projects / ceph.git / blame
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1 | <?xml version="1.0" encoding="utf-8" ?> |
| 2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> | |
| 3 | <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> | |
| 4 | <head> | |
| 5 | <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> | |
| 6 | <meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> | |
| 7 | <title>The MPL Reference Manual: begin</title> | |
| 8 | <link rel="stylesheet" href="../style.css" type="text/css" /> | |
| 9 | </head> | |
| 10 | <body class="docframe refmanual"> | |
| 11 | <table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./back.html" class="navigation-link">Prev</a> <a href="./clear.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./back.html" class="navigation-link">Back</a> <a href="./clear.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./intrinsic-metafunctions.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> | |
| 12 | <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="./intrinsic-metafunctions.html" class="navigation-link">Intrinsic Metafunctions</a> / <a href="./begin.html" class="navigation-link">begin</a></td> | |
| 13 | </tr></table><div class="header-separator"></div> | |
| 14 | <div class="section" id="begin"> | |
| 15 | <h1><a class="toc-backref" href="./intrinsic-metafunctions.html#id1428">begin</a></h1> | |
| 16 | <div class="section" id="id202"> | |
| 17 | <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> | |
| 18 | <pre class="literal-block"> | |
| 19 | template< | |
| 20 | typename X | |
| 21 | > | |
| 22 | struct <a href="./begin.html" class="identifier">begin</a> | |
| 23 | { | |
| 24 | typedef <em>unspecified</em> type; | |
| 25 | }; | |
| 26 | </pre> | |
| 27 | </div> | |
| 28 | <div class="section" id="id203"> | |
| 29 | <h3><a class="subsection-title" href="#description" name="description">Description</a></h3> | |
| 30 | <p>Returns an iterator that points to the first element of the sequence. If | |
| 31 | the argument is not a <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a>, returns <a class="reference internal" href="./void.html">void_</a>.</p> | |
| 32 | </div> | |
| 33 | <div class="section" id="id204"> | |
| 34 | <h3><a class="subsection-title" href="#header" name="header">Header</a></h3> | |
| 35 | <pre class="literal-block"> | |
| 36 | #include <<a href="../../../../boost/mpl/begin_end.hpp" class="header">boost/mpl/begin_end.hpp</a>> | |
| 37 | </pre> | |
| 38 | </div> | |
| 39 | <div class="section" id="id205"> | |
| 40 | <h3><a class="subsection-title" href="#model-of" name="model-of">Model of</a></h3> | |
| 41 | <p><a class="reference internal" href="./tag-dispatched-metafunction.html">Tag Dispatched Metafunction</a></p> | |
| 42 | </div> | |
| 43 | <div class="section" id="id206"> | |
| 44 | <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> | |
| 45 | <table border="1" class="docutils table"> | |
| 46 | <colgroup> | |
| 47 | <col width="18%" /> | |
| 48 | <col width="22%" /> | |
| 49 | <col width="60%" /> | |
| 50 | </colgroup> | |
| 51 | <thead valign="bottom"> | |
| 52 | <tr><th class="head">Parameter</th> | |
| 53 | <th class="head">Requirement</th> | |
| 54 | <th class="head">Description</th> | |
| 55 | </tr> | |
| 56 | </thead> | |
| 57 | <tbody valign="top"> | |
| 58 | <tr><td><tt class="literal"><span class="pre">X</span></tt></td> | |
| 59 | <td>Any type</td> | |
| 60 | <td>A type whose begin iterator, if any, will be | |
| 61 | returned.</td> | |
| 62 | </tr> | |
| 63 | </tbody> | |
| 64 | </table> | |
| 65 | </div> | |
| 66 | <div class="section" id="id207"> | |
| 67 | <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> | |
| 68 | <p>For any arbitrary type <tt class="literal"><span class="pre">x</span></tt>:</p> | |
| 69 | <pre class="literal-block"> | |
| 70 | typedef <a href="./begin.html" class="identifier">begin</a><x>::type first; | |
| 71 | </pre> | |
| 72 | <table class="docutils field-list" frame="void" rules="none"> | |
| 73 | <col class="field-name" /> | |
| 74 | <col class="field-body" /> | |
| 75 | <tbody valign="top"> | |
| 76 | <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><a class="reference internal" href="./forward-iterator.html">Forward Iterator</a> or <a class="reference internal" href="./void.html">void_</a>.</td> | |
| 77 | </tr> | |
| 78 | <tr class="field"><th class="field-name">Semantics:</th><td class="field-body">If <tt class="literal"><span class="pre">x</span></tt> is a <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a>, <tt class="literal"><span class="pre">first</span></tt> is an iterator pointing to the | |
| 79 | first element of <tt class="literal"><span class="pre">s</span></tt>; otherwise <tt class="literal"><span class="pre">first</span></tt> is <a class="reference internal" href="./void.html">void_</a>.</td> | |
| 80 | </tr> | |
| 81 | <tr class="field"><th class="field-name">Postcondition:</th><td class="field-body">If <tt class="literal"><span class="pre">first</span></tt> is an iterator, it is either dereferenceable or past-the-end; it | |
| 82 | is past-the-end if and only if <tt class="literal"><span class="pre"><a href="./size.html" class="identifier">size</a><x>::value</span> <span class="pre">==</span> <span class="pre">0</span></tt>.</td> | |
| 83 | </tr> | |
| 84 | </tbody> | |
| 85 | </table> | |
| 86 | </div> | |
| 87 | <div class="section" id="id208"> | |
| 88 | <h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3> | |
| 89 | <p>Amortized constant time.</p> | |
| 90 | </div> | |
| 91 | <div class="section" id="id209"> | |
| 92 | <h3><a class="subsection-title" href="#example" name="example">Example</a></h3> | |
| 93 | <pre class="literal-block"> | |
| 94 | typedef <a href="./vector.html" class="identifier">vector</a>< unsigned char,unsigned short, | |
| 95 | unsigned int,unsigned long > unsigned_types; | |
| 96 | ||
| 97 | typedef <a href="./begin.html" class="identifier">begin</a><unsigned_types>::type iter; | |
| 98 | <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same< <a href="./deref.html" class="identifier">deref</a><iter>::type, unsigned char > )); | |
| 99 | ||
| 100 | <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same< <a href="./begin.html" class="identifier">begin</a><int>::type, <a href="./void.html" class="identifier">void_</a> > )); | |
| 101 | </pre> | |
| 102 | </div> | |
| 103 | <div class="section" id="id210"> | |
| 104 | <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> | |
| 105 | <p><a class="reference internal" href="./iterators.html">Iterators</a>, <a class="reference internal" href="./forward-sequence.html">Forward Sequence</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></p> | |
| 106 | <!-- Sequences/Intrinsic Metafunctions//clear --> | |
| 107 | </div> | |
| 108 | </div> | |
| 109 | ||
| 110 | <div class="footer-separator"></div> | |
| 111 | <table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./back.html" class="navigation-link">Prev</a> <a href="./clear.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./back.html" class="navigation-link">Back</a> <a href="./clear.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./intrinsic-metafunctions.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> | |
| 112 | <td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> | |
| 113 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
| 114 | 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> | |
| 115 | </html> |