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Applied use of iterator-category to specialized adapters

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[SVN r21745]
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Dave Abrahams
2004-01-15 00:01:33 +00:00
parent 33f630beca
commit c3fd7076c1
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@ -56,83 +56,83 @@ by adapting other iterators.</td>
<div class="contents topic" id="table-of-contents">
<p class="topic-title"><a name="table-of-contents">Table of Contents</a></p>
<ul class="simple">
<li><a class="reference" href="#motivation" id="id13" name="id13">Motivation</a></li>
<li><a class="reference" href="#impact-on-the-standard" id="id14" name="id14">Impact on the Standard</a></li>
<li><a class="reference" href="#design" id="id15" name="id15">Design</a><ul>
<li><a class="reference" href="#iterator-concepts" id="id16" name="id16">Iterator Concepts</a></li>
<li><a class="reference" href="#interoperability" id="id17" name="id17">Interoperability</a></li>
<li><a class="reference" href="#iterator-facade" id="id18" name="id18">Iterator Facade</a><ul>
<li><a class="reference" href="#usage" id="id19" name="id19">Usage</a></li>
<li><a class="reference" href="#iterator-core-access" id="id20" name="id20">Iterator Core Access</a></li>
<li><a class="reference" href="#operator" id="id21" name="id21"><tt class="literal"><span class="pre">operator[]</span></tt></a></li>
<li><a class="reference" href="#id6" id="id22" name="id22"><tt class="literal"><span class="pre">operator-&gt;</span></tt></a></li>
<li><a class="reference" href="#motivation" id="id14" name="id14">Motivation</a></li>
<li><a class="reference" href="#impact-on-the-standard" id="id15" name="id15">Impact on the Standard</a></li>
<li><a class="reference" href="#design" id="id16" name="id16">Design</a><ul>
<li><a class="reference" href="#iterator-concepts" id="id17" name="id17">Iterator Concepts</a></li>
<li><a class="reference" href="#interoperability" id="id18" name="id18">Interoperability</a></li>
<li><a class="reference" href="#iterator-facade" id="id19" name="id19">Iterator Facade</a><ul>
<li><a class="reference" href="#usage" id="id20" name="id20">Usage</a></li>
<li><a class="reference" href="#iterator-core-access" id="id21" name="id21">Iterator Core Access</a></li>
<li><a class="reference" href="#operator" id="id22" name="id22"><tt class="literal"><span class="pre">operator[]</span></tt></a></li>
<li><a class="reference" href="#id6" id="id23" name="id23"><tt class="literal"><span class="pre">operator-&gt;</span></tt></a></li>
</ul>
</li>
<li><a class="reference" href="#iterator-adaptor" id="id23" name="id23">Iterator Adaptor</a></li>
<li><a class="reference" href="#specialized-adaptors" id="id24" name="id24">Specialized Adaptors</a></li>
<li><a class="reference" href="#iterator-adaptor" id="id24" name="id24">Iterator Adaptor</a></li>
<li><a class="reference" href="#specialized-adaptors" id="id25" name="id25">Specialized Adaptors</a></li>
</ul>
</li>
<li><a class="reference" href="#proposed-text" id="id25" name="id25">Proposed Text</a><ul>
<li><a class="reference" href="#header-iterator-helper-synopsis-lib-iterator-helper-synopsis" id="id26" name="id26">Header <tt class="literal"><span class="pre">&lt;iterator_helper&gt;</span></tt> synopsis [lib.iterator.helper.synopsis]</a></li>
<li><a class="reference" href="#iterator-facade-lib-iterator-facade" id="id27" name="id27">Iterator facade [lib.iterator.facade]</a><ul>
<li><a class="reference" href="#class-template-iterator-facade" id="id28" name="id28">Class template <tt class="literal"><span class="pre">iterator_facade</span></tt></a></li>
<li><a class="reference" href="#iterator-facade-requirements" id="id29" name="id29"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></li>
<li><a class="reference" href="#iterator-facade-operations" id="id30" name="id30"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></li>
<li><a class="reference" href="#proposed-text" id="id26" name="id26">Proposed Text</a><ul>
<li><a class="reference" href="#header-iterator-helper-synopsis-lib-iterator-helper-synopsis" id="id27" name="id27">Header <tt class="literal"><span class="pre">&lt;iterator_helper&gt;</span></tt> synopsis [lib.iterator.helper.synopsis]</a></li>
<li><a class="reference" href="#iterator-facade-lib-iterator-facade" id="id28" name="id28">Iterator facade [lib.iterator.facade]</a><ul>
<li><a class="reference" href="#class-template-iterator-facade" id="id29" name="id29">Class template <tt class="literal"><span class="pre">iterator_facade</span></tt></a></li>
<li><a class="reference" href="#iterator-facade-requirements" id="id30" name="id30"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></li>
<li><a class="reference" href="#iterator-facade-operations" id="id31" name="id31"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></li>
</ul>
</li>
<li><a class="reference" href="#iterator-adaptor-lib-iterator-adaptor" id="id31" name="id31">Iterator adaptor [lib.iterator.adaptor]</a><ul>
<li><a class="reference" href="#class-template-iterator-adaptor" id="id32" name="id32">Class template <tt class="literal"><span class="pre">iterator_adaptor</span></tt></a></li>
<li><a class="reference" href="#iterator-adaptor-requirements" id="id33" name="id33"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> requirements</a></li>
<li><a class="reference" href="#iterator-adaptor-base-class-parameters" id="id34" name="id34"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> base class parameters</a></li>
<li><a class="reference" href="#iterator-adaptor-models" id="id35" name="id35"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> models</a></li>
<li><a class="reference" href="#iterator-adaptor-public-operations" id="id36" name="id36"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> public operations</a></li>
<li><a class="reference" href="#iterator-adaptor-protected-member-functions" id="id37" name="id37"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> protected member functions</a></li>
<li><a class="reference" href="#iterator-adaptor-private-member-functions" id="id38" name="id38"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> private member functions</a></li>
<li><a class="reference" href="#iterator-adaptor-lib-iterator-adaptor" id="id32" name="id32">Iterator adaptor [lib.iterator.adaptor]</a><ul>
<li><a class="reference" href="#class-template-iterator-adaptor" id="id33" name="id33">Class template <tt class="literal"><span class="pre">iterator_adaptor</span></tt></a></li>
<li><a class="reference" href="#iterator-adaptor-requirements" id="id34" name="id34"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> requirements</a></li>
<li><a class="reference" href="#iterator-adaptor-base-class-parameters" id="id35" name="id35"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> base class parameters</a></li>
<li><a class="reference" href="#iterator-adaptor-models" id="id36" name="id36"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> models</a></li>
<li><a class="reference" href="#iterator-adaptor-public-operations" id="id37" name="id37"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> public operations</a></li>
<li><a class="reference" href="#iterator-adaptor-protected-member-functions" id="id38" name="id38"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> protected member functions</a></li>
<li><a class="reference" href="#iterator-adaptor-private-member-functions" id="id39" name="id39"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> private member functions</a></li>
</ul>
