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added pseudo-code for facade_iterator_category type function

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[SVN r21736]
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Jeremy Siek
2004-01-14 19:57:11 +00:00
parent 731576fbfe
commit 2854c5c761
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@ -54,29 +54,28 @@ and associated types, to be supplied by a derived iterator class.</td>
</li>
<li><a class="reference" href="#reference" id="id25" name="id25">Reference</a><ul>
<li><a class="reference" href="#iterator-facade-requirements" id="id26" name="id26"><tt class="literal"><span class="pre">iterator_facade</span></tt> Requirements</a></li>
<li><a class="reference" href="#iterator-facade-iterator-category" id="id27" name="id27"><tt class="literal"><span class="pre">iterator_facade</span></tt> iterator category</a></li>
<li><a class="reference" href="#iterator-facade-operations" id="id28" name="id28"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></li>
<li><a class="reference" href="#iterator-facade-operations" id="id27" name="id27"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></li>
</ul>
</li>
<li><a class="reference" href="#tutorial-example" id="id29" name="id29">Tutorial Example</a><ul>
<li><a class="reference" href="#the-problem" id="id30" name="id30">The Problem</a></li>
<li><a class="reference" href="#a-basic-iterator-using-iterator-facade" id="id31" name="id31">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="id32" name="id32">Template Arguments for <tt class="literal"><span class="pre">iterator_facade</span></tt></a><ul>
<li><a class="reference" href="#derived" id="id33" name="id33"><tt class="literal"><span class="pre">Derived</span></tt></a></li>
<li><a class="reference" href="#value" id="id34" name="id34"><tt class="literal"><span class="pre">Value</span></tt></a></li>
<li><a class="reference" href="#categoryortraversal" id="id35" name="id35"><tt class="literal"><span class="pre">CategoryOrTraversal</span></tt></a></li>
<li><a class="reference" href="#id10" id="id36" name="id36"><tt class="literal"><span class="pre">Reference</span></tt></a></li>
<li><a class="reference" href="#difference" id="id37" name="id37"><tt class="literal"><span class="pre">Difference</span></tt></a></li>
<li><a class="reference" href="#tutorial-example" id="id28" name="id28">Tutorial Example</a><ul>
<li><a class="reference" href="#the-problem" id="id29" name="id29">The Problem</a></li>
<li><a class="reference" href="#a-basic-iterator-using-iterator-facade" id="id30" name="id30">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="id31" name="id31">Template Arguments for <tt class="literal"><span class="pre">iterator_facade</span></tt></a><ul>
<li><a class="reference" href="#derived" id="id32" name="id32"><tt class="literal"><span class="pre">Derived</span></tt></a></li>
<li><a class="reference" href="#value" id="id33" name="id33"><tt class="literal"><span class="pre">Value</span></tt></a></li>
<li><a class="reference" href="#categoryortraversal" id="id34" name="id34"><tt class="literal"><span class="pre">CategoryOrTraversal</span></tt></a></li>
<li><a class="reference" href="#id10" id="id35" name="id35"><tt class="literal"><span class="pre">Reference</span></tt></a></li>
<li><a class="reference" href="#difference" id="id36" name="id36"><tt class="literal"><span class="pre">Difference</span></tt></a></li>
</ul>
</li>
<li><a class="reference" href="#constructors-and-data-members" id="id38" name="id38">Constructors and Data Members</a></li>
<li><a class="reference" href="#implementing-the-core-operations" id="id39" name="id39">Implementing the Core Operations</a></li>
<li><a class="reference" href="#constructors-and-data-members" id="id37" name="id37">Constructors and Data Members</a></li>
<li><a class="reference" href="#implementing-the-core-operations" id="id38" name="id38">Implementing the Core Operations</a></li>
</ul>
</li>
<li><a class="reference" href="#a-constant-node-iterator" id="id40" name="id40">A constant <tt class="literal"><span class="pre">node_iterator</span></tt></a></li>
