augmentations.java

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/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2000-2002 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. 
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 *    distribution.
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 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 * 4. The names "Xerces" and "Apache Software Foundation" must
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 * 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 and was
 * originally based on software copyright (c) 1999, International
 * Business Machines, Inc., http://www.apache.org.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package com.sun.org.apache.xerces.internal.xni;

import java.util.Enumeration;

/**
 * The Augmentations interface defines a table of additional data that may
 * be passed along the document pipeline. The information can contain extra
 * arguments or infoset augmentations, for example PSVI. This additional
 * information is identified by a String key.
 * <p>
 * <strong>Note:</strong>
 * Methods that receive Augmentations are required to copy the information
 * if it is to be saved for use beyond the scope of the method.
 * The Augmentations content is volatile, and maybe modified by any method in
 * any component in the pipeline. Therefore, methods passed this structure
 * should not save any reference to the structure.
 * 
 * @author Elena Litani, IBM
 * @version $Id: Augmentations.java,v 1.6 2003/01/23 17:27:12 sandygao Exp $
 */

public interface Augmentations {
    
    
    /**
     * Add additional information identified by a key to the Augmentations structure.
     * 
     * @param key    Identifier, can't be <code>null</code>
     * @param item   Additional information
     *
     * @return the previous value of the specified key in the Augmentations structure,
     *         or <code>null</code> if it did not have one.
     */
    public Object putItem (String key, Object item);


    /**
     * Get information identified by a key from the Augmentations structure
     * 
     * @param key    Identifier, can't be <code>null</code>
     *
     * @return the value to which the key is mapped in the Augmentations structure;
     *         <code>null</code> if the key is not mapped to any value.
     */
    public Object getItem(String key);
    
    
    /**
     * Remove additional info from the Augmentations structure
     * 
     * @param key    Identifier, can't be <code>null</code>
     * @return the previous value of the specified key in the Augmentations structure,
     *         or <code>null</code> if it did not have one.
     */
    public Object removeItem (String key);

    
    /**
     * Returns an enumeration of the keys in the Augmentations structure
     *
     */
    public Enumeration keys ();


    /**
     * Remove all objects from the Augmentations structure.
     */
    public void removeAllItems ();

}