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| <div><h2 class="title"> |
| <a name="circular_buffer"></a>Chapter 7. Boost.Circular Buffer</h2></div> |
| <div><div class="authorgroup"><div class="author"><h3 class="author"> |
| <span class="firstname">Jan</span> <span class="surname">Gaspar</span> |
| </h3></div></div></div> |
| <div><p class="copyright">Copyright © 2003-2013 Jan Gaspar</p></div> |
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| <a name="circular_buffer.legal"></a><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>) |
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| <p><b>Table of Contents</b></p> |
| <dl class="toc"> |
| <dt><span class="section"><a href="circular_buffer.html#circular_buffer.intro">Introduction</a></span></dt> |
| <dt><span class="section"><a href="circular_buffer/example.html">Circular_buffer example</a></span></dt> |
| <dt><span class="section"><a href="circular_buffer/rationale.html">Rationale</a></span></dt> |
| <dt><span class="section"><a href="circular_buffer/implementation.html">Implementation </a></span></dt> |
| <dt><span class="section"><a href="circular_buffer/examples.html">More Examples</a></span></dt> |
| <dt><span class="section"><a href="circular_buffer/headers.html">Header Files</a></span></dt> |
| <dt><span class="section"><a href="circular_buffer/concepts.html">Modelled Concepts</a></span></dt> |
| <dt><span class="section"><a href="circular_buffer/template_params.html">Template Parameters</a></span></dt> |
| <dt><span class="section"><a href="circular_buffer/tickets.html">Trac Tickets</a></span></dt> |
| <dt><span class="section"><a href="circular_buffer/release.html">Release Notes</a></span></dt> |
| <dt><span class="section"><a href="circular_buffer/acknowledgements.html">Acknowledgements</a></span></dt> |
| <dt><span class="section"><a href="circular_buffer/version_id.html">Documentation Version Info</a></span></dt> |
| <dt><span class="section"><a href="boost_circular_buffer_c___reference.html">Boost.Circular_buffer C++ Reference</a></span></dt> |
| <dd><dl> |
| <dt><span class="section"><a href="boost_circular_buffer_c___reference.html#header.boost.circular_buffer_hpp">Header <boost/circular_buffer.hpp></a></span></dt> |
| <dt><span class="section"><a href="boost_circular_buffer_c___reference.html#header.boost.circular_buffer.base_hpp">Header <boost/circular_buffer/base.hpp></a></span></dt> |
| <dt><span class="section"><a href="boost_circular_buffer_c___reference.html#header.boost.circular_buffer.debug_hpp">Header <boost/circular_buffer/debug.hpp></a></span></dt> |
| <dt><span class="section"><a href="boost_circular_buffer_c___reference.html#header.boost.circular_buffer.details_hpp">Header <boost/circular_buffer/details.hpp></a></span></dt> |
| <dt><span class="section"><a href="boost_circular_buffer_c___reference.html#header.boost.circular_buffer.space_optimized_hpp">Header <boost/circular_buffer/space_optimized.hpp></a></span></dt> |
| </dl></dd> |
| <dt><span class="section"><a href="circular_buffer/s14.html">Index</a></span></dt> |
| </dl> |
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| <th align="left">Note</th> |
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| A printer-friendly PDF version of this manual is also available. |
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| <div class="section"> |
| <div class="titlepage"><div><div><h2 class="title" style="clear: both"> |
| <a name="circular_buffer.intro"></a><a class="link" href="circular_buffer.html#circular_buffer.intro" title="Introduction">Introduction</a> |
| </h2></div></div></div> |
| <p> |
| A Circular Buffer. |
| </p> |
| <h3> |
| <a name="circular_buffer.intro.h0"></a> |
| <span class="phrase"><a name="circular_buffer.intro.description"></a></span><a class="link" href="circular_buffer.html#circular_buffer.intro.description">Description</a> |
| </h3> |
| <p> |
| The term <a href="http://en.wikipedia.org/wiki/Circular_buffer" target="_top">circular |
| buffer</a> (also called a <span class="emphasis"><em>ring</em></span> or <span class="emphasis"><em>cyclic |
| buffer</em></span>) refers to an area in memory which is used to store incoming |
| data. When the buffer is filled, new data is written starting at the beginning |
| of the buffer and overwriting the old. |
| </p> |
| <p> |
| <code class="computeroutput"><a class="link" href="boost/circular_buffer.html" title="Class template circular_buffer">boost::circular_buffer</a></code> |
| is a STL compliant container. |
| </p> |
| <p> |
| It is a kind of sequence similar to <a href="http://www.sgi.com/tech/stl/List.html" target="_top">std::list</a> |
| or <a href="http://www.sgi.com/tech/stl/Deque.html" target="_top">std::deque</a>. |
| It supports random access iterators, constant time insert and erase operations |
| at the beginning or the end of the buffer and interoperability with std algorithms. |
| </p> |
| <p> |
| The <code class="computeroutput"><a class="link" href="boost/circular_buffer.html" title="Class template circular_buffer">circular_buffer</a></code> is |
| especially designed to provide <span class="bold"><strong>fixed capacity</strong></span> |
| storage. When its capacity is exhausted, newly inserted elements will cause |
| elements to be overwritten, either at the beginning or end of the buffer (depending |
| on what insert operation is used). |
| </p> |
| <p> |
| The <code class="computeroutput"><a class="link" href="boost/circular_buffer.html" title="Class template circular_buffer">circular_buffer</a></code> only |
| allocates memory when created, when the capacity is adjusted explicitly, or |
| as necessary to accommodate resizing or assign operations. |
| </p> |
| <p> |
| <span class="inlinemediaobject"><img src="../../libs/circular_buffer/doc/images/circular_buffer.png"></span> |
| </p> |
| <p> |
| There is also a <code class="computeroutput"><a class="link" href="boost/circular_buffe_idp38268896.html" title="Class template circular_buffer_space_optimized">circular_buffer_space_optimized</a></code> |
| version available. |
| </p> |
| <p> |
| <span class="inlinemediaobject"><img src="../../libs/circular_buffer/doc/images/space_optimized.png"></span> |
| </p> |
| <p> |
| <code class="computeroutput"><a class="link" href="boost/circular_buffe_idp38268896.html" title="Class template circular_buffer_space_optimized">circular_buffer_space_optimized</a></code> |
| is an adaptation of the <code class="computeroutput"><a class="link" href="boost/circular_buffer.html" title="Class template circular_buffer">circular_buffer</a></code> |
| which <span class="bold"><strong>does not allocate memory all at once when created</strong></span>, |
| instead it allocates memory as needed. |
| </p> |
| <p> |
| The predictive memory allocation is similar to typical <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span></code> |
| implementation. Memory is automatically freed as the size of the container |
| decreases. |
| </p> |
| <p> |
| The memory allocation process of the space-optimized circular buffer. The |
| <code class="computeroutput">min_capacity</code> |
| of the capacity controller represents the minimal guaranteed amount of allocated |
| memory. The allocated memory will never drop under this value. The default |
| value of the <code class="computeroutput"><span class="identifier">min_capacity</span></code> is |
| set to 0. The <code class="computeroutput"><span class="identifier">min_capacity</span></code> |
| can be set using the constructor parameter <code class="computeroutput">() |
| capacity_control </code> or the function <code class="computeroutput"><span class="identifier">set_capacity</span></code>. |
| </p> |
| <p> |
| The space-optimized version is, of course, a little slower. |
| </p> |
| </div> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"><p><small>Last revised: April 07, 2015 at 22:48:45 GMT</small></p></td> |
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