Script' is an open source software library for resolving Java-like script expressions, forked from Databene Scripts written by Volker Bergmann.

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/*
 * Copyright (C) 2011-2014 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * 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 com.rapiddweller.script.expression;

import com.rapiddweller.commons.Context;
import com.rapiddweller.script.Expression;

/**
 * Expression that returns true, if a source expression returns null, 
 * else false.


 * Created: 08.10.2010 23:04:01
 * @since 0.5.4
 * @author Volker Bergmann
 */
public class IsNullExpression extends UnaryExpression {

	public IsNullExpression(Expression term) {
	    super("", term);
    }

	@Override
	public Boolean evaluate(Context context) {
	    return term.evaluate(context) == null;
    }

	@Override
	public String toString() {
		return "(" + term + "IS NULL)";
	}
	
}