    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
    018package org.apache.commons.jxpath;
    019
    020/**
    021 * Extension function interface. Extension functions are grouped into {@link Functions Functions} objects, which are installed on JXPathContexts using the
    022 * {@link JXPathContext#setFunctions JXPathContext.setFunctions()} call.
    023 * <p>
    024 * The Function interface can be implemented directly. However, most of the time JXPath's built-in implementations should suffice. See {@link ClassFunctions
    025 * ClassFunctions} and {@link PackageFunctions PackageFunctions}.
    026 */
    027public interface Function {
    028
    029    /**
    030     * Computes the value of the function. Each implementation of Function is responsible for conversion of supplied parameters to the required argument types.
    031     *
    032     * @param context    can be used to acquire the context in which the function is being evaluted.
    033     * @param parameters function arguments
    034     * @return Object result
    035     */
    036    Object invoke(ExpressionContext context, Object[] parameters);
    037}