a little progress with indirect iterator

[SVN r21294]
This commit is contained in:
Jeremy Siek
2003-12-16 22:15:48 +00:00
parent 9387c05d12
commit 84f22cde8d
3 changed files with 138 additions and 229 deletions

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@@ -3,203 +3,12 @@
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<title>Iterator Facade and Adaptor</title>
<meta name="author" content="David Abrahams, Jeremy Siek, Thomas Witt" />
<meta name="organization" content="Boost Consulting, Indiana University Open Systems Lab, University of Hanover Institute for Transport Railway Operation and Construction" />
<meta name="date" content="2003-11-24" />
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<div class="document" id="iterator-facade-and-adaptor">
@@ -510,7 +319,7 @@ of the derived iterator type. These member functions are described
briefly below and in more detail in the iterator facade
requirements.</p>
<blockquote>
<table border class="table">
<table class="table" frame="border" rules="all">
<colgroup>
<col width="44%" />
<col width="56%" />
@@ -903,7 +712,7 @@ object of type <tt class="literal"><span class="pre">X</span></tt>, <tt class="l
object of a single pass iterator type interoperable with <tt class="literal"><span class="pre">X</span></tt>, and <tt class="literal"><span class="pre">z</span></tt>
is a constant object of a random access traversal iterator type
interoperable with <tt class="literal"><span class="pre">X</span></tt>.</p>
<table border class="table">
<table class="table" frame="border" rules="all">
<colgroup>
<col width="19%" />
<col width="21%" />
@@ -1442,25 +1251,32 @@ iterators over smart pointers, which the impl handles. -JGS -->
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;
: public iterator_adaptor&lt;
indirect_iterator&lt;Iterator, Value, Access, Traversal,
Reference, Difference&gt;,
Iterator,
/* Value = see below */,
CategoryOrTraversal,
Reference,
Difference&gt;
{
friend class iterator_core_access;
public:
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
);
@@ -1474,29 +1290,27 @@ private: // as-if specification
</div>
<div class="section" id="indirect-iterator-requirements">
<h4><a class="toc-backref" href="#id42" name="indirect-iterator-requirements"><tt class="literal"><span class="pre">indirect_iterator</span></tt> requirements</a></h4>
<p>The <tt class="literal"><span class="pre">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>
<p>The following requirements are placed on the type
<tt class="literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt>. Let <tt class="literal"><span class="pre">i</span></tt> be an object of
type <tt class="literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt>. Then <tt class="literal"><span class="pre">*i</span></tt> must be a
valid expression, and the type of <tt class="literal"><span class="pre">*i</span></tt> must be the same as the
<tt class="literal"><span class="pre">Reference</span></tt> template parameter.</p>
<p>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 cv-qualified. If <tt class="literal"><span class="pre">Value</span></tt>
is cv-qualified then <tt class="literal"><span class="pre">value_type</span></tt> will be non-qualified version of
the type. 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>
<!-- THE ABOVE IS NO LONGER IN SYNC WITH THE CODE. -Jeremy -->
<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>
concept that is modeled by the <tt class="literal"><span class="pre">Iterator</span></tt> type and that refines the
traversal category specified in the <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt> parameter.
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>
</div>
<div class="section" id="indirect-iterator-operations">
<h4><a class="toc-backref" href="#id43" name="indirect-iterator-operations"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></h4>
@@ -1507,8 +1321,8 @@ 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>
@@ -1540,7 +1354,8 @@ 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>
@@ -2131,11 +1946,5 @@ LocalWords: OtherIncrementable Coplien -->
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