freemarker-core/src/main/java/freemarker/template/TemplateHashModel.java

/*
 * 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 freemarker.template;

/**
 * "hash" template language data type: an object that contains other objects accessible through string keys
 * (sub-variable names). It, in itself, doesn't support listing the keys or values ({@link TemplateHashModelEx} does).
 * 
 * <p>In templates they are used like {@code myHash.myKey} or {@code myHash[myDynamicKey]}.
 */
public interface TemplateHashModel extends TemplateModel {
    
    /**
     * Gets a {@code TemplateModel} from the hash.
     *
     * @param key the name by which the {@code TemplateModel}
     * is identified in the template.
     * @return the {@code TemplateModel} referred to by the key,
     * or null if not found.
     */
    TemplateModel get(String key) throws TemplateModelException;

    boolean isEmpty() throws TemplateModelException;
}