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Some progress on indirect_iterator

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[SVN r21710]
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Dave Abrahams
2004-01-13 23:03:18 +00:00
parent 736044938d
commit 0f8c236e9d
15 changed files with 524 additions and 127 deletions
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@ -7,7 +7,7 @@
<title>Iterator Facade and Adaptor</title>
<meta name="author" content="David Abrahams, Jeremy Siek, Thomas Witt" />
<meta name="organization" content="Boost Consulting, Indiana University Open Systems Lab, University of Hanover Institute for Transport Railway Operation and Construction" />
<meta name="date" content="2004-01-12" />
<meta name="date" content="2004-01-13" />
<link rel="stylesheet" href="default.css" type="text/css" />
</head>
<body>
@ -26,7 +26,7 @@
Lab</a>, University of Hanover <a class="last reference" href="http://www.ive.uni-hannover.de">Institute for Transport
Railway Operation and Construction</a></td></tr>
<tr><th class="docinfo-name">Date:</th>
<td>2004-01-12</td></tr>
<td>2004-01-13</td></tr>
<tr class="field"><th class="docinfo-name">Number:</th><td class="field-body">This is a revised version of <a class="reference" href="http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/papers/2003/n1530.html">N1530</a>=03-0113, which was
accepted for Technical Report 1 by the C++ standard
committee's library working group.</td>
@ -802,8 +802,7 @@ Iterator</td>
<div class="section" id="iterator-facade-iterator-category">
<h3><a class="toc-backref" href="#id30" name="iterator-facade-iterator-category"><tt class="literal"><span class="pre">iterator_facade</span></tt> iterator category</a></h3>
<p>The <tt class="literal"><span class="pre">iterator_category</span></tt> member of <tt class="literal"><span class="pre">iterator_facade&lt;X,V,R,C,D&gt;</span></tt>
is a type which satisfies the following conditions:</p>
<blockquote>
satisfies the following conditions:</p>
<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
<tt class="literal"><span class="pre">C</span></tt> is convertible to <tt class="literal"><span class="pre">std::output_iterator_tag</span></tt>,
@ -845,7 +844,9 @@ convertible, and not to any more-derived traversal tag type.</p>
</ul>
</li>
</ul>
</blockquote>
<!-- Copyright David Abrahams 2004. Use, modification and distribution is -->
<!-- subject to the Boost Software License, Version 1.0. (See accompanying -->
<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) -->
</div>
<div class="section" id="iterator-facade-operations">
<h3><a class="toc-backref" href="#id31" name="iterator-facade-operations"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></h3>
@ -1410,37 +1411,72 @@ if (Difference is use_default)
else
typedef Difference difference_type;
</pre>
<p>If <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt> is not <tt class="literal"><span class="pre">use_default</span></tt> then
<tt class="literal"><span class="pre">iterator_category</span></tt> is <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt>. Otherwise
<tt class="literal"><span class="pre">iterator_category</span></tt> is a type convertible to the tag determined by
the following algorithm. Let <tt class="literal"><span class="pre">C</span></tt> be <tt class="literal"><span class="pre">traversal_category&lt;Iterator&gt;::type</span></tt>.</p>
<p><tt class="literal"><span class="pre">iterator_category</span></tt> satisfies the following conditions, where
<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>
<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
<tt class="literal"><span class="pre">C</span></tt> is convertible to <tt class="literal"><span class="pre">std::output_iterator_tag</span></tt>,
<tt class="literal"><span class="pre">iterator_category</span></tt> is the same as <tt class="literal"><span class="pre">C</span></tt>.</p>
</li>
<li><p class="first">Otherwise, if <tt class="literal"><span class="pre">C</span></tt> is not convertible to
<tt class="literal"><span class="pre">incrementable_traversal_tag</span></tt>, the program is ill-formed</p>
</li>
<li><p class="first">Otherwise:</p>
<ul>
<li><p class="first"><tt class="literal"><span class="pre">iterator_category</span></tt> is convertible to the iterator
category tag or tags given by the following algorithm, and
not to any more-derived iterator category tag or tags:</p>
<pre class="literal-block">
if (reference is a reference to value_type) then
if (C is convertible to random_access_traversal_tag) then
if (R is a reference type
&amp;&amp; C is convertible to forward_traversal_tag)
{
if (C is convertible to random_access_traversal_tag)
random_access_iterator_tag
else if (C is convertible to bidirectional_traversal_tag) then
else if (C is convertible to bidirectional_traversal_tag)
bidirectional_iterator_tag
else
forward_iterator_tag
}
else
input_iterator_tag
{
if (C is convertible to single_pass_traversal_tag
&amp;&amp; R is convertible to V)
input_iterator_tag
else
C
}
</pre>
</li>
<li><p class="first"><tt class="literal"><span class="pre">iterator_traversal&lt;X&gt;::type</span></tt> is convertible to the most
derived traversal tag type to which <tt class="literal"><span class="pre">C</span></tt> is also
convertible, and not to any more-derived traversal tag type.</p>
</li>
</ul>
</li>
</ul>
<!-- Copyright David Abrahams 2004. Use, modification and distribution is -->
<!-- subject to the Boost Software License, Version 1.0. (See accompanying -->
<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) -->
</blockquote>
</div>
<div class="section" id="indirect-iterator-requirements">
<h4><a class="toc-backref" href="#id45" name="indirect-iterator-requirements"><tt class="literal"><span class="pre">indirect_iterator</span></tt> requirements</a></h4>
<p>The <tt class="literal"><span class="pre">Iterator</span></tt> argument shall meet the requirements of Readable
Iterator. The <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt> argument shall be one of the
standard iterator tags or <tt class="literal"><span class="pre">use_default</span></tt>. If <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt>
is an iterator tag, the template parameter <tt class="literal"><span class="pre">Iterator</span></tt> argument shall
meet the requirements corresponding to the iterator tag.</p>
<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
<tt class="literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt>, must be a valid expression
and must be convertible to <tt class="literal"><span class="pre">indirect_iterator::reference</span></tt>. Also
<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> 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>
<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>
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>
</div>
<div class="section" id="indirect-iterator-models">
<h4><a class="toc-backref" href="#id46" name="indirect-iterator-models"><tt class="literal"><span class="pre">indirect_iterator</span></tt> models</a></h4>
@ -2436,7 +2472,6 @@ LocalWords: OtherIncrementable Coplien -->
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