1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.jxpath;
18
19 /**
20 * Extension function interface. Extension functions are grouped into
21 * {@link Functions Functions} objects, which are installed on
22 * JXPathContexts using the
23 * {@link JXPathContext#setFunctions JXPathContext.setFunctions()}
24 * call.
25 * <p>
26 * The Function interface can be implemented directly. However,
27 * most of the time JXPath's built-in implementations should suffice.
28 * See {@link ClassFunctions ClassFunctions} and
29 * {@link PackageFunctions PackageFunctions}.
30 *
31 * @author Dmitri Plotnikov
32 * @version $Revision: 652845 $ $Date: 2008-05-02 19:46:46 +0200 (Fr, 02 Mai 2008) $
33 */
34 public interface Function {
35
36 /**
37 * Computes the value of the function. Each implementation of Function
38 * is responsible for conversion of supplied parameters to the required
39 * argument types.
40 *
41 * @param context can be used to acquire the context in which the
42 * function is being evaluted.
43 * @param parameters function arguments
44 * @return Object result
45 */
46 Object invoke(ExpressionContext context, Object[] parameters);
47 }