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More progress on indirect_iterator

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[SVN r21720]
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Dave Abrahams
2004-01-14 04:16:27 +00:00
parent 5f3b97ceff
commit dd50d3f2ab
8 changed files with 126 additions and 89 deletions
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@ -129,7 +129,7 @@ else
<tt class="literal"><span class="pre">R</span></tt> is <tt class="literal"><span class="pre">reference</span></tt> and <tt class="literal"><span class="pre">V</span></tt> is <tt class="literal"><span class="pre">value_type</span></tt>, and where: if
<tt class="literal"><span class="pre">CategoryOrTraversal</span></tt> is <tt class="literal"><span class="pre">use_default</span></tt>, <tt class="literal"><span class="pre">C</span></tt> is
<tt class="literal"><span class="pre">iterator_traversal&lt;Iterator&gt;::type</span></tt> and otherwise <tt class="literal"><span class="pre">C</span></tt> is
<tt class="literal"><span class="pre">CategoryOrTraversal</span></tt>:</p>
<tt class="literal"><span class="pre">CategoryOrTraversal</span></tt>.</p>
<blockquote>
<ul>
<li><p class="first">if <tt class="literal"><span class="pre">C</span></tt> is convertible to <tt class="literal"><span class="pre">std::input_iterator_tag</span></tt> or
@ -179,38 +179,42 @@ convertible, and not to any more-derived traversal tag type.</p>
</div>
<div class="section" id="indirect-iterator-requirements">
<h1><a class="toc-backref" href="#id3" name="indirect-iterator-requirements"><tt class="literal"><span class="pre">indirect_iterator</span></tt> requirements</a></h1>
<p><tt class="literal"><span class="pre">CategoryOrTraversal</span></tt> argument shall be <tt class="literal"><span class="pre">use_default</span></tt> or it
shall be convertible to one of the standard iterator or traversal
tags. If <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt> is not <tt class="literal"><span class="pre">use_default</span></tt>, it shall
indicate the traversal category modeled by <tt class="literal"><span class="pre">Iterator</span></tt>. If</p>
<p>The expression <tt class="literal"><span class="pre">*v</span></tt>, where <tt class="literal"><span class="pre">v</span></tt> is an object of type
<p>The expression <tt class="literal"><span class="pre">*v</span></tt>, where <tt class="literal"><span class="pre">v</span></tt> is an object of
<tt class="literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt>, shall be valid
expression and convertible to <tt class="literal"><span class="pre">reference</span></tt>. Also
<tt class="literal"><span class="pre">indirect_iterator::reference</span></tt> must be convertible to
<tt class="literal"><span class="pre">indirect_iterator::value</span></tt>. There are further requirements on
the <tt class="literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt> if the <tt class="literal"><span class="pre">Value</span></tt>
expression and convertible to <tt class="literal"><span class="pre">reference</span></tt>. <tt class="literal"><span class="pre">Iterator</span></tt> shall
model the traversal concept indicated by <tt class="literal"><span class="pre">iterator_category</span></tt>.
<tt class="literal"><span class="pre">Value</span></tt>, <tt class="literal"><span class="pre">Reference</span></tt>, and <tt class="literal"><span class="pre">Difference</span></tt> shall be chosen so
that <tt class="literal"><span class="pre">value_type</span></tt>, <tt class="literal"><span class="pre">reference</span></tt>, and <tt class="literal"><span class="pre">difference_type</span></tt> meet
the requirements indicated by <tt class="literal"><span class="pre">iterator_category</span></tt>.</p>
<p>[Note: there are further requirements on the
<tt class="literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt> if the <tt class="literal"><span class="pre">Value</span></tt>
parameter is not <tt class="literal"><span class="pre">use_default</span></tt>, as implied by the algorithm for
deducing the default for the <tt class="literal"><span class="pre">value_type</span></tt> member.</p>
deducing the default for the <tt class="literal"><span class="pre">value_type</span></tt> member.]</p>
</div>
<div class="section" id="indirect-iterator-models">
<h1><a class="toc-backref" href="#id4" name="indirect-iterator-models"><tt class="literal"><span class="pre">indirect_iterator</span></tt> models</a></h1>
<p>If <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt> is a standard iterator tag,
<tt class="literal"><span class="pre">indirect_iterator</span></tt> is a model of the iterator concept corresponding
to the tag, otherwise <tt class="literal"><span class="pre">indirect_iterator</span></tt> satisfies the requirements
of the most refined standard traversal concept that is satisfied by
the <tt class="literal"><span class="pre">Iterator</span></tt> argument.</p>
<p><tt class="literal"><span class="pre">indirect_iterator</span></tt> models Readable Iterator. If
<tt class="literal"><span class="pre">indirect_iterator::reference(*v)</span> <span class="pre">=</span> <span class="pre">t</span></tt> is a valid expression (where
<tt class="literal"><span class="pre">t</span></tt> is an object of type <tt class="literal"><span class="pre">indirect_iterator::value_type</span></tt>) then
<tt class="literal"><span class="pre">indirect_iterator</span></tt> models Writable Iterator. If
<tt class="literal"><span class="pre">indirect_iterator::reference</span></tt> is a reference then
<tt class="literal"><span class="pre">indirect_iterator</span></tt> models Lvalue Iterator.</p>
<p>In addition to the concepts indicated by <tt class="literal"><span class="pre">iterator_category</span></tt>, a
specialization of <tt class="literal"><span class="pre">indirect_iterator</span></tt> models the following
concepts, Where <tt class="literal"><span class="pre">v</span></tt> is an object of
<tt class="literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt>:</p>
<blockquote>
<ul class="simple">
<li>Readable Iterator if <tt class="literal"><span class="pre">reference(*v)</span></tt> is convertible to
<tt class="literal"><span class="pre">value_type</span></tt>.</li>
<li>Writable Iterator if <tt class="literal"><span class="pre">reference(*v)</span> <span class="pre">=</span> <span class="pre">t</span></tt> is a valid
expression (where <tt class="literal"><span class="pre">t</span></tt> is an object of type
<tt class="literal"><span class="pre">indirect_iterator::value_type</span></tt>)</li>
<li>Lvalue Iterator if <tt class="literal"><span class="pre">reference</span></tt> is a reference type.</li>
</ul>
</blockquote>
<p>Two specializations of <tt class="literal"><span class="pre">indirect_iterator</span></tt> are interoperable if
their <tt class="literal"><span class="pre">Iterator</span></tt> parameters are interoperable.</p>
</div>
<div class="section" id="indirect-iterator-operations">
<h1><a class="toc-backref" href="#id5" name="indirect-iterator-operations"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></h1>
<p>In addition to the operations required by the concepts modeled by
<tt class="literal"><span class="pre">indirect_iterator</span></tt>, <tt class="literal"><span class="pre">indirect_iterator</span></tt> provides the following
operations.</p>
<p>In addition to the operations required by the concepts described
above, specializations of <tt class="literal"><span class="pre">indirect_iterator</span></tt> provide the
following operations.</p>
<p><tt class="literal"><span class="pre">indirect_iterator();</span></tt></p>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />