boost_iterator/doc/iterator_adaptor_ref.html

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<div class="document">
<!-- Distributed under 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) -->
<!-- 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. -->
<pre class="literal-block">
template &lt;
    class Derived
  , class Base
  , class Value               = use_default
  , class CategoryOrTraversal = use_default
  , class Reference           = use_default
  , class Difference = use_default
&gt;
class iterator_adaptor
  : public iterator_facade&lt;Derived, <em>V'</em>, <em>C'</em>, <em>R'</em>, <em>D'</em>&gt; // see <a class="reference" href="#base-parameters">details</a>
{
    friend class iterator_core_access;
 public:
    iterator_adaptor();
    explicit iterator_adaptor(Base const&amp; iter);
    typedef Base base_type;
    Base const&amp; base() const;
 protected:
    typedef iterator_adaptor iterator_adaptor_;
    Base const&amp; base_reference() const;
    Base&amp; base_reference();
 private: // Core iterator interface for iterator_facade.
    typename iterator_adaptor::reference dereference() const;

    template &lt;
    class OtherDerived, class OtherIterator, class V, class C, class R, class D
    &gt;
    bool equal(iterator_adaptor&lt;OtherDerived, OtherIterator, V, C, R, D&gt; const&amp; x) const;

    void advance(typename iterator_adaptor::difference_type n);
    void increment();
    void decrement();

    template &lt;
        class OtherDerived, class OtherIterator, class V, class C, class R, class D
    &gt;
    typename iterator_adaptor::difference_type distance_to(
        iterator_adaptor&lt;OtherDerived, OtherIterator, V, C, R, D&gt; const&amp; y) const;

 private:
    Base m_iterator; // exposition only
};
</pre>
<div class="section">
<h1><a id="iterator-adaptor-requirements" name="iterator-adaptor-requirements"><span id="requirements"></span><tt class="docutils literal"><span class="pre">iterator_adaptor</span></tt> requirements</a></h1>
<p><tt class="docutils literal"><span class="pre">static_cast&lt;Derived*&gt;(iterator_adaptor*)</span></tt> shall be well-formed.
The <tt class="docutils literal"><span class="pre">Base</span></tt> argument shall be Assignable and Copy Constructible.</p>
</div>
<div class="section">
<h1><a id="iterator-adaptor-base-class-parameters" name="iterator-adaptor-base-class-parameters"><span id="base-parameters"></span><tt class="docutils literal"><span class="pre">iterator_adaptor</span></tt> base class parameters</a></h1>
<p>The <em>V'</em>, <em>C'</em>, <em>R'</em>, and <em>D'</em> parameters of the <tt class="docutils literal"><span class="pre">iterator_facade</span></tt>
used as a base class in the summary of <tt class="docutils literal"><span class="pre">iterator_adaptor</span></tt>
above are defined as follows:</p>
<pre class="literal-block">
<em>V'</em> = if (Value is use_default)
          return iterator_traits&lt;Base&gt;::value_type
      else
          return Value

<em>C'</em> = if (CategoryOrTraversal is use_default)
          return iterator_traversal&lt;Base&gt;::type
      else
          return CategoryOrTraversal

<em>R'</em> = if (Reference is use_default)
          if (Value is use_default)
              return iterator_traits&lt;Base&gt;::reference
          else
              return Value&amp;
      else
          return Reference

<em>D'</em> = if (Difference is use_default)
          return iterator_traits&lt;Base&gt;::difference_type
      else
          return Difference
</pre>
<!-- ``iterator_adaptor`` models
- - - - - - - - - - - - - - - - - - - - - - - - - - -

