<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Issue 647: Inconsistent regex_search params</title>
<meta property="og:title" content="Issue 647: Inconsistent regex_search params">
<meta property="og:description" content="C++ library issue. Status: NAD Editorial">
<meta property="og:url" content="https://cplusplus.github.io/LWG/issue647.html">
<meta property="og:type" content="website">
<meta property="og:image" content="http://cplusplus.github.io/LWG/images/cpp_logo.png">
<meta property="og:image:alt" content="C++ logo">
<style>
  p {text-align:justify}
  li {text-align:justify}
  pre code.backtick::before { content: "`" }
  pre code.backtick::after { content: "`" }
  blockquote.note
  {
    background-color:#E0E0E0;
    padding-left: 15px;
    padding-right: 15px;
    padding-top: 1px;
    padding-bottom: 1px;
  }
  ins {background-color:#A0FFA0}
  del {background-color:#FFA0A0}
  table.issues-index { border: 1px solid; border-collapse: collapse; }
  table.issues-index th { text-align: center; padding: 4px; border: 1px solid; }
  table.issues-index td { padding: 4px; border: 1px solid; }
  table.issues-index td:nth-child(1) { text-align: right; }
  table.issues-index td:nth-child(2) { text-align: left; }
  table.issues-index td:nth-child(3) { text-align: left; }
  table.issues-index td:nth-child(4) { text-align: left; }
  table.issues-index td:nth-child(5) { text-align: center; }
  table.issues-index td:nth-child(6) { text-align: center; }
  table.issues-index td:nth-child(7) { text-align: left; }
  table.issues-index td:nth-child(5) span.no-pr { color: red; }
  @media (prefers-color-scheme: dark) {
     html {
        color: #ddd;
        background-color: black;
     }
     ins {
        background-color: #225522
     }
     del {
        background-color: #662222
     }
     a {
        color: #6af
     }
     a:visited {
        color: #6af
     }
     blockquote.note
     {
        background-color: rgba(255, 255, 255, .10)
     }
  }
</style>
</head>
<body>
<hr>
<p><em>This page is a snapshot from the LWG issues list, see the <a href="lwg-active.html">Library Active Issues List</a> for more information and the meaning of <a href="lwg-active.html#NAD_Editorial">NAD Editorial</a> status.</em></p>
<h3 id="647"><a href="lwg-closed.html#647">647</a>. Inconsistent <code>regex_search</code> params</h3>
<p><b>Section:</b> 28.6.10.3 <a href="https://wg21.link/re.alg.search">[re.alg.search]</a> <b>Status:</b> <a href="lwg-active.html#NAD_Editorial">NAD Editorial</a>
 <b>Submitter:</b> Daniel Kr&uuml;gler <b>Opened:</b> 2007-02-26 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all issues with</b> <a href="lwg-status.html#NAD Editorial">NAD Editorial</a> status.</p>
<p><b>Discussion:</b></p>
<p>
28.6.10.3 <a href="https://wg21.link/re.alg.search">[re.alg.search]</a>/5 declares
</p>

<blockquote><pre>
template &lt;class iterator, class charT, class traits&gt;
bool regex_search(iterator first, iterator last,
                  const basic_regex&lt;charT, traits&gt;&amp; e,
                  regex_constants::match_flag_type flags =
                      regex_constants::match_default);
</pre></blockquote>

<p>
where it's not explained, which iterator category
the parameter iterator belongs to. This is inconsistent
to the preceding declaration in the synopsis section
28.6.3 <a href="https://wg21.link/re.syn">[re.syn]</a>, which says:
</p>

<blockquote><pre>
template &lt;class BidirectionalIterator, class charT, class traits&gt;
bool regex_search(BidirectionalIterator first, BidirectionalIterator last,
                  const basic_regex&lt;charT, traits&gt;&amp; e,
                  regex_constants::match_flag_type flags =
                      regex_constants::match_default);
</pre></blockquote>


<p id="res-647"><b>Proposed resolution:</b></p>
<p>
In 28.6.10.3 <a href="https://wg21.link/re.alg.search">[re.alg.search]</a>/5 replace all three occurences of param "iterator" with
"BidirectionalIterator"
</p>

<blockquote><pre>
template &lt;class <del>iterator</del> <ins>BidirectionalIterator</ins>, class charT, class traits&gt;
  bool regex_search(<del>iterator</del> <ins>BidirectionalIterator</ins> first, <del>iterator</del> <ins>BidirectionalIterator</ins> last, 
                    const basic_regex&lt;charT, traits&gt;&amp; e, 
                    regex_constants::match_flag_type flags = 
                      regex_constants::match_default);
</pre>
<p>
-6- <i>Effects:</i> Behaves "as if" by constructing an object what of
type <code>match_results&lt;<del>iterator</del>
<ins>BidirectionalIterator</ins>&gt;</code> and then returning the result
of <code>regex_search(first, last, what, e, flags)</code>.
</p>
</blockquote>


<p><b>Rationale:</b></p><p>
Applied to working paper while issue was still in New status.
</p>




</body>
</html>
