001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.jexl2;
018    
019    /**
020     * 
021     * This interface declares how to resolve a namespace from its name; it is used by the interpreter during evalutation.
022     * <p>
023     * In JEXL, a namespace is an object that serves the purpose of encapsulating functions; for instance,
024     * the "math" namespace would be the proper object to expose functions like "log(...)", "sinus(...)", etc.
025     * </p>
026     * In expressions like "ns:function(...)", the resolver is called with resolveNamespace("ns").
027     * <p>
028     * JEXL itself reserves 'jexl' and 'ujexl' as namespaces for internal purpose; resolving those may lead to unexpected
029     * results.
030     * </p>
031     * @since 2.1
032     */
033    public interface NamespaceResolver {
034        /**
035         * Resolves a namespace by its name.
036         * @param name the name
037         * @return the namespace object
038         */
039        Object resolveNamespace(String name);
040    }