forked from boostorg/iterator
164 lines
9.4 KiB
HTML
164 lines
9.4 KiB
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<?xml version="1.0" encoding="utf-8" ?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="generator" content="Docutils 0.3.0: http://docutils.sourceforge.net/" />
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<title>Indirect Iterator</title>
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<meta name="author" content="David Abrahams, Jeremy Siek, Thomas Witt" />
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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" />
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<meta name="date" content="2003-08-05" />
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<meta name="copyright" content="Copyright Dave Abrahams, Jeremy Siek, and Thomas Witt 2003. All rights reserved" />
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<link rel="stylesheet" href="default.css" type="text/css" />
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</head>
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<body>
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<div class="document" id="indirect-iterator">
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<h1 class="title">Indirect Iterator</h1>
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<table class="docinfo" frame="void" rules="none">
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<col class="docinfo-name" />
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<col class="docinfo-content" />
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<tbody valign="top">
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<tr><th class="docinfo-name">Author:</th>
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<td>David Abrahams, Jeremy Siek, Thomas Witt</td></tr>
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<tr><th class="docinfo-name">Contact:</th>
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<td><a class="first reference" href="mailto:dave@boost-consulting.com">dave@boost-consulting.com</a>, <a class="reference" href="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</a>, <a class="last reference" href="mailto:witt@ive.uni-hannover.de">witt@ive.uni-hannover.de</a></td></tr>
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<tr><th class="docinfo-name">Organization:</th>
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<td><a class="first reference" href="http://www.boost-consulting.com">Boost Consulting</a>, Indiana University <a class="reference" href="http://www.osl.iu.edu">Open Systems
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Lab</a>, University of Hanover <a class="last reference" href="http://www.ive.uni-hannover.de">Institute for Transport
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Railway Operation and Construction</a></td></tr>
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<tr><th class="docinfo-name">Date:</th>
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<td>2003-08-05</td></tr>
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<tr><th class="docinfo-name">Copyright:</th>
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<td>Copyright Dave Abrahams, Jeremy Siek, and Thomas Witt 2003. All rights reserved</td></tr>
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</tbody>
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</table>
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<table class="field-list" frame="void" rules="none">
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<col class="field-name" />
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<col class="field-body" />
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<tbody valign="top">
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<tr class="field"><th class="field-name">abstract:</th><td class="field-body"></td>
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</tr>
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</tbody>
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</table>
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<p>The indirect iterator adapts an iterator by applying an <em>extra</em>
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dereference inside of <tt class="literal"><span class="pre">operator*()</span></tt>. For example, this iterator
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adaptor makes it possible to view a container of pointers
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(e.g. <tt class="literal"><span class="pre">list<foo*></span></tt>) as if it were a container of the pointed-to type
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(e.g. <tt class="literal"><span class="pre">list<foo></span></tt>) .</p>
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<!-- At some point we should add the capability to handle
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iterators over smart pointers, which the impl handles. -JGS -->
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<div class="contents topic" id="table-of-contents">
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<p class="topic-title"><a name="table-of-contents">Table of Contents</a></p>
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<ul class="simple">
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<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>
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<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>
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</ul>
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</div>
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<pre class="literal-block">
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template <
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class Iterator
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, class Value = use_default
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, class Category = use_default
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, class Reference = use_default
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, class Difference = use_default
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>
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class indirect_iterator
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: public iterator_adaptor</* see discussion */>
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{
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friend class iterator_core_access;
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public:
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indirect_iterator();
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indirect_iterator(Iterator x);
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template <
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class Iterator2, class Value2, class Category2
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, class Reference2, class Difference2
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>
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indirect_iterator(
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indirect_iterator<
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Iterator2, Value2, Category2, Reference2, Difference2
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> const& y
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, typename enable_if_convertible<Iterator2, Iterator>::type* = 0 // exposition
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);
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private: // as-if specification
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typename indirect_iterator::reference dereference() const
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{
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return **this->base();
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}
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};
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</pre>
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<div class="section" id="indirect-iterator-requirements">
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<h1><a class="toc-backref" href="#id1" name="indirect-iterator-requirements"><tt class="literal"><span class="pre">indirect_iterator</span></tt> requirements</a></h1>
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<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
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itself be dereferenceable. The return type of the <tt class="literal"><span class="pre">operator*</span></tt> for
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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
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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>
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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>
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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
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default for <tt class="literal"><span class="pre">Value</span></tt> is</p>
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<pre class="literal-block">
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iterator_traits< iterator_traits<Iterator>::value_type >::value_type
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</pre>
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<p>If the default is used for <tt class="literal"><span class="pre">Value</span></tt>, then there must be a valid
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specialization of <tt class="literal"><span class="pre">iterator_traits</span></tt> for the value type of the base
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iterator.</p>
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<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
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<tt class="literal"><span class="pre">indirect_iterator</span></tt>. The default is <tt class="literal"><span class="pre">Value&</span></tt>.</p>
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<p>The <tt class="literal"><span class="pre">Category</span></tt> parameter is the <tt class="literal"><span class="pre">iterator_category</span></tt> type for the
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<tt class="literal"><span class="pre">indirect_iterator</span></tt>. The default is
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<tt class="literal"><span class="pre">iterator_traits<Iterator>::iterator_category</span></tt>.</p>
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<p>The indirect iterator will model the most refined standard traversal
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concept that is modeled by the <tt class="literal"><span class="pre">Iterator</span></tt> type. The indirect
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iterator will model the most refined standard access concept that is
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modeled by the value type of <tt class="literal"><span class="pre">Iterator</span></tt>.</p>
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</div>
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<div class="section" id="indirect-iterator-operations">
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<h1><a class="toc-backref" href="#id2" name="indirect-iterator-operations"><tt class="literal"><span class="pre">indirect_iterator</span></tt> operations</a></h1>
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<p><tt class="literal"><span class="pre">indirect_iterator();</span></tt></p>
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<table class="field-list" frame="void" rules="none">
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<col class="field-name" />
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<col class="field-body" />
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<tbody valign="top">
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<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>
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</tr>
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<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
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a default constructed base object.</td>
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</tr>
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</tbody>
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</table>
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<p><tt class="literal"><span class="pre">indirect_iterator(Iterator</span> <span class="pre">x);</span></tt></p>
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<table class="field-list" frame="void" rules="none">
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<col class="field-name" />
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<col class="field-body" />
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<tbody valign="top">
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<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
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the <tt class="literal"><span class="pre">iterator_adaptor</span></tt> subobject copy constructed from <tt class="literal"><span class="pre">x</span></tt>.</td>
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</tr>
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</tbody>
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</table>
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<pre class="literal-block">
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template <
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class Iterator2, class Value2, class Category2
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, class Reference2, class Difference2
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>
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indirect_iterator(
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indirect_iterator<
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Iterator2, Value2, Category2, Reference2, Difference2
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> const& y
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, typename enable_if_convertible<Iterator2, Iterator>::type* = 0 // exposition
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);
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</pre>
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<table class="field-list" frame="void" rules="none">
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<col class="field-name" />
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<col class="field-body" />
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<tbody valign="top">
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<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>
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</tr>
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<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>
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</tr>
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</tbody>
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</table>
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</div>
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</div>
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