boost_1_45_0/libs/iterator/doc/indirect_iterator.html - nest-learning-thermostat/5.0/boost - Git at Google

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 <title>Indirect Iterator</title>
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 <div class="document" id="indirect-iterator">
 <h1 class="title">Indirect Iterator</h1>
 <table class="docinfo" frame="void" rules="none">
 <col class="docinfo-name" />
 <col class="docinfo-content" />
 <tbody valign="top">
 <tr><th class="docinfo-name">Author:</th>
 <td>David Abrahams, Jeremy Siek, Thomas Witt</td></tr>
 <tr><th class="docinfo-name">Contact:</th>
 <td><a class="first reference external" href="mailto:dave&#64;boost-consulting.com">dave&#64;boost-consulting.com</a>, <a class="reference external" href="mailto:jsiek&#64;osl.iu.edu">jsiek&#64;osl.iu.edu</a>, <a class="last reference external" href="mailto:witt&#64;ive.uni-hannover.de">witt&#64;ive.uni-hannover.de</a></td></tr>
 <tr><th class="docinfo-name">Organization:</th>
 <td><a class="first reference external" href="http://www.boost-consulting.com">Boost Consulting</a>, Indiana University <a class="reference external" href="http://www.osl.iu.edu">Open Systems
 Lab</a>, University of Hanover <a class="last reference external" href="http://www.ive.uni-hannover.de">Institute for Transport
 Railway Operation and Construction</a></td></tr>
 <tr><th class="docinfo-name">Date:</th>
 <td>2006-09-11</td></tr>
 <tr><th class="docinfo-name">Copyright:</th>
 <td>Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003.</td></tr>
 </tbody>
 </table>
 <!-- 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) -->
 <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">abstract:</th><td class="field-body"><!-- Copyright David Abrahams 2006. 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) -->
 <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> adapts an iterator by applying an
 <em>extra</em> dereference inside of <tt class="docutils literal"><span class="pre">operator*()</span></tt>. For example, this
 iterator adaptor makes it possible to view a container of pointers
 (e.g. <tt class="docutils literal"><span class="pre">list&lt;foo*&gt;</span></tt>) as if it were a container of the pointed-to type
 (e.g. <tt class="docutils literal"><span class="pre">list&lt;foo&gt;</span></tt>).  <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> depends on two
 auxiliary traits, <tt class="docutils literal"><span class="pre">pointee</span></tt> and <tt class="docutils literal"><span class="pre">indirect_reference</span></tt>, to
 provide support for underlying iterators whose <tt class="docutils literal"><span class="pre">value_type</span></tt> is
 not an iterator.</td>
 </tr>
 </tbody>
 </table>
 <div class="contents topic" id="table-of-contents">
 <p class="topic-title first">Table of Contents</p>
 <ul class="simple">
 <li><a class="reference internal" href="#indirect-iterator-synopsis" id="id2"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> synopsis</a></li>
 <li><a class="reference internal" href="#indirect-iterator-requirements" id="id3"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> requirements</a></li>
 <li><a class="reference internal" href="#indirect-iterator-models" id="id4"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> models</a></li>
 <li><a class="reference internal" href="#indirect-iterator-operations" id="id5"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> operations</a></li>
 <li><a class="reference internal" href="#example" id="id6">Example</a></li>
 </ul>
 </div>
 <div class="section" id="indirect-iterator-synopsis">
 <h1><a class="toc-backref" href="#id2"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> synopsis</a></h1>
 <!-- Copyright David Abrahams 2006. 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) -->
 <pre class="literal-block">
 template &lt;
     class Iterator
   , class Value = use_default
   , class CategoryOrTraversal = use_default
   , class Reference = use_default
   , class Difference = use_default
 &gt;
 class indirect_iterator
 {
  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, class Category2
       , class Reference2, class Difference2
     &gt;
     indirect_iterator(
         indirect_iterator&lt;
              Iterator2, Value2, Category2, Reference2, Difference2
         &gt; const&amp; y
       , typename enable_if_convertible&lt;Iterator2, Iterator&gt;::type* = 0 // exposition
     );