</li>
<li><a class="reference" href="#specialized-adaptors-lib-iterator-special-adaptors" id="id39" name="id39">Specialized adaptors [lib.iterator.special.adaptors]</a><ul>
<li><a class="reference" href="#indirect-iterator" id="id40" name="id40">Indirect iterator</a><ul>
<li><a class="reference" href="#class-template-pointee" id="id41" name="id41">Class template <tt class="literal"><span class="pre">pointee</span></tt></a></li>
<li><a class="reference" href="#class-template-indirect-reference" id="id42" name="id42">Class template <tt class="literal"><span class="pre">indirect_reference</span></tt></a></li>
<li><a class="reference" href="#class-template-indirect-iterator" id="id43" name="id43">Class template <tt class="literal"><span class="pre">indirect_iterator</span></tt></a></li>
<li><a class="reference" href="#indirect-iterator-requirements" id="id44" name="id44"><tt class="literal"><span class="pre">indirect_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#indirect-iterator-models" id="id45" name="id45"><tt class="literal"><span class="pre">indirect_iterator</span></tt> models</a></li>
<li><a class="reference" href="#indirect-iterator-operations" id="id46" name="id46"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></li>
<li><a class="reference" href="#specialized-adaptors-lib-iterator-special-adaptors" id="id40" name="id40">Specialized adaptors [lib.iterator.special.adaptors]</a><ul>
<li><a class="reference" href="#indirect-iterator" id="id41" name="id41">Indirect iterator</a><ul>
<li><a class="reference" href="#class-template-pointee" id="id42" name="id42">Class template <tt class="literal"><span class="pre">pointee</span></tt></a></li>
<li><a class="reference" href="#class-template-indirect-reference" id="id43" name="id43">Class template <tt class="literal"><span class="pre">indirect_reference</span></tt></a></li>
<li><a class="reference" href="#class-template-indirect-iterator" id="id44" name="id44">Class template <tt class="literal"><span class="pre">indirect_iterator</span></tt></a></li>
<li><a class="reference" href="#indirect-iterator-requirements" id="id45" name="id45"><tt class="literal"><span class="pre">indirect_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#indirect-iterator-models" id="id46" name="id46"><tt class="literal"><span class="pre">indirect_iterator</span></tt> models</a></li>
<li><a class="reference" href="#indirect-iterator-operations" id="id47" name="id47"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></li>
</ul>
</li>
<li><a class="reference" href="#reverse-iterator" id="id47" name="id47">Reverse iterator</a><ul>
<li><a class="reference" href="#class-template-reverse-iterator" id="id48" name="id48">Class template <tt class="literal"><span class="pre">reverse_iterator</span></tt></a></li>
<li><a class="reference" href="#reverse-iterator-requirements" id="id49" name="id49"><tt class="literal"><span class="pre">reverse_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#reverse-iterator-models" id="id50" name="id50"><tt class="literal"><span class="pre">reverse_iterator</span></tt> models</a></li>
<li><a class="reference" href="#reverse-iterator-operations" id="id51" name="id51"><tt class="literal"><span class="pre">reverse_iterator</span></tt> operations</a></li>
<li><a class="reference" href="#reverse-iterator" id="id48" name="id48">Reverse iterator</a><ul>
<li><a class="reference" href="#class-template-reverse-iterator" id="id49" name="id49">Class template <tt class="literal"><span class="pre">reverse_iterator</span></tt></a></li>
<li><a class="reference" href="#reverse-iterator-requirements" id="id50" name="id50"><tt class="literal"><span class="pre">reverse_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#reverse-iterator-models" id="id51" name="id51"><tt class="literal"><span class="pre">reverse_iterator</span></tt> models</a></li>
<li><a class="reference" href="#reverse-iterator-operations" id="id52" name="id52"><tt class="literal"><span class="pre">reverse_iterator</span></tt> operations</a></li>
</ul>
</li>
<li><a class="reference" href="#transform-iterator" id="id52" name="id52">Transform iterator</a><ul>
<li><a class="reference" href="#class-template-transform-iterator" id="id53" name="id53">Class template <tt class="literal"><span class="pre">transform_iterator</span></tt></a></li>
<li><a class="reference" href="#transform-iterator-requirements" id="id54" name="id54"><tt class="literal"><span class="pre">transform_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#transform-iterator-models" id="id55" name="id55"><tt class="literal"><span class="pre">transform_iterator</span></tt> models</a></li>
<li><a class="reference" href="#transform-iterator-operations" id="id56" name="id56"><tt class="literal"><span class="pre">transform_iterator</span></tt> operations</a></li>
<li><a class="reference" href="#transform-iterator" id="id53" name="id53">Transform iterator</a><ul>
<li><a class="reference" href="#class-template-transform-iterator" id="id54" name="id54">Class template <tt class="literal"><span class="pre">transform_iterator</span></tt></a></li>
<li><a class="reference" href="#transform-iterator-requirements" id="id55" name="id55"><tt class="literal"><span class="pre">transform_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#transform-iterator-models" id="id56" name="id56"><tt class="literal"><span class="pre">transform_iterator</span></tt> models</a></li>
<li><a class="reference" href="#transform-iterator-operations" id="id57" name="id57"><tt class="literal"><span class="pre">transform_iterator</span></tt> operations</a></li>
</ul>
</li>
<li><a class="reference" href="#filter-iterator" id="id57" name="id57">Filter iterator</a><ul>
<li><a class="reference" href="#class-template-filter-iterator" id="id58" name="id58">Class template <tt class="literal"><span class="pre">filter_iterator</span></tt></a></li>
<li><a class="reference" href="#filter-iterator-requirements" id="id59" name="id59"><tt class="literal"><span class="pre">filter_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#filter-iterator-models" id="id60" name="id60"><tt class="literal"><span class="pre">filter_iterator</span></tt> models</a></li>
<li><a class="reference" href="#filter-iterator-operations" id="id61" name="id61"><tt class="literal"><span class="pre">filter_iterator</span></tt> operations</a></li>
<li><a class="reference" href="#filter-iterator" id="id58" name="id58">Filter iterator</a><ul>
<li><a class="reference" href="#class-template-filter-iterator" id="id59" name="id59">Class template <tt class="literal"><span class="pre">filter_iterator</span></tt></a></li>
<li><a class="reference" href="#filter-iterator-requirements" id="id60" name="id60"><tt class="literal"><span class="pre">filter_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#filter-iterator-models" id="id61" name="id61"><tt class="literal"><span class="pre">filter_iterator</span></tt> models</a></li>
<li><a class="reference" href="#filter-iterator-operations" id="id62" name="id62"><tt class="literal"><span class="pre">filter_iterator</span></tt> operations</a></li>
</ul>
</li>
<li><a class="reference" href="#counting-iterator" id="id62" name="id62">Counting iterator</a><ul>
<li><a class="reference" href="#class-template-counting-iterator" id="id63" name="id63">Class template <tt class="literal"><span class="pre">counting_iterator</span></tt></a></li>
<li><a class="reference" href="#counting-iterator-requirements" id="id64" name="id64"><tt class="literal"><span class="pre">counting_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#counting-iterator-models" id="id65" name="id65"><tt class="literal"><span class="pre">counting_iterator</span></tt> models</a></li>