In order for ``Derived`` to model the iterator concepts corresponding
to ``iterator_traits<Derived>::iterator_category``, the expressions
involving ``m_iterator`` in the specifications of those private member
functions of ``iterator_adaptor`` that may be called by
``iterator_facade<Derived, V, C, R, D>`` in evaluating any valid
expression involving ``Derived`` in those concepts' requirements. -->
<!-- The above is confusing and needs a rewrite. -JGS -->
<!-- That's why it's removed.  We're embracing inheritance, remember? -->
</div>
<div class="section">
<h1><a id="iterator-adaptor-public-operations" name="iterator-adaptor-public-operations"><tt class="docutils literal"><span class="pre">iterator_adaptor</span></tt> public operations</a></h1>
<p><tt class="docutils literal"><span class="pre">iterator_adaptor();</span></tt></p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Requires:</th><td class="field-body">The <tt class="docutils literal"><span class="pre">Base</span></tt> type must be Default Constructible.</td>
</tr>
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">An instance of <tt class="docutils literal"><span class="pre">iterator_adaptor</span></tt> with
<tt class="docutils literal"><span class="pre">m_iterator</span></tt> default constructed.</td>
</tr>
</tbody>
</table>
<p><tt class="docutils literal"><span class="pre">explicit</span> <span class="pre">iterator_adaptor(Base</span> <span class="pre">const&amp;</span> <span class="pre">iter);</span></tt></p>
<table class="docutils 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">An instance of <tt class="docutils literal"><span class="pre">iterator_adaptor</span></tt> with
<tt class="docutils literal"><span class="pre">m_iterator</span></tt> copy constructed from <tt class="docutils literal"><span class="pre">iter</span></tt>.</td>
</tr>
</tbody>
</table>
<p><tt class="docutils literal"><span class="pre">Base</span> <span class="pre">const&amp;</span> <span class="pre">base()</span> <span class="pre">const;</span></tt></p>
<table class="docutils 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"><tt class="docutils literal"><span class="pre">m_iterator</span></tt></td>
</tr>
</tbody>
</table>
</div>
<div class="section">
<h1><a id="iterator-adaptor-protected-member-functions" name="iterator-adaptor-protected-member-functions"><tt class="docutils literal"><span class="pre">iterator_adaptor</span></tt> protected member functions</a></h1>
<p><tt class="docutils 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="docutils 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">A const reference to <tt class="docutils literal"><span class="pre">m_iterator</span></tt>.</td>
</tr>
</tbody>
</table>
<p><tt class="docutils literal"><span class="pre">Base&amp;</span> <span class="pre">base_reference();</span></tt></p>
<table class="docutils 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">A non-const reference to <tt class="docutils literal"><span class="pre">m_iterator</span></tt>.</td>
</tr>
</tbody>
</table>
</div>
<div class="section">
<h1><a id="iterator-adaptor-private-member-functions" name="iterator-adaptor-private-member-functions"><tt class="docutils literal"><span class="pre">iterator_adaptor</span></tt> private member functions</a></h1>
<p><tt class="docutils 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="docutils 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"><tt class="docutils literal"><span class="pre">*m_iterator</span></tt></td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;
class OtherDerived, class OtherIterator, class V, class C, class R, class D
&gt;
bool equal(iterator_adaptor&lt;OtherDerived, OtherIterator, V, C, R, D&gt; const&amp; x) const;
</pre>
<table class="docutils 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"><tt class="docutils literal"><span class="pre">m_iterator</span> <span class="pre">==</span> <span class="pre">x.base()</span></tt></td>
</tr>
</tbody>
</table>
<p><tt class="docutils literal"><span class="pre">void</span> <span class="pre">advance(typename</span> <span class="pre">iterator_adaptor::difference_type</span> <span class="pre">n);</span></tt></p>
<table class="docutils 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"><tt class="docutils literal"><span class="pre">m_iterator</span> <span class="pre">+=</span> <span class="pre">n;</span></tt></td>
</tr>
</tbody>
</table>
<p><tt class="docutils literal"><span class="pre">void</span> <span class="pre">increment();</span></tt></p>
<table class="docutils 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"><tt class="docutils literal"><span class="pre">++m_iterator;</span></tt></td>
</tr>
</tbody>
</table>
<p><tt class="docutils literal"><span class="pre">void</span> <span class="pre">decrement();</span></tt></p>
<table class="docutils 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"><tt class="docutils literal"><span class="pre">--m_iterator;</span></tt></td>
</tr>
</tbody>
</table>
<pre class="literal-block">
template &lt;
    class OtherDerived, class OtherIterator, class V, class C, class R, class D
&gt;
typename iterator_adaptor::difference_type distance_to(
    iterator_adaptor&lt;OtherDerived, OtherIterator, V, C, R, D&gt; const&amp; y) const;
</pre>
<table class="docutils 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"><tt class="docutils literal"><span class="pre">y.base()</span> <span class="pre">-</span> <span class="pre">m_iterator</span></tt></td>
</tr>
</tbody>
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