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Handled the rest of my issues.

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[SVN r21752]
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Dave Abrahams
2004-01-15 04:31:50 +00:00
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@ -56,83 +56,84 @@ 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="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>
<li><a class="reference" href="#motivation" id="id15" name="id15">Motivation</a></li>
<li><a class="reference" href="#impact-on-the-standard" id="id16" name="id16">Impact on the Standard</a></li>
<li><a class="reference" href="#design" id="id17" name="id17">Design</a><ul>
<li><a class="reference" href="#iterator-concepts" id="id18" name="id18">Iterator Concepts</a></li>
<li><a class="reference" href="#interoperability" id="id19" name="id19">Interoperability</a></li>
<li><a class="reference" href="#iterator-facade" id="id20" name="id20">Iterator Facade</a><ul>
<li><a class="reference" href="#usage" id="id21" name="id21">Usage</a></li>
<li><a class="reference" href="#iterator-core-access" id="id22" name="id22">Iterator Core Access</a></li>
<li><a class="reference" href="#operator" id="id23" name="id23"><tt class="literal"><span class="pre">operator[]</span></tt></a></li>
<li><a class="reference" href="#id6" id="id24" name="id24"><tt class="literal"><span class="pre">operator-&gt;</span></tt></a></li>
</ul>
</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>
<li><a class="reference" href="#iterator-adaptor" id="id25" name="id25">Iterator Adaptor</a></li>
<li><a class="reference" href="#specialized-adaptors" id="id26" name="id26">Specialized Adaptors</a></li>
</ul>
</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>
<li><a class="reference" href="#proposed-text" id="id27" name="id27">Proposed Text</a><ul>
<li><a class="reference" href="#header-iterator-helper-synopsis-lib-iterator-helper-synopsis" id="id28" name="id28">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="id29" name="id29">Iterator facade [lib.iterator.facade]</a><ul>
<li><a class="reference" href="#class-template-iterator-facade" id="id30" name="id30">Class template <tt class="literal"><span class="pre">iterator_facade</span></tt></a></li>
<li><a class="reference" href="#iterator-facade-requirements" id="id31" name="id31"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></li>
<li><a class="reference" href="#iterator-facade-operations" id="id32" name="id32"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></li>
<li><a class="reference" href="#iterator-facade-interoperability" id="id33" name="id33"><tt class="literal"><span class="pre">iterator_facade</span></tt> interoperability</a></li>
</ul>
</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>
<li><a class="reference" href="#iterator-adaptor-lib-iterator-adaptor" id="id34" name="id34">Iterator adaptor [lib.iterator.adaptor]</a><ul>
<li><a class="reference" href="#class-template-iterator-adaptor" id="id35" name="id35">Class template <tt class="literal"><span class="pre">iterator_adaptor</span></tt></a></li>
<li><a class="reference" href="#iterator-adaptor-requirements" id="id36" name="id36"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> requirements</a></li>
<li><a class="reference" href="#iterator-adaptor-base-class-parameters" id="id37" name="id37"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> base class parameters</a></li>
<li><a class="reference" href="#iterator-adaptor-models" id="id38" name="id38"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> models</a></li>
<li><a class="reference" href="#iterator-adaptor-public-operations" id="id39" name="id39"><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="id40" name="id40"><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="id41" name="id41"><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="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>
<li><a class="reference" href="#specialized-adaptors-lib-iterator-special-adaptors" id="id42" name="id42">Specialized adaptors [lib.iterator.special.adaptors]</a><ul>
<li><a class="reference" href="#indirect-iterator" id="id43" name="id43">Indirect iterator</a><ul>
<li><a class="reference" href="#class-template-pointee" id="id44" name="id44">Class template <tt class="literal"><span class="pre">pointee</span></tt></a></li>
<li><a class="reference" href="#class-template-indirect-reference" id="id45" name="id45">Class template <tt class="literal"><span class="pre">indirect_reference</span></tt></a></li>
<li><a class="reference" href="#class-template-indirect-iterator" id="id46" name="id46">Class template <tt class="literal"><span class="pre">indirect_iterator</span></tt></a></li>
<li><a class="reference" href="#indirect-iterator-requirements" id="id47" name="id47"><tt class="literal"><span class="pre">indirect_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#indirect-iterator-models" id="id48" name="id48"><tt class="literal"><span class="pre">indirect_iterator</span></tt> models</a></li>
<li><a class="reference" href="#indirect-iterator-operations" id="id49" name="id49"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></li>
</ul>
</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>
<li><a class="reference" href="#reverse-iterator" id="id50" name="id50">Reverse iterator</a><ul>
<li><a class="reference" href="#class-template-reverse-iterator" id="id51" name="id51">Class template <tt class="literal"><span class="pre">reverse_iterator</span></tt></a></li>
<li><a class="reference" href="#reverse-iterator-requirements" id="id52" name="id52"><tt class="literal"><span class="pre">reverse_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#reverse-iterator-models" id="id53" name="id53"><tt class="literal"><span class="pre">reverse_iterator</span></tt> models</a></li>
<li><a class="reference" href="#reverse-iterator-operations" id="id54" name="id54"><tt class="literal"><span class="pre">reverse_iterator</span></tt> operations</a></li>
</ul>
</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>
<li><a class="reference" href="#transform-iterator" id="id55" name="id55">Transform iterator</a><ul>
<li><a class="reference" href="#class-template-transform-iterator" id="id56" name="id56">Class template <tt class="literal"><span class="pre">transform_iterator</span></tt></a></li>
<li><a class="reference" href="#transform-iterator-requirements" id="id57" name="id57"><tt class="literal"><span class="pre">transform_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#transform-iterator-models" id="id58" name="id58"><tt class="literal"><span class="pre">transform_iterator</span></tt> models</a></li>
<li><a class="reference" href="#transform-iterator-operations" id="id59" name="id59"><tt class="literal"><span class="pre">transform_iterator</span></tt> operations</a></li>
</ul>
</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>
<li><a class="reference" href="#filter-iterator" id="id60" name="id60">Filter iterator</a><ul>
<li><a class="reference" href="#class-template-filter-iterator" id="id61" name="id61">Class template <tt class="literal"><span class="pre">filter_iterator</span></tt></a></li>
<li><a class="reference" href="#filter-iterator-requirements" id="id62" name="id62"><tt class="literal"><span class="pre">filter_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#filter-iterator-models" id="id63" name="id63"><tt class="literal"><span class="pre">filter_iterator</span></tt> models</a></li>
<li><a class="reference" href="#filter-iterator-operations" id="id64" name="id64"><tt class="literal"><span class="pre">filter_iterator</span></tt> operations</a></li>
</ul>
</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>
<li><a class="reference" href="#counting-iterator" id="id65" name="id65">Counting iterator</a><ul>
<li><a class="reference" href="#class-template-counting-iterator" id="id66" name="id66">Class template <tt class="literal"><span class="pre">counting_iterator</span></tt></a></li>
<li><a class="reference" href="#counting-iterator-requirements" id="id67" name="id67"><tt class="literal"><span class="pre">counting_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#counting-iterator-models" id="id68" name="id68"><tt class="literal"><span class="pre">counting_iterator</span></tt> models</a></li>
<li><a class="reference" href="#counting-iterator-operations" id="id69" name="id69"><tt class="literal"><span class="pre">counting_iterator</span></tt> operations</a></li>
</ul>
</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>
<li><a class="reference" href="#function-output-iterator" id="id70" name="id70">Function output iterator</a><ul>
<li><a class="reference" href="#class-template-function-output-iterator" id="id71" name="id71">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="id72" name="id72"><tt class="literal"><span class="pre">function_output_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#function-output-iterator-models" id="id73" name="id73"><tt class="literal"><span class="pre">function_output_iterator</span></tt> models</a></li>
<li><a class="reference" href="#function-output-iterator-operations" id="id74" name="id74"><tt class="literal"><span class="pre">function_output_iterator</span></tt> operations</a></li>
</ul>
</li>
</ul>
@ -142,7 +143,7 @@ by adapting other iterators.</td>
</ul>
</div>
<div class="section" id="motivation">
<h1><a class="toc-backref" href="#id14" name="motivation">Motivation</a></h1>
<h1><a class="toc-backref" href="#id15" 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 +228,15 @@ 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="#id15" name="impact-on-the-standard">Impact on the Standard</a></h1>
<h1><a class="toc-backref" href="#id16" 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="#id16" name="design">Design</a></h1>
<h1><a class="toc-backref" href="#id17" name="design">Design</a></h1>
<div class="section" id="iterator-concepts">
<h2><a class="toc-backref" href="#id17" name="iterator-concepts">Iterator Concepts</a></h2>
<h2><a class="toc-backref" href="#id18" 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 +246,7 @@ 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="#id18" name="interoperability">Interoperability</a></h2>
<h2><a class="toc-backref" href="#id19" 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 +266,7 @@ 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="#id19" name="iterator-facade">Iterator Facade</a></h2>
<h2><a class="toc-backref" href="#id20" 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 +311,7 @@ impossible.</li>
</ol>
</blockquote>
<div class="section" id="usage">
<h3><a class="toc-backref" href="#id20" name="usage">Usage</a></h3>
<h3><a class="toc-backref" href="#id21" 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 +375,7 @@ 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="#id21" name="iterator-core-access">Iterator Core Access</a></h3>
<h3><a class="toc-backref" href="#id22" 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 +409,7 @@ 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="#id22" name="operator"><tt class="literal"><span class="pre">operator[]</span></tt></a></h3>
