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  27 <a name="boost_regex.syntax.leftmost_longest_rule"></a><a class="link" href="leftmost_longest_rule.html" title="The Leftmost Longest Rule">The Leftmost
  28       Longest Rule</a>
  29 </h3></div></div></div>
  30 <p>
  31         Often there is more than one way of matching a regular expression at a particular
  32         location, for POSIX basic and extended regular expressions, the "best"
  33         match is determined as follows:
  34       </p>
  35 <div class="orderedlist"><ol class="orderedlist" type="1">
  36 <li class="listitem">
  37             Find the leftmost match, if there is only one match possible at this
  38             location then return it.
  39           </li>
  40 <li class="listitem">
  41             Find the longest of the possible matches, along with any ties. If there
  42             is only one such possible match then return it.
  43           </li>
  44 <li class="listitem">
  45             If there are no marked sub-expressions, then all the remaining alternatives
  46             are indistinguishable; return the first of these found.
  47           </li>
  48 <li class="listitem">
  49             Find the match which has matched the first sub-expression in the leftmost
  50             position, along with any ties. If there is only on such match possible
  51             then return it.
  52           </li>
  53 <li class="listitem">
  54             Find the match which has the longest match for the first sub-expression,
  55             along with any ties. If there is only one such match then return it.
  56           </li>
  57 <li class="listitem">
  58             Repeat steps 4 and 5 for each additional marked sub-expression.
  59           </li>
  60 <li class="listitem">
  61             If there is still more than one possible match remaining, then they are
  62             indistinguishable; return the first one found.
  63           </li>
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  68 <td align="right"><div class="copyright-footer">Copyright &#169; 1998-2013 John Maddock<p>
  69         Distributed under the Boost Software License, Version 1.0. (See accompanying
  70         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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