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[SVN r21577]
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Dave Abrahams
2004-01-10 19:00:48 +00:00
parent c903cf4801
commit dd5fb425fa
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doc/indirect_iterator.html
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@ -242,70 +242,104 @@ iterators over smart pointers, which the impl handles. -JGS -->
<p class="topic-title"><a name="table-of-contents">Table of Contents</a></p>
<ul class="simple">
<li><a class="reference" href="#indirect-iterator-requirements" id="id1" name="id1"><tt class="literal"><span class="pre">indirect_iterator</span></tt> requirements</a></li>
<li><a class="reference" href="#indirect-iterator-operations" id="id2" name="id2"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></li>
<li><a class="reference" href="#indirect-iterator-models" id="id2" name="id2"><tt class="literal"><span class="pre">indirect_iterator</span></tt> models</a></li>
<li><a class="reference" href="#indirect-iterator-operations" id="id3" name="id3"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></li>
</ul>
</div>
<pre class="literal-block">
template &lt;
class Iterator
, class Value = use_default
, unsigned Access = use_default_access
, class Traversal = use_default
, class CategoryOrTraversal = use_default
, class Reference = use_default
, class Difference = use_default
&gt;
class indirect_iterator
: public iterator_adaptor&lt;/* see discussion */&gt;
{
friend class iterator_core_access;
public:
typedef /* see below */ value_type;
typedef /* see below */ reference;
typedef /* see below */ pointer;
typedef /* see below */ difference_type;
typedef /* see below */ iterator_category;
indirect_iterator();
indirect_iterator(Iterator x);
template &lt;
class Iterator2, class Value2, unsigned Access2, class Traversal2
class Iterator2, class Value2, class Category2
, class Reference2, class Difference2
&gt;
indirect_iterator(
indirect_iterator&lt;
Iterator2, Value2, Access2, Traversal2, Reference2, Difference2
Iterator2, Value2, Category2, Reference2, Difference2
&gt; const&amp; y
, typename enable_if_convertible&lt;Iterator2, Iterator&gt;::type* = 0 // exposition
);
private: // as-if specification
typename indirect_iterator::reference dereference() const
{
return **this-&gt;base();
}
};
</pre>
<p>The member types of <tt class="literal"><span class="pre">indirect_iterator</span></tt> are defined according to the
following pseudo-code. We use the abbreviation
<tt class="literal"><span class="pre">V=iterator_traits&lt;Iterator&gt;::value_type</span></tt>.:</p>
<pre class="literal-block">
if (Value is use_default) then
typedef iterator_traits&lt;V&gt;::value_type value_type;
else
typedef remove_const&lt;Value&gt;::type value_type;
if (Reference is use_default) then
if (Value is use_default) then
typedef iterator_traits&lt;V&gt;::reference reference;
else
typedef Value&amp; reference;
else
typedef Reference reference;
if (Value is use_default) then
typedef ?? pointer;
else
typedef Value* pointer;
if (Difference is use_default)
typedef iterator_traits&lt;Iterator&gt;::difference_type difference_type;
else
typedef Difference difference_type;
</pre>
<p>The member <tt class="literal"><span class="pre">indirect_iterator::iterator_category</span></tt> is a type that
satisfies the requirements of the concepts modeled by the indirect
iterator as specified in the models section.</p>
<div class="section" id="indirect-iterator-requirements">
<h1><a class="toc-backref" href="#id1" name="indirect-iterator-requirements"><tt class="literal"><span class="pre">indirect_iterator</span></tt> requirements</a></h1>
<p>The <tt class="literal"><span class="pre">value_type</span></tt> of the <tt class="literal"><span class="pre">Iterator</span></tt> template parameter should
itself be dereferenceable. The return type of the <tt class="literal"><span class="pre">operator*</span></tt> for
the <tt class="literal"><span class="pre">value_type</span></tt> must be the same type as the <tt class="literal"><span class="pre">Reference</span></tt> template
parameter. The <tt class="literal"><span class="pre">Value</span></tt> template parameter will be the <tt class="literal"><span class="pre">value_type</span></tt>
for the <tt class="literal"><span class="pre">indirect_iterator</span></tt>, unless <tt class="literal"><span class="pre">Value</span></tt> is const. If <tt class="literal"><span class="pre">Value</span></tt>
is <tt class="literal"><span class="pre">const</span> <span class="pre">X</span></tt>, then <tt class="literal"><span class="pre">value_type</span></tt> will be <em>non-</em> <tt class="literal"><span class="pre">const</span> <span class="pre">X</span></tt>. The
default for <tt class="literal"><span class="pre">Value</span></tt> is</p>
<pre class="literal-block">
iterator_traits&lt; iterator_traits&lt;Iterator&gt;::value_type &gt;::value_type
</pre>
<p>If the default is used for <tt class="literal"><span class="pre">Value</span></tt>, then there must be a valid
specialization of <tt class="literal"><span class="pre">iterator_traits</span></tt> for the value type of the base
iterator.</p>
<p>The <tt class="literal"><span class="pre">Reference</span></tt> parameter will be the <tt class="literal"><span class="pre">reference</span></tt> type of the
<tt class="literal"><span class="pre">indirect_iterator</span></tt>. The default is <tt class="literal"><span class="pre">Value&amp;</span></tt>.</p>
<p>The <tt class="literal"><span class="pre">Access</span></tt> and <tt class="literal"><span class="pre">Traversal</span></tt> parameters are passed unchanged to