<h3><a class="toc-backref" href="#id23" 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 +432,7 @@ 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="#id23" name="id6"><tt class="literal"><span class="pre">operator-&gt;</span></tt></a></h3>
<h3><a class="toc-backref" href="#id24" 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 +455,7 @@ Patterns, C++ Report, February 1995, pp. 24-27.</td></tr>
</div>
</div>
<div class="section" id="iterator-adaptor">
<h2><a class="toc-backref" href="#id24" name="iterator-adaptor">Iterator Adaptor</a></h2>
<h2><a class="toc-backref" href="#id25" 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 +496,7 @@ 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="#id25" name="specialized-adaptors">Specialized Adaptors</a></h2>
<h2><a class="toc-backref" href="#id26" 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 +533,9 @@ Standard compliant iterators).</p>
</div>
</div>
<div class="section" id="proposed-text">
<h1><a class="toc-backref" href="#id26" name="proposed-text">Proposed Text</a></h1>
<h1><a class="toc-backref" href="#id27" 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="#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>
<h2><a class="toc-backref" href="#id28" 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 +601,12 @@ class function_output_iterator;
</pre>
</div>
<div class="section" id="iterator-facade-lib-iterator-facade">
<h2><a class="toc-backref" href="#id28" name="iterator-facade-lib-iterator-facade">Iterator facade [lib.iterator.facade]</a></h2>
<h2><a class="toc-backref" href="#id29" 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="#id29" 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="#id30" 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
@ -641,64 +642,62 @@ public:
// Comparison operators
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type // exposition
operator ==(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type // exposition
operator ==(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator !=(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator !=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator &lt;(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &lt;(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator &lt;=(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &lt;=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator &gt;(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &gt;(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator &gt;=(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator &gt;=(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &gt;=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
// Iterator difference
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator -(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
/* see <a class="reference" href="#minus">below</a> */
operator-(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
// Iterator addition
template &lt;class Derived, class V, class TC, class R, class D&gt;
Derived operator+ (iterator_facade&lt;Derived, V, TC, R, D&gt; const&amp;,
typename Derived::difference_type n)
template &lt;class Dr, class V, class TC, class R, class D&gt;
Derived operator+ (iterator_facade&lt;Dr,V,TC,R,D&gt; const&amp;,
typename Derived::difference_type n);
template &lt;class Dr, class V, class TC, class R, class D&gt;
Derived operator+ (typename Derived::difference_type n,
iterator_facade&lt;Dr,V,TC,R,D&gt; const&amp;);
</pre>
<a class="target" id="iterator-category" name="iterator-category"></a><p>The <tt class="literal"><span class="pre">iterator_category</span></tt> member of <tt class="literal"><span class="pre">iterator_facade</span></tt> is</p>
<pre class="literal-block">
<em>iterator-category</em>(CategoryOrTraversal, value_type, reference)
</pre>
<p>where <em>iterator-category</em> is defined as follows:</p>
<a class="target" id="id11" name="id11"></a><pre class="literal-block">
<a class="target" id="id12" name="id12"></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
@ -776,12 +775,13 @@ struct enable_if_interoperable
</pre>
</div>
<div class="section" id="iterator-facade-requirements">
<h3><a class="toc-backref" href="#id30" name="iterator-facade-requirements"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></h3>
<h3><a class="toc-backref" href="#id31" 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
column must be made accessible to member functions of class
<tt class="literal"><span class="pre">iterator_core_access</span></tt>.</p>
<tt class="literal"><span class="pre">iterator_core_access</span></tt>. In addition,
<tt class="literal"><span class="pre">static_cast&lt;Derived*&gt;(iterator_facade*)</span></tt> shall be well-formed.</p>
<p>In the table below, <tt class="literal"><span class="pre">F</span></tt> is <tt class="literal"><span class="pre">iterator_facade&lt;X,V,C,R,D&gt;</span></tt>, <tt class="literal"><span class="pre">a</span></tt> is an
object of type <tt class="literal"><span class="pre">X</span></tt>, <tt class="literal"><span class="pre">b</span></tt> and <tt class="literal"><span class="pre">c</span></tt> are objects of type <tt class="literal"><span class="pre">const</span> <span class="pre">X</span></tt>,
<tt class="literal"><span class="pre">n</span></tt> is an object of <tt class="literal"><span class="pre">F::difference_type</span></tt>, <tt class="literal"><span class="pre">y</span></tt> is a constant
@ -792,10 +792,10 @@ interoperable with <tt class="literal"><span class="pre">X</span></tt>.</p>
<p class="topic-title"><tt class="literal"><span class="pre">iterator_facade</span></tt> Core Operations</p>
<table border class="table">
<colgroup>
<col width="19%" />
<col width="21%" />
<col width="35%" />
<col width="25%" />
<col width="23%" />
<col width="27%" />
<col width="29%" />
</colgroup>
<thead valign="bottom">
<tr><th>Expression</th>
@ -814,8 +814,9 @@ Iterator</td>
</tr>
<tr><td><tt class="literal"><span class="pre">c.equal(y)</span></tt></td>
<td>convertible to bool</td>
<td>true iff <tt class="literal"><span class="pre">c</span></tt> and <tt class="literal"><span class="pre">y</span></tt> refer to the
same position.</td>
<td>true iff <tt class="literal"><span class="pre">c</span></tt> and <tt class="literal"><span class="pre">y</span></tt>
refer to the same
position.</td>
<td>Single Pass Iterator</td>
</tr>
<tr><td><tt class="literal"><span class="pre">a.increment()</span></tt></td>
@ -838,7 +839,8 @@ Iterator</td>
<tr><td><tt class="literal"><span class="pre">c.distance_to(z)</span></tt></td>
<td>convertible to
<tt class="literal"><span class="pre">F::difference_type</span></tt></td>
<td>equivalent to <tt class="literal"><span class="pre">distance(c,</span> <span class="pre">X(z))</span></tt>.</td>
<td>equivalent to
<tt class="literal"><span class="pre">distance(c,</span> <span class="pre">X(z))</span></tt>.</td>
<td>Random Access Traversal
Iterator</td>
</tr>
@ -847,7 +849,7 @@ Iterator</td>
</div>
</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>
<h3><a class="toc-backref" href="#id32" 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
@ -985,10 +987,156 @@ return tmp -= n;
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr, class V, class TC, class R, class D&gt;
Derived operator+ (iterator_facade&lt;Dr,V,TC,R,D&gt; const&amp;,
typename Derived::difference_type n);
template &lt;class Dr, class V, class TC, class R, class D&gt;
Derived operator+ (typename Derived::difference_type n,
iterator_facade&lt;Dr,V,TC,R,D&gt; const&amp;);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Effects:</th><td class="field-body"><pre class="first last literal-block">
Derived tmp(static_cast&lt;Derived const*&gt;(this));
return tmp += n;
</pre>
</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="iterator-facade-interoperability">
<h3><a class="toc-backref" href="#id33" name="iterator-facade-interoperability"><tt class="literal"><span class="pre">iterator_facade</span></tt> interoperability</a></h3>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator ==(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">lhs.equal(rhs)</span></tt>. Otherwise, <tt class="literal"><span class="pre">rhs.equal(lhs)</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator !=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">!lhs.equal(rhs)</span></tt>. Otherwise, <tt class="literal"><span class="pre">!rhs.equal(lhs)</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &lt;(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">lhs.distance_to(rhs)</span> <span class="pre">&lt;</span> <span class="pre">0</span></tt>. Otherwise, <tt class="literal"><span class="pre">rhs.distance_to(lhs)</span> <span class="pre">&gt;</span>
<span class="pre">0</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &lt;=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">lhs.distance_to(rhs)</span> <span class="pre">&lt;=</span> <span class="pre">0</span></tt>. Otherwise, <tt class="literal"><span class="pre">rhs.distance_to(lhs)</span>
<span class="pre">&gt;=</span> <span class="pre">0</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &gt;(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">lhs.distance_to(rhs)</span> <span class="pre">&gt;</span> <span class="pre">0</span></tt>. Otherwise,
<tt class="literal"><span class="pre">rhs.distance_to(lhs)</span> <span class="pre">&lt;</span> <span class="pre">0</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &gt;=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">lhs.distance_to(rhs)</span> <span class="pre">&gt;=</span> <span class="pre">0</span></tt>. Otherwise,
<tt class="literal"><span class="pre">rhs.distance_to(lhs)</span> <span class="pre">&lt;=</span> <span class="pre">0</span></tt>.</td>
</tr>
</tbody>
</table>
<a class="target" id="minus" name="minus"></a><pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,difference_type&gt;::type
operator -(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Return Type:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then <tt class="literal"><span class="pre">difference_type</span></tt> shall be
<tt class="literal"><span class="pre">iterator_traits&lt;Dr1&gt;::difference_type</span></tt>. Otherwise,
<tt class="literal"><span class="pre">difference_type</span></tt> shall be
<tt class="literal"><span class="pre">iterator_traits&lt;Dr2&gt;::difference_type</span></tt>.</td>
</tr>
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">-lhs.distance_to(rhs)</span></tt>. Otherwise,
<tt class="literal"><span class="pre">-rhs.distance_to(lhs)</span></tt>.</td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="section" id="iterator-adaptor-lib-iterator-adaptor">
<h2><a class="toc-backref" href="#id32" name="iterator-adaptor-lib-iterator-adaptor">Iterator adaptor [lib.iterator.adaptor]</a></h2>
<h2><a class="toc-backref" href="#id34" 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 +1152,7 @@ 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="#id33" 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="#id35" 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 +1201,13 @@ 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="#id34" name="iterator-adaptor-requirements"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> requirements</a></h3>
