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< title > The MPL Reference Manual: Reversible Algorithm</ title >
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< body class = "docframe refmanual" >
< table class = "header" >< tr class = "header" >< td class = "header-group navigation-bar" >< span class = "navigation-group" >< a href = "./inserter.html" class = "navigation-link" > Prev</ a > < a href = "./inserters.html" class = "navigation-link" > Next</ a ></ span >< span class = "navigation-group-separator" > | </ span >< span class = "navigation-group" >< a href = "./inserter.html" class = "navigation-link" > Back</ a > Along</ span >< span class = "navigation-group-separator" > | </ span >< span class = "navigation-group" >< a href = "./algorithms-concepts.html" class = "navigation-link" > Up</ a > < a href = "../refmanual.html" class = "navigation-link" > Home</ a ></ span >< span class = "navigation-group-separator" > | </ span >< span class = "navigation-group" >< a href = "./refmanual_toc.html" class = "navigation-link" > Full TOC</ a ></ span ></ td >
< td class = "header-group page-location" >< a href = "../refmanual.html" class = "navigation-link" > Front Page</ a > / < a href = "./algorithms.html" class = "navigation-link" > Algorithms</ a > / < a href = "./algorithms-concepts.html" class = "navigation-link" > Concepts</ a > / < a href = "./reversible-algorithm.html" class = "navigation-link" > Reversible Algorithm</ a ></ td >
</ tr ></ table >< div class = "header-separator" ></ div >
< div class = "section" id = "reversible-algorithm" >
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< h1 >< a class = "toc-backref" href = "./algorithms-concepts.html#id1463" > Reversible Algorithm</ a ></ h1 >
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< div class = "section" id = "id459" >
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< h3 >< a class = "subsection-title" href = "#description" name = "description" > Description</ a ></ h3 >
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< p > A < a class = "reference internal" href = "./reversible-algorithm.html" > Reversible Algorithm</ a > is a member of a pair of
transformation algorithms that iterate over their input sequence(s)
in opposite directions. For each reversible
algorithm < tt class = "literal" >< span class = "pre" > x</ span ></ tt > there exists a < em > counterpart</ em > algorithm < tt class = "literal" >< span class = "pre" > reverse_x</ span ></ tt > ,
that exhibits the exact semantics of < tt class = "literal" >< span class = "pre" > x</ span ></ tt > except that the elements
of its input sequence argument(s) are processed in the reverse
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order.</ p >
</ div >
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< div class = "section" id = "id460" >
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< h3 >< a class = "subsection-title" href = "#expression-requirements" name = "expression-requirements" > Expression requirements</ a ></ h3 >
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< p > In the following table and subsequent specifications, < tt class = "literal" >< span class = "pre" > x</ span ></ tt > is a placeholder token for the actual
< a class = "reference internal" href = "./reversible-algorithm.html" > Reversible Algorithm</ a > 's name, < em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > are
< a class = "reference internal" href = "./forward-sequence.html" > Forward Sequence</ a > s, and < tt class = "literal" >< span class = "pre" > in</ span ></ tt > is an < a class = "reference internal" href = "./inserter.html" > Inserter</ a > .</ p >
< table border = "1" class = "docutils table" >
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< colgroup >
< col width = "48%" />
< col width = "28%" />
< col width = "23%" />
</ colgroup >
< thead valign = "bottom" >
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< tr >< th class = "head" > Expression</ th >
< th class = "head" > Type</ th >
< th class = "head" > Complexity</ th >
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</ tr >
</ thead >
< tbody valign = "top" >
< tr >< td >< tt class = "literal" >< span class = "pre" > x< </ span ></ tt >< em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > , ...< tt class = "literal" >< span class = "pre" > > ::type</ span ></ tt ></ td >
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< td >< a class = "reference internal" href = "./forward-sequence.html" > Forward Sequence</ a ></ td >
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< td > Unspecified.</ td >
</ tr >
< tr >< td >< tt class = "literal" >< span class = "pre" > x< </ span ></ tt >< em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > , ... < tt class = "literal" >< span class = "pre" > in> ::type</ span ></ tt ></ td >
< td > Any type</ td >
< td > Unspecified.</ td >
</ tr >
< tr >< td >< tt class = "literal" >< span class = "pre" > reverse_x< </ span ></ tt >< em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > , ...< tt class = "literal" >< span class = "pre" > > ::type</ span ></ tt ></ td >
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< td >< a class = "reference internal" href = "./forward-sequence.html" > Forward Sequence</ a ></ td >
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< td > Unspecified.</ td >
</ tr >
< tr >< td >< tt class = "literal" >< span class = "pre" > reverse_x< </ span ></ tt >< em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > , ... < tt class = "literal" >< span class = "pre" > in> ::type</ span ></ tt ></ td >
< td > Any type</ td >
< td > Unspecified.</ td >
</ tr >
</ tbody >
</ table >
</ div >
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< div class = "section" id = "id461" >
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< h3 >< a class = "subsection-title" href = "#expression-semantics" name = "expression-semantics" > Expression semantics</ a ></ h3 >
< pre class = "literal-block" >
typedef x< < em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > ,...> ::type t;
</ pre >
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< table class = "docutils field-list" frame = "void" rules = "none" >
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< col class = "field-name" />
< col class = "field-body" />
< tbody valign = "top" >
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< tr class = "field" >< th class = "field-name" > Precondition:</ th >< td class = "field-body" >< p class = "first" >< em > s</ em >< sub > 1</ sub > is an < a class = "reference internal" href = "./extensible-sequence.html" > Extensible Sequence</ a > .</ p >
</ td >
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</ tr >
< tr class = "field" >< th class = "field-name" > Semantics:</ th >< td class = "field-body" >< p class = "first" >< tt class = "literal" >< span class = "pre" > t</ span ></ tt > is equivalent to</ p >
< pre class = "literal-block" >
x<
< em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > ,...