<li><a class="reference" href="#counting-iterator-operations" id="id66" name="id66"><tt class="literal"><span class="pre">counting_iterator</span></tt> operations</a></li>
<li><a class="reference" href="#counting-iterator" id="id63" name="id63">Counting iterator</a><ul>
<li><a class="reference" href="#class-template-counting-iterator" id="id64" name="id64">Class template <tt class="literal"><span class="pre">counting_iterator</span></tt></a></li>
<li><a class="reference" href="#counting-iterator-requirements" id="id65" name="id65"><tt class="literal"><span class="pre">counting_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#counting-iterator-models" id="id66" name="id66"><tt class="literal"><span class="pre">counting_iterator</span></tt> models</a></li>
<li><a class="reference" href="#counting-iterator-operations" id="id67" name="id67"><tt class="literal"><span class="pre">counting_iterator</span></tt> operations</a></li>
</ul>
</li>
<li><a class="reference" href="#function-output-iterator" id="id67" name="id67">Function output iterator</a><ul>
<li><a class="reference" href="#class-template-function-output-iterator" id="id68" name="id68">Class template <tt class="literal"><span class="pre">function_output_iterator</span></tt></a></li>
<li><a class="reference" href="#function-output-iterator-requirements" id="id69" name="id69"><tt class="literal"><span class="pre">function_output_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#function-output-iterator-models" id="id70" name="id70"><tt class="literal"><span class="pre">function_output_iterator</span></tt> models</a></li>
<li><a class="reference" href="#function-output-iterator-operations" id="id71" name="id71"><tt class="literal"><span class="pre">function_output_iterator</span></tt> operations</a></li>
<li><a class="reference" href="#function-output-iterator" id="id68" name="id68">Function output iterator</a><ul>
<li><a class="reference" href="#class-template-function-output-iterator" id="id69" name="id69">Class template <tt class="literal"><span class="pre">function_output_iterator</span></tt></a></li>
<li><a class="reference" href="#function-output-iterator-requirements" id="id70" name="id70"><tt class="literal"><span class="pre">function_output_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#function-output-iterator-models" id="id71" name="id71"><tt class="literal"><span class="pre">function_output_iterator</span></tt> models</a></li>
<li><a class="reference" href="#function-output-iterator-operations" id="id72" name="id72"><tt class="literal"><span class="pre">function_output_iterator</span></tt> operations</a></li>
</ul>
</li>
</ul>
@ -142,7 +142,7 @@ by adapting other iterators.</td>
</ul>
</div>
<div class="section" id="motivation">
<h1><a class="toc-backref" href="#id13" name="motivation">Motivation</a></h1>
<h1><a class="toc-backref" href="#id14" name="motivation">Motivation</a></h1>
<p>Iterators play an important role in modern C++ programming. The
iterator is the central abstraction of the algorithms of the Standard
Library, allowing algorithms to be re-used in in a wide variety of
@ -227,15 +227,15 @@ applies some user-specified function during the dereference of the
iterator.</p>
</div>
<div class="section" id="impact-on-the-standard">
<h1><a class="toc-backref" href="#id14" name="impact-on-the-standard">Impact on the Standard</a></h1>
<h1><a class="toc-backref" href="#id15" name="impact-on-the-standard">Impact on the Standard</a></h1>
<p>This proposal is purely an addition to the C++ standard library.
However, note that this proposal relies on the proposal for New
Iterator Concepts.</p>
</div>
<div class="section" id="design">
<h1><a class="toc-backref" href="#id15" name="design">Design</a></h1>
<h1><a class="toc-backref" href="#id16" name="design">Design</a></h1>
<div class="section" id="iterator-concepts">
<h2><a class="toc-backref" href="#id16" name="iterator-concepts">Iterator Concepts</a></h2>
<h2><a class="toc-backref" href="#id17" name="iterator-concepts">Iterator Concepts</a></h2>
<p>This proposal is formulated in terms of the new <tt class="literal"><span class="pre">iterator</span> <span class="pre">concepts</span></tt>
as proposed in <a class="reference" href="http://anubis.dkuug.dk/JTC1/SC22/WG21/docs/papers/2003/n1550.html">n1550</a>, since user-defined and especially adapted
iterators suffer from the well known categorization problems that are
@ -245,7 +245,7 @@ is a direct mapping between new and old categories. This proposal
could be reformulated using this mapping if <a class="reference" href="http://anubis.dkuug.dk/JTC1/SC22/WG21/docs/papers/2003/n1550.html">n1550</a> was not accepted.</p>
</div>
<div class="section" id="interoperability">
<h2><a class="toc-backref" href="#id17" name="interoperability">Interoperability</a></h2>
<h2><a class="toc-backref" href="#id18" name="interoperability">Interoperability</a></h2>
<p>The question of iterator interoperability is poorly addressed in the
current standard. There are currently two defect reports that are
concerned with interoperability issues.</p>
@ -265,7 +265,7 @@ fixes the issues raised in 280. It provides the desired
interoperability without introducing unwanted overloads.</p>
</div>
<div class="section" id="iterator-facade">
<h2><a class="toc-backref" href="#id18" name="iterator-facade">Iterator Facade</a></h2>
<h2><a class="toc-backref" href="#id19" name="iterator-facade">Iterator Facade</a></h2>
<!-- Version 1.1 of this ReStructuredText document corresponds to
n1530_, the paper accepted by the LWG for TR1. -->
<!-- Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003. All
@ -310,7 +310,7 @@ impossible.</li>
</ol>
</blockquote>
<div class="section" id="usage">
<h3><a class="toc-backref" href="#id19" name="usage">Usage</a></h3>
<h3><a class="toc-backref" href="#id20" name="usage">Usage</a></h3>
<p>The user of <tt class="literal"><span class="pre">iterator_facade</span></tt> derives his iterator class from a
specialization of <tt class="literal"><span class="pre">iterator_facade</span></tt> and passes the derived
iterator class as <tt class="literal"><span class="pre">iterator_facade</span></tt>'s first template parameter.
@ -374,7 +374,7 @@ Iterator or a more-refined iterator concept, a default constructor is
required.</p>
</div>
<div class="section" id="iterator-core-access">
<h3><a class="toc-backref" href="#id20" name="iterator-core-access">Iterator Core Access</a></h3>
<h3><a class="toc-backref" href="#id21" name="iterator-core-access">Iterator Core Access</a></h3>
<p><tt class="literal"><span class="pre">iterator_facade</span></tt> and the operator implementations need to be able
to access the core member functions in the derived class. Making the
core member functions public would expose an implementation detail to
@ -408,7 +408,7 @@ open a safety loophole, as every core member function preserves the
invariants of the iterator.</p>
</div>
<div class="section" id="operator">
<h3><a class="toc-backref" href="#id21" name="operator"><tt class="literal"><span class="pre">operator[]</span></tt></a></h3>
<h3><a class="toc-backref" href="#id22" name="operator"><tt class="literal"><span class="pre">operator[]</span></tt></a></h3>
<p>The indexing operator for a generalized iterator presents special
challenges. A random access iterator's <tt class="literal"><span class="pre">operator[]</span></tt> is only
required to return something convertible to its <tt class="literal"><span class="pre">value_type</span></tt>.