the corresponding parameters of the <tt class="literal"><span class="pre">iterator_adaptor</span></tt> base
class, and the <tt class="literal"><span class="pre">Iterator</span></tt> parameter is passed unchanged as the
<tt class="literal"><span class="pre">Base</span></tt> parameter to the <tt class="literal"><span class="pre">iterator_adaptor</span></tt> base class.</p>
<p>The indirect iterator will model the most refined standard traversal
concept that is modeled by the <tt class="literal"><span class="pre">Iterator</span></tt> type. The indirect
iterator will model the most refined standard access concept that is
modeled by the value type of <tt class="literal"><span class="pre">Iterator</span></tt>.</p>
<p>The <tt class="literal"><span class="pre">Iterator</span></tt> argument shall meet the requirements of Readable
Iterator. The <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt> argument shall be one of the
standard iterator tags or <tt class="literal"><span class="pre">use_default</span></tt>. If <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt>
is an iterator tag, the template parameter <tt class="literal"><span class="pre">Iterator</span></tt> argument shall
meet the traversal requirements corresponding to the iterator tag.</p>
<p>The expression <tt class="literal"><span class="pre">*v</span></tt>, where <tt class="literal"><span class="pre">v</span></tt> is an object of type
<tt class="literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt>, must be a valid expression
and must be convertible to <tt class="literal"><span class="pre">indirect_iterator::reference</span></tt>. Also
<tt class="literal"><span class="pre">indirect_iterator::reference</span></tt> must be convertible to
<tt class="literal"><span class="pre">indirect_iterator::value</span></tt>. There are further requirements on the
<tt class="literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt> if the <tt class="literal"><span class="pre">Value</span></tt> parameter
is not <tt class="literal"><span class="pre">use_default</span></tt>, as implied by the algorithm for deducing the
default for the <tt class="literal"><span class="pre">value_type</span></tt> member.</p>
</div>
<div class="section" id="indirect-iterator-models">
<h1><a class="toc-backref" href="#id2" name="indirect-iterator-models"><tt class="literal"><span class="pre">indirect_iterator</span></tt> models</a></h1>
<p>If <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt> is a standard iterator tag,
<tt class="literal"><span class="pre">indirect_iterator</span></tt> is a model of the iterator concept corresponding
to the tag, otherwise <tt class="literal"><span class="pre">indirect_iterator</span></tt> satisfies the requirements
of the most refined standard traversal concept that is satisfied by
the <tt class="literal"><span class="pre">Iterator</span></tt> argument.</p>
<p><tt class="literal"><span class="pre">indirect_iterator</span></tt> models Readable Iterator. If
<tt class="literal"><span class="pre">indirect_iterator::reference(*v)</span> <span class="pre">=</span> <span class="pre">t</span></tt> is a valid expression (where
<tt class="literal"><span class="pre">t</span></tt> is an object of type <tt class="literal"><span class="pre">indirect_iterator::value_type</span></tt>) then
<tt class="literal"><span class="pre">indirect_iterator</span></tt> models Writable Iterator. If
<tt class="literal"><span class="pre">indirect_iterator::reference</span></tt> is a reference then
<tt class="literal"><span class="pre">indirect_iterator</span></tt> models Lvalue Iterator.</p>
</div>
<div class="section" id="indirect-iterator-operations">
<h1><a class="toc-backref" href="#id2" name="indirect-iterator-operations"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></h1>
<h1><a class="toc-backref" href="#id3" name="indirect-iterator-operations"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></h1>
<p><tt class="literal"><span class="pre">indirect_iterator();</span></tt></p>
<table class="field-list" frame="void" rules="none">
<col class="field-name" />
@ -313,8 +347,8 @@ modeled by the value type of <tt class="literal"><span class="pre">Iterator</spa
<tbody valign="top">
<tr class="field"><th class="field-name">Requires:</th><td class="field-body"><tt class="literal"><span class="pre">Iterator</span></tt> must be Default Constructible.</td>
</tr>
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="literal"><span class="pre">indirect_iterator</span></tt> with
a default constructed base object.</td>
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="literal"><span class="pre">indirect_iterator</span></tt> with
a default-constructed <tt class="literal"><span class="pre">iterator_adaptor</span></tt> subobject.</td>
</tr>
</tbody>
</table>
@ -346,7 +380,8 @@ indirect_iterator(
<tbody valign="top">
<tr class="field"><th class="field-name">Requires:</th><td class="field-body"><tt class="literal"><span class="pre">Iterator2</span></tt> is implicitly convertible to <tt class="literal"><span class="pre">Iterator</span></tt>.</td>
</tr>
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="literal"><span class="pre">indirect_iterator</span></tt> that is a copy of <tt class="literal"><span class="pre">y</span></tt>.</td>
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="literal"><span class="pre">indirect_iterator</span></tt> whose
<tt class="literal"><span class="pre">iterator_adaptor</span></tt> subobject is constructed from <tt class="literal"><span class="pre">y.base()</span></tt>.</td>
</tr>
</tbody>
</table>
@ -355,7 +390,7 @@ indirect_iterator(
<hr class="footer" />
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