/*
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999-2002 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
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 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
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 *    Foundation" must not be used to endorse or promote products derived
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 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
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 */

package org.apache.commons.discovery.resource.names;

import org.apache.commons.discovery.ResourceNameDiscover;
import org.apache.commons.discovery.ResourceNameIterator;
import org.apache.commons.discovery.log.DiscoveryLogFactory;
import org.apache.commons.logging.Log;


/**
 * Recover resource name from System Properties.
 * 
 * @author Richard A. Sitze
 */
public class DiscoverNamesInSystemProperties
    extends ResourceNameDiscoverImpl
    implements ResourceNameDiscover
{
    private static Log log = DiscoveryLogFactory.newLog(DiscoverNamesInSystemProperties.class);
    public static void setLog(Log _log) {
        log = _log;
    }
    
    /** Construct a new resource discoverer
     */
    public DiscoverNamesInSystemProperties() {
    }

    /**
     * @return Enumeration of ResourceInfo
     */
    public ResourceNameIterator findResourceNames(final String resourceName) {
        if (log.isDebugEnabled())
            log.debug("find: resourceName='" + resourceName + "'");

        return new ResourceNameIterator() {
            private String resource = System.getProperty(resourceName);
            
            public boolean hasNext() {
                return resource != null;
            }
            
            public String nextResourceName() {
                String element = resource;
                resource = null;
                return element;
            }
        };
    }
}