     Iterator const&amp; base() const;
     reference operator*() const;
     indirect_iterator&amp; operator++();
     indirect_iterator&amp; operator--();
 private:
    Iterator m_iterator; // exposition
 };
 </pre>
 <p>The member types of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> are defined according to
 the following pseudo-code, where <tt class="docutils literal"><span class="pre">V</span></tt> is
 <tt class="docutils literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt></p>
 <pre class="literal-block">
 if (Value is use_default) then
     typedef remove_const&lt;pointee&lt;V&gt;::type&gt;::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 indirect_reference&lt;V&gt;::type reference;
     else
         typedef Value&amp; reference;
 else
     typedef Reference reference;

 if (Value is use_default) then
     typedef pointee&lt;V&gt;::type* 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;

 if (CategoryOrTraversal is use_default)
     typedef <em>iterator-category</em> (
         iterator_traversal&lt;Iterator&gt;::type,``reference``,``value_type``
     ) iterator_category;
 else
     typedef <em>iterator-category</em> (
         CategoryOrTraversal,``reference``,``value_type``
     ) iterator_category;
 </pre>
 </div>
 <div class="section" id="indirect-iterator-requirements">
 <h1><a class="toc-backref" href="#id3"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> requirements</a></h1>
 <p>The expression <tt class="docutils literal"><span class="pre">*v</span></tt>, where <tt class="docutils literal"><span class="pre">v</span></tt> is an object of
 <tt class="docutils literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt>, shall be valid
 expression and convertible to <tt class="docutils literal"><span class="pre">reference</span></tt>.  <tt class="docutils literal"><span class="pre">Iterator</span></tt> shall
 model the traversal concept indicated by <tt class="docutils literal"><span class="pre">iterator_category</span></tt>.
 <tt class="docutils literal"><span class="pre">Value</span></tt>, <tt class="docutils literal"><span class="pre">Reference</span></tt>, and <tt class="docutils literal"><span class="pre">Difference</span></tt> shall be chosen so
 that <tt class="docutils literal"><span class="pre">value_type</span></tt>, <tt class="docutils literal"><span class="pre">reference</span></tt>, and <tt class="docutils literal"><span class="pre">difference_type</span></tt> meet
 the requirements indicated by <tt class="docutils literal"><span class="pre">iterator_category</span></tt>.</p>
 <p>[Note: there are further requirements on the
 <tt class="docutils literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt> if the <tt class="docutils literal"><span class="pre">Value</span></tt>
 parameter is not <tt class="docutils literal"><span class="pre">use_default</span></tt>, as implied by the algorithm for
 deducing the default for the <tt class="docutils literal"><span class="pre">value_type</span></tt> member.]</p>
 </div>
 <div class="section" id="indirect-iterator-models">
 <h1><a class="toc-backref" href="#id4"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> models</a></h1>
 <p>In addition to the concepts indicated by <tt class="docutils literal"><span class="pre">iterator_category</span></tt>
 and by <tt class="docutils literal"><span class="pre">iterator_traversal&lt;indirect_iterator&gt;::type</span></tt>, a
 specialization of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> models the following
 concepts, Where <tt class="docutils literal"><span class="pre">v</span></tt> is an object of
 <tt class="docutils literal"><span class="pre">iterator_traits&lt;Iterator&gt;::value_type</span></tt>:</p>
 <blockquote>
 <ul class="simple">
 <li>Readable Iterator if <tt class="docutils literal"><span class="pre">reference(*v)</span></tt> is convertible to
 <tt class="docutils literal"><span class="pre">value_type</span></tt>.</li>
 <li>Writable Iterator if <tt class="docutils literal"><span class="pre">reference(*v)</span> <span class="pre">=</span> <span class="pre">t</span></tt> is a valid
 expression (where <tt class="docutils literal"><span class="pre">t</span></tt> is an object of type
 <tt class="docutils literal"><span class="pre">indirect_iterator::value_type</span></tt>)</li>
 <li>Lvalue Iterator if <tt class="docutils literal"><span class="pre">reference</span></tt> is a reference type.</li>
 </ul>
 </blockquote>
 <p><tt class="docutils literal"><span class="pre">indirect_iterator&lt;X,V1,C1,R1,D1&gt;</span></tt> is interoperable with
 <tt class="docutils literal"><span class="pre">indirect_iterator&lt;Y,V2,C2,R2,D2&gt;</span></tt> if and only if <tt class="docutils literal"><span class="pre">X</span></tt> is
 interoperable with <tt class="docutils literal"><span class="pre">Y</span></tt>.</p>
 </div>
 <div class="section" id="indirect-iterator-operations">
 <h1><a class="toc-backref" href="#id5"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> operations</a></h1>
 <p>In addition to the operations required by the concepts described
 above, specializations of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> provide the
 following operations.</p>
 <p><tt class="docutils literal"><span class="pre">indirect_iterator();</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"><tt class="docutils literal"><span class="pre">Iterator</span></tt> must be Default Constructible.</td>
 </tr>
 <tr class="field"><th class="field-name">Effects:</th><td class="field-body">Constructs an instance of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> with
 a default-constructed <tt class="docutils literal"><span class="pre">m_iterator</span></tt>.</td>
 </tr>
 </tbody>
 </table>
 <p><tt class="docutils literal"><span class="pre">indirect_iterator(Iterator</span> <span class="pre">x);</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">Constructs an instance of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> with
 <tt class="docutils literal"><span class="pre">m_iterator</span></tt> copy constructed from <tt class="docutils literal"><span class="pre">x</span></tt>.</td>
 </tr>
 </tbody>
 </table>
 <pre class="literal-block">
 template &lt;
     class Iterator2, class Value2, unsigned Access, class Traversal
   , class Reference2, class Difference2
 &gt;
 indirect_iterator(
     indirect_iterator&lt;
          Iterator2, Value2, Access, Traversal, Reference2, Difference2
     &gt; const&amp; y
   , typename enable_if_convertible&lt;Iterator2, Iterator&gt;::type* = 0 // exposition
 );
 </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">Requires:</th><td class="field-body"><tt class="docutils literal"><span class="pre">Iterator2</span></tt> is implicitly convertible to <tt class="docutils literal"><span class="pre">Iterator</span></tt>.</td>
 </tr>
 <tr class="field"><th class="field-name">Effects:</th><td class="field-body">Constructs an instance of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> whose
 <tt class="docutils literal"><span class="pre">m_iterator</span></tt> subobject is constructed from <tt class="docutils literal"><span class="pre">y.base()</span></tt>.</td>
 </tr>
 </tbody>
 </table>
 <p><tt class="docutils literal"><span class="pre">Iterator</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>
 <p><tt class="docutils literal"><span class="pre">reference</span> <span class="pre">operator*()</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>
 <p><tt class="docutils literal"><span class="pre">indirect_iterator&amp;</span> <span class="pre">operator++();</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>
 <tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="docutils literal"><span class="pre">*this</span></tt></td>
 </tr>
 </tbody>
 </table>
 <p><tt class="docutils literal"><span class="pre">indirect_iterator&amp;</span> <span class="pre">operator--();</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>
 <tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="docutils literal"><span class="pre">*this</span></tt></td>
 </tr>
 </tbody>
 </table>
 <!-- Copyright David Abrahams 2006. 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) -->
 </div>
 <div class="section" id="example">
 <h1><a class="toc-backref" href="#id6">Example</a></h1>
 <p>This example prints an array of characters, using
 <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> to access the array of characters through an
 array of pointers. Next <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> is used with the
 <tt class="docutils literal"><span class="pre">transform</span></tt> algorithm to copy the characters (incremented by one) to
 another array. A constant indirect iterator is used for the source and
 a mutable indirect iterator is used for the destination. The last part
 of the example prints the original array of characters, but this time
 using the <tt class="docutils literal"><span class="pre">make_indirect_iterator</span></tt> helper function.</p>
 <pre class="literal-block">
 char characters[] = &quot;abcdefg&quot;;
 const int N = sizeof(characters)/sizeof(char) - 1; // -1 since characters has a null char
 char* pointers_to_chars[N];                        // at the end.
 for (int i = 0; i &lt; N; ++i)
   pointers_to_chars[i] = &amp;characters[i];

