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Really re-resolved title level problem

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A few minor edits


[SVN r21634]
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Dave Abrahams
2004-01-12 18:02:50 +00:00
parent 129815f3dd
commit b4f1b069be
5 changed files with 65 additions and 59 deletions
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@@ -75,14 +75,12 @@ by adapting other iterators.</td>
<li><a class="reference" href="#proposed-text" id="id25" name="id25">Proposed Text</a><ul>
<li><a class="reference" href="#header-iterator-helper-synopsis-lib-iterator-helper-synopsis" id="id26" name="id26">Header <tt class="literal"><span class="pre">&lt;iterator_helper&gt;</span></tt> synopsis [lib.iterator.helper.synopsis]</a></li>
<li><a class="reference" href="#iterator-facade-lib-iterator-facade" id="id27" name="id27">Iterator facade [lib.iterator.facade]</a><ul>
<li><a class="reference" href="#class-template-iterator-facade" id="id28" name="id28">Class template <tt class="literal"><span class="pre">iterator_facade</span></tt></a><ul>
<li><a class="reference" href="#class-template-iterator-facade" id="id28" name="id28">Class template <tt class="literal"><span class="pre">iterator_facade</span></tt></a></li>
<li><a class="reference" href="#iterator-facade-requirements" id="id29" name="id29"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></li>
<li><a class="reference" href="#iterator-facade-iterator-category" id="id30" name="id30"><tt class="literal"><span class="pre">iterator_facade</span></tt> iterator category</a></li>
<li><a class="reference" href="#iterator-facade-operations" id="id31" name="id31"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></li>
</ul>
</li>
</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-base-class-parameters" id="id34" name="id34"><tt class="literal"><span class="pre">iterator_adaptor</span></tt> base class parameters</a></li>
@@ -285,11 +283,11 @@ identified the following core behaviors for iterators:</p>
include the associated types exposed through iterator traits:
<tt class="literal"><span class="pre">value_type</span></tt>, <tt class="literal"><span class="pre">reference</span></tt>, <tt class="literal"><span class="pre">difference_type</span></tt>, and
<tt class="literal"><span class="pre">iterator_category</span></tt>.</p>
<p>Iterator facade uses the Curiously Recurring Template Pattern (CRTP)
<a class="citation-reference" href="#cop95" id="id4" name="id4">[Cop95]</a> so that the user can specify the behavior of
<tt class="literal"><span class="pre">iterator_facade</span></tt> in a derived class. Former designs used policy
objects to specify the behavior. <tt class="literal"><span class="pre">iterator_facade</span></tt> does not use policy
objects for several reasons:</p>
<p>Iterator facade uses the Curiously Recurring Template
Pattern (CRTP) <a class="citation-reference" href="#cop95" id="id4" name="id4">[Cop95]</a> so that the user can specify the behavior
of <tt class="literal"><span class="pre">iterator_facade</span></tt> in a derived class. Former designs used
policy objects to specify the behavior, but that approach was
discarded for several reasons:</p>
<blockquote>
<ol class="arabic simple">
<li>the creation and eventual copying of the policy object may create
@@ -299,9 +297,11 @@ on the created iterator types, an essential feature if
<tt class="literal"><span class="pre">iterator_facade</span></tt> should be used in other library
implementations.</li>
<li>Without the use of CRTP, the standard requirement that an
iterator's <tt class="literal"><span class="pre">operator++</span></tt> returns the iterator type itself means
that all iterators generated by <tt class="literal"><span class="pre">iterator_facade</span></tt> would be
specializations of <tt class="literal"><span class="pre">iterator_facade</span></tt>. Cumbersome type generator
iterator's <tt class="literal"><span class="pre">operator++</span></tt> returns the iterator type itself
would mean that all iterators built with the library would
have to be specializations of <tt class="literal"><span class="pre">iterator_facade&lt;...&gt;</span></tt>, rather
than something more descriptive like
<tt class="literal"><span class="pre">indirect_iterator&lt;T*&gt;</span></tt>. Cumbersome type generator
metafunctions would be needed to build new parameterized
iterators, and a separate <tt class="literal"><span class="pre">iterator_adaptor</span></tt> layer would be
impossible.</li>
@@ -437,9 +437,10 @@ is a class, however, it must still be possible to access members
through <tt class="literal"><span class="pre">operator-&gt;</span></tt>. Therefore, an iterator whose <tt class="literal"><span class="pre">reference</span></tt>
type is not in fact a reference must return a proxy containing a copy
of the referenced value from its <tt class="literal"><span class="pre">operator-&gt;</span></tt>.</p>
<p>The return type for <tt class="literal"><span class="pre">operator-&gt;</span></tt> and <tt class="literal"><span class="pre">operator[]</span></tt> is not
explicitly specified. Instead it requires each <tt class="literal"><span class="pre">iterator_facade</span></tt>
specialization to meet the requirements of its <tt class="literal"><span class="pre">iterator_category</span></tt>.</p>
<p>The return types for <tt class="literal"><span class="pre">iterator_facade</span></tt>'s <tt class="literal"><span class="pre">operator-&gt;</span></tt> and
<tt class="literal"><span class="pre">operator[]</span></tt> are not explicitly specified. Instead, those types
are described in terms of a set of requirements, which must be
satisfied by the <tt class="literal"><span class="pre">iterator_facade</span></tt> implementation.</p>
<table class="citation" frame="void" id="cop95" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<col />
@@ -707,8 +708,9 @@ struct enable_if_interoperable
&gt;
{};
</pre>
</div>
<div class="section" id="iterator-facade-requirements">
<h4><a class="toc-backref" href="#id29" name="iterator-facade-requirements"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></h4>
<h3><a class="toc-backref" href="#id29" 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
@@ -789,7 +791,7 @@ Iterator</td>
</div>
<a class="target" id="facade-iterator-category" name="facade-iterator-category"></a></div>
<div class="section" id="iterator-facade-iterator-category">
<h4><a class="toc-backref" href="#id30" name="iterator-facade-iterator-category"><tt class="literal"><span class="pre">iterator_facade</span></tt> iterator category</a></h4>
<h3><a class="toc-backref" href="#id30" name="iterator-facade-iterator-category"><tt class="literal"><span class="pre">iterator_facade</span></tt> iterator category</a></h3>
<p>The <tt class="literal"><span class="pre">iterator_category</span></tt> member of <tt class="literal"><span class="pre">iterator_facade&lt;X,V,R,C,D&gt;</span></tt>
is a type which satisfies the following conditions:</p>
<blockquote>
@@ -842,7 +844,7 @@ convertible, and not to any more-derived traversal tag type.</p>
</blockquote>
</div>
<div class="section" id="iterator-facade-operations">
<h4><a class="toc-backref" href="#id31" name="iterator-facade-operations"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></h4>
<h3><a class="toc-backref" href="#id31" name="iterator-facade-operations"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></h3>
<p>The operations in this section are described in terms of operations on
the core interface of <tt class="literal"><span class="pre">Derived</span></tt> which may be inaccessible
(i.e. private). The implementation should access these operations
@@ -983,7 +985,6 @@ return tmp -= n;
</table>
</div>
</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>
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@@ -2237,7 +2238,7 @@ LocalWords: OtherIncrementable Coplien -->
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