<h3><a class="toc-backref" href="#id36" 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="#id35" 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="#id37" 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 +1237,7 @@ above are defined as follows:</p>
</pre>
</div>
<div class="section" id="iterator-adaptor-models">
<h3><a class="toc-backref" href="#id36" name="iterator-adaptor-models"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> models</a></h3>
<h3><a class="toc-backref" href="#id38" 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 +1247,7 @@ 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="#id37" 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="#id39" 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 +1281,7 @@ 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="#id38" 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="#id40" 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 +1302,7 @@ 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="#id39" 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="#id41" 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 +1371,7 @@ 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="#id40" name="specialized-adaptors-lib-iterator-special-adaptors">Specialized adaptors [lib.iterator.special.adaptors]</a></h2>
<h2><a class="toc-backref" href="#id42" 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 +1400,7 @@ 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="#id41" name="indirect-iterator">Indirect iterator</a></h3>
<h3><a class="toc-backref" href="#id43" 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 +1410,7 @@ 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="#id42" name="class-template-pointee">Class template <tt class="literal"><span class="pre">pointee</span></tt></a></h4>
<h4><a class="toc-backref" href="#id44" 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 +1454,7 @@ else
</pre>
</div>
<div class="section" id="class-template-indirect-reference">
<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>
<h4><a class="toc-backref" href="#id45" 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 +1489,7 @@ else
</pre>
</div>
<div class="section" id="class-template-indirect-iterator">
<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>
<h4><a class="toc-backref" href="#id46" 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
@ -1409,17 +1557,17 @@ else
typedef Difference difference_type;
if (CategoryOrTraversal is use_default)
typedef <a class="reference" href="#id11"><em>iterator-category</em></a>(
typedef <a class="reference" href="#id12"><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>(
typedef <a class="reference" href="#id12"><em>iterator-category</em></a>(
CategoryOrTraversal,``reference``,``value_type``
) iterator_category;
</pre>
</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>
<h4><a class="toc-backref" href="#id47" 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
@ -1433,7 +1581,7 @@ 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="#id46" name="indirect-iterator-models"><tt class="literal"><span class="pre">indirect_iterator</span></tt> models</a></h4>
<h4><a class="toc-backref" href="#id48" 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
@ -1454,7 +1602,7 @@ expression (where <tt class="literal"><span class="pre">t</span></tt> is an obje
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="#id47" name="indirect-iterator-operations"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></h4>
<h4><a class="toc-backref" href="#id49" 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>
@ -1546,11 +1694,11 @@ indirect_iterator(
</div>
</div>
<div class="section" id="reverse-iterator">
<h3><a class="toc-backref" href="#id48" name="reverse-iterator">Reverse iterator</a></h3>
<h3><a class="toc-backref" href="#id50" 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="#id49" 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="#id51" 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
@ -1587,11 +1735,11 @@ 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="#id50" name="reverse-iterator-requirements"><tt class="literal"><span class="pre">reverse_iterator</span></tt> requirements</a></h4>
<h4><a class="toc-backref" href="#id52" 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="#id51" name="reverse-iterator-models"><tt class="literal"><span class="pre">reverse_iterator</span></tt> models</a></h4>
<h4><a class="toc-backref" href="#id53" 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 iterator
traversal and iterator access concepts modeled by its <tt class="literal"><span class="pre">Iterator</span></tt>
argument. In addition, it may model old iterator concepts
@ -1630,7 +1778,7 @@ Random Access Traversal Iterator</td>
<tt class="literal"><span class="pre">Y</span></tt>.</p>
</div>
<div class="section" id="reverse-iterator-operations">
<h4><a class="toc-backref" href="#id52" name="reverse-iterator-operations"><tt class="literal"><span class="pre">reverse_iterator</span></tt> operations</a></h4>
<h4><a class="toc-backref" href="#id54" 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>
@ -1720,12 +1868,12 @@ return *--tmp;
</div>
</div>
<div class="section" id="transform-iterator">
<h3><a class="toc-backref" href="#id53" name="transform-iterator">Transform iterator</a></h3>
<h3><a class="toc-backref" href="#id55" 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="#id54" 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="#id56" 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,
@ -1778,7 +1926,7 @@ 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="#id55" name="transform-iterator-requirements"><tt class="literal"><span class="pre">transform_iterator</span></tt> requirements</a></h4>
<h4><a class="toc-backref" href="#id57" 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
@ -1787,7 +1935,7 @@ 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="#id56" name="transform-iterator-models"><tt class="literal"><span class="pre">transform_iterator</span></tt> models</a></h4>
<h4><a class="toc-backref" href="#id58" 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>
@ -1834,7 +1982,7 @@ mutable iterator (as defined in the old iterator requirements).</p>
interoperable with <tt class="literal"><span class="pre">Y</span></tt>.</p>
</div>
<div class="section" id="transform-iterator-operations">
<h4><a class="toc-backref" href="#id57" name="transform-iterator-operations"><tt class="literal"><span class="pre">transform_iterator</span></tt> operations</a></h4>
<h4><a class="toc-backref" href="#id59" 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>
@ -1927,7 +2075,7 @@ transform_iterator(
</div>
</div>
<div class="section" id="filter-iterator">
<h3><a class="toc-backref" href="#id58" name="filter-iterator">Filter iterator</a></h3>
<h3><a class="toc-backref" href="#id60" 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
@ -1939,7 +2087,7 @@ 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="#id59" 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="#id61" 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 -->
@ -1980,7 +2128,7 @@ 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="#id60" name="filter-iterator-requirements"><tt class="literal"><span class="pre">filter_iterator</span></tt> requirements</a></h4>
<h4><a class="toc-backref" href="#id62" 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
@ -1991,7 +2139,7 @@ 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="#id61" name="filter-iterator-models"><tt class="literal"><span class="pre">filter_iterator</span></tt> models</a></h4>
<h4><a class="toc-backref" href="#id63" 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>
@ -2062,7 +2210,7 @@ following tables.</p>
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="filter-iterator-operations">
<h4><a class="toc-backref" href="#id62" name="filter-iterator-operations"><tt class="literal"><span class="pre">filter_iterator</span></tt> operations</a></h4>
<h4><a class="toc-backref" href="#id64" 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>
@ -2173,12 +2321,12 @@ 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="#id63" name="counting-iterator">Counting iterator</a></h3>
<h3><a class="toc-backref" href="#id65" 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="#id64" 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="#id66" 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
@ -2214,10 +2362,10 @@ algorithm:</p>
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>(
return <a class="reference" href="#id12"><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>(
return <a class="reference" href="#id12"><em>iterator-category</em></a>(
iterator_traversal&lt;Incrementable&gt;::type,
Incrementable, const Incrementable&amp;)
</pre>
@ -2226,7 +2374,7 @@ of <tt class="literal"><span class="pre">operator-</span></tt> and a default <tt
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="#id65" name="counting-iterator-requirements"><tt class="literal"><span class="pre">counting_iterator</span></tt> requirements</a></h4>
<h4><a class="toc-backref" href="#id67" 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>
@ -2252,7 +2400,7 @@ i &lt; j;
</pre>
</div>
<div class="section" id="counting-iterator-models">
<h4><a class="toc-backref" href="#id66" name="counting-iterator-models"><tt class="literal"><span class="pre">counting_iterator</span></tt> models</a></h4>
<h4><a class="toc-backref" href="#id68" 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.
@ -2268,7 +2416,7 @@ concepts modeled by <tt class="literal"><span class="pre">Incrementable</span></
interoperable with <tt class="literal"><span class="pre">Y</span></tt>.</p>
</div>
<div class="section" id="counting-iterator-operations">
<h4><a class="toc-backref" href="#id67" name="counting-iterator-operations"><tt class="literal"><span class="pre">counting_iterator</span></tt> operations</a></h4>
<h4><a class="toc-backref" href="#id69" 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>
@ -2344,7 +2492,7 @@ operations.</p>
</div>
</div>
<div class="section" id="function-output-iterator">
<h3><a class="toc-backref" href="#id68" name="function-output-iterator">Function output iterator</a></h3>
<h3><a class="toc-backref" href="#id70" 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
@ -2353,7 +2501,7 @@ 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="#id69" 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="#id71" 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 {
@ -2375,16 +2523,16 @@ private:
</pre>
</div>
<div class="section" id="function-output-iterator-requirements">
<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>
<h4><a class="toc-backref" href="#id72" 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="#id71" 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="#id73" 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="#id72" 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="#id74" 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>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />

45
doc/iter-issue-list.rst
View File

@ -62,8 +62,8 @@ to be members or non-members.
or non-members.