@ -431,7 +431,7 @@ class; it will hide the one supplied by <tt class="literal"><span class="pre">it
clients of her iterator.</p>
<a class="target" id="operator-arrow" name="operator-arrow"></a></div>
<div class="section" id="id6">
<h3><a class="toc-backref" href="#id22" name="id6"><tt class="literal"><span class="pre">operator-&gt;</span></tt></a></h3>
<h3><a class="toc-backref" href="#id23" name="id6"><tt class="literal"><span class="pre">operator-&gt;</span></tt></a></h3>
<p>The <tt class="literal"><span class="pre">reference</span></tt> type of a readable iterator (and today's input
iterator) need not in fact be a reference, so long as it is
convertible to the iterator's <tt class="literal"><span class="pre">value_type</span></tt>. When the <tt class="literal"><span class="pre">value_type</span></tt>
@ -454,7 +454,7 @@ Patterns, C++ Report, February 1995, pp. 24-27.</td></tr>
</div>
</div>
<div class="section" id="iterator-adaptor">
<h2><a class="toc-backref" href="#id23" name="iterator-adaptor">Iterator Adaptor</a></h2>
<h2><a class="toc-backref" href="#id24" name="iterator-adaptor">Iterator Adaptor</a></h2>
<!-- Version 1.2 of this ReStructuredText document corresponds to
n1530_, the paper accepted by the LWG for TR1. -->
<!-- Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003. All
@ -495,7 +495,7 @@ template parameter may not always be identical to the iterator's
that assumption.</p>
</div>
<div class="section" id="specialized-adaptors">
<h2><a class="toc-backref" href="#id24" name="specialized-adaptors">Specialized Adaptors</a></h2>
<h2><a class="toc-backref" href="#id25" name="specialized-adaptors">Specialized Adaptors</a></h2>
<p>This proposal also contains several examples of specialized adaptors
which were easily implemented using <tt class="literal"><span class="pre">iterator_adaptor</span></tt>:</p>
<ul class="simple">
@ -532,9 +532,9 @@ Standard compliant iterators).</p>
</div>
</div>
<div class="section" id="proposed-text">
<h1><a class="toc-backref" href="#id25" name="proposed-text">Proposed Text</a></h1>
<h1><a class="toc-backref" href="#id26" name="proposed-text">Proposed Text</a></h1>
<div class="section" id="header-iterator-helper-synopsis-lib-iterator-helper-synopsis">
<h2><a class="toc-backref" href="#id26" name="header-iterator-helper-synopsis-lib-iterator-helper-synopsis">Header <tt class="literal"><span class="pre">&lt;iterator_helper&gt;</span></tt> synopsis [lib.iterator.helper.synopsis]</a></h2>
<h2><a class="toc-backref" href="#id27" name="header-iterator-helper-synopsis-lib-iterator-helper-synopsis">Header <tt class="literal"><span class="pre">&lt;iterator_helper&gt;</span></tt> synopsis [lib.iterator.helper.synopsis]</a></h2>
<pre class="literal-block">
struct use_default;
@ -600,12 +600,12 @@ class function_output_iterator;
</pre>
</div>
<div class="section" id="iterator-facade-lib-iterator-facade">
<h2><a class="toc-backref" href="#id27" name="iterator-facade-lib-iterator-facade">Iterator facade [lib.iterator.facade]</a></h2>
<h2><a class="toc-backref" href="#id28" name="iterator-facade-lib-iterator-facade">Iterator facade [lib.iterator.facade]</a></h2>
<p><tt class="literal"><span class="pre">iterator_facade</span></tt> is a base class template that implements the
interface of standard iterators in terms of a few core functions
and associated types, to be supplied by a derived iterator class.</p>
<div class="section" id="class-template-iterator-facade">
<h3><a class="toc-backref" href="#id28" name="class-template-iterator-facade">Class template <tt class="literal"><span class="pre">iterator_facade</span></tt></a></h3>
<h3><a class="toc-backref" href="#id29" name="class-template-iterator-facade">Class template <tt class="literal"><span class="pre">iterator_facade</span></tt></a></h3>
<!-- Version 1.3 of this ReStructuredText document corresponds to
n1530_, the paper accepted by the LWG for TR1. -->
<!-- Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003. All
@ -698,7 +698,7 @@ Derived operator+ (iterator_facade&lt;Derived, V, TC, R, D&gt; const&amp;,
<em>iterator-category</em>(CategoryOrTraversal, value_type, reference)
</pre>
<p>where <em>iterator-category</em> is defined as follows:</p>
<pre class="literal-block">
<a class="target" id="id11" name="id11"></a><pre class="literal-block">
<em>iterator-category</em>(C,R,V) :=
if (C is convertible to std::input_iterator_tag
|| C is convertible to std::output_iterator_tag
@ -776,7 +776,7 @@ struct enable_if_interoperable
</pre>
</div>
<div class="section" id="iterator-facade-requirements">
<h3><a class="toc-backref" href="#id29" name="iterator-facade-requirements"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></h3>
<h3><a class="toc-backref" href="#id30" name="iterator-facade-requirements"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></h3>
<p>The following table describes the typical valid expressions on
<tt class="literal"><span class="pre">iterator_facade</span></tt>'s <tt class="literal"><span class="pre">Derived</span></tt> parameter, depending on the
iterator concept(s) it will model. The operations in the first
@ -847,7 +847,7 @@ Iterator</td>
</div>
</div>
<div class="section" id="iterator-facade-operations">
<h3><a class="toc-backref" href="#id30" name="iterator-facade-operations"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></h3>
<h3><a class="toc-backref" href="#id31" name="iterator-facade-operations"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></h3>
<p>The operations in this section are described in terms of operations on
the core interface of <tt class="literal"><span class="pre">Derived</span></tt> which may be inaccessible
(i.e. private). The implementation should access these operations
@ -988,7 +988,7 @@ return tmp -= n;
</div>
</div>
<div class="section" id="iterator-adaptor-lib-iterator-adaptor">
<h2><a class="toc-backref" href="#id31" name="iterator-adaptor-lib-iterator-adaptor">Iterator adaptor [lib.iterator.adaptor]</a></h2>
<h2><a class="toc-backref" href="#id32" name="iterator-adaptor-lib-iterator-adaptor">Iterator adaptor [lib.iterator.adaptor]</a></h2>
<!-- Version 1.1 of this ReStructuredText document corresponds to
n1530_, the paper accepted by the LWG. -->
<!-- Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003. All
@ -1004,7 +1004,7 @@ depends on the operations supported by the <tt class="literal"><span class="pre"
core interface functions of <tt class="literal"><span class="pre">iterator_facade</span></tt> are redefined in the
<tt class="literal"><span class="pre">Derived</span></tt> class.</p>
<div class="section" id="class-template-iterator-adaptor">
<h3><a class="toc-backref" href="#id32" name="class-template-iterator-adaptor">Class template <tt class="literal"><span class="pre">iterator_adaptor</span></tt></a></h3>
<h3><a class="toc-backref" href="#id33" name="class-template-iterator-adaptor">Class template <tt class="literal"><span class="pre">iterator_adaptor</span></tt></a></h3>
<!-- Version 1.4 of this ReStructuredText document corresponds to
n1530_, the paper accepted by the LWG for TR1. -->
<!-- Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003. All
@ -1053,13 +1053,13 @@ class iterator_adaptor
</pre>
<a class="target" id="requirements" name="requirements"></a></div>
<div class="section" id="iterator-adaptor-requirements">
<h3><a class="toc-backref" href="#id33" name="iterator-adaptor-requirements"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> requirements</a></h3>
<h3><a class="toc-backref" href="#id34" name="iterator-adaptor-requirements"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> requirements</a></h3>
<p>The <tt class="literal"><span class="pre">Derived</span></tt> template argument must be a publicly derived from
<tt class="literal"><span class="pre">iterator_adaptor</span></tt>.</p>
<p>The <tt class="literal"><span class="pre">Base</span></tt> argument shall be Assignable and Copy Constructible.</p>
