File: overload3.html

package info (click to toggle)
boost1.42 1.42.0-4
  • links: PTS, VCS
  • area: main
  • in suites: squeeze
  • size: 277,864 kB
  • ctags: 401,076
  • sloc: cpp: 1,235,659; xml: 74,142; ansic: 41,313; python: 26,756; sh: 11,840; cs: 2,118; makefile: 655; perl: 494; yacc: 456; asm: 353; csh: 6
file content (159 lines) | stat: -rwxr-xr-x 11,850 bytes parent folder | download 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
 
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>async_read_until (3 of 4 overloads)</title>
<link rel="stylesheet" href="../../../boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
<link rel="home" href="../../../boost_asio.html" title="Boost.Asio">
<link rel="up" href="../async_read_until.html" title="async_read_until">
<link rel="prev" href="overload2.html" title="async_read_until (2 of 4 overloads)">
<link rel="next" href="overload4.html" title="async_read_until (4 of 4 overloads)">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr>
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td>
<td align="center"><a href="../../../../../index.html">Home</a></td>
<td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td>
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
<td align="center"><a href="../../../../../more/index.htm">More</a></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="overload2.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../async_read_until.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="overload4.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
</div>
<div class="section" title="async_read_until (3 of 4 overloads)">
<div class="titlepage"><div><div><h4 class="title">
<a name="boost_asio.reference.async_read_until.overload3"></a><a class="link" href="overload3.html" title="async_read_until (3 of 4 overloads)"> async_read_until
        (3 of 4 overloads)</a>
</h4></div></div></div>
<p>
          Start an asynchronous operation to read data into a streambuf until some
          part of its data matches a regular expression.
        </p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <a class="link" href="../AsyncReadStream.html" title="Buffer-oriented asynchronous read stream requirements">AsyncReadStream</a><span class="special">,</span>
    <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">,</span>
    <span class="keyword">typename</span> <a class="link" href="../ReadHandler.html" title="Read handler requirements">ReadHandler</a><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">async_read_until</span><span class="special">(</span>
    <span class="identifier">AsyncReadStream</span> <span class="special">&amp;</span> <span class="identifier">s</span><span class="special">,</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">basic_streambuf</span><span class="special">&lt;</span> <span class="identifier">Allocator</span> <span class="special">&gt;</span> <span class="special">&amp;</span> <span class="identifier">b</span><span class="special">,</span>
    <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">regex</span> <span class="special">&amp;</span> <span class="identifier">expr</span><span class="special">,</span>
    <span class="identifier">ReadHandler</span> <span class="identifier">handler</span><span class="special">);</span>
</pre>
<p>
          This function is used to asynchronously read data into the specified streambuf
          until the streambuf's get area contains some data that matches a regular
          expression. The function call always returns immediately. The asynchronous
          operation will continue until one of the following conditions is true:
        </p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
            A substring of the streambuf's get area matches the regular expression.
          </li>
<li class="listitem">
            An error occurred.
          </li>
</ul></div>
<p>
          This operation is implemented in terms of zero or more calls to the stream's
          async_read_some function. If the streambuf's get area already contains
          data that matches the regular expression, the function returns immediately.
        </p>
<a name="boost_asio.reference.async_read_until.overload3.parameters"></a><h6>
<a name="id673347"></a>
          <a class="link" href="overload3.html#boost_asio.reference.async_read_until.overload3.parameters">Parameters</a>
        </h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term">s</span></dt>
<dd><p>
              The stream from which the data is to be read. The type must support
              the AsyncReadStream concept.
            </p></dd>
<dt><span class="term">b</span></dt>
<dd><p>
              A streambuf object into which the data will be read. Ownership of the
              streambuf is retained by the caller, which must guarantee that it remains
              valid until the handler is called.
            </p></dd>
<dt><span class="term">expr</span></dt>
<dd><p>
              The regular expression.
            </p></dd>
<dt><span class="term">handler</span></dt>
<dd>
<p>
              The handler to be called when the read operation completes. Copies
              will be made of the handler as required. The function signature of
              the handler must be: 
</p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span class="special">(</span>
  <span class="comment">// Result of operation.
</span>  <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&amp;</span> <span class="identifier">error</span><span class="special">,</span>

  <span class="comment">// The number of bytes in the streambuf's get
</span>  <span class="comment">// area up to and including the substring
</span>  <span class="comment">// that matches the regular. expression.
</span>  <span class="comment">// 0 if an error occurred.
</span>  <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_transferred</span>
<span class="special">);</span> 
</pre>
<p>
              Regardless of whether the asynchronous operation completes immediately
              or not, the handler will not be invoked from within this function.
              Invocation of the handler will be performed in a manner equivalent
              to using <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">io_service</span><span class="special">::</span><span class="identifier">post</span><span class="special">()</span></code>.
            </p>
</dd>
</dl>
</div>
<a name="boost_asio.reference.async_read_until.overload3.remarks"></a><h6>
<a name="id673597"></a>
          <a class="link" href="overload3.html#boost_asio.reference.async_read_until.overload3.remarks">Remarks</a>
        </h6>
<p>
          After a successful async_read_until operation, the streambuf may contain
          additional data beyond that which matched the regular expression. An application
          will typically leave that data in the streambuf for a subsequent async_read_until
          operation to examine.
        </p>
<a name="boost_asio.reference.async_read_until.overload3.example"></a><h6>
<a name="id673628"></a>
          <a class="link" href="overload3.html#boost_asio.reference.async_read_until.overload3.example">Example</a>
        </h6>
<p>
          To asynchronously read data into a streambuf until a CR-LF sequence is
          encountered:
        </p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">streambuf</span> <span class="identifier">b</span><span class="special">;</span>
<span class="special">...</span>
<span class="keyword">void</span> <span class="identifier">handler</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&amp;</span> <span class="identifier">e</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">)</span>
<span class="special">{</span>
  <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">e</span><span class="special">)</span>
  <span class="special">{</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">istream</span> <span class="identifier">is</span><span class="special">(&amp;</span><span class="identifier">b</span><span class="special">);</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">line</span><span class="special">;</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">getline</span><span class="special">(</span><span class="identifier">is</span><span class="special">,</span> <span class="identifier">line</span><span class="special">);</span>
    <span class="special">...</span>
  <span class="special">}</span>
<span class="special">}</span>
<span class="special">...</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">async_read_until</span><span class="special">(</span><span class="identifier">s</span><span class="special">,</span> <span class="identifier">b</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">regex</span><span class="special">(</span><span class="string">"\r\n"</span><span class="special">),</span> <span class="identifier">handler</span><span class="special">);</span> 
</pre>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright &#169; 2003 - 2010 Christopher M. Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="overload2.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../async_read_until.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="overload4.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
</div>
</body>
</html>