9.3 enable_if_interoperable needs standardese (Dave)
====================================================
9.3 enable_if_interoperable needs standardese
=============================================
:Submitter: Pete Becker
:Status: New
@ -81,11 +81,7 @@ N1541 48
behavior of these functions is undefined if the two types aren't
interoperable.
**Needs work** (Dave) I'm not happy with Pete's proposal.
(thw) Pete is correct with regard to the requirement. Removing the
interoperable stuff would be an error. By all means we don't want
undefined behaviour here.
**Needs diffs** (fixed in text).
9.4 enable_if_convertible unspecified, conflicts with requires
==============================================================
@ -526,16 +522,12 @@ like "when using iterator_facade to define an iterator class Iter, the class Ite
from a specialization of iterator_facade whose first template argument is Iter." That's a bit
awkward, but at the moment I don't see a better way of phrasing it.
:Proposed resolution: **Needs work** (Dave) Reword.
01/01/04 thw
The wording is certainly insufficient. AFAICS there are two issues.
First the issue addressed by Pete i.e. specifying the requirements for
implementing a valid iterator. The other issue I can see is that we
need to be able to unambigously cast the iterator_facade specialisation
to Iter.
:Proposed resolution: Add: In addition,
``static_cast<Derived*>(iterator_facade*)`` shall be
well-formed.
9.22 return type of Iterator difference for iterator facade (Dave)
==================================================================
9.22 return type of Iterator difference for iterator facade
===========================================================
:Submitter: Pete Becker
:Status: New
@ -554,20 +546,7 @@ to the other type, then the subtraction is okay. Seems like the
return type should then be the type that was converted to. Is that
right?
:Proposed resolution:
Change the return type from ::
typename enable_if_interoperable<Dr1, Dr2, bool>::type
to ::
typename enable_if_interoperable<Dr1, Dr2, D1>::type
01/01/04 thw
Almost, the return type should be the difference_type of the
converted to iterator. BTW how does std::distance handle
different but interoperable iterator types?
:Proposed resolution: **Needs diffs** (fixed in text)
9.23 Iterator_facade: minor wording Issue
=========================================
@ -818,8 +797,8 @@ c++std-lib-12333:
this issue for Readable Iterator and Lvalue Iterator.
9.34 iterator_facade free functions unspecified (Dave)
======================================================
9.34 iterator_facade free functions unspecified
===============================================
:Submitter: Pete Becker
:Status: New
@ -834,7 +813,7 @@ c++std-lib-12562:
iterator_facade and an argument of type difference_type has no
specification.
:Proposed resolution: **Needs work** Add the missing specifications.
:Proposed resolution: **Needs diffs** Added the missing specifications.
9.35 iterator_facade: too many equals?

336
doc/iterator_facade.html
View File

@ -45,43 +45,44 @@ and associated types, to be supplied by a derived iterator class.</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="#overview" id="id22" name="id22">Overview</a><ul>
<li><a class="reference" href="#usage" id="id23" name="id23">Usage</a></li>
<li><a class="reference" href="#iterator-core-access" id="id24" name="id24">Iterator Core Access</a></li>
<li><a class="reference" href="#operator" id="id25" name="id25"><tt class="literal"><span class="pre">operator[]</span></tt></a></li>
<li><a class="reference" href="#id2" id="id26" name="id26"><tt class="literal"><span class="pre">operator-&gt;</span></tt></a></li>
<li><a class="reference" href="#overview" id="id23" name="id23">Overview</a><ul>
<li><a class="reference" href="#usage" id="id24" name="id24">Usage</a></li>
<li><a class="reference" href="#iterator-core-access" id="id25" name="id25">Iterator Core Access</a></li>
<li><a class="reference" href="#operator" id="id26" name="id26"><tt class="literal"><span class="pre">operator[]</span></tt></a></li>
<li><a class="reference" href="#id2" id="id27" name="id27"><tt class="literal"><span class="pre">operator-&gt;</span></tt></a></li>
</ul>
</li>
<li><a class="reference" href="#reference" id="id27" name="id27">Reference</a><ul>
<li><a class="reference" href="#iterator-facade-requirements" id="id28" name="id28"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></li>
<li><a class="reference" href="#iterator-facade-operations" id="id29" name="id29"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></li>
<li><a class="reference" href="#reference" id="id28" name="id28">Reference</a><ul>
<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="#iterator-facade-interoperability" id="id31" name="id31"><tt class="literal"><span class="pre">iterator_facade</span></tt> interoperability</a></li>
</ul>
</li>
<li><a class="reference" href="#tutorial-example" id="id30" name="id30">Tutorial Example</a><ul>
<li><a class="reference" href="#the-problem" id="id31" name="id31">The Problem</a></li>
<li><a class="reference" href="#a-basic-iterator-using-iterator-facade" id="id32" name="id32">A Basic Iterator Using <tt class="literal"><span class="pre">iterator_facade</span></tt></a><ul>
<li><a class="reference" href="#template-arguments-for-iterator-facade" id="id33" name="id33">Template Arguments for <tt class="literal"><span class="pre">iterator_facade</span></tt></a><ul>
<li><a class="reference" href="#derived" id="id34" name="id34"><tt class="literal"><span class="pre">Derived</span></tt></a></li>
<li><a class="reference" href="#value" id="id35" name="id35"><tt class="literal"><span class="pre">Value</span></tt></a></li>
<li><a class="reference" href="#categoryortraversal" id="id36" name="id36"><tt class="literal"><span class="pre">CategoryOrTraversal</span></tt></a></li>
<li><a class="reference" href="#id11" id="id37" name="id37"><tt class="literal"><span class="pre">Reference</span></tt></a></li>
<li><a class="reference" href="#difference" id="id38" name="id38"><tt class="literal"><span class="pre">Difference</span></tt></a></li>
<li><a class="reference" href="#tutorial-example" id="id32" name="id32">Tutorial Example</a><ul>
<li><a class="reference" href="#the-problem" id="id33" name="id33">The Problem</a></li>
<li><a class="reference" href="#a-basic-iterator-using-iterator-facade" id="id34" name="id34">A Basic Iterator Using <tt class="literal"><span class="pre">iterator_facade</span></tt></a><ul>
<li><a class="reference" href="#template-arguments-for-iterator-facade" id="id35" name="id35">Template Arguments for <tt class="literal"><span class="pre">iterator_facade</span></tt></a><ul>
<li><a class="reference" href="#derived" id="id36" name="id36"><tt class="literal"><span class="pre">Derived</span></tt></a></li>
<li><a class="reference" href="#value" id="id37" name="id37"><tt class="literal"><span class="pre">Value</span></tt></a></li>
<li><a class="reference" href="#categoryortraversal" id="id38" name="id38"><tt class="literal"><span class="pre">CategoryOrTraversal</span></tt></a></li>
<li><a class="reference" href="#id12" id="id39" name="id39"><tt class="literal"><span class="pre">Reference</span></tt></a></li>
<li><a class="reference" href="#difference" id="id40" name="id40"><tt class="literal"><span class="pre">Difference</span></tt></a></li>
</ul>
</li>
<li><a class="reference" href="#constructors-and-data-members" id="id39" name="id39">Constructors and Data Members</a></li>
<li><a class="reference" href="#implementing-the-core-operations" id="id40" name="id40">Implementing the Core Operations</a></li>
<li><a class="reference" href="#constructors-and-data-members" id="id41" name="id41">Constructors and Data Members</a></li>
<li><a class="reference" href="#implementing-the-core-operations" id="id42" name="id42">Implementing the Core Operations</a></li>
</ul>
</li>
<li><a class="reference" href="#a-constant-node-iterator" id="id41" name="id41">A constant <tt class="literal"><span class="pre">node_iterator</span></tt></a></li>
<li><a class="reference" href="#interoperability" id="id42" name="id42">Interoperability</a></li>
<li><a class="reference" href="#telling-the-truth" id="id43" name="id43">Telling the Truth</a></li>
<li><a class="reference" href="#wrap-up" id="id44" name="id44">Wrap Up</a></li>
<li><a class="reference" href="#a-constant-node-iterator" id="id43" name="id43">A constant <tt class="literal"><span class="pre">node_iterator</span></tt></a></li>
<li><a class="reference" href="#interoperability" id="id44" name="id44">Interoperability</a></li>
<li><a class="reference" href="#telling-the-truth" id="id45" name="id45">Telling the Truth</a></li>
<li><a class="reference" href="#wrap-up" id="id46" name="id46">Wrap Up</a></li>
</ul>
</li>
</ul>
</div>
<div class="section" id="overview">
<h1><a class="toc-backref" href="#id22" name="overview">Overview</a></h1>
<h1><a class="toc-backref" href="#id23" name="overview">Overview</a></h1>
<!-- 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
@ -126,7 +127,7 @@ impossible.</li>
</ol>
</blockquote>
<div class="section" id="usage">
<h2><a class="toc-backref" href="#id23" name="usage">Usage</a></h2>
<h2><a class="toc-backref" href="#id24" name="usage">Usage</a></h2>
<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.