<a class="target" id="base-parameters" name="base-parameters"></a></div>
<div class="section" id="iterator-adaptor-base-class-parameters">
<h3><a class="toc-backref" href="#id34" name="iterator-adaptor-base-class-parameters"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> base class parameters</a></h3>
<h3><a class="toc-backref" href="#id35" name="iterator-adaptor-base-class-parameters"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> base class parameters</a></h3>
<p>The <em>V</em>, <em>C</em>, <em>R</em>, and <em>D</em> parameters of the <tt class="literal"><span class="pre">iterator_facade</span></tt>
used as a base class in the summary of <tt class="literal"><span class="pre">iterator_adaptor</span></tt>
above are defined as follows:</p>
@ -1089,7 +1089,7 @@ above are defined as follows:</p>
</pre>
</div>
<div class="section" id="iterator-adaptor-models">
<h3><a class="toc-backref" href="#id35" name="iterator-adaptor-models"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> models</a></h3>
<h3><a class="toc-backref" href="#id36" name="iterator-adaptor-models"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> models</a></h3>
<p>In order for <tt class="literal"><span class="pre">Derived</span></tt> to model the iterator concepts corresponding
to <tt class="literal"><span class="pre">iterator_traits&lt;Derived&gt;::iterator_category</span></tt>, the expressions
involving <tt class="literal"><span class="pre">m_iterator</span></tt> in the specifications of those private member
@ -1099,7 +1099,7 @@ expression involving <tt class="literal"><span class="pre">Derived</span></tt> i
<!-- The above is confusing and needs a rewrite. -JGS -->
</div>
<div class="section" id="iterator-adaptor-public-operations">
<h3><a class="toc-backref" href="#id36" name="iterator-adaptor-public-operations"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> public operations</a></h3>
<h3><a class="toc-backref" href="#id37" name="iterator-adaptor-public-operations"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> public operations</a></h3>
<p><tt class="literal"><span class="pre">iterator_adaptor();</span></tt></p>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
@ -1133,7 +1133,7 @@ expression involving <tt class="literal"><span class="pre">Derived</span></tt> i
</table>
</div>
<div class="section" id="iterator-adaptor-protected-member-functions">
<h3><a class="toc-backref" href="#id37" name="iterator-adaptor-protected-member-functions"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> protected member functions</a></h3>
<h3><a class="toc-backref" href="#id38" name="iterator-adaptor-protected-member-functions"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> protected member functions</a></h3>
<p><tt class="literal"><span class="pre">Base</span> <span class="pre">const&amp;</span> <span class="pre">base_reference()</span> <span class="pre">const;</span></tt></p>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
@ -1154,7 +1154,7 @@ expression involving <tt class="literal"><span class="pre">Derived</span></tt> i
</table>
</div>
<div class="section" id="iterator-adaptor-private-member-functions">
<h3><a class="toc-backref" href="#id38" name="iterator-adaptor-private-member-functions"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> private member functions</a></h3>
<h3><a class="toc-backref" href="#id39" name="iterator-adaptor-private-member-functions"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> private member functions</a></h3>
<p><tt class="literal"><span class="pre">typename</span> <span class="pre">iterator_adaptor::reference</span> <span class="pre">dereference()</span> <span class="pre">const;</span></tt></p>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
@ -1223,7 +1223,7 @@ typename iterator_adaptor::difference_type distance_to(
</div>
</div>
<div class="section" id="specialized-adaptors-lib-iterator-special-adaptors">
<h2><a class="toc-backref" href="#id39" name="specialized-adaptors-lib-iterator-special-adaptors">Specialized adaptors [lib.iterator.special.adaptors]</a></h2>
<h2><a class="toc-backref" href="#id40" name="specialized-adaptors-lib-iterator-special-adaptors">Specialized adaptors [lib.iterator.special.adaptors]</a></h2>
<p>The <tt class="literal"><span class="pre">enable_if_convertible&lt;X,Y&gt;::type</span></tt> expression used in
this section is for exposition purposes. The converting constructors
for specialized adaptors should be only be in an overload set provided
@ -1252,7 +1252,7 @@ take the constructor out of the overload set when the types are not
implicitly convertible.
]</p>
<div class="section" id="indirect-iterator">
<h3><a class="toc-backref" href="#id40" name="indirect-iterator">Indirect iterator</a></h3>
<h3><a class="toc-backref" href="#id41" name="indirect-iterator">Indirect iterator</a></h3>
<p><tt class="literal"><span class="pre">indirect_iterator</span></tt> adapts an iterator by applying an
<em>extra</em> dereference inside of <tt class="literal"><span class="pre">operator*()</span></tt>. For example, this
iterator adaptor makes it possible to view a container of pointers
@ -1262,7 +1262,7 @@ auxiliary traits, <tt class="literal"><span class="pre">pointee</span></tt> and
provide support for underlying iterators whose <tt class="literal"><span class="pre">value_type</span></tt> is
not an iterator.</p>
<div class="section" id="class-template-pointee">
<h4><a class="toc-backref" href="#id41" name="class-template-pointee">Class template <tt class="literal"><span class="pre">pointee</span></tt></a></h4>
<h4><a class="toc-backref" href="#id42" name="class-template-pointee">Class template <tt class="literal"><span class="pre">pointee</span></tt></a></h4>
<!-- 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) -->
@ -1306,7 +1306,7 @@ else
</pre>
</div>
<div class="section" id="class-template-indirect-reference">
<h4><a class="toc-backref" href="#id42" name="class-template-indirect-reference">Class template <tt class="literal"><span class="pre">indirect_reference</span></tt></a></h4>
<h4><a class="toc-backref" href="#id43" name="class-template-indirect-reference">Class template <tt class="literal"><span class="pre">indirect_reference</span></tt></a></h4>
<!-- 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) -->
@ -1341,7 +1341,7 @@ else
</pre>
</div>
<div class="section" id="class-template-indirect-iterator">
<h4><a class="toc-backref" href="#id43" name="class-template-indirect-iterator">Class template <tt class="literal"><span class="pre">indirect_iterator</span></tt></a></h4>
<h4><a class="toc-backref" href="#id44" name="class-template-indirect-iterator">Class template <tt class="literal"><span class="pre">indirect_iterator</span></tt></a></h4>
<pre class="literal-block">
template &lt;
class Iterator
@ -1381,9 +1381,9 @@ private:
Iterator m_iterator; // exposition
};
</pre>
<p>The member types of <tt class="literal"><span class="pre">indirect_iterator</span></tt> are defined according to the
following pseudo-code. We use the abbreviation
<tt class="literal"><span class="pre">V=iterator_traits&lt;Iterator&gt;::value_type</span></tt>.:</p>
<p>The member types of <tt class="literal"><span class="pre">indirect_iterator</span></tt> are defined according to
the following pseudo-code, where <tt class="literal"><span class="pre">V</span></tt> is
<tt class="literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt></p>
<pre class="literal-block">
if (Value is use_default) then
typedef remove_const&lt;pointee&lt;V&gt;::type&gt;::type value_type;
@ -1407,14 +1407,19 @@ if (Difference is use_default)
typedef iterator_traits&lt;Iterator&gt;::difference_type difference_type;
else
typedef Difference difference_type;
if (CategoryOrTraversal is use_default)
typedef <a class="reference" href="#id11"><em>iterator-category</em></a>(
iterator_traversal&lt;Iterator&gt;::type,``reference``,``value_type``
) iterator_category;
else
