content: /*
   * Filter.java May 2006
   *
   * Copyright (C) 2006, Niall Gallagher <niallg@users.sf.net>
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or 
   * implied. See the License for the specific language governing 
   * permissions and limitations under the License.
   */
  
  package com.aliyun.odps.simpleframework.xml.filter;
  
  /**
   * The <code>Filter</code> object is used to provide replacement string
   * values for a provided key. This allows values within the XML source
   * document to be replaced using sources such as OS environment variables
   * and Java system properties.
   * <p>
   * All filtered variables appear within the source text using a template
   * and variable keys marked like <code>${example}</code>. When the XML 
   * source file is read all template variables are replaced with the 
   * values provided by the filter. If no replacement exists then the XML
   * source text remains unchanged.
   * 
   * @author Niall Gallagher
   */
  public interface Filter {
  
     /**
      * Replaces the text provided with some property. This method 
      * acts much like a the get method of the <code>Map</code>
      * object, in that it uses the provided text as a key to some 
      * value. However it can also be used to evaluate expressions
      * and output the result for inclusion in the generated XML.
      *
      * @param text this is the text value that is to be replaced
      * 
      * @return returns a replacement for the provided text value
      */
     String replace(String text);        
  }
  