@ -190,7 +191,7 @@ Iterator or a more-refined iterator concept, a default constructor is
required.</p>
</div>
<div class="section" id="iterator-core-access">
<h2><a class="toc-backref" href="#id24" name="iterator-core-access">Iterator Core Access</a></h2>
<h2><a class="toc-backref" href="#id25" name="iterator-core-access">Iterator Core Access</a></h2>
<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
@ -224,7 +225,7 @@ open a safety loophole, as every core member function preserves the
invariants of the iterator.</p>
</div>
<div class="section" id="operator">
<h2><a class="toc-backref" href="#id25" name="operator"><tt class="literal"><span class="pre">operator[]</span></tt></a></h2>
<h2><a class="toc-backref" href="#id26" name="operator"><tt class="literal"><span class="pre">operator[]</span></tt></a></h2>
<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>.
@ -247,7 +248,7 @@ 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="id2">
<h2><a class="toc-backref" href="#id26" name="id2"><tt class="literal"><span class="pre">operator-&gt;</span></tt></a></h2>
<h2><a class="toc-backref" href="#id27" name="id2"><tt class="literal"><span class="pre">operator-&gt;</span></tt></a></h2>
<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>
@ -263,14 +264,14 @@ satisfied by the <tt class="literal"><span class="pre">iterator_facade</span></t
<colgroup><col class="label" /><col /></colgroup>
<col />
<tbody valign="top">
<tr><td class="label"><a name="cop95">[Cop95]</a></td><td><em>(<a class="fn-backref" href="#id1">1</a>, <a class="fn-backref" href="#id9">2</a>)</em> [Coplien, 1995] Coplien, J., Curiously Recurring Template
<tr><td class="label"><a name="cop95">[Cop95]</a></td><td><em>(<a class="fn-backref" href="#id1">1</a>, <a class="fn-backref" href="#id10">2</a>)</em> [Coplien, 1995] Coplien, J., Curiously Recurring Template
Patterns, C++ Report, February 1995, pp. 24-27.</td></tr>
</tbody>
</table>
</div>
</div>
<div class="section" id="reference">
<h1><a class="toc-backref" href="#id27" name="reference">Reference</a></h1>
<h1><a class="toc-backref" href="#id28" name="reference">Reference</a></h1>
<!-- 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
@ -306,64 +307,62 @@ public:
// Comparison operators
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type // exposition
operator ==(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type // exposition
operator ==(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator !=(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator !=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator &lt;(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &lt;(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator &lt;=(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &lt;=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator &gt;(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &gt;(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator &gt;=(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator &gt;=(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &gt;=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
// Iterator difference
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1, Dr2, bool&gt;::type
operator -(iterator_facade&lt;Dr1, V1, TC1, R1, D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2, V2, TC2, R2, D2&gt; const&amp; rhs);
/* see <a class="reference" href="#minus">below</a> */
operator-(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
// Iterator addition
template &lt;class Derived, class V, class TC, class R, class D&gt;
Derived operator+ (iterator_facade&lt;Derived, V, TC, R, D&gt; const&amp;,
typename Derived::difference_type n)
template &lt;class Dr, class V, class TC, class R, class D&gt;
Derived operator+ (iterator_facade&lt;Dr,V,TC,R,D&gt; const&amp;,
typename Derived::difference_type n);
template &lt;class Dr, class V, class TC, class R, class D&gt;
Derived operator+ (typename Derived::difference_type n,
iterator_facade&lt;Dr,V,TC,R,D&gt; const&amp;);
</pre>
<a class="target" id="iterator-category" name="iterator-category"></a><p>The <tt class="literal"><span class="pre">iterator_category</span></tt> member of <tt class="literal"><span class="pre">iterator_facade</span></tt> is</p>
<pre class="literal-block">
<em>iterator-category</em>(CategoryOrTraversal, value_type, reference)
</pre>
<p>where <em>iterator-category</em> is defined as follows:</p>
<a class="target" id="id6" name="id6"></a><pre class="literal-block">
<a class="target" id="id7" name="id7"></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
@ -440,12 +439,13 @@ struct enable_if_interoperable
{};
</pre>
<div class="section" id="iterator-facade-requirements">
<h2><a class="toc-backref" href="#id28" name="iterator-facade-requirements"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></h2>
<h2><a class="toc-backref" href="#id29" name="iterator-facade-requirements"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></h2>
<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
column must be made accessible to member functions of class
<tt class="literal"><span class="pre">iterator_core_access</span></tt>.</p>
<tt class="literal"><span class="pre">iterator_core_access</span></tt>. In addition,
<tt class="literal"><span class="pre">static_cast&lt;Derived*&gt;(iterator_facade*)</span></tt> shall be well-formed.</p>
<p>In the table below, <tt class="literal"><span class="pre">F</span></tt> is <tt class="literal"><span class="pre">iterator_facade&lt;X,V,C,R,D&gt;</span></tt>, <tt class="literal"><span class="pre">a</span></tt> is an
object of type <tt class="literal"><span class="pre">X</span></tt>, <tt class="literal"><span class="pre">b</span></tt> and <tt class="literal"><span class="pre">c</span></tt> are objects of type <tt class="literal"><span class="pre">const</span> <span class="pre">X</span></tt>,
<tt class="literal"><span class="pre">n</span></tt> is an object of <tt class="literal"><span class="pre">F::difference_type</span></tt>, <tt class="literal"><span class="pre">y</span></tt> is a constant
@ -456,10 +456,10 @@ interoperable with <tt class="literal"><span class="pre">X</span></tt>.</p>
<p class="topic-title"><tt class="literal"><span class="pre">iterator_facade</span></tt> Core Operations</p>
<table border class="table">
<colgroup>
<col width="19%" />
<col width="21%" />
<col width="35%" />
<col width="25%" />
<col width="23%" />
<col width="27%" />
<col width="29%" />
</colgroup>
<thead valign="bottom">
<tr><th>Expression</th>
@ -478,8 +478,9 @@ Iterator</td>
</tr>
<tr><td><tt class="literal"><span class="pre">c.equal(y)</span></tt></td>
<td>convertible to bool</td>
<td>true iff <tt class="literal"><span class="pre">c</span></tt> and <tt class="literal"><span class="pre">y</span></tt> refer to the
same position.</td>
<td>true iff <tt class="literal"><span class="pre">c</span></tt> and <tt class="literal"><span class="pre">y</span></tt>
refer to the same
position.</td>
<td>Single Pass Iterator</td>
</tr>
<tr><td><tt class="literal"><span class="pre">a.increment()</span></tt></td>
@ -502,7 +503,8 @@ Iterator</td>
<tr><td><tt class="literal"><span class="pre">c.distance_to(z)</span></tt></td>
<td>convertible to
<tt class="literal"><span class="pre">F::difference_type</span></tt></td>
<td>equivalent to <tt class="literal"><span class="pre">distance(c,</span> <span class="pre">X(z))</span></tt>.</td>
<td>equivalent to
<tt class="literal"><span class="pre">distance(c,</span> <span class="pre">X(z))</span></tt>.</td>
<td>Random Access Traversal
Iterator</td>
</tr>
@ -511,7 +513,7 @@ Iterator</td>
</div>
</div>
<div class="section" id="iterator-facade-operations">
<h2><a class="toc-backref" href="#id29" name="iterator-facade-operations"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></h2>
<h2><a class="toc-backref" href="#id30" name="iterator-facade-operations"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></h2>
<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
@ -649,10 +651,156 @@ return tmp -= n;
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr, class V, class TC, class R, class D&gt;
Derived operator+ (iterator_facade&lt;Dr,V,TC,R,D&gt; const&amp;,
typename Derived::difference_type n);
template &lt;class Dr, class V, class TC, class R, class D&gt;
Derived operator+ (typename Derived::difference_type n,
iterator_facade&lt;Dr,V,TC,R,D&gt; const&amp;);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Effects:</th><td class="field-body"><pre class="first last literal-block">
Derived tmp(static_cast&lt;Derived const*&gt;(this));
return tmp += n;
</pre>
</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="iterator-facade-interoperability">
<h2><a class="toc-backref" href="#id31" name="iterator-facade-interoperability"><tt class="literal"><span class="pre">iterator_facade</span></tt> interoperability</a></h2>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator ==(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">lhs.equal(rhs)</span></tt>. Otherwise, <tt class="literal"><span class="pre">rhs.equal(lhs)</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator !=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">!lhs.equal(rhs)</span></tt>. Otherwise, <tt class="literal"><span class="pre">!rhs.equal(lhs)</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &lt;(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">lhs.distance_to(rhs)</span> <span class="pre">&lt;</span> <span class="pre">0</span></tt>. Otherwise, <tt class="literal"><span class="pre">rhs.distance_to(lhs)</span> <span class="pre">&gt;</span>
<span class="pre">0</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &lt;=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">lhs.distance_to(rhs)</span> <span class="pre">&lt;=</span> <span class="pre">0</span></tt>. Otherwise, <tt class="literal"><span class="pre">rhs.distance_to(lhs)</span>