typedef <a class="reference" href="#id11"><em>iterator-category</em></a>(
CategoryOrTraversal,``reference``,``value_type``
) iterator_category;
</pre>
<p>The <tt class="literal"><span class="pre">iterator_category</span></tt> member is <tt class="literal"><span class="pre">facade_iterator_category(C,</span>
<span class="pre">value_type,</span> <span class="pre">reference)</span></tt> 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>
</div>
<div class="section" id="indirect-iterator-requirements">
<h4><a class="toc-backref" href="#id44" name="indirect-iterator-requirements"><tt class="literal"><span class="pre">indirect_iterator</span></tt> requirements</a></h4>
<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 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>. <tt class="literal"><span class="pre">Iterator</span></tt> shall
@ -1428,7 +1433,7 @@ parameter is not <tt class="literal"><span class="pre">use_default</span></tt>,
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="#id45" name="indirect-iterator-models"><tt class="literal"><span class="pre">indirect_iterator</span></tt> models</a></h4>
<h4><a class="toc-backref" href="#id46" name="indirect-iterator-models"><tt class="literal"><span class="pre">indirect_iterator</span></tt> models</a></h4>
<p>In addition to the concepts indicated by <tt class="literal"><span class="pre">iterator_category</span></tt>
and by <tt class="literal"><span class="pre">iterator_traversal&lt;indirect_iterator&gt;::type</span></tt>, a
specialization of <tt class="literal"><span class="pre">indirect_iterator</span></tt> models the following
@ -1445,11 +1450,11 @@ expression (where <tt class="literal"><span class="pre">t</span></tt> is an obje
</ul>
</blockquote>
<p><tt class="literal"><span class="pre">indirect_iterator&lt;X,V1,C1,R1,D1&gt;</span></tt> is interoperable with
<tt class="literal"><span class="pre">indirect_iterator&lt;Y,V2,C2,R2,D2&gt;</span></tt> if and only if iterator <tt class="literal"><span class="pre">X</span></tt> is
interoperable with iterator <tt class="literal"><span class="pre">Y</span></tt>.</p>
<tt class="literal"><span class="pre">indirect_iterator&lt;Y,V2,C2,R2,D2&gt;</span></tt> if and only if <tt class="literal"><span class="pre">X</span></tt> is
interoperable with <tt class="literal"><span class="pre">Y</span></tt>.</p>
</div>
<div class="section" id="indirect-iterator-operations">
<h4><a class="toc-backref" href="#id46" name="indirect-iterator-operations"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></h4>
<h4><a class="toc-backref" href="#id47" name="indirect-iterator-operations"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></h4>
<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>
@ -1541,11 +1546,11 @@ indirect_iterator(
</div>
</div>
<div class="section" id="reverse-iterator">
<h3><a class="toc-backref" href="#id47" name="reverse-iterator">Reverse iterator</a></h3>
<h3><a class="toc-backref" href="#id48" name="reverse-iterator">Reverse iterator</a></h3>
<p>The reverse iterator adaptor iterates through the adapted iterator
range in the opposite direction.</p>
<div class="section" id="class-template-reverse-iterator">
<h4><a class="toc-backref" href="#id48" name="class-template-reverse-iterator">Class template <tt class="literal"><span class="pre">reverse_iterator</span></tt></a></h4>
<h4><a class="toc-backref" href="#id49" name="class-template-reverse-iterator">Class template <tt class="literal"><span class="pre">reverse_iterator</span></tt></a></h4>
<pre class="literal-block">
template &lt;class Iterator&gt;
class reverse_iterator
@ -1582,11 +1587,11 @@ Lvalue Iterator, then <tt class="literal"><span class="pre">iterator_category</s
convertible to <tt class="literal"><span class="pre">input_iterator_tag</span></tt>.</p>
</div>
<div class="section" id="reverse-iterator-requirements">
<h4><a class="toc-backref" href="#id49" name="reverse-iterator-requirements"><tt class="literal"><span class="pre">reverse_iterator</span></tt> requirements</a></h4>
<h4><a class="toc-backref" href="#id50" name="reverse-iterator-requirements"><tt class="literal"><span class="pre">reverse_iterator</span></tt> requirements</a></h4>
<p><tt class="literal"><span class="pre">Iterator</span></tt> must be a model of Bidirectional Traversal Iterator.</p>
</div>
<div class="section" id="reverse-iterator-models">
<h4><a class="toc-backref" href="#id50" name="reverse-iterator-models"><tt class="literal"><span class="pre">reverse_iterator</span></tt> models</a></h4>
<h4><a class="toc-backref" href="#id51" name="reverse-iterator-models"><tt class="literal"><span class="pre">reverse_iterator</span></tt> models</a></h4>
<p>A specialization of <tt class="literal"><span class="pre">reverse_iterator</span></tt> models the same standard
traversal and access iterator concepts modeled by its <tt class="literal"><span class="pre">Iterator</span></tt>
argument. In addition, it models the old iterator concepts
@ -1624,7 +1629,7 @@ Random Access Traversal Iterator</td>
if and only if iterator <tt class="literal"><span class="pre">X</span></tt> is interoperable with iterator <tt class="literal"><span class="pre">Y</span></tt>.</p>
</div>
<div class="section" id="reverse-iterator-operations">
<h4><a class="toc-backref" href="#id51" name="reverse-iterator-operations"><tt class="literal"><span class="pre">reverse_iterator</span></tt> operations</a></h4>
<h4><a class="toc-backref" href="#id52" name="reverse-iterator-operations"><tt class="literal"><span class="pre">reverse_iterator</span></tt> operations</a></h4>
<p>In addition to the operations required by the concepts modeled by
<tt class="literal"><span class="pre">reverse_iterator</span></tt>, <tt class="literal"><span class="pre">reverse_iterator</span></tt> provides the following
operations.</p>
@ -1714,12 +1719,12 @@ return *--tmp;
</div>
</div>
<div class="section" id="transform-iterator">
<h3><a class="toc-backref" href="#id52" name="transform-iterator">Transform iterator</a></h3>
<h3><a class="toc-backref" href="#id53" name="transform-iterator">Transform iterator</a></h3>
<p>The transform iterator adapts an iterator by modifying the
<tt class="literal"><span class="pre">operator*</span></tt> to apply a function object to the result of
dereferencing the iterator and returning the result.</p>
<div class="section" id="class-template-transform-iterator">
<h4><a class="toc-backref" href="#id53" name="class-template-transform-iterator">Class template <tt class="literal"><span class="pre">transform_iterator</span></tt></a></h4>
<h4><a class="toc-backref" href="#id54" name="class-template-transform-iterator">Class template <tt class="literal"><span class="pre">transform_iterator</span></tt></a></h4>
<!-- Version 1.3 of this document was accepted for TR1 -->
<pre class="literal-block">
template &lt;class UnaryFunction,
@ -1772,7 +1777,7 @@ model Readable Lvalue Iterator then <tt class="literal"><span class="pre">iterat
convertible to <tt class="literal"><span class="pre">input_iterator_tag</span></tt>.</p>
</div>
<div class="section" id="transform-iterator-requirements">
<h4><a class="toc-backref" href="#id54" name="transform-iterator-requirements"><tt class="literal"><span class="pre">transform_iterator</span></tt> requirements</a></h4>
<h4><a class="toc-backref" href="#id55" name="transform-iterator-requirements"><tt class="literal"><span class="pre">transform_iterator</span></tt> requirements</a></h4>
<p>The type <tt class="literal"><span class="pre">UnaryFunction</span></tt> must be Assignable, Copy Constructible, and
the expression <tt class="literal"><span class="pre">f(*i)</span></tt> must be valid where <tt class="literal"><span class="pre">f</span></tt> is an object of
type <tt class="literal"><span class="pre">UnaryFunction</span></tt>, <tt class="literal"><span class="pre">i</span></tt> is an object of type <tt class="literal"><span class="pre">Iterator</span></tt>, and