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, < a href = "./back-inserter.html" class = "identifier" > back_inserter</ a > < < a href = "./clear.html" class = "identifier" > clear</ a > < < em > s</ em >< sub > 1</ sub > > ::type >
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> ::type
</ pre >
< p > if < tt class = "literal" >< span class = "pre" > has_push_back< </ span ></ tt >< em > s</ em >< sub > 1</ sub >< tt class = "literal" >< span class = "pre" > > ::value</ span > < span class = "pre" > ==</ span > < span class = "pre" > true</ span ></ tt > and</ p >
< pre class = "literal-block" >
reverse_x<
< em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > ,...
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, < a href = "./front-inserter.html" class = "identifier" > front_inserter</ a > < < a href = "./clear.html" class = "identifier" > clear</ a > < < em > s</ em >< sub > 1</ sub > > ::type >
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> ::type
</ pre >
< p class = "last" > otherwise.</ p >
</ td >
</ tr >
</ tbody >
</ table >
<!-- .......................................................................... -->
< pre class = "literal-block" >
typedef x< < em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > ,...in> ::type t;
</ pre >
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< table class = "docutils field-list" frame = "void" rules = "none" >
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< col class = "field-name" />
< col class = "field-body" />
< tbody valign = "top" >
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< tr class = "field" >< th class = "field-name" > Semantics:</ th >< td class = "field-body" >< tt class = "literal" >< span class = "pre" > t</ span ></ tt > is the result of an < tt class = "literal" >< span class = "pre" > x</ span ></ tt > invocation with arguments
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< em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,... < em > s</ em >< sub > n</ sub > ,...< tt class = "literal" >< span class = "pre" > in</ span ></ tt > .</ td >
</ tr >
</ tbody >
</ table >
<!-- .......................................................................... -->
< pre class = "literal-block" >
typedef reverse_x< < em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,... < em > s</ em >< sub > n</ sub > ,... > ::type t;
</ pre >
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< table class = "docutils field-list" frame = "void" rules = "none" >
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< col class = "field-name" />
< col class = "field-body" />
< tbody valign = "top" >
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< tr class = "field" >< th class = "field-name" > Precondition:</ th >< td class = "field-body" >< p class = "first" >< em > s</ em >< sub > 1</ sub > is an < a class = "reference internal" href = "./extensible-sequence.html" > Extensible Sequence</ a > .</ p >
</ td >
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</ tr >
< tr class = "field" >< th class = "field-name" > Semantics:</ th >< td class = "field-body" >< p class = "first" >< tt class = "literal" >< span class = "pre" > t</ span ></ tt > is equivalent to</ p >
< pre class = "literal-block" >
x<
< em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > ,...
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, < a href = "./front-inserter.html" class = "identifier" > front_inserter</ a > < < a href = "./clear.html" class = "identifier" > clear</ a > < < em > s</ em >< sub > 1</ sub > > ::type >
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> ::type
</ pre >
< p > if < tt class = "literal" >< span class = "pre" > has_push_front< </ span ></ tt >< em > s</ em >< sub > 1</ sub >< tt class = "literal" >< span class = "pre" > > ::value</ span > < span class = "pre" > ==</ span > < span class = "pre" > true</ span ></ tt > and</ p >
< pre class = "literal-block" >
reverse_x<
< em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > ,...
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, < a href = "./back-inserter.html" class = "identifier" > back_inserter</ a > < < a href = "./clear.html" class = "identifier" > clear</ a > < < em > s</ em >< sub > 1</ sub > > ::type >
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> ::type
</ pre >
< p class = "last" > otherwise.</ p >
</ td >
</ tr >
</ tbody >
</ table >
<!-- .......................................................................... -->
< pre class = "literal-block" >
typedef reverse_x< < em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > ,... in> ::type t;
</ pre >
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< table class = "docutils field-list" frame = "void" rules = "none" >
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< col class = "field-name" />
< col class = "field-body" />
< tbody valign = "top" >
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< tr class = "field" >< th class = "field-name" > Semantics:</ th >< td class = "field-body" >< tt class = "literal" >< span class = "pre" > t</ span ></ tt > is the result of a < tt class = "literal" >< span class = "pre" > reverse_x</ span ></ tt > invocation with arguments
