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<title>Issue 909: regex_token_iterator should use initializer_list</title>
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<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#C++11">C++11</a> status.</em></p>
<h3 id="909"><a href="lwg-defects.html#909">909</a>. <code>regex_token_iterator</code> should use <code>initializer_list</code></h3>
<p><b>Section:</b> 28.6.11.2 <a href="https://wg21.link/re.tokiter">[re.tokiter]</a> <b>Status:</b> <a href="lwg-active.html#C++11">C++11</a>
 <b>Submitter:</b> Daniel Kr&uuml;gler <b>Opened:</b> 2008-09-26 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#re.tokiter">issues</a> in [re.tokiter].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++11">C++11</a> status.</p>
<p><b>Discussion:</b></p>

<p><b>Addresses UK 319</b></p>
<p>
Construction of a <code>regex_token_iterator</code> (28.6.11.2 <a href="https://wg21.link/re.tokiter">[re.tokiter]</a>/6+) usually
requires the provision of a sequence of integer values, which
can currently be done via a <code>std::vector&lt;int&gt;</code> or
a C array of <code>int</code>. Since the introduction of <code>initializer_list</code> in the
standard it seems much more reasonable to provide a
corresponding constructor that accepts an <code>initializer_list&lt;int&gt;</code>
instead. This could be done as a pure addition or one could
even consider replacement. The author suggests the
replacement strategy (A), but provides an alternative additive
proposal (B) as a fall-back, because of the handiness of this
range type:
</p>

<p><i>[
Batavia (2009-05):
]</i></p>

<blockquote><p>
We strongly recommend alternative B of the proposed resolution
in order that existing code not be broken.
With that understanding, move to Tentatively Ready.
</p></blockquote>

<p><b>Original proposed wording:</b></p>

<ol style="list-style-type:upper-alpha">
<li><br/>
<ol>
<li>
<p>
In 28.6.11.2 <a href="https://wg21.link/re.tokiter">[re.tokiter]</a>/6 and the list 28.6.11.2.2 <a href="https://wg21.link/re.tokiter.cnstr">[re.tokiter.cnstr]</a>/10-11 change the
constructor declaration:
</p>

<blockquote><pre>
<del>template &lt;std::size_t N&gt;</del>
regex_token_iterator(BidirectionalIterator a, BidirectionalIterator b,
                     const regex_type&amp; re,
                     <del>const int (&amp;submatches)[N]</del> <ins>initializer_list&lt;int&gt; submatches</ins>,
                     regex_constants::match_flag_type m =
                       regex_constants::match_default);
</pre></blockquote>
</li>

<li>
<p>
In 28.6.11.2.2 <a href="https://wg21.link/re.tokiter.cnstr">[re.tokiter.cnstr]</a>/12 change the last sentence
</p>

<blockquote><p>
The third constructor initializes the member <code>subs</code> to hold
a copy of the sequence of integer values pointed to by the
iterator range <code>[<del>&amp;</del>submatches<ins>.begin()</ins>,
<del>&amp;</del>submatches<ins>.end()</ins> <del>+ N</del>)</code>.
</p></blockquote>
</li>
</ol>
</li>

<li><br/>
<ol>
<li>
<p>
In 28.6.11.2 <a href="https://wg21.link/re.tokiter">[re.tokiter]</a>/6 and the list 28.6.11.2.2 <a href="https://wg21.link/re.tokiter.cnstr">[re.tokiter.cnstr]</a>/10-11 <em>insert</em> the
following constructor declaration between the already existing ones
accepting a <code>std::vector</code> and a C array of <code>int</code>, resp.:
</p>

<blockquote><pre>
regex_token_iterator(BidirectionalIterator a, BidirectionalIterator b,
                     const regex_type&amp; re,
                     initializer_list&lt;int&gt; submatches,
                     regex_constants::match_flag_type m =
                       regex_constants::match_default);
</pre></blockquote>
</li>
<li>
<p>
In 28.6.11.2.2 <a href="https://wg21.link/re.tokiter.cnstr">[re.tokiter.cnstr]</a>/12 change the last sentence
</p>

<blockquote><p>
The third <ins>and fourth</ins> constructor initialize<del>s</del> the member <code>subs</code>
to hold a copy of the sequence of integer values pointed to
by the iterator range <code>[&amp;submatches,&amp;submatches + N)</code>
<ins>and <code>[submatches.begin(),submatches.end())</code>, respectively</ins>.
</p></blockquote>
</li>
</ol>
</li>

</ol>



<p id="res-909"><b>Proposed resolution:</b></p>

<ol style="list-style-type:upper-alpha">
<li>[&hellip;]</li>
<li><br/>
<ol>
<li>
<p>
In 28.6.11.2 <a href="https://wg21.link/re.tokiter">[re.tokiter]</a>/6 and the list 28.6.11.2.2 <a href="https://wg21.link/re.tokiter.cnstr">[re.tokiter.cnstr]</a>/10-11 <em>insert</em> the
following constructor declaration between the already existing ones
accepting a <code>std::vector</code> and a C array of <code>int</code>, resp.:
</p>

<blockquote><pre>
regex_token_iterator(BidirectionalIterator a, BidirectionalIterator b,
                     const regex_type&amp; re,
                     initializer_list&lt;int&gt; submatches,
                     regex_constants::match_flag_type m =
                       regex_constants::match_default);
</pre></blockquote>
</li>
<li>
<p>
In 28.6.11.2.2 <a href="https://wg21.link/re.tokiter.cnstr">[re.tokiter.cnstr]</a>/12 change the last sentence
</p>

<blockquote><p>
The third <ins>and fourth</ins> constructor initialize<del>s</del> the member <code>subs</code>
to hold a copy of the sequence of integer values pointed to
by the iterator range <code>[&amp;submatches,&amp;submatches + N)</code>
<ins>and <code>[submatches.begin(),submatches.end())</code>, respectively</ins>.
</p></blockquote>
</li>
</ol>
</li>

</ol>






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