80 lines
4.4 KiB
HTML
80 lines
4.4 KiB
HTML
<html>
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
|
|
<title>The Leftmost Longest Rule</title>
|
|
<link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css">
|
|
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
|
|
<link rel="home" href="../../index.html" title="Boost.Regex 5.1.4">
|
|
<link rel="up" href="../syntax.html" title="Regular Expression Syntax">
|
|
<link rel="prev" href="collating_names/named_unicode.html" title="Named Unicode Characters">
|
|
<link rel="next" href="../format.html" title="Search and Replace Format String Syntax">
|
|
</head>
|
|
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
|
|
<table cellpadding="2" width="100%"><tr>
|
|
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../boost.png"></td>
|
|
<td align="center"><a href="../../../../../../index.html">Home</a></td>
|
|
<td align="center"><a href="../../../../../../libs/libraries.htm">Libraries</a></td>
|
|
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
|
|
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
|
|
<td align="center"><a href="../../../../../../more/index.htm">More</a></td>
|
|
</tr></table>
|
|
<hr>
|
|
<div class="spirit-nav">
|
|
<a accesskey="p" href="collating_names/named_unicode.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../syntax.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../format.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a>
|
|
</div>
|
|
<div class="section">
|
|
<div class="titlepage"><div><div><h3 class="title">
|
|
<a name="boost_regex.syntax.leftmost_longest_rule"></a><a class="link" href="leftmost_longest_rule.html" title="The Leftmost Longest Rule">The Leftmost
|
|
Longest Rule</a>
|
|
</h3></div></div></div>
|
|
<p>
|
|
Often there is more than one way of matching a regular expression at a particular
|
|
location, for POSIX basic and extended regular expressions, the "best"
|
|
match is determined as follows:
|
|
</p>
|
|
<div class="orderedlist"><ol class="orderedlist" type="1">
|
|
<li class="listitem">
|
|
Find the leftmost match, if there is only one match possible at this
|
|
location then return it.
|
|
</li>
|
|
<li class="listitem">
|
|
Find the longest of the possible matches, along with any ties. If there
|
|
is only one such possible match then return it.
|
|
</li>
|
|
<li class="listitem">
|
|
If there are no marked sub-expressions, then all the remaining alternatives
|
|
are indistinguishable; return the first of these found.
|
|
</li>
|
|
<li class="listitem">
|
|
Find the match which has matched the first sub-expression in the leftmost
|
|
position, along with any ties. If there is only on such match possible
|
|
then return it.
|
|
</li>
|
|
<li class="listitem">
|
|
Find the match which has the longest match for the first sub-expression,
|
|
along with any ties. If there is only one such match then return it.
|
|
</li>
|
|
<li class="listitem">
|
|
Repeat steps 4 and 5 for each additional marked sub-expression.
|
|
</li>
|
|
<li class="listitem">
|
|
If there is still more than one possible match remaining, then they are
|
|
indistinguishable; return the first one found.
|
|
</li>
|
|
</ol></div>
|
|
</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 © 1998-2013 John Maddock<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="collating_names/named_unicode.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../syntax.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../format.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a>
|
|
</div>
|
|
</body>
|
|
</html>
|