@ -1781,7 +1786,7 @@ where the type of <tt class="literal"><span class="pre">f(*i)</span></tt> must b
<p>The argument <tt class="literal"><span class="pre">Iterator</span></tt> shall model Readable Iterator.</p>
</div>
<div class="section" id="transform-iterator-models">
<h4><a class="toc-backref" href="#id55" name="transform-iterator-models"><tt class="literal"><span class="pre">transform_iterator</span></tt> models</a></h4>
<h4><a class="toc-backref" href="#id56" name="transform-iterator-models"><tt class="literal"><span class="pre">transform_iterator</span></tt> models</a></h4>
<p>The resulting <tt class="literal"><span class="pre">transform_iterator</span></tt> models the most refined of the
following options that is also modeled by <tt class="literal"><span class="pre">Iterator</span></tt>.</p>
<blockquote>
@ -1828,7 +1833,7 @@ mutable iterator (as defined in the old iterator requirements).</p>
interoperable with iterator <tt class="literal"><span class="pre">Y</span></tt>.</p>
</div>
<div class="section" id="transform-iterator-operations">
<h4><a class="toc-backref" href="#id56" name="transform-iterator-operations"><tt class="literal"><span class="pre">transform_iterator</span></tt> operations</a></h4>
<h4><a class="toc-backref" href="#id57" name="transform-iterator-operations"><tt class="literal"><span class="pre">transform_iterator</span></tt> operations</a></h4>
<p>In addition to the operations required by the concepts modeled by
<tt class="literal"><span class="pre">transform_iterator</span></tt>, <tt class="literal"><span class="pre">transform_iterator</span></tt> provides the following
operations.</p>
@ -1921,7 +1926,7 @@ transform_iterator(
</div>
</div>
<div class="section" id="filter-iterator">
<h3><a class="toc-backref" href="#id57" name="filter-iterator">Filter iterator</a></h3>
<h3><a class="toc-backref" href="#id58" name="filter-iterator">Filter iterator</a></h3>
<p>The filter iterator adaptor creates a view of an iterator range in
which some elements of the range are skipped. A predicate function
object controls which elements are skipped. When the predicate is
@ -1933,7 +1938,7 @@ underlying range. A filter iterator is therefore constructed with pair
of iterators indicating the range of elements in the unfiltered
sequence to be traversed.</p>
<div class="section" id="class-template-filter-iterator">
<h4><a class="toc-backref" href="#id58" name="class-template-filter-iterator">Class template <tt class="literal"><span class="pre">filter_iterator</span></tt></a></h4>
<h4><a class="toc-backref" href="#id59" name="class-template-filter-iterator">Class template <tt class="literal"><span class="pre">filter_iterator</span></tt></a></h4>
<!-- Copyright David Abrahams, Jeremy Siek, and Thomas Witt -->
<!-- 2004. Use, modification and distribution is subject to the Boost -->
<!-- Software License, Version 1.0. (See accompanying file -->
@ -1974,7 +1979,7 @@ Iterator then <tt class="literal"><span class="pre">iterator_category</span></tt
convertible to <tt class="literal"><span class="pre">std::input_iterator_tag</span></tt>.</p>
</div>
<div class="section" id="filter-iterator-requirements">
<h4><a class="toc-backref" href="#id59" name="filter-iterator-requirements"><tt class="literal"><span class="pre">filter_iterator</span></tt> requirements</a></h4>
<h4><a class="toc-backref" href="#id60" name="filter-iterator-requirements"><tt class="literal"><span class="pre">filter_iterator</span></tt> requirements</a></h4>
<p>The <tt class="literal"><span class="pre">Predicate</span></tt> argument must be Assignable, Copy Constructible, and
the expression <tt class="literal"><span class="pre">p(x)</span></tt> must be valid where <tt class="literal"><span class="pre">p</span></tt> is an object of type
<tt class="literal"><span class="pre">Predicate</span></tt>, <tt class="literal"><span class="pre">x</span></tt> is an object of type
@ -1985,7 +1990,7 @@ Iterator and Single Pass Iterator or it shall meet the requirements of
Input Iterator.</p>
</div>
<div class="section" id="filter-iterator-models">
<h4><a class="toc-backref" href="#id60" name="filter-iterator-models"><tt class="literal"><span class="pre">filter_iterator</span></tt> models</a></h4>
<h4><a class="toc-backref" href="#id61" name="filter-iterator-models"><tt class="literal"><span class="pre">filter_iterator</span></tt> models</a></h4>
<p>The concepts that <tt class="literal"><span class="pre">filter_iterator</span></tt> models are dependent on which
concepts the <tt class="literal"><span class="pre">Iterator</span></tt> argument models, as specified in the
following tables.</p>
@ -2056,7 +2061,7 @@ following tables.</p>
if and only if iterator <tt class="literal"><span class="pre">X</span></tt> is interoperable with iterator <tt class="literal"><span class="pre">Y</span></tt>.</p>
</div>
<div class="section" id="filter-iterator-operations">
<h4><a class="toc-backref" href="#id61" name="filter-iterator-operations"><tt class="literal"><span class="pre">filter_iterator</span></tt> operations</a></h4>
<h4><a class="toc-backref" href="#id62" name="filter-iterator-operations"><tt class="literal"><span class="pre">filter_iterator</span></tt> operations</a></h4>
<p>In addition to those operations required by the concepts that
<tt class="literal"><span class="pre">filter_iterator</span></tt> models, <tt class="literal"><span class="pre">filter_iterator</span></tt> provides the following
operations.</p>
@ -2167,12 +2172,12 @@ or <tt class="literal"><span class="pre">m_pred(*m_iter)</span> <span class="pre
</div>
</div>
<div class="section" id="counting-iterator">
<h3><a class="toc-backref" href="#id62" name="counting-iterator">Counting iterator</a></h3>
<h3><a class="toc-backref" href="#id63" name="counting-iterator">Counting iterator</a></h3>
<p><tt class="literal"><span class="pre">counting_iterator</span></tt> adapts an object by adding an <tt class="literal"><span class="pre">operator*</span></tt> that
returns the current value of the object. All other iterator operations
are forwarded to the adapted object.</p>
<div class="section" id="class-template-counting-iterator">
<h4><a class="toc-backref" href="#id63" name="class-template-counting-iterator">Class template <tt class="literal"><span class="pre">counting_iterator</span></tt></a></h4>
<h4><a class="toc-backref" href="#id64" name="class-template-counting-iterator">Class template <tt class="literal"><span class="pre">counting_iterator</span></tt></a></h4>
<pre class="literal-block">
template &lt;
class Incrementable
@ -2199,24 +2204,28 @@ class counting_iterator
Incrementable m_inc; // exposition
};
</pre>
<p>If the <tt class="literal"><span class="pre">Difference</span></tt> argument is <tt class="literal"><span class="pre">use_default</span></tt> then the
<tt class="literal"><span class="pre">difference_type</span></tt> member is an unspecified signed integral
<p>If the <tt class="literal"><span class="pre">Difference</span></tt> argument is <tt class="literal"><span class="pre">use_default</span></tt> then
<tt class="literal"><span class="pre">difference_type</span></tt> is an unspecified signed integral
type. Otherwise <tt class="literal"><span class="pre">difference_type</span></tt> is <tt class="literal"><span class="pre">Difference</span></tt>.</p>
<p>If <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt> is not <tt class="literal"><span class="pre">use_default</span></tt> then the member
<tt class="literal"><span class="pre">iterator_category</span></tt> is <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt>. Otherwise, if
<tt class="literal"><span class="pre">numeric_limits&lt;Incrementable&gt;::is_specialized</span></tt>, then
<tt class="literal"><span class="pre">iterator_category</span></tt> is a
<tt class="literal"><span class="pre">facade_iterator_category(random_access_traversal_tag,</span> <span class="pre">Incrementable,</span> <span class="pre">const</span> <span class="pre">Incrementable&amp;)</span></tt>.