 // Example of using indirect_iterator

 boost::indirect_iterator&lt;char**, char&gt;
   indirect_first(pointers_to_chars), indirect_last(pointers_to_chars + N);

 std::copy(indirect_first, indirect_last, std::ostream_iterator&lt;char&gt;(std::cout, &quot;,&quot;));
 std::cout &lt;&lt; std::endl;


 // Example of making mutable and constant indirect iterators

 char mutable_characters[N];
 char* pointers_to_mutable_chars[N];
 for (int j = 0; j &lt; N; ++j)
   pointers_to_mutable_chars[j] = &amp;mutable_characters[j];

 boost::indirect_iterator&lt;char* const*&gt; mutable_indirect_first(pointers_to_mutable_chars),
   mutable_indirect_last(pointers_to_mutable_chars + N);
 boost::indirect_iterator&lt;char* const*, char const&gt; const_indirect_first(pointers_to_chars),
   const_indirect_last(pointers_to_chars + N);

 std::transform(const_indirect_first, const_indirect_last,
                mutable_indirect_first, std::bind1st(std::plus&lt;char&gt;(), 1));

 std::copy(mutable_indirect_first, mutable_indirect_last,
           std::ostream_iterator&lt;char&gt;(std::cout, &quot;,&quot;));
 std::cout &lt;&lt; std::endl;


 // Example of using make_indirect_iterator()

 std::copy(boost::make_indirect_iterator(pointers_to_chars),
           boost::make_indirect_iterator(pointers_to_chars + N),
           std::ostream_iterator&lt;char&gt;(std::cout, &quot;,&quot;));
 std::cout &lt;&lt; std::endl;
 </pre>
 <p>The output is:</p>
 <pre class="literal-block">
 a,b,c,d,e,f,g,
 b,c,d,e,f,g,h,
 a,b,c,d,e,f,g,
 </pre>
 <p>The source code for this example can be found <a class="reference external" href="../example/indirect_iterator_example.cpp">here</a>.</p>
 </div>
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	<title>Indirect Iterator</title>
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	<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="2006-09-11" />
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	<link rel="stylesheet" href="../../../rst.css" type="text/css" />
	</head>
	<body>
	<div class="document" id="indirect-iterator">
	<h1 class="title">Indirect Iterator</h1>
	<table class="docinfo" frame="void" rules="none">
	<col class="docinfo-name" />
	<col class="docinfo-content" />
	<tbody valign="top">
	<tr><th class="docinfo-name">Author:</th>
	<td>David Abrahams, Jeremy Siek, Thomas Witt</td></tr>
	<tr><th class="docinfo-name">Contact:</th>
	<td><a class="first reference external" href="mailto:dave@boost-consulting.com">dave@boost-consulting.com</a>, <a class="reference external" href="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</a>, <a class="last reference external" href="mailto:witt@ive.uni-hannover.de">witt@ive.uni-hannover.de</a></td></tr>
	<tr><th class="docinfo-name">Organization:</th>
	<td><a class="first reference external" href="http://www.boost-consulting.com">Boost Consulting</a>, Indiana University <a class="reference external" href="http://www.osl.iu.edu">Open Systems
	Lab</a>, University of Hanover <a class="last reference external" href="http://www.ive.uni-hannover.de">Institute for Transport
	Railway Operation and Construction</a></td></tr>
	<tr><th class="docinfo-name">Date:</th>
	<td>2006-09-11</td></tr>
	<tr><th class="docinfo-name">Copyright:</th>
	<td>Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003.</td></tr>
	</tbody>
	</table>
	<!-- 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) -->
	<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">abstract:</th><td class="field-body"><!-- Copyright David Abrahams 2006. 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) -->
	<tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> adapts an iterator by applying an
	<em>extra</em> dereference inside of <tt class="docutils literal"><span class="pre">operator*()</span></tt>. For example, this
	iterator adaptor makes it possible to view a container of pointers
	(e.g. <tt class="docutils literal"><span class="pre">list<foo*></span></tt>) as if it were a container of the pointed-to type
	(e.g. <tt class="docutils literal"><span class="pre">list<foo></span></tt>). <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> depends on two
	auxiliary traits, <tt class="docutils literal"><span class="pre">pointee</span></tt> and <tt class="docutils literal"><span class="pre">indirect_reference</span></tt>, to
	provide support for underlying iterators whose <tt class="docutils literal"><span class="pre">value_type</span></tt> is
	not an iterator.</td>
	</tr>
	</tbody>
	</table>
	<div class="contents topic" id="table-of-contents">
	<p class="topic-title first">Table of Contents</p>
	<ul class="simple">
	<li><a class="reference internal" href="#indirect-iterator-synopsis" id="id2"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> synopsis</a></li>
	<li><a class="reference internal" href="#indirect-iterator-requirements" id="id3"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> requirements</a></li>
	<li><a class="reference internal" href="#indirect-iterator-models" id="id4"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> models</a></li>
	<li><a class="reference internal" href="#indirect-iterator-operations" id="id5"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> operations</a></li>
	<li><a class="reference internal" href="#example" id="id6">Example</a></li>
	</ul>
	</div>
	<div class="section" id="indirect-iterator-synopsis">
	<h1><a class="toc-backref" href="#id2"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> synopsis</a></h1>
	<!-- Copyright David Abrahams 2006. 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) -->
	<pre class="literal-block">
	template <
	class Iterator
	, class Value = use_default
	, class CategoryOrTraversal = use_default
	, class Reference = use_default
	, class Difference = use_default
	>
	class indirect_iterator
	{
	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 <
	class Iterator2, class Value2, class Category2
	, class Reference2, class Difference2
	>
	indirect_iterator(
	indirect_iterator<
	Iterator2, Value2, Category2, Reference2, Difference2
	> const& y
	, typename enable_if_convertible<Iterator2, Iterator>::type* = 0 // exposition
	);

