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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  
28  package org.apache.http.message;
29  
30  import org.apache.http.HeaderElement;
31  import org.apache.http.NameValuePair;
32  import org.apache.http.util.CharArrayBuffer;
33  
34  /**
35   * Interface for formatting elements of a header value.
36   * This is the complement to {@link HeaderValueParser}.
37   * Instances of this interface are expected to be stateless and thread-safe.
38   *
39   * <p>
40   * All formatting methods accept an optional buffer argument.
41   * If a buffer is passed in, the formatted element will be appended
42   * and the modified buffer is returned. If no buffer is passed in,
43   * a new buffer will be created and filled with the formatted element.
44   * In both cases, the caller is allowed to modify the returned buffer.
45   * </p>
46   *
47   * @since 4.0
48   */
49  public interface HeaderValueFormatter {
50  
51      /**
52       * Formats an array of header elements.
53       *
54       * @param buffer    the buffer to append to, or
55       *                  <code>null</code> to create a new buffer
56       * @param elems     the header elements to format
57       * @param quote     <code>true</code> to always format with quoted values,
58       *                  <code>false</code> to use quotes only when necessary
59       *
60       * @return  a buffer with the formatted header elements.
61       *          If the <code>buffer</code> argument was not <code>null</code>,
62       *          that buffer will be used and returned.
63       */
64      CharArrayBuffer formatElements(CharArrayBuffer buffer,
65                                     HeaderElement[] elems,
66                                     boolean quote);
67  
68      /**
69       * Formats one header element.
70       *
71       * @param buffer    the buffer to append to, or
72       *                  <code>null</code> to create a new buffer
73       * @param elem      the header element to format
74       * @param quote     <code>true</code> to always format with quoted values,
75       *                  <code>false</code> to use quotes only when necessary
76       *
77       * @return  a buffer with the formatted header element.
78       *          If the <code>buffer</code> argument was not <code>null</code>,
79       *          that buffer will be used and returned.
80       */
81      CharArrayBuffer formatHeaderElement(CharArrayBuffer buffer,
82                                          HeaderElement elem,
83                                          boolean quote);
84  
85      /**
86       * Formats the parameters of a header element.
87       * That's a list of name-value pairs, to be separated by semicolons.
88       * This method will <i>not</i> generate a leading semicolon.
89       *
90       * @param buffer    the buffer to append to, or
91       *                  <code>null</code> to create a new buffer
92       * @param nvps      the parameters (name-value pairs) to format
93       * @param quote     <code>true</code> to always format with quoted values,
94       *                  <code>false</code> to use quotes only when necessary
95       *
96       * @return  a buffer with the formatted parameters.
97       *          If the <code>buffer</code> argument was not <code>null</code>,
98       *          that buffer will be used and returned.
99       */
100     CharArrayBuffer formatParameters(CharArrayBuffer buffer,
101                                      NameValuePair[] nvps,
102                                      boolean quote);
103 
104     /**
105      * Formats one name-value pair, where the value is optional.
106      *
107      * @param buffer    the buffer to append to, or
108      *                  <code>null</code> to create a new buffer
109      * @param nvp       the name-value pair to format
110      * @param quote     <code>true</code> to always format with a quoted value,
111      *                  <code>false</code> to use quotes only when necessary
112      *
113      * @return  a buffer with the formatted name-value pair.
114      *          If the <code>buffer</code> argument was not <code>null</code>,
115      *          that buffer will be used and returned.
116      */
117     CharArrayBuffer formatNameValuePair(CharArrayBuffer buffer,
118                                         NameValuePair nvp,
119                                         boolean quote);
120 
121 }
122