/*
 * Copyright  2002-2004 The Apache Software Foundation
 *
 *  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.apache.tools.ant.taskdefs.condition;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.ProjectComponent;

/**
 * Condition that tests whether a given string evals to false
 *
 * @since Ant 1.5
 */
public class IsFalse extends ProjectComponent implements Condition {
    /**
     * what we eval
     */
    private Boolean value = null;

    /**
     * set the value to be tested; let ant eval it to true/false
     * @param value the value to test
     */
    public void setValue(boolean value) {
        this.value = value ? Boolean.TRUE : Boolean.FALSE;
    }

    /**
     * @return the inverted value;
     * @throws BuildException if someone forgot to spec a value
     */
    public boolean eval() throws BuildException {
        if (value == null) {
            throw new BuildException("Nothing to test for falsehood");
        }
        return !value.booleanValue();
    }

}