package at.gv.egovernment.moa.util;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * Implementation of the <code>org.xml.sax.EntityResolver</code>,
 * for use by a <code>org.apache.xerces.parsers.DOMParser</code>.
 * 
 * @author Patrick Peck
 * @version $Id$
 */
public class EntityResolverChain implements EntityResolver {
  /** The <code>EntityResolver</code>s in the chain. */
  private List resolvers = new ArrayList();

  /**
   * @see org.xml.sax.EntityResolver#resolveEntity(java.lang.String, java.lang.String)
   */
  public InputSource resolveEntity(String publicId, String systemId)
    throws SAXException, IOException {
    
    Iterator iter;
    
    for (iter = resolvers.iterator(); iter.hasNext(); ) {
      EntityResolver resolver = (EntityResolver) iter.next();
      InputSource is = resolver.resolveEntity(publicId, systemId);
      
      if (is != null) {
        return is;
      }
    }
    
    return null;
  }
  
  /**
   * Add an <code>EntityResolver</code> to the chain.
   * 
   * @param entityResolver The <code>EntityResolver</code> to add.
   */
  public void addEntityResolver(EntityResolver entityResolver) {
    resolvers.add(entityResolver);
  }

}