<span class="pre">&gt;=</span> <span class="pre">0</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &gt;(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">lhs.distance_to(rhs)</span> <span class="pre">&gt;</span> <span class="pre">0</span></tt>. Otherwise,
<tt class="literal"><span class="pre">rhs.distance_to(lhs)</span> <span class="pre">&lt;</span> <span class="pre">0</span></tt>.</td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,bool&gt;::type
operator &gt;=(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">lhs.distance_to(rhs)</span> <span class="pre">&gt;=</span> <span class="pre">0</span></tt>. Otherwise,
<tt class="literal"><span class="pre">rhs.distance_to(lhs)</span> <span class="pre">&lt;=</span> <span class="pre">0</span></tt>.</td>
</tr>
</tbody>
</table>
<a class="target" id="minus" name="minus"></a><pre class="literal-block">
template &lt;class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2&gt;
typename enable_if_interoperable&lt;Dr1,Dr2,difference_type&gt;::type
operator -(iterator_facade&lt;Dr1,V1,TC1,R1,D1&gt; const&amp; lhs,
iterator_facade&lt;Dr2,V2,TC2,R2,D2&gt; const&amp; rhs);
</pre>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Return Type:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then <tt class="literal"><span class="pre">difference_type</span></tt> shall be
<tt class="literal"><span class="pre">iterator_traits&lt;Dr1&gt;::difference_type</span></tt>. Otherwise,
<tt class="literal"><span class="pre">difference_type</span></tt> shall be
<tt class="literal"><span class="pre">iterator_traits&lt;Dr2&gt;::difference_type</span></tt>.</td>
</tr>
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">if <tt class="literal"><span class="pre">is_convertible&lt;Dr2,Dr1&gt;::value</span></tt>, then
<tt class="literal"><span class="pre">-lhs.distance_to(rhs)</span></tt>. Otherwise,
<tt class="literal"><span class="pre">-rhs.distance_to(lhs)</span></tt>.</td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="section" id="tutorial-example">
<h1><a class="toc-backref" href="#id30" name="tutorial-example">Tutorial Example</a></h1>
<h1><a class="toc-backref" href="#id32" name="tutorial-example">Tutorial Example</a></h1>
<!-- 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) -->
@ -662,7 +810,7 @@ example of a linked list of polymorphic objects. This example was
inspired by a <a class="reference" href="http://thread.gmane.org/gmane.comp.lib.boost.user/5100">posting</a> by Keith Macdonald on the <a class="reference" href="../../../more/mailing_lists.htm#users">Boost-Users</a>
mailing list.</p>
<div class="section" id="the-problem">
<h2><a class="toc-backref" href="#id31" name="the-problem">The Problem</a></h2>
<h2><a class="toc-backref" href="#id33" name="the-problem">The Problem</a></h2>
<p>Say we've written a polymorphic linked list node base class:</p>
<pre class="literal-block">
# include &lt;iostream&gt;
@ -724,7 +872,7 @@ inline std::ostream&amp; operator&lt;&lt;(std::ostream&amp; s, node_base const&a
lists.</p>
</div>
<div class="section" id="a-basic-iterator-using-iterator-facade">
<h2><a class="toc-backref" href="#id32" name="a-basic-iterator-using-iterator-facade">A Basic Iterator Using <tt class="literal"><span class="pre">iterator_facade</span></tt></a></h2>
<h2><a class="toc-backref" href="#id34" name="a-basic-iterator-using-iterator-facade">A Basic Iterator Using <tt class="literal"><span class="pre">iterator_facade</span></tt></a></h2>
<p>We will construct a <tt class="literal"><span class="pre">node_iterator</span></tt> class using inheritance from
<tt class="literal"><span class="pre">iterator_facade</span></tt> to implement most of the iterator's operations.</p>
<pre class="literal-block">
@ -738,24 +886,24 @@ class node_iterator
};
</pre>
<div class="section" id="template-arguments-for-iterator-facade">
<h3><a class="toc-backref" href="#id33" name="template-arguments-for-iterator-facade">Template Arguments for <tt class="literal"><span class="pre">iterator_facade</span></tt></a></h3>
<h3><a class="toc-backref" href="#id35" name="template-arguments-for-iterator-facade">Template Arguments for <tt class="literal"><span class="pre">iterator_facade</span></tt></a></h3>
<p><tt class="literal"><span class="pre">iterator_facade</span></tt> has several template parameters, so we must decide
what types to use for the arguments. The parameters are <tt class="literal"><span class="pre">Derived</span></tt>,
<tt class="literal"><span class="pre">Value</span></tt>, <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt>, <tt class="literal"><span class="pre">Reference</span></tt>, and <tt class="literal"><span class="pre">Difference</span></tt>.</p>
<div class="section" id="derived">
<h4><a class="toc-backref" href="#id34" name="derived"><tt class="literal"><span class="pre">Derived</span></tt></a></h4>
<h4><a class="toc-backref" href="#id36" name="derived"><tt class="literal"><span class="pre">Derived</span></tt></a></h4>
<p>Because <tt class="literal"><span class="pre">iterator_facade</span></tt> is meant to be used with the CRTP
<a class="citation-reference" href="#cop95" id="id9" name="id9">[Cop95]</a> the first parameter is the iterator class name itself,
<a class="citation-reference" href="#cop95" id="id10" name="id10">[Cop95]</a> the first parameter is the iterator class name itself,
<tt class="literal"><span class="pre">node_iterator</span></tt>.</p>
</div>
<div class="section" id="value">
<h4><a class="toc-backref" href="#id35" name="value"><tt class="literal"><span class="pre">Value</span></tt></a></h4>
<h4><a class="toc-backref" href="#id37" name="value"><tt class="literal"><span class="pre">Value</span></tt></a></h4>
<p>The <tt class="literal"><span class="pre">Value</span></tt> parameter determines the <tt class="literal"><span class="pre">node_iterator</span></tt>'s
<tt class="literal"><span class="pre">value_type</span></tt>. In this case, we are iterating over <tt class="literal"><span class="pre">node_base</span></tt>
objects, so <tt class="literal"><span class="pre">Value</span></tt> will be <tt class="literal"><span class="pre">node_base</span></tt>.</p>
</div>
<div class="section" id="categoryortraversal">
<h4><a class="toc-backref" href="#id36" name="categoryortraversal"><tt class="literal"><span class="pre">CategoryOrTraversal</span></tt></a></h4>
<h4><a class="toc-backref" href="#id38" name="categoryortraversal"><tt class="literal"><span class="pre">CategoryOrTraversal</span></tt></a></h4>
<p>Now we have to determine which <a class="reference" href="new-iter-concepts.html#iterator-traversal-concepts-lib-iterator-traversal">iterator traversal concept</a> our
<tt class="literal"><span class="pre">node_iterator</span></tt> is going to model. Singly-linked lists only have
forward links, so our iterator can't can't be a <a class="reference" href="new-iter-concepts.html#bidirectional-traversal-iterators-lib-bidirectional-traversal-iterators">bidirectional
@ -763,19 +911,19 @@ traversal iterator</a>. Our iterator should be able to make multiple
passes over the same linked list (unlike, say, an
<tt class="literal"><span class="pre">istream_iterator</span></tt> which consumes the stream it traverses), so it
must be a <a class="reference" href="new-iter-concepts.html#forward-traversal-iterators-lib-forward-traversal-iterators">forward traversal iterator</a>. Therefore, we'll pass
<tt class="literal"><span class="pre">boost::forward_traversal_tag</span></tt> in this position <a class="footnote-reference" href="#category" id="id10" name="id10"><sup>1</sup></a>.</p>
<tt class="literal"><span class="pre">boost::forward_traversal_tag</span></tt> in this position <a class="footnote-reference" href="#category" id="id11" name="id11"><sup>1</sup></a>.</p>
<table class="footnote" frame="void" id="category" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id10" name="category">[1]</a></td><td><tt class="literal"><span class="pre">iterator_facade</span></tt> also supports old-style category
<tr><td class="label"><a class="fn-backref" href="#id11" name="category">[1]</a></td><td><tt class="literal"><span class="pre">iterator_facade</span></tt> also supports old-style category
tags, so we could have passed <tt class="literal"><span class="pre">std::forward_iterator_tag</span></tt> here;
either way, the resulting iterator's <tt class="literal"><span class="pre">iterator_category</span></tt> will
end up being <tt class="literal"><span class="pre">std::forward_iterator_tag</span></tt>.</td></tr>
</tbody>
</table>
</div>
<div class="section" id="id11">
<h4><a class="toc-backref" href="#id37" name="id11"><tt class="literal"><span class="pre">Reference</span></tt></a></h4>
<div class="section" id="id12">
<h4><a class="toc-backref" href="#id39" name="id12"><tt class="literal"><span class="pre">Reference</span></tt></a></h4>
<p>The <tt class="literal"><span class="pre">Reference</span></tt> argument becomes the type returned by
<tt class="literal"><span class="pre">node_iterator</span></tt>'s dereference operation, and will also be the
same as <tt class="literal"><span class="pre">std::iterator_traits&lt;node_iterator&gt;::reference</span></tt>. The
@ -784,7 +932,7 @@ library's default for this parameter is <tt class="literal"><span class="pre">Va
type, we can omit this argument, or pass <tt class="literal"><span class="pre">use_default</span></tt>.</p>
</div>
<div class="section" id="difference">
<h4><a class="toc-backref" href="#id38" name="difference"><tt class="literal"><span class="pre">Difference</span></tt></a></h4>
<h4><a class="toc-backref" href="#id40" name="difference"><tt class="literal"><span class="pre">Difference</span></tt></a></h4>
<p>The <tt class="literal"><span class="pre">Difference</span></tt> argument determines how the distance between
two <tt class="literal"><span class="pre">node_iterator</span></tt>s will be measured and will also be the
same as <tt class="literal"><span class="pre">std::iterator_traits&lt;node_iterator&gt;::difference_type</span></tt>.
