<?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> <title>The MPL Reference Manual: Forward Sequence</title> <link rel="stylesheet" href="../style.css" type="text/css" /> </head> <body class="docframe refmanual"> <table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./concepts.html" class="navigation-link">Prev</a> <a href="./bidirectional-sequence.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group">Back <a href="./bidirectional-sequence.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./concepts.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> <td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./sequences.html" class="navigation-link">Sequences</a> / <a href="./concepts.html" class="navigation-link">Concepts</a> / <a href="./forward-sequence.html" class="navigation-link">Forward Sequence</a></td> </tr></table><div class="header-separator"></div> <div class="section" id="forward-sequence"> <h1><a class="toc-backref" href="./concepts.html#id1395">Forward Sequence</a></h1> <div class="section" id="description"> <h3>Description</h3> <p>A <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a> is an MPL concept representing a compile-time sequence of elements. Sequence elements are types, and are accessible through <a class="reference internal" href="./iterators.html">Iterators</a>. The <a class="reference internal" href="./begin.html">begin</a> and <a class="reference internal" href="./end.html">end</a> metafunctions provide iterators delimiting the range of the sequence elements. A sequence guarantees that its elements are arranged in a definite, but possibly unspecified, order. Every MPL sequence is a <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a>.</p> </div> <div class="section" id="definitions"> <h3>Definitions</h3> <ul class="simple"> <li>The <em>size</em> of a sequence is the number of elements it contains. The size is a nonnegative number.</li> <li>A sequence is <em>empty</em> if its size is zero.</li> </ul> </div> <div class="section" id="expression-requirements"> <h3>Expression requirements</h3> <p>For any <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a> <tt class="literal"><span class="pre">s</span></tt> the following expressions must be valid:</p> <table border="1" class="docutils table"> <colgroup> <col width="30%" /> <col width="39%" /> <col width="30%" /> </colgroup> <thead valign="bottom"> <tr><th class="head">Expression</th> <th class="head">Type</th> <th class="head">Complexity</th> </tr> </thead> <tbody valign="top"> <tr><td><tt class="literal"><span class="pre"><a href="./begin.html" class="identifier">begin</a><s>::type</span></tt></td> <td><a class="reference internal" href="./forward-iterator.html">Forward Iterator</a></td> <td>Amortized constant time</td> </tr> <tr><td><tt class="literal"><span class="pre"><a href="./end.html" class="identifier">end</a><s>::type</span></tt></td> <td><a class="reference internal" href="./forward-iterator.html">Forward Iterator</a></td> <td>Amortized constant time</td> </tr> <tr><td><tt class="literal"><span class="pre"><a href="./size.html" class="identifier">size</a><s>::type</span></tt></td> <td><a class="reference internal" href="./integral-constant.html">Integral Constant</a></td> <td>Unspecified</td> </tr> <tr><td><tt class="literal"><span class="pre"><a href="./empty.html" class="identifier">empty</a><s>::type</span></tt></td> <td>Boolean <a class="reference internal" href="./integral-constant.html">Integral Constant</a></td> <td>Constant time</td> </tr> <tr><td><tt class="literal"><span class="pre"><a href="./front.html" class="identifier">front</a><s>::type</span></tt></td> <td>Any type</td> <td>Amortized constant time</td> </tr> </tbody> </table> </div> <div class="section" id="expression-semantics"> <h3>Expression semantics</h3> <table border="1" class="docutils table"> <colgroup> <col width="28%" /> <col width="72%" /> </colgroup> <thead valign="bottom"> <tr><th class="head">Expression</th> <th class="head">Semantics</th> </tr> </thead> <tbody valign="top"> <tr><td><tt class="literal"><span class="pre"><a href="./begin.html" class="identifier">begin</a><s>::type</span></tt></td> <td>An iterator to the first element of the sequence; see <a class="reference internal" href="./begin.html">begin</a>.