001// Copyright 2008, 2011 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.corelib.components;
016
017import org.apache.tapestry5.annotations.Parameter;
018import org.apache.tapestry5.corelib.base.AbstractConditional;
019
020/**
021 * A close relative of the {@link org.apache.tapestry5.corelib.components.If} component that inverts the meaning of its
022 * test. This is easier than an {@link org.apache.tapestry5.corelib.components.If} component with the negate parameter set to {@code true}.
023 * 
024 * @tapestrydoc
025 */
026public class Unless extends AbstractConditional
027{
028    /**
029     * If true, then the body of the component is omitted. If false, the body is rendered.
030     */
031    @Parameter(required = true)
032    private boolean test;
033
034    /**
035     * @return test parameter inverted
036     */
037    protected boolean test()
038    {
039        return !test;
040    }
041}