	Iterator const& base() const;
	reference operator*() const;
	indirect_iterator& operator++();
	indirect_iterator& operator--();
	private:
	Iterator m_iterator; // exposition
	};
	</pre>
	<p>The member types of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> are defined according to
	the following pseudo-code, where <tt class="docutils literal"><span class="pre">V</span></tt> is
	<tt class="docutils literal"><span class="pre">iterator_traits<Iterator>::value_type</span></tt></p>
	<pre class="literal-block">
	if (Value is use_default) then
	typedef remove_const<pointee<V>::type>::type value_type;
	else
	typedef remove_const<Value>::type value_type;

	if (Reference is use_default) then
	if (Value is use_default) then
	typedef indirect_reference<V>::type reference;
	else
	typedef Value& reference;
	else
	typedef Reference reference;

	if (Value is use_default) then
	typedef pointee<V>::type* pointer;
	else
	typedef Value* pointer;

	if (Difference is use_default)
	typedef iterator_traits<Iterator>::difference_type difference_type;
	else
	typedef Difference difference_type;

	if (CategoryOrTraversal is use_default)
	typedef <em>iterator-category</em> (
	iterator_traversal<Iterator>::type,``reference``,``value_type``
	) iterator_category;
	else
	typedef <em>iterator-category</em> (
	CategoryOrTraversal,``reference``,``value_type``
	) iterator_category;
	</pre>
	</div>
	<div class="section" id="indirect-iterator-requirements">
	<h1><a class="toc-backref" href="#id3"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> requirements</a></h1>
	<p>The expression <tt class="docutils literal"><span class="pre">*v</span></tt>, where <tt class="docutils literal"><span class="pre">v</span></tt> is an object of
	<tt class="docutils literal"><span class="pre">iterator_traits<Iterator>::value_type</span></tt>, shall be valid
	expression and convertible to <tt class="docutils literal"><span class="pre">reference</span></tt>. <tt class="docutils literal"><span class="pre">Iterator</span></tt> shall
	model the traversal concept indicated by <tt class="docutils literal"><span class="pre">iterator_category</span></tt>.
	<tt class="docutils literal"><span class="pre">Value</span></tt>, <tt class="docutils literal"><span class="pre">Reference</span></tt>, and <tt class="docutils literal"><span class="pre">Difference</span></tt> shall be chosen so
	that <tt class="docutils literal"><span class="pre">value_type</span></tt>, <tt class="docutils literal"><span class="pre">reference</span></tt>, and <tt class="docutils literal"><span class="pre">difference_type</span></tt> meet
	the requirements indicated by <tt class="docutils literal"><span class="pre">iterator_category</span></tt>.</p>
	<p>[Note: there are further requirements on the
	<tt class="docutils literal"><span class="pre">iterator_traits<Iterator>::value_type</span></tt> if the <tt class="docutils literal"><span class="pre">Value</span></tt>
	parameter is not <tt class="docutils literal"><span class="pre">use_default</span></tt>, as implied by the algorithm for
	deducing the default for the <tt class="docutils literal"><span class="pre">value_type</span></tt> member.]</p>
	</div>
	<div class="section" id="indirect-iterator-models">
	<h1><a class="toc-backref" href="#id4"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> models</a></h1>
	<p>In addition to the concepts indicated by <tt class="docutils literal"><span class="pre">iterator_category</span></tt>
	and by <tt class="docutils literal"><span class="pre">iterator_traversal<indirect_iterator>::type</span></tt>, a
	specialization of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> models the following
	concepts, Where <tt class="docutils literal"><span class="pre">v</span></tt> is an object of
	<tt class="docutils literal"><span class="pre">iterator_traits<Iterator>::value_type</span></tt>:</p>
	<blockquote>
	<ul class="simple">
	<li>Readable Iterator if <tt class="docutils literal"><span class="pre">reference(*v)</span></tt> is convertible to
	<tt class="docutils literal"><span class="pre">value_type</span></tt>.</li>
	<li>Writable Iterator if <tt class="docutils literal"><span class="pre">reference(*v)</span> <span class="pre">=</span> <span class="pre">t</span></tt> is a valid
	expression (where <tt class="docutils literal"><span class="pre">t</span></tt> is an object of type
	<tt class="docutils literal"><span class="pre">indirect_iterator::value_type</span></tt>)</li>
	<li>Lvalue Iterator if <tt class="docutils literal"><span class="pre">reference</span></tt> is a reference type.</li>
	</ul>
	</blockquote>
	<p><tt class="docutils literal"><span class="pre">indirect_iterator<X,V1,C1,R1,D1></span></tt> is interoperable with