<li><a class="reference" href="#interoperability" id="id41" name="id41">Interoperability</a></li>
<li><a class="reference" href="#telling-the-truth" id="id42" name="id42">Telling the Truth</a></li>
<li><a class="reference" href="#wrap-up" id="id43" name="id43">Wrap Up</a></li>
<li><a class="reference" href="#a-constant-node-iterator" id="id39" name="id39">A constant <tt class="literal"><span class="pre">node_iterator</span></tt></a></li>
<li><a class="reference" href="#interoperability" id="id40" name="id40">Interoperability</a></li>
<li><a class="reference" href="#telling-the-truth" id="id41" name="id41">Telling the Truth</a></li>
<li><a class="reference" href="#wrap-up" id="id42" name="id42">Wrap Up</a></li>
</ul>
</li>
</ul>
@ -290,7 +289,7 @@ public:
typedef Reference reference;
typedef Value* pointer;
typedef Difference difference_type;
typedef /* see <a class="reference" href="#facade-iterator-category">below</a> */ iterator_category;
typedef /* see <a class="reference" href="#iterator-category">below</a> */ iterator_category;
reference operator*() const;
/* see <a class="reference" href="#operator-arrow">below</a> */ operator-&gt;() const;
@ -359,6 +358,39 @@ 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)
</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
<tt class="literal"><span class="pre">facade_iterator_category(CategoryOrTraversal,</span> <span class="pre">value_type,</span>
<span class="pre">reference)</span></tt>, as specified by the following pseudo-code:</p>
<pre class="literal-block">
facade_iterator_category(C, V, R) =
if (C is convertible to input_iterator_tag or output_iterator_tag) then
return C
else if (C is convertible to incrementable_traversal_tag) then
if (R is a reference type
and C is convertible to forward_traversal_tag) then
if (C is convertible to random_access_traversal_tag)
return a type convertible to random_access_iterator_tag
else if (C is convertible to bidirectional_traversal_tag)
return a type convertible to bidirectional_iterator_tag
else
return a type convertible to forward_iterator_tag
else if (C is convertible to single_pass_traversal_tag
and R is convertible to V)
return a type convertible to input_iterator_tag
else
return C
</pre>
<!-- 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) -->
<p>If <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt> is <tt class="literal"><span class="pre">use_default</span></tt> then
<tt class="literal"><span class="pre">iterator_traversal&lt;Derived&gt;::type</span></tt> is convertible to the most
derived standard traversal tag type to which
<tt class="literal"><span class="pre">iterator_traversal&lt;Iterator&gt;::type</span></tt> is also convertible, and not to
any more-derived traversal tag type. Otherwise
<tt class="literal"><span class="pre">iterator_traversal&lt;Derived&gt;::type</span></tt> is convertible to the most
derived standard traversal tag type to which <tt class="literal"><span class="pre">CategoryOrTraversal</span></tt>
is also convertible, and not to any more-derived traversal tag type.</p>
<p>The <tt class="literal"><span class="pre">enable_if_interoperable</span></tt> template used above is for exposition
purposes. The member operators should be only be in an overload set
provided the derived types <tt class="literal"><span class="pre">Dr1</span></tt> and <tt class="literal"><span class="pre">Dr2</span></tt> are interoperable,
@ -422,8 +454,7 @@ Iterator</td>
<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. Implements <tt class="literal"><span class="pre">c</span> <span class="pre">==</span> <span class="pre">y</span></tt>
and <tt class="literal"><span class="pre">c</span> <span class="pre">!=</span> <span class="pre">y</span></tt>.</td>
same position.</td>
<td>Single Pass Iterator</td>
</tr>
<tr><td><tt class="literal"><span class="pre">a.increment()</span></tt></td>
@ -443,77 +474,19 @@ Iterator</td>
<td>Random Access Traversal
Iterator</td>
</tr>
<tr><td><tt class="literal"><span class="pre">c.distance_to(b)</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">b)</span></tt></td>
<td>Random Access Traversal
Iterator</td>
</tr>
<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">z)</span></tt>.