@ -811,14 +959,14 @@ class node_iterator
</div>
</div>
<div class="section" id="constructors-and-data-members">
<h3><a class="toc-backref" href="#id39" name="constructors-and-data-members">Constructors and Data Members</a></h3>
<h3><a class="toc-backref" href="#id41" name="constructors-and-data-members">Constructors and Data Members</a></h3>
<p>Next we need to decide how to represent the iterator's position.
This representation will take the form of data members, so we'll
also need to write constructors to initialize them. The
<tt class="literal"><span class="pre">node_iterator</span></tt>'s position is quite naturally represented using
a pointer to a <tt class="literal"><span class="pre">node_base</span></tt>. We'll need a constructor to build an
iterator from a <tt class="literal"><span class="pre">node_base*</span></tt>, and a default constructor to
satisfy the <a class="reference" href="new-iter-concepts.html#forward-traversal-iterators-lib-forward-traversal-iterators">forward traversal iterator</a> requirements <a class="footnote-reference" href="#default" id="id12" name="id12"><sup>2</sup></a>.
satisfy the <a class="reference" href="new-iter-concepts.html#forward-traversal-iterators-lib-forward-traversal-iterators">forward traversal iterator</a> requirements <a class="footnote-reference" href="#default" id="id13" name="id13"><sup>2</sup></a>.
Our <tt class="literal"><span class="pre">node_iterator</span></tt> then becomes:</p>
<pre class="literal-block">
# include &quot;node.hpp&quot;
@ -848,7 +996,7 @@ class node_iterator
<table class="footnote" frame="void" id="default" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id12" name="default">[2]</a></td><td>Technically, the C++ standard places almost no
<tr><td class="label"><a class="fn-backref" href="#id13" name="default">[2]</a></td><td>Technically, the C++ standard places almost no
requirements on a default-constructed iterator, so if we were
really concerned with efficiency, we could've written the
default constructor to leave <tt class="literal"><span class="pre">m_node</span></tt> uninitialized.</td></tr>
@ -856,7 +1004,7 @@ default constructor to leave <tt class="literal"><span class="pre">m_node</span>
</table>
</div>
<div class="section" id="implementing-the-core-operations">
<h3><a class="toc-backref" href="#id40" name="implementing-the-core-operations">Implementing the Core Operations</a></h3>
<h3><a class="toc-backref" href="#id42" name="implementing-the-core-operations">Implementing the Core Operations</a></h3>
<p>The last step is to implement the <a class="reference" href="#core-operations">core operations</a> required by
the concepts we want our iterator to model. Referring to the
<a class="reference" href="#core-operations">table</a>, we can see that the first three rows are applicable
@ -907,7 +1055,7 @@ iterator! For a working example of its use, see <a class="reference" href="../e
</div>
</div>
<div class="section" id="a-constant-node-iterator">
<h2><a class="toc-backref" href="#id41" name="a-constant-node-iterator">A constant <tt class="literal"><span class="pre">node_iterator</span></tt></a></h2>
<h2><a class="toc-backref" href="#id43" name="a-constant-node-iterator">A constant <tt class="literal"><span class="pre">node_iterator</span></tt></a></h2>
<div class="sidebar">
<p class="sidebar-title">Constant and Mutable iterators</p>
<p>The term <strong>mutable iterator</strong> means an iterator through which
@ -1008,7 +1156,7 @@ typedef node_iter&lt;node_base const&gt; node_const_iterator;
</pre>
</div>
<div class="section" id="interoperability">
<h2><a class="toc-backref" href="#id42" name="interoperability">Interoperability</a></h2>
<h2><a class="toc-backref" href="#id44" name="interoperability">Interoperability</a></h2>
<p>Our <tt class="literal"><span class="pre">const_node_iterator</span></tt> works perfectly well on its own, but
taken together with <tt class="literal"><span class="pre">node_iterator</span></tt> it doesn't quite meet
expectations. For example, we'd like to be able to pass a
@ -1020,7 +1168,7 @@ compare them for equality.</p>
<p>This expected ability to use two different iterator types together
is known as <a class="reference" href="new-iter-concepts.html#interoperable-iterators-lib-interoperable-iterators"><strong>interoperability</strong></a>. Achieving interoperability in
our case is as simple as templatizing the <tt class="literal"><span class="pre">equal</span></tt> function and
adding a templatized converting constructor <a class="footnote-reference" href="#broken" id="id15" name="id15"><sup>3</sup></a> <a class="footnote-reference" href="#random" id="id16" name="id16"><sup>4</sup></a>:</p>
adding a templatized converting constructor <a class="footnote-reference" href="#broken" id="id16" name="id16"><sup>3</sup></a> <a class="footnote-reference" href="#random" id="id17" name="id17"><sup>4</sup></a>:</p>
<pre class="literal-block">
template &lt;class Value&gt;
class node_iter
@ -1065,14 +1213,14 @@ typedef impl::node_iterator&lt;node_base const&gt; node_const_iterator;
<table class="footnote" frame="void" id="broken" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id15" name="broken">[3]</a></td><td>If you're using an older compiler and it can't handle
<tr><td class="label"><a class="fn-backref" href="#id16" name="broken">[3]</a></td><td>If you're using an older compiler and it can't handle
this example, see the <a class="reference" href="../example/node_iterator2.hpp">example code</a> for workarounds.</td></tr>
</tbody>
</table>
<table class="footnote" frame="void" id="random" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id16" name="random">[4]</a></td><td>If <tt class="literal"><span class="pre">node_iterator</span></tt> had been a <a class="reference" href="new-iter-concepts.html#random-access-traversal-iterators-lib-random-access-traversal-iterators">random access
<tr><td class="label"><a class="fn-backref" href="#id17" name="random">[4]</a></td><td>If <tt class="literal"><span class="pre">node_iterator</span></tt> had been a <a class="reference" href="new-iter-concepts.html#random-access-traversal-iterators-lib-random-access-traversal-iterators">random access
traversal iterator</a>, we'd have had to templatize its
<tt class="literal"><span class="pre">distance_to</span></tt> function as well.</td></tr>
</tbody>
@ -1081,7 +1229,7 @@ traversal iterator</a>, we'd have had to templatize its
iterators <a class="reference" href="../example/node_iterator2.cpp">here</a>.</p>
</div>
<div class="section" id="telling-the-truth">
<h2><a class="toc-backref" href="#id43" name="telling-the-truth">Telling the Truth</a></h2>
<h2><a class="toc-backref" href="#id45" name="telling-the-truth">Telling the Truth</a></h2>
<p>Now <tt class="literal"><span class="pre">node_iterator</span></tt> and <tt class="literal"><span class="pre">node_const_iterator</span></tt> behave exactly as
you'd expect... almost. We can compare them and we can convert in
one direction: from <tt class="literal"><span class="pre">node_iterator</span></tt> to <tt class="literal"><span class="pre">node_const_iterator</span></tt>.
@ -1119,7 +1267,7 @@ appropriate:</p>
</pre>
</div>
<div class="section" id="wrap-up">
<h2><a class="toc-backref" href="#id44" name="wrap-up">Wrap Up</a></h2>
<h2><a class="toc-backref" href="#id46" name="wrap-up">Wrap Up</a></h2>
<p>This concludes our <tt class="literal"><span class="pre">iterator_facade</span></tt> tutorial, but before you
stop reading we urge you to take a look at <a class="reference" href="iterator_adaptor.html"><tt class="literal"><span class="pre">iterator_adaptor</span></tt></a>.