	<tt class="docutils literal"><span class="pre">indirect_iterator<Y,V2,C2,R2,D2></span></tt> if and only if <tt class="docutils literal"><span class="pre">X</span></tt> is
	interoperable with <tt class="docutils literal"><span class="pre">Y</span></tt>.</p>
	</div>
	<div class="section" id="indirect-iterator-operations">
	<h1><a class="toc-backref" href="#id5"><tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> operations</a></h1>
	<p>In addition to the operations required by the concepts described
	above, specializations of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> provide the
	following operations.</p>
	<p><tt class="docutils literal"><span class="pre">indirect_iterator();</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"><tt class="docutils literal"><span class="pre">Iterator</span></tt> must be Default Constructible.</td>
	</tr>
	<tr class="field"><th class="field-name">Effects:</th><td class="field-body">Constructs an instance of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> with
	a default-constructed <tt class="docutils literal"><span class="pre">m_iterator</span></tt>.</td>
	</tr>
	</tbody>
	</table>
	<p><tt class="docutils literal"><span class="pre">indirect_iterator(Iterator</span> <span class="pre">x);</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">Constructs an instance of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> with
	<tt class="docutils literal"><span class="pre">m_iterator</span></tt> copy constructed from <tt class="docutils literal"><span class="pre">x</span></tt>.</td>
	</tr>
	</tbody>
	</table>
	<pre class="literal-block">
	template <
	class Iterator2, class Value2, unsigned Access, class Traversal
	, class Reference2, class Difference2
	>
	indirect_iterator(
	indirect_iterator<
	Iterator2, Value2, Access, Traversal, Reference2, Difference2
	> const& y
	, typename enable_if_convertible<Iterator2, Iterator>::type* = 0 // exposition
	);
	</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">Requires:</th><td class="field-body"><tt class="docutils literal"><span class="pre">Iterator2</span></tt> is implicitly convertible to <tt class="docutils literal"><span class="pre">Iterator</span></tt>.</td>
	</tr>
	<tr class="field"><th class="field-name">Effects:</th><td class="field-body">Constructs an instance of <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> whose
	<tt class="docutils literal"><span class="pre">m_iterator</span></tt> subobject is constructed from <tt class="docutils literal"><span class="pre">y.base()</span></tt>.</td>
	</tr>
	</tbody>
	</table>
	<p><tt class="docutils literal"><span class="pre">Iterator</span> <span class="pre">const&</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>
	<p><tt class="docutils literal"><span class="pre">reference</span> <span class="pre">operator*()</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>
	<p><tt class="docutils literal"><span class="pre">indirect_iterator&</span> <span class="pre">operator++();</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>
	<tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="docutils literal"><span class="pre">*this</span></tt></td>
	</tr>
	</tbody>
	</table>
	<p><tt class="docutils literal"><span class="pre">indirect_iterator&</span> <span class="pre">operator--();</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>
	<tr class="field"><th class="field-name">Returns:</th><td class="field-body"><tt class="docutils literal"><span class="pre">*this</span></tt></td>
	</tr>
	</tbody>
	</table>
	<!-- Copyright David Abrahams 2006. 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) -->
	</div>
	<div class="section" id="example">
	<h1><a class="toc-backref" href="#id6">Example</a></h1>
	<p>This example prints an array of characters, using
	<tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> to access the array of characters through an
	array of pointers. Next <tt class="docutils literal"><span class="pre">indirect_iterator</span></tt> is used with the
	<tt class="docutils literal"><span class="pre">transform</span></tt> algorithm to copy the characters (incremented by one) to
	another array. A constant indirect iterator is used for the source and
	a mutable indirect iterator is used for the destination. The last part
	of the example prints the original array of characters, but this time
	using the <tt class="docutils literal"><span class="pre">make_indirect_iterator</span></tt> helper function.</p>
	<pre class="literal-block">
	char characters[] = "abcdefg";
	const int N = sizeof(characters)/sizeof(char) - 1; // -1 since characters has a null char
	char* pointers_to_chars[N]; // at the end.
	for (int i = 0; i < N; ++i)
	pointers_to_chars[i] = &characters[i];

