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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  
18  package org.apache.commons.jxpath;
19  
20  /**
21   * Extension function interface. Extension functions are grouped into {@link Functions Functions} objects, which are installed on JXPathContexts using the
22   * {@link JXPathContext#setFunctions JXPathContext.setFunctions()} call.
23   * <p>
24   * The Function interface can be implemented directly. However, most of the time JXPath's built-in implementations should suffice. See {@link ClassFunctions
25   * ClassFunctions} and {@link PackageFunctions PackageFunctions}.
26   */
27  public interface Function {
28  
29      /**
30       * Computes the value of the function. Each implementation of Function is responsible for conversion of supplied parameters to the required argument types.
31       *
32       * @param context    can be used to acquire the context in which the function is being evaluted.
33       * @param parameters function arguments
34       * @return Object result
35       */
36      Object invoke(ExpressionContext context, Object[] parameters);
37  }