There's another way to approach writing these iterators which might

219
doc/iterator_facade_ref.rst
View File

@ -18,7 +18,7 @@
public:
typedef remove_const<Value>::type value_type;
typedef Reference reference;
typedef Value* pointer;
typedef Value\* pointer;
typedef Difference difference_type;
typedef /* see below__ \*/ iterator_category;
@ -37,57 +37,55 @@
// Comparison operators
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1, Dr2, bool>::type // exposition
operator ==(iterator_facade<Dr1, V1, TC1, R1, D1> const& lhs,
iterator_facade<Dr2, V2, TC2, R2, D2> const& rhs);
typename enable_if_interoperable<Dr1,Dr2,bool>::type // exposition
operator ==(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1, Dr2, bool>::type
operator !=(iterator_facade<Dr1, V1, TC1, R1, D1> const& lhs,
iterator_facade<Dr2, V2, TC2, R2, D2> const& rhs);
typename enable_if_interoperable<Dr1,Dr2,bool>::type
operator !=(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1, Dr2, bool>::type
operator <(iterator_facade<Dr1, V1, TC1, R1, D1> const& lhs,
iterator_facade<Dr2, V2, TC2, R2, D2> const& rhs);
typename enable_if_interoperable<Dr1,Dr2,bool>::type
operator <(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1, Dr2, bool>::type
operator <=(iterator_facade<Dr1, V1, TC1, R1, D1> const& lhs,
iterator_facade<Dr2, V2, TC2, R2, D2> const& rhs);
typename enable_if_interoperable<Dr1,Dr2,bool>::type
operator <=(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1, Dr2, bool>::type
operator >(iterator_facade<Dr1, V1, TC1, R1, D1> const& lhs,
iterator_facade<Dr2, V2, TC2, R2, D2> const& rhs);
typename enable_if_interoperable<Dr1,Dr2,bool>::type
operator >(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1, Dr2, bool>::type
operator >=(iterator_facade<Dr1, V1, TC1, R1, D1> const& lhs,
iterator_facade<Dr2, V2, TC2, R2, D2> const& rhs);
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1, Dr2, bool>::type
operator >=(iterator_facade<Dr1, V1, TC1, R1, D1> const& lhs,
iterator_facade<Dr2, V2, TC2, R2, D2> const& rhs);
typename enable_if_interoperable<Dr1,Dr2,bool>::type
operator >=(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
// Iterator difference
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1, Dr2, bool>::type
operator -(iterator_facade<Dr1, V1, TC1, R1, D1> const& lhs,
iterator_facade<Dr2, V2, TC2, R2, D2> const& rhs);
/* see below__ \*/
operator-(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
// Iterator addition
template <class Derived, class V, class TC, class R, class D>
Derived operator+ (iterator_facade<Derived, V, TC, R, D> const&,
typename Derived::difference_type n)
template <class Dr, class V, class TC, class R, class D>
Derived operator+ (iterator_facade<Dr,V,TC,R,D> const&,
typename Derived::difference_type n);
template <class Dr, class V, class TC, class R, class D>
Derived operator+ (typename Derived::difference_type n,
iterator_facade<Dr,V,TC,R,D> const&);
__ `iterator category`_
@ -95,6 +93,8 @@ __ `operator arrow`_
__ brackets_
__ minus_
.. _`iterator category`:
The ``iterator_category`` member of ``iterator_facade`` is
@ -138,7 +138,8 @@ The following table describes the typical valid expressions on
``iterator_facade``\ 's ``Derived`` parameter, depending on the
iterator concept(s) it will model. The operations in the first
column must be made accessible to member functions of class
``iterator_core_access``.
``iterator_core_access``. In addition,
``static_cast<Derived*>(iterator_facade*)`` shall be well-formed.
In the table below, ``F`` is ``iterator_facade<X,V,C,R,D>``, ``a`` is an
object of type ``X``, ``b`` and ``c`` are objects of type ``const X``,
@ -151,27 +152,28 @@ interoperable with ``X``.
.. topic:: ``iterator_facade`` Core Operations
+--------------------+----------------------+-------------------------------------+---------------------------+
|Expression |Return Type |Assertion/Note |Used to implement Iterator |
| | | |Concept(s) |
+====================+======================+=====================================+===========================+
|``c.dereference()`` |``F::reference`` | |Readable Iterator, Writable|
| | | |Iterator |
+--------------------+----------------------+-------------------------------------+---------------------------+
|``c.equal(y)`` |convertible to bool |true iff ``c`` and ``y`` refer to the|Single Pass Iterator |
| | |same position. | |
+--------------------+----------------------+-------------------------------------+---------------------------+
|``a.increment()`` |unused | |Incrementable Iterator |
+--------------------+----------------------+-------------------------------------+---------------------------+
|``a.decrement()`` |unused | |Bidirectional Traversal |
| | | |Iterator |
+--------------------+----------------------+-------------------------------------+---------------------------+
|``a.advance(n)`` |unused | |Random Access Traversal |
| | | |Iterator |
+--------------------+----------------------+-------------------------------------+---------------------------+
|``c.distance_to(z)``|convertible to |equivalent to ``distance(c, X(z))``. |Random Access Traversal |
| |``F::difference_type``| |Iterator |
+--------------------+----------------------+-------------------------------------+---------------------------+
+--------------------+----------------------+-------------------------+---------------------------+
|Expression |Return Type |Assertion/Note |Used to implement Iterator |
| | | |Concept(s) |
+====================+======================+=========================+===========================+
|``c.dereference()`` |``F::reference`` | |Readable Iterator, Writable|
| | | |Iterator |
+--------------------+----------------------+-------------------------+---------------------------+
|``c.equal(y)`` |convertible to bool |true iff ``c`` and ``y`` |Single Pass Iterator |
| | |refer to the same | |
| | |position. | |
+--------------------+----------------------+-------------------------+---------------------------+
|``a.increment()`` |unused | |Incrementable Iterator |
+--------------------+----------------------+-------------------------+---------------------------+
|``a.decrement()`` |unused | |Bidirectional Traversal |
| | | |Iterator |
+--------------------+----------------------+-------------------------+---------------------------+
|``a.advance(n)`` |unused | |Random Access Traversal |
| | | |Iterator |
+--------------------+----------------------+-------------------------+---------------------------+
|``c.distance_to(z)``|convertible to |equivalent to |Random Access Traversal |
| |``F::difference_type``|``distance(c, X(z))``. |Iterator |
+--------------------+----------------------+-------------------------+---------------------------+
@ -280,8 +282,115 @@ __ `operator arrow`_
::
Derived tmp(static_cast<Derived const*>(this));
return tmp -= n;
Derived tmp(static_cast<Derived const*>(this));
return tmp -= n;
::
template <class Dr, class V, class TC, class R, class D>
Derived operator+ (iterator_facade<Dr,V,TC,R,D> const&,
typename Derived::difference_type n);
template <class Dr, class V, class TC, class R, class D>
Derived operator+ (typename Derived::difference_type n,
iterator_facade<Dr,V,TC,R,D> const&);
:Effects:
::
Derived tmp(static_cast<Derived const*>(this));
return tmp += n;
``iterator_facade`` interoperability
------------------------------------
::
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1,Dr2,bool>::type
operator ==(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
:Returns: if ``is_convertible<Dr2,Dr1>::value``, then
``lhs.equal(rhs)``. Otherwise, ``rhs.equal(lhs)``.
::
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1,Dr2,bool>::type
operator !=(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
:Returns: if ``is_convertible<Dr2,Dr1>::value``, then
``!lhs.equal(rhs)``. Otherwise, ``!rhs.equal(lhs)``.
::
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1,Dr2,bool>::type
operator <(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
:Returns: if ``is_convertible<Dr2,Dr1>::value``, then
``lhs.distance_to(rhs) < 0``. Otherwise, ``rhs.distance_to(lhs) >
0``.
::
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1,Dr2,bool>::type
operator <=(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
:Returns: if ``is_convertible<Dr2,Dr1>::value``, then
``lhs.distance_to(rhs) <= 0``. Otherwise, ``rhs.distance_to(lhs)
>= 0``.
::
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1,Dr2,bool>::type
operator >(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
:Returns: if ``is_convertible<Dr2,Dr1>::value``, then
``lhs.distance_to(rhs) > 0``. Otherwise,
``rhs.distance_to(lhs) < 0``.
::
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1,Dr2,bool>::type
operator >=(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
:Returns: if ``is_convertible<Dr2,Dr1>::value``, then
``lhs.distance_to(rhs) >= 0``. Otherwise,
``rhs.distance_to(lhs) <= 0``.
.. _minus:
::
template <class Dr1, class V1, class TC1, class R1, class D1,
class Dr2, class V2, class TC2, class R2, class D2>
typename enable_if_interoperable<Dr1,Dr2,difference_type>::type
operator -(iterator_facade<Dr1,V1,TC1,R1,D1> const& lhs,
iterator_facade<Dr2,V2,TC2,R2,D2> const& rhs);
:Return Type: if ``is_convertible<Dr2,Dr1>::value``, then ``difference_type`` shall be
``iterator_traits<Dr1>::difference_type``. Otherwise,
``difference_type`` shall be
``iterator_traits<Dr2>::difference_type``.
:Returns: if ``is_convertible<Dr2,Dr1>::value``, then
``-lhs.distance_to(rhs)``. Otherwise,
``-rhs.distance_to(lhs)``.