	// Example of using indirect_iterator

	boost::indirect_iterator<char**, char>
	indirect_first(pointers_to_chars), indirect_last(pointers_to_chars + N);

	std::copy(indirect_first, indirect_last, std::ostream_iterator<char>(std::cout, ","));
	std::cout << std::endl;


	// Example of making mutable and constant indirect iterators

	char mutable_characters[N];
	char* pointers_to_mutable_chars[N];
	for (int j = 0; j < N; ++j)
	pointers_to_mutable_chars[j] = &mutable_characters[j];

	boost::indirect_iterator<char* const*> mutable_indirect_first(pointers_to_mutable_chars),
	mutable_indirect_last(pointers_to_mutable_chars + N);
	boost::indirect_iterator<char* const*, char const> const_indirect_first(pointers_to_chars),
	const_indirect_last(pointers_to_chars + N);

	std::transform(const_indirect_first, const_indirect_last,
	mutable_indirect_first, std::bind1st(std::plus<char>(), 1));

	std::copy(mutable_indirect_first, mutable_indirect_last,
	std::ostream_iterator<char>(std::cout, ","));
	std::cout << std::endl;


	// Example of using make_indirect_iterator()

	std::copy(boost::make_indirect_iterator(pointers_to_chars),
	boost::make_indirect_iterator(pointers_to_chars + N),
	std::ostream_iterator<char>(std::cout, ","));
	std::cout << std::endl;
	</pre>
	<p>The output is:</p>
	<pre class="literal-block">
	a,b,c,d,e,f,g,
	b,c,d,e,f,g,h,
	a,b,c,d,e,f,g,
	</pre>
	<p>The source code for this example can be found <a class="reference external" href="../example/indirect_iterator_example.cpp">here</a>.</p>
	</div>
	</div>
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