src/main/java/freemarker/template/TemplateHashModelEx.java

/*
 * Copyright (c) 2003 The Visigoth Software Society. All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
 * 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.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Visigoth Software Society (http://www.visigoths.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the 
 *    project contributors may be used to endorse or promote products derived
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 * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
 *    nor may "FreeMarker" or "Visigoth" appear in their names
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 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Visigoth Software Society. For more
 * information on the Visigoth Software Society, please see
 * http://www.visigoths.org/
 */

package freemarker.template;

/**
 * "extended hash" template language data type; extends {@link TemplateHashModel} by allowing
 * iterating through its keys and values.
 * 
 * <p>In templates they are used like hashes, but these will also work (among others):
 * {@code myExtHash?size}, {@code myExtHash?keys}, {@code myExtHash?values}.
 * 
 * @author <a href="mailto:jon@revusky.com">Jonathan Revusky</a>
 * @see SimpleHash
 */
public interface TemplateHashModelEx extends TemplateHashModel {

    /**
     * @return the number of key/value mappings in the hash.
     */
    int size() throws TemplateModelException;

    /**
     * @return a collection containing the keys in the hash. Every element of 
     *      the returned collection must implement the {@link TemplateScalarModel}
     *      (as the keys of hashes are always strings).
     */
    TemplateCollectionModel keys() throws TemplateModelException;

    /**
     * @return a collection containing the values in the hash. The elements of the
     * returned collection can be any kind of {@link TemplateModel}-s.
     */
    TemplateCollectionModel values() throws TemplateModelException;
}