tri11paragon
/
Insane_DNS
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
Insane_DNS/libraries/asio-1.28.1/doc/asio/reference/read_until/overload15.html

206 lines
17 KiB
HTML
Raw Normal View History

can extract domain names
2023-10-24 21:59:30 -04:00
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>read_until (15 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="overload14.html" title="read_until (14 of 24 overloads)">
<link rel="next" href="overload16.html" title="read_until (16 of 24 overloads)">
<meta name="viewport" content="width=device-width, initial-scale=1">
</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="overload14.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="overload16.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.overload15"></a><a class="link" href="overload15.html" title="read_until (15 of 24 overloads)">read_until (15
of 24 overloads)</a>
</h4></div></div></div>
<p>
Read data into a streambuf until a function object indicates a match.
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
<span class="keyword">typename</span> <a class="link" href="../SyncReadStream.html" title="Buffer-oriented synchronous read stream requirements">SyncReadStream</a><span class="special">,</span>
<span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">,</span>
<span class="keyword">typename</span> <span class="identifier">MatchCondition</span><span class="special">&gt;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">read_until</span><span class="special">(</span>
<span class="identifier">SyncReadStream</span> <span class="special">&amp;</span> <span class="identifier">s</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="identifier">MatchCondition</span> <span class="identifier">match_condition</span><span class="special">,</span>
<span class="keyword">typename</span> <span class="identifier">constraint</span><span class="special">&lt;</span> <span class="identifier">is_match_condition</span><span class="special">&lt;</span> <span class="identifier">MatchCondition</span> <span class="special">&gt;::</span><span class="identifier">value</span> <span class="special">&gt;::</span><span class="identifier">type</span> <span class="special">=</span> <span class="number">0</span><span class="special">);</span>
</pre>
<p>
This function is used to read data into the specified streambuf until a
user-defined match condition function object, when applied to the data
contained in the streambuf, indicates a successful match. The call will
block until one of the following conditions is true:
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
The match condition function object returns a std::pair where the second
element evaluates to true.
</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 match condition function object already indicates
a match, the function returns immediately.
</p>
<h6>
<a name="asio.reference.read_until.overload15.h0"></a>
<span><a name="asio.reference.read_until.overload15.parameters"></a></span><a class="link" href="overload15.html#asio.reference.read_until.overload15.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">match_condition</span></dt>
<dd>
<p>
The function object to be called to determine whether a match exists.
The signature of the function object must be:
</p>
<pre class="programlisting"><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">&gt;</span> <span class="identifier">match_condition</span><span class="special">(</span><span class="identifier">iterator</span> <span class="identifier">begin</span><span class="special">,</span> <span class="identifier">iterator</span> <span class="identifier">end</span><span class="special">);</span>
</pre>
<p>
where <code class="computeroutput"><span class="identifier">iterator</span></code> represents
the type:
</p>
<pre class="programlisting"><span class="identifier">buffers_iterator</span><span class="special">&lt;</span><span class="identifier">basic_streambuf</span><span class="special">&lt;</span><span class="identifier">Allocator</span><span class="special">&gt;::</span><span class="identifier">const_buffers_type</span><span class="special">&gt;</span>
</pre>
<p>
The iterator parameters <code class="computeroutput"><span class="identifier">begin</span></code>
and <code class="computeroutput"><span class="identifier">end</span></code> define the
range of bytes to be scanned to determine whether there is a match.
The <code class="computeroutput"><span class="identifier">first</span></code> member
of the return value is an iterator marking one-past-the-end of the
bytes that have been consumed by the match function. This iterator
is used to calculate the <code class="computeroutput"><span class="identifier">begin</span></code>
parameter for any subsequent invocation of the match condition. The
<code class="computeroutput"><span class="identifier">second</span></code> member of
the return value is true if a match has been found, false otherwise.
</p>
</dd>
</dl>
</div>
<h6>
<a name="asio.reference.read_until.overload15.h1"></a>
<span><a name="asio.reference.read_until.overload15.return_value"></a></span><a class="link" href="overload15.html#asio.reference.read_until.overload15.return_value">Return
Value</a>
</h6>
<p>
The number of bytes in the streambuf's get area that have been fully consumed
by the match function.
</p>
<h6>
<a name="asio.reference.read_until.overload15.h2"></a>
<span><a name="asio.reference.read_until.overload15.exceptions"></a></span><a class="link" href="overload15.html#asio.reference.read_until.overload15.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.overload15.h3"></a>
<span><a name="asio.reference.read_until.overload15.remarks"></a></span><a class="link" href="overload15.html#asio.reference.read_until.overload15.remarks">Remarks</a>
</h6>
<p>
After a successful read_until operation, the streambuf may contain additional
data beyond that which matched the function object. An application will
typically leave that data in the streambuf for a subsequent read_until
operation to examine.
