overload13.html
7.16 KB
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
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>read_until (13 of 24 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="../../../index.html" title="Asio">
<link rel="up" href="../read_until.html" title="read_until">
<link rel="prev" href="overload12.html" title="read_until (12 of 24 overloads)">
<link rel="next" href="overload14.html" title="read_until (14 of 24 overloads)">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr><td valign="top"><img alt="asio C++ library" width="250" height="60" src="../../../asio.png"></td></tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="overload12.html"><img src="../../../prev.png" alt="Prev"></a><a accesskey="u" href="../read_until.html"><img src="../../../up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../home.png" alt="Home"></a><a accesskey="n" href="overload14.html"><img src="../../../next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="asio.reference.read_until.overload13"></a><a class="link" href="overload13.html" title="read_until (13 of 24 overloads)">read_until (13
of 24 overloads)</a>
</h4></div></div></div>
<p>
Read data into a streambuf until some part of the data it contains matches
a regular expression.
</p>
<pre class="programlisting">template<
typename <a class="link" href="../SyncReadStream.html" title="Buffer-oriented synchronous read stream requirements">SyncReadStream</a>,
typename Allocator>
std::size_t read_until(
SyncReadStream & s,
asio::basic_streambuf< Allocator > & b,
const boost::regex & expr);
</pre>
<p>
This function is used to read data into the specified streambuf until the
streambuf's get area contains some data that matches a regular expression.
The call will block 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
read_some function. If the streambuf's get area already contains data that
matches the regular expression, the function returns immediately.
</p>
<h6>
<a name="asio.reference.read_until.overload13.h0"></a>
<span><a name="asio.reference.read_until.overload13.parameters"></a></span><a class="link" href="overload13.html#asio.reference.read_until.overload13.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 SyncReadStream concept.
</p></dd>
<dt><span class="term">b</span></dt>
<dd><p>
A streambuf object into which the data will be read.
</p></dd>
<dt><span class="term">expr</span></dt>
<dd><p>
The regular expression.
</p></dd>
</dl>
</div>
<h6>
<a name="asio.reference.read_until.overload13.h1"></a>
<span><a name="asio.reference.read_until.overload13.return_value"></a></span><a class="link" href="overload13.html#asio.reference.read_until.overload13.return_value">Return
Value</a>
</h6>
<p>
The number of bytes in the streambuf's get area up to and including the
substring that matches the regular expression.
</p>
<h6>
<a name="asio.reference.read_until.overload13.h2"></a>
<span><a name="asio.reference.read_until.overload13.exceptions"></a></span><a class="link" href="overload13.html#asio.reference.read_until.overload13.exceptions">Exceptions</a>
</h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term">asio::system_error</span></dt>
<dd><p>
Thrown on failure.
</p></dd>
</dl>
</div>
<h6>
<a name="asio.reference.read_until.overload13.h3"></a>
<span><a name="asio.reference.read_until.overload13.remarks"></a></span><a class="link" href="overload13.html#asio.reference.read_until.overload13.remarks">Remarks</a>
</h6>
<p>
After a successful 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 read_until
operation to examine.
</p>
<h6>
<a name="asio.reference.read_until.overload13.h4"></a>
<span><a name="asio.reference.read_until.overload13.example"></a></span><a class="link" href="overload13.html#asio.reference.read_until.overload13.example">Example</a>
</h6>
<p>
To read data into a streambuf until a CR-LF sequence is encountered:
</p>
<pre class="programlisting">asio::streambuf b;
asio::read_until(s, b, boost::regex("\r\n"));
std::istream is(&b);
std::string line;
std::getline(is, line);
</pre>
<p>
After the <code class="computeroutput">read_until</code> operation completes successfully, the
buffer <code class="computeroutput">b</code> contains the data which matched the regular expression:
</p>
<pre class="programlisting">{ 'a', 'b', ..., 'c', '\r', '\n', 'd', 'e', ... }
</pre>
<p>
The call to <code class="computeroutput">std::getline</code> then extracts the data up to and
including the newline (which is discarded), so that the string <code class="computeroutput">line</code>
contains:
</p>
<pre class="programlisting">{ 'a', 'b', ..., 'c', '\r' }
</pre>
<p>
The remaining data is left in the buffer <code class="computeroutput">b</code> as follows:
</p>
<pre class="programlisting">{ 'd', 'e', ... }
</pre>
<p>
This data may be the start of a new line, to be extracted by a subsequent
<code class="computeroutput">read_until</code> operation.
</p>
</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 © 2003-2020 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="overload12.html"><img src="../../../prev.png" alt="Prev"></a><a accesskey="u" href="../read_until.html"><img src="../../../up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../home.png" alt="Home"></a><a accesskey="n" href="overload14.html"><img src="../../../next.png" alt="Next"></a>
</div>
</body>
</html>