Implements <tt class="literal"><span class="pre">c</span> <span class="pre">-</span> <span class="pre">z</span></tt>, <tt class="literal"><span class="pre">c</span> <span class="pre">&lt;</span> <span class="pre">z</span></tt>, <tt class="literal"><span class="pre">c</span>
<span class="pre">&lt;=</span> <span class="pre">z</span></tt>, <tt class="literal"><span class="pre">c</span> <span class="pre">&gt;</span> <span class="pre">z</span></tt>, and <tt class="literal"><span class="pre">c</span> <span class="pre">&gt;=</span> <span class="pre">c</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>
</tbody>
</table>
</div>
<a class="target" id="facade-iterator-category" name="facade-iterator-category"></a></div>
<div class="section" id="iterator-facade-iterator-category">
<h2><a class="toc-backref" href="#id27" name="iterator-facade-iterator-category"><tt class="literal"><span class="pre">iterator_facade</span></tt> iterator category</a></h2>
<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>
satisfies the following conditions:</p>
<ul>
<li><p class="first">if <tt class="literal"><span class="pre">C</span></tt> is convertible to <tt class="literal"><span class="pre">std::input_iterator_tag</span></tt> or
<tt class="literal"><span class="pre">C</span></tt> is convertible to <tt class="literal"><span class="pre">std::output_iterator_tag</span></tt>,
<tt class="literal"><span class="pre">iterator_category</span></tt> is the same as <tt class="literal"><span class="pre">C</span></tt>.</p>
</li>
<li><p class="first">Otherwise, if <tt class="literal"><span class="pre">C</span></tt> is not convertible to
<tt class="literal"><span class="pre">incrementable_traversal_tag</span></tt>, the program is ill-formed</p>
</li>
<li><p class="first">Otherwise:</p>
<ul>
<li><p class="first"><tt class="literal"><span class="pre">iterator_category</span></tt> is convertible to the iterator
category tag or tags given by the following algorithm, and
not to any more-derived iterator category tag or tags:</p>
<pre class="literal-block">
if (R is a reference type
&amp;&amp; C is convertible to forward_traversal_tag)
{
if (C is convertible to random_access_traversal_tag)
random_access_iterator_tag
else if (C is convertible to bidirectional_traversal_tag)
bidirectional_iterator_tag
else
forward_iterator_tag
}
else
{
if (C is convertible to single_pass_traversal_tag
&amp;&amp; R is convertible to V)
input_iterator_tag
else
C
}
</pre>
</li>
<li><p class="first"><tt class="literal"><span class="pre">iterator_traversal&lt;X&gt;::type</span></tt> is convertible to the most
derived traversal tag type to which <tt class="literal"><span class="pre">C</span></tt> is also
convertible, and not to any more-derived traversal tag type.</p>
</li>
</ul>
</li>
</ul>
<!-- 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) -->
</div>
<div class="section" id="iterator-facade-operations">
<h2><a class="toc-backref" href="#id28" name="iterator-facade-operations"><tt class="literal"><span class="pre">iterator_facade</span></tt> operations</a></h2>
<h2><a class="toc-backref" href="#id27" 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
@ -551,11 +524,10 @@ of type <tt class="literal"><span class="pre">pointer</span></tt> equal to:</p>
<tbody valign="top">
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">an object convertible to <tt class="literal"><span class="pre">value_type</span></tt>. For constant
objects <tt class="literal"><span class="pre">v</span></tt> of type <tt class="literal"><span class="pre">value_type</span></tt>, and <tt class="literal"><span class="pre">n</span></tt> of type
<tt class="literal"><span class="pre">difference_type</span></tt>, and reference <tt class="literal"><span class="pre">p</span></tt> equal to
<tt class="literal"><span class="pre">*static_cast&lt;Derived</span> <span class="pre">const*&gt;(this)</span></tt>, <tt class="literal"><span class="pre">(*this)[n]</span> <span class="pre">=</span> <span class="pre">v</span></tt> is
equivalent to <tt class="literal"><span class="pre">*(p+</span> <span class="pre">n)</span> <span class="pre">=</span> <span class="pre">v</span></tt>, and <tt class="literal"><span class="pre">static_cast&lt;value_type</span>
<tt class="literal"><span class="pre">difference_type</span></tt>, <tt class="literal"><span class="pre">(*this)[n]</span> <span class="pre">=</span> <span class="pre">v</span></tt> is equivalent to
