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<title>Issue 2826: string_view iterators use old wording</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++17">C++17</a> status.</em></p>
<h3 id="2826"><a href="lwg-defects.html#2826">2826</a>. <code>string_view</code> iterators use old wording</h3>
<p><b>Section:</b> 27.3.3.4 <a href="https://wg21.link/string.view.iterators">[string.view.iterators]</a> <b>Status:</b> <a href="lwg-active.html#C++17">C++17</a>
 <b>Submitter:</b> Alisdair Meredith <b>Opened:</b> 2016-11-17 <b>Last modified:</b> 2017-07-30</p>
<p><b>Priority: </b>0
</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++17">C++17</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The wording for <code>basic_string_view</code> was written before the definition of
a contiguous iterator was added to C++17 to avoid repeating redundant
wording.
</p>
<p>
Suggested modification of 27.3.3.4 <a href="https://wg21.link/string.view.iterators">[string.view.iterators]</a> p1 (stealing words from <code>valarray begin</code>/<code>end</code>):
</p>
<blockquote><p>
-1- <del>A constant random-access iterator type such that, for a <code>const_iterator it</code>, if <code>&amp;*(it + N)</code> is valid,
then <code>&amp;*(it + N) == (&amp;*it) + N</code></del><ins>A type that meets the requirements of a constant random access iterator 
(24.2.7) and of a contiguous iterator (24.2.1) whose <code>value_type</code> is the template parameter <code>charT</code></ins>.
</p></blockquote>

<p><i>[2017-01-27 Telecon]</i></p>

<p>Priority 0</p>


<p id="res-2826"><b>Proposed resolution:</b></p>
<p>
This wording is relative to N4606.
</p>
<ol>
<li><p>Modify 27.3.3.4 <a href="https://wg21.link/string.view.iterators">[string.view.iterators]</a> as indicated:</p>
<blockquote>
<pre>
using const_iterator = <i>implementation-defined</i>;
</pre>
<blockquote>
<p>
-1- A <del>constant random-access iterator type such that, for a <code>const_iterator it</code>, if <code>&amp;*(it + N)</code> is valid,
then <code>&amp;*(it + N) == (&amp;*it) + N</code></del><ins>type that meets the requirements of a constant random access 
iterator (24.3.5.7 <a href="https://wg21.link/random.access.iterators">[random.access.iterators]</a>) and of a contiguous iterator (24.3.1 <a href="https://wg21.link/iterator.requirements.general">[iterator.requirements.general]</a>)
whose <code>value_type</code> is the template parameter <code>charT</code></ins>.
<p/>
-2- For a <code>basic_string_view str</code>, any operation that invalidates a pointer in the range <code>[str.data(),
str.data() + str.size())</code> invalidates pointers, iterators, and references returned from <code>str</code>'s methods.
<p/>
-3- All requirements on container iterators (23.2 <a href="https://wg21.link/container.requirements">[container.requirements]</a>) apply to 
<code>basic_string_view::const_iterator</code> as well.
</p>
</blockquote>
</blockquote>
</li>
</ol>





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