</td> </tr> <tr><td><tt class="literal"><span class="pre"><a href="./end.html" class="identifier">end</a><s>::type</span></tt></td> <td>A past-the-end iterator to the sequence; see <a class="reference internal" href="./end.html">end</a>.</td> </tr> <tr><td><tt class="literal"><span class="pre"><a href="./size.html" class="identifier">size</a><s>::type</span></tt></td> <td>The size of the sequence; see <a class="reference internal" href="./size.html">size</a>.</td> </tr> <tr><td><tt class="literal"><span class="pre"><a href="./empty.html" class="identifier">empty</a><s>::type</span></tt></td> <td>A boolean <a class="reference internal" href="./integral-constant.html">Integral Constant</a> <tt class="literal"><span class="pre">c</span></tt> such that <tt class="literal"><span class="pre">c::value</span> <span class="pre">==</span> <span class="pre">true</span></tt> if and only if the sequence is empty; see <a class="reference internal" href="./empty.html">empty</a>.</td> </tr> <tr><td><tt class="literal"><span class="pre"><a href="./front.html" class="identifier">front</a><s>::type</span></tt></td> <td>The first element in the sequence; see <a class="reference internal" href="./front.html">front</a>.</td> </tr> </tbody> </table> </div> <div class="section" id="invariants"> <h3>Invariants</h3> <p>For any <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a> <tt class="literal"><span class="pre">s</span></tt> the following invariants always hold:</p> <ul class="simple"> <li>[<tt class="literal"><span class="pre"><a href="./begin.html" class="identifier">begin</a><s>::type</span></tt>, <tt class="literal"><span class="pre"><a href="./end.html" class="identifier">end</a><s>::type</span></tt>) is always a valid range.</li> <li>An algorithm that iterates through the range [<tt class="literal"><span class="pre"><a href="./begin.html" class="identifier">begin</a><s>::type</span></tt>, <tt class="literal"><span class="pre"><a href="./end.html" class="identifier">end</a><s>::type</span></tt>) will pass through every element of <tt class="literal"><span class="pre">s</span></tt> exactly once.</li> <li><tt class="literal"><span class="pre"><a href="./begin.html" class="identifier">begin</a><s>::type</span></tt> is identical to <tt class="literal"><span class="pre"><a href="./end.html" class="identifier">end</a><s>::type</span></tt> if and only if <tt class="literal"><span class="pre">s</span></tt> is empty.</li> <li>Two different iterations through <tt class="literal"><span class="pre">s</span></tt> will access its elements in the same order.</li> </ul> </div> <div class="section" id="models"> <h3>Models</h3> <ul class="simple"> <li><a class="reference internal" href="./vector.html">vector</a></li> <li><a class="reference internal" href="./map.html">map</a></li> <li><a class="reference internal" href="./range-c.html">range_c</a></li> <li><a class="reference internal" href="./iterator-range.html">iterator_range</a></li> <li><a class="reference internal" href="./filter-view.html">filter_view</a></li> </ul> </div> <div class="section" id="see-also"> <h3>See also</h3> <p><a class="reference internal" href="./sequences.html">Sequences</a>, <a class="reference internal" href="./bidirectional-sequence.html">Bidirectional Sequence</a>, <a class="reference internal" href="./forward-iterator.html">Forward Iterator</a>, <a class="reference internal" href="./begin.html">begin</a> / <a class="reference internal" href="./end.html">end</a>, <a class="reference internal" href="./size.html">size</a>, <a class="reference internal" href="./empty.html">empty</a>, <a class="reference internal" href="./front.html">front</a></p> <!-- Sequences/Concepts//Bidirectional Sequence |20 --> </div> </div> <div class="footer-separator"></div> <table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./concepts.html" class="navigation-link">Prev</a> <a href="./bidirectional-sequence.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group">Back <a href="./bidirectional-sequence.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./concepts.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> <td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</div></td></tr></table></body> </html>