/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.cocoon.selection;

import java.util.Map;

import org.apache.avalon.framework.parameters.Parameters;

/**
 * A very simple selector that operates on string literals, useful especially 
 * in conjunction with input modules. Usage example:
 * <pre>
 *    <map:selector name="simple" src="org.apache.cocoon.selection.SimpleSelector"/>
 * 
 *    <map:select type="simple">
 *       <map:parameter name="value" value="{request:method}"/>
 *       <map:when test="GET">
 *           ...
 *       </map:when>
 *       <map:when test="POST">
 *           ...
 *       </map:when>
 *       <map:when test="PUT">
 *           ...
 *       </map:when>
 *       <map:otherwise>
 *           ...
 *       </map:otherwise>
 *    </map:select>
 * </pre>
 * 
 * @author <a href="mailto:haul@apache.org">Christian Haul</a>
 * @version CVS $Id$
 * @since 2.1
 */
public class SimpleSelector extends AbstractSwitchSelector {

    public Object getSelectorContext(Map objectModel, Parameters parameters) {
        return parameters.getParameter("value", "");
    }

    public boolean select(String expression, Object selectorContext) {
        if (selectorContext == null) {
            if (getLogger().isWarnEnabled()) 
                getLogger().warn("Value not set -- failing.");
            return false;
        }

        return selectorContext.equals(expression);
    }

}