Otherwise, <tt class="literal"><span class="pre">iterator_category</span></tt> is
<tt class="literal"><span class="pre">facade_iterator_category(iterator_traversal&lt;Incrementable&gt;::type,</span> <span class="pre">Incrementable,</span> <span class="pre">const</span> <span class="pre">Incrementable&amp;)</span></tt>.</p>
<dl>
<dt>[<em>Note:</em> implementers are encouraged to provide an implementation of</dt>
<dd><tt class="literal"><span class="pre">operator-</span></tt> and the default <tt class="literal"><span class="pre">difference_type</span></tt> that avoids overflows in
the cases when the <tt class="literal"><span class="pre">Incrementable</span></tt> type is a numeric type.]</dd>
</dl>
<p><tt class="literal"><span class="pre">iterator_category</span></tt> is determined according to the following
algorithm:</p>
<pre class="literal-block">
if (CategoryOrTraversal is not use_default)
return CategoryOrTraversal
else if (numeric_limits&lt;Incrementable&gt;::is_specialized)
return <a class="reference" href="#id11"><em>iterator-category</em></a>(
random_access_traversal_tag, Incrementable, const Incrementable&amp;)
else
return <a class="reference" href="#id11"><em>iterator-category</em></a>(
iterator_traversal&lt;Incrementable&gt;::type,
Incrementable, const Incrementable&amp;)
</pre>
<p>[<em>Note:</em> implementers are encouraged to provide an implementation
of <tt class="literal"><span class="pre">operator-</span></tt> and a default <tt class="literal"><span class="pre">difference_type</span></tt> that avoid
overflows when <tt class="literal"><span class="pre">Incrementable</span></tt> is a numeric type.]</p>
</div>
<div class="section" id="counting-iterator-requirements">
<h4><a class="toc-backref" href="#id64" name="counting-iterator-requirements"><tt class="literal"><span class="pre">counting_iterator</span></tt> requirements</a></h4>
<h4><a class="toc-backref" href="#id65" name="counting-iterator-requirements"><tt class="literal"><span class="pre">counting_iterator</span></tt> requirements</a></h4>
<p>The <tt class="literal"><span class="pre">Incrementable</span></tt> argument shall be Copy Constructible and Assignable.</p>
<p>If <tt class="literal"><span class="pre">iterator_category</span></tt> is convertible to <tt class="literal"><span class="pre">forward_iterator_tag</span></tt>
or <tt class="literal"><span class="pre">forward_traversal_tag</span></tt>, the following must be well-formed:</p>
@ -2242,7 +2251,7 @@ i &lt; j;
</pre>
</div>
<div class="section" id="counting-iterator-models">
<h4><a class="toc-backref" href="#id65" name="counting-iterator-models"><tt class="literal"><span class="pre">counting_iterator</span></tt> models</a></h4>
<h4><a class="toc-backref" href="#id66" name="counting-iterator-models"><tt class="literal"><span class="pre">counting_iterator</span></tt> models</a></h4>
<p>Specializations of <tt class="literal"><span class="pre">counting_iterator</span></tt> model Readable Lvalue
Iterator. In addition, they model the concepts corresponding to the
iterator tags to which their <tt class="literal"><span class="pre">iterator_category</span></tt> is convertible.
@ -2258,7 +2267,7 @@ concepts modeled by <tt class="literal"><span class="pre">Incrementable</span></
interoperable with iterator <tt class="literal"><span class="pre">Y</span></tt>.</p>
</div>
<div class="section" id="counting-iterator-operations">
<h4><a class="toc-backref" href="#id66" name="counting-iterator-operations"><tt class="literal"><span class="pre">counting_iterator</span></tt> operations</a></h4>
<h4><a class="toc-backref" href="#id67" name="counting-iterator-operations"><tt class="literal"><span class="pre">counting_iterator</span></tt> operations</a></h4>
<p>In addition to the operations required by the concepts modeled by
<tt class="literal"><span class="pre">counting_iterator</span></tt>, <tt class="literal"><span class="pre">counting_iterator</span></tt> provides the following
operations.</p>
@ -2334,7 +2343,7 @@ operations.</p>
</div>
</div>
<div class="section" id="function-output-iterator">
<h3><a class="toc-backref" href="#id67" name="function-output-iterator">Function output iterator</a></h3>
<h3><a class="toc-backref" href="#id68" name="function-output-iterator">Function output iterator</a></h3>
<p>The function output iterator adaptor makes it easier to create custom
output iterators. The adaptor takes a unary function and creates a
model of Output Iterator. Each item assigned to the output iterator is
@ -2343,7 +2352,7 @@ iterator is that creating a conforming output iterator is non-trivial,
particularly because the proper implementation usually requires a
proxy object.</p>
<div class="section" id="class-template-function-output-iterator">
<h4><a class="toc-backref" href="#id68" name="class-template-function-output-iterator">Class template <tt class="literal"><span class="pre">function_output_iterator</span></tt></a></h4>
<h4><a class="toc-backref" href="#id69" name="class-template-function-output-iterator">Class template <tt class="literal"><span class="pre">function_output_iterator</span></tt></a></h4>
<pre class="literal-block">
template &lt;class UnaryFunction&gt;
class function_output_iterator {
@ -2365,16 +2374,16 @@ private:
</pre>
</div>
<div class="section" id="function-output-iterator-requirements">
<h4><a class="toc-backref" href="#id69" name="function-output-iterator-requirements"><tt class="literal"><span class="pre">function_output_iterator</span></tt> requirements</a></h4>
<h4><a class="toc-backref" href="#id70" name="function-output-iterator-requirements"><tt class="literal"><span class="pre">function_output_iterator</span></tt> requirements</a></h4>
<p><tt class="literal"><span class="pre">UnaryFunction</span></tt> must be Assignable and Copy Constructible.</p>
</div>
<div class="section" id="function-output-iterator-models">
<h4><a class="toc-backref" href="#id70" name="function-output-iterator-models"><tt class="literal"><span class="pre">function_output_iterator</span></tt> models</a></h4>
<h4><a class="toc-backref" href="#id71" name="function-output-iterator-models"><tt class="literal"><span class="pre">function_output_iterator</span></tt> models</a></h4>
<p><tt class="literal"><span class="pre">function_output_iterator</span></tt> is a model of the Writable and
Incrementable Iterator concepts.</p>
</div>
<div class="section" id="function-output-iterator-operations">
<h4><a class="toc-backref" href="#id71" name="function-output-iterator-operations"><tt class="literal"><span class="pre">function_output_iterator</span></tt> operations</a></h4>
<h4><a class="toc-backref" href="#id72" name="function-output-iterator-operations"><tt class="literal"><span class="pre">function_output_iterator</span></tt> operations</a></h4>
<p><tt class="literal"><span class="pre">explicit</span> <span class="pre">function_output_iterator(const</span> <span class="pre">UnaryFunction&amp;</span> <span class="pre">f</span> <span class="pre">=</span> <span class="pre">UnaryFunction());</span></tt></p>
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