<tt class="literal"><span class="pre">*(*this</span> <span class="pre">+</span> <span class="pre">n)</span> <span class="pre">=</span> <span class="pre">v</span></tt>, and <tt class="literal"><span class="pre">static_cast&lt;value_type</span>
<span class="pre">const&amp;&gt;((*this)[n])</span></tt> is equivalent to
<tt class="literal"><span class="pre">static_cast&lt;value_type</span> <span class="pre">const&amp;&gt;(*(p+n))</span></tt></td>
<tt class="literal"><span class="pre">static_cast&lt;value_type</span> <span class="pre">const&amp;&gt;(*(*this</span> <span class="pre">+</span> <span class="pre">n))</span></tt></td>
</tr>
</tbody>
</table>
@ -655,7 +627,7 @@ return tmp -= n;
</div>
</div>
<div class="section" id="tutorial-example">
<h1><a class="toc-backref" href="#id29" name="tutorial-example">Tutorial Example</a></h1>
<h1><a class="toc-backref" href="#id28" 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) -->
@ -665,7 +637,7 @@ 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="#id30" name="the-problem">The Problem</a></h2>
<h2><a class="toc-backref" href="#id29" 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;
@ -727,7 +699,7 @@ 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="#id31" 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="#id30" 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">
@ -741,24 +713,24 @@ class node_iterator
};
</pre>
<div class="section" id="template-arguments-for-iterator-facade">
<h3><a class="toc-backref" href="#id32" 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="#id31" 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="#id33" name="derived"><tt class="literal"><span class="pre">Derived</span></tt></a></h4>
<h4><a class="toc-backref" href="#id32" 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="id8" name="id8">[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="#id34" name="value"><tt class="literal"><span class="pre">Value</span></tt></a></h4>
<h4><a class="toc-backref" href="#id33" 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="#id35" name="categoryortraversal"><tt class="literal"><span class="pre">CategoryOrTraversal</span></tt></a></h4>
<h4><a class="toc-backref" href="#id34" 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
@ -778,7 +750,7 @@ end up being <tt class="literal"><span class="pre">std::forward_iterator_tag</sp
</table>
</div>
<div class="section" id="id10">
<h4><a class="toc-backref" href="#id36" name="id10"><tt class="literal"><span class="pre">Reference</span></tt></a></h4>
<h4><a class="toc-backref" href="#id35" name="id10"><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
@ -787,7 +759,7 @@ 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="#id37" name="difference"><tt class="literal"><span class="pre">Difference</span></tt></a></h4>
<h4><a class="toc-backref" href="#id36" 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>.
@ -814,7 +786,7 @@ class node_iterator
</div>
</div>
<div class="section" id="constructors-and-data-members">
<h3><a class="toc-backref" href="#id38" name="constructors-and-data-members">Constructors and Data Members</a></h3>
<h3><a class="toc-backref" href="#id37" 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
@ -859,7 +831,7 @@ 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="#id39" name="implementing-the-core-operations">Implementing the Core Operations</a></h3>
<h3><a class="toc-backref" href="#id38" 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
@ -910,7 +882,7 @@ 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="#id40" 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="#id39" 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
@ -1011,7 +983,7 @@ typedef node_iter&lt;node_base const&gt; node_const_iterator;
</pre>
</div>
<div class="section" id="interoperability">
<h2><a class="toc-backref" href="#id41" name="interoperability">Interoperability</a></h2>
<h2><a class="toc-backref" href="#id40" 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
@ -1084,7 +1056,7 @@ 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="#id42" name="telling-the-truth">Telling the Truth</a></h2>
<h2><a class="toc-backref" href="#id41" 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>.
@ -1122,7 +1094,7 @@ appropriate:</p>
</pre>
</div>
<div class="section" id="wrap-up">
<h2><a class="toc-backref" href="#id43" name="wrap-up">Wrap Up</a></h2>
<h2><a class="toc-backref" href="#id42" 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