1/*
2 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/message/LineFormatter.java $
3 * $Revision: 573864 $
4 * $Date: 2007-09-08 08:53:25 -0700 (Sat, 08 Sep 2007) $
5 *
6 * ====================================================================
7 * Licensed to the Apache Software Foundation (ASF) under one
8 * or more contributor license agreements.  See the NOTICE file
9 * distributed with this work for additional information
10 * regarding copyright ownership.  The ASF licenses this file
11 * to you under the Apache License, Version 2.0 (the
12 * "License"); you may not use this file except in compliance
13 * with the License.  You may obtain a copy of the License at
14 *
15 *   http://www.apache.org/licenses/LICENSE-2.0
16 *
17 * Unless required by applicable law or agreed to in writing,
18 * software distributed under the License is distributed on an
19 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
20 * KIND, either express or implied.  See the License for the
21 * specific language governing permissions and limitations
22 * under the License.
23 * ====================================================================
24 *
25 * This software consists of voluntary contributions made by many
26 * individuals on behalf of the Apache Software Foundation.  For more
27 * information on the Apache Software Foundation, please see
28 * <http://www.apache.org/>.
29 *
30 */
31
32package org.apache.http.message;
33
34
35import org.apache.http.ProtocolVersion;
36import org.apache.http.RequestLine;
37import org.apache.http.StatusLine;
38import org.apache.http.Header;
39import org.apache.http.util.CharArrayBuffer;
40
41
42/**
43 * Interface for formatting elements of the HEAD section of an HTTP message.
44 * This is the complement to {@link LineParser}.
45 * There are individual methods for formatting a request line, a
46 * status line, or a header line. The formatting does <i>not</i> include the
47 * trailing line break sequence CR-LF.
48 * Instances of this interface are expected to be stateless and thread-safe.
49 *
50 * <p>
51 * The formatted lines are returned in memory, the formatter does not depend
52 * on any specific IO mechanism.
53 * In order to avoid unnecessary creation of temporary objects,
54 * a buffer can be passed as argument to all formatting methods.
55 * The implementation may or may not actually use that buffer for formatting.
56 * If it is used, the buffer will first be cleared by the
57 * <code>formatXXX</code> methods.
58 * The argument buffer can always be re-used after the call. The buffer
59 * returned as the result, if it is different from the argument buffer,
60 * MUST NOT be modified.
61 * </p>
62 *
63 *
64 * @author <a href="mailto:rolandw AT apache.org">Roland Weber</a>
65 *
66 *
67 * <!-- empty lines above to avoid 'svn diff' context problems -->
68 * @version $Revision: 573864 $ $Date: 2007-09-08 08:53:25 -0700 (Sat, 08 Sep 2007) $
69 *
70 * @since 4.0
71 */
72public interface LineFormatter {
73
74
75
76    /**
77     * Formats a protocol version.
78     * This method does <i>not</i> follow the general contract for
79     * <code>buffer</code> arguments.
80     * It does <i>not</i> clear the argument buffer, but appends instead.
81     * The returned buffer can always be modified by the caller.
82     * Because of these differing conventions, it is not named
83     * <code>formatProtocolVersion</code>.
84     *
85     * @param buffer    a buffer to which to append, or <code>null</code>
86     * @param version   the protocol version to format
87     *
88     * @return  a buffer with the formatted protocol version appended.
89     *          The caller is allowed to modify the result buffer.
90     *          If the <code>buffer</code> argument is not <code>null</code>,
91     *          the returned buffer is the argument buffer.
92     */
93    CharArrayBuffer appendProtocolVersion(CharArrayBuffer buffer,
94                                          ProtocolVersion version)
95        ;
96
97
98    /**
99     * Formats a request line.
100     *
101     * @param buffer    a buffer available for formatting, or
102     *                  <code>null</code>.
103     *                  The buffer will be cleared before use.
104     * @param reqline   the request line to format
105     *
106     * @return  the formatted request line
107     */
108    CharArrayBuffer formatRequestLine(CharArrayBuffer buffer,
109                                      RequestLine reqline)
110        ;
111
112
113    /**
114     * Formats a status line.
115     *
116     * @param buffer    a buffer available for formatting, or
117     *                  <code>null</code>.
118     *                  The buffer will be cleared before use.
119     * @param statline  the status line to format
120     *
121     * @return  the formatted status line
122     *
123     * @throws ParseException        in case of a parse error
124     */
125    CharArrayBuffer formatStatusLine(CharArrayBuffer buffer,
126                                     StatusLine statline)
127        ;
128
129
130    /**
131     * Formats a header.
132     * Due to header continuation, the result may be multiple lines.
133     * In order to generate well-formed HTTP, the lines in the result
134     * must be separated by the HTTP line break sequence CR-LF.
135     * There is <i>no</i> trailing CR-LF in the result.
136     * <br/>
137     * See the class comment for details about the buffer argument.
138     *
139     * @param buffer    a buffer available for formatting, or
140     *                  <code>null</code>.
141     *                  The buffer will be cleared before use.
142     * @param header    the header to format
143     *
144     * @return  a buffer holding the formatted header, never <code>null</code>.
145     *          The returned buffer may be different from the argument buffer.
146     *
147     * @throws ParseException        in case of a parse error
148     */
149    CharArrayBuffer formatHeader(CharArrayBuffer buffer,
150                                 Header header)
151        ;
152
153}
154