</p>
<p>
The default implementation of the <code class="computeroutput"><span class="identifier">is_match_condition</span></code>
type trait evaluates to true for function pointers and function objects
with a <code class="computeroutput"><span class="identifier">result_type</span></code> typedef.
It must be specialised for other user-defined function objects.
</p>
<h6>
<a name="asio.reference.read_until.overload15.h4"></a>
<span><a name="asio.reference.read_until.overload15.examples"></a></span><a class="link" href="overload15.html#asio.reference.read_until.overload15.examples">Examples</a>
</h6>
<p>
To read data into a streambuf until whitespace is encountered:
</p>
<pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffers_iterator</span><span class="special">&lt;</span>
<span class="identifier">asio</span><span class="special">::</span><span class="identifier">streambuf</span><span class="special">::</span><span class="identifier">const_buffers_type</span><span class="special">&gt;</span> <span class="identifier">iterator</span><span class="special">;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">&gt;</span>
<span class="identifier">match_whitespace</span><span class="special">(</span><span class="identifier">iterator</span> <span class="identifier">begin</span><span class="special">,</span> <span class="identifier">iterator</span> <span class="identifier">end</span><span class="special">)</span>
<span class="special">{</span>
<span class="identifier">iterator</span> <span class="identifier">i</span> <span class="special">=</span> <span class="identifier">begin</span><span class="special">;</span>
<span class="keyword">while</span> <span class="special">(</span><span class="identifier">i</span> <span class="special">!=</span> <span class="identifier">end</span><span class="special">)</span>
<span class="keyword">if</span> <span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">isspace</span><span class="special">(*</span><span class="identifier">i</span><span class="special">++))</span>
<span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span class="special">,</span> <span class="keyword">true</span><span class="special">);</span>
<span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span class="special">,</span> <span class="keyword">false</span><span class="special">);</span>
<span class="special">}</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="identifier">asio</span><span class="special">::</span><span class="identifier">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">match_whitespace</span><span class="special">);</span>
</pre>
<p>
To read data into a streambuf until a matching character is found:
</p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">match_char</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
<span class="keyword">explicit</span> <span class="identifier">match_char</span><span class="special">(</span><span class="keyword">char</span> <span class="identifier">c</span><span class="special">)</span> <span class="special">:</span> <span class="identifier">c_</span><span class="special">(</span><span class="identifier">c</span><span class="special">)</span> <span class="special">{}</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">&gt;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span><span class="identifier">Iterator</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">&gt;</span> <span class="keyword">operator</span><span class="special">()(</span>
<span class="identifier">Iterator</span> <span class="identifier">begin</span><span class="special">,</span> <span class="identifier">Iterator</span> <span class="identifier">end</span><span class="special">)</span> <span class="keyword">const</span>
<span class="special">{</span>
<span class="identifier">Iterator</span> <span class="identifier">i</span> <span class="special">=</span> <span class="identifier">begin</span><span class="special">;</span>
<span class="keyword">while</span> <span class="special">(</span><span class="identifier">i</span> <span class="special">!=</span> <span class="identifier">end</span><span class="special">)</span>
<span class="keyword">if</span> <span class="special">(</span><span class="identifier">c_</span> <span class="special">==</span> <span class="special">*</span><span class="identifier">i</span><span class="special">++)</span>
<span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span class="special">,</span> <span class="keyword">true</span><span class="special">);</span>
<span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span class="special">,</span> <span class="keyword">false</span><span class="special">);</span>
<span class="special">}</span>
<span class="keyword">private</span><span class="special">:</span>
<span class="keyword">char</span> <span class="identifier">c_</span><span class="special">;</span>
<span class="special">};</span>
<span class="keyword">namespace</span> <span class="identifier">asio</span> <span class="special">{</span>
<span class="keyword">template</span> <span class="special">&lt;&gt;</span> <span class="keyword">struct</span> <span class="identifier">is_match_condition</span><span class="special">&lt;</span><span class="identifier">match_char</span><span class="special">&gt;</span>
<span class="special">:</span> <span class="keyword">public</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">true_type</span> <span class="special">{};</span>
<span class="special">}</span> <span class="comment">// namespace asio</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="identifier">asio</span><span class="special">::</span><span class="identifier">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">match_char</span><span class="special">(</span><span class="char">'a'</span><span class="special">));</span>
</pre>
</div>
<div class="copyright-footer">Copyright © 2003-2023 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>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="overload14.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="overload16.html"><img src="../../../next.png" alt="Next"></a>
</div>
</body>
</html>