View Javadoc

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 13:46:46 -0400 (Fri, 02 May 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  }