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    1   /*
    2    * Copyright 1999-2004 The Apache Software Foundation
    3    *
    4    * Licensed under the Apache License, Version 2.0 (the "License");
    5    * you may not use this file except in compliance with the License.
    6    * You may obtain a copy of the License at
    7    *
    8    *     http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  package org.apache.commons.jxpath;
    17
    18  /***
    19   * Extension function interface. Extension functions are grouped into
    20   * {@link Functions Functions} objects, which are installed on
    21   * JXPathContexts using the
    22   * {@link JXPathContext#setFunctions JXPathContext.setFunctions()}
    23   * call.
    24   * <p>
    25   * The Function interface can be implemented directly. However,
    26   * most of the time JXPath's built-in implementations should suffice.
    27   * See {@link ClassFunctions ClassFunctions} and
    28   * {@link PackageFunctions PackageFunctions}.
    29   *
    30   * @author Dmitri Plotnikov
    31   * @version $Revision: 1.7 $ $Date: 2004/02/29 14:17:42 $
    32   */
    33  public interface Function {
    34
    35      /***
    36       * Computes the value of the function. Each implementation of Function
    37       * is responsible for conversion of supplied parameters to the required
    38       * argument types.
    39       *
    40       * @param context can be used to acquire the context in which the
    41       *    function is being evaluted.
    42       */
    43      Object invoke(ExpressionContext context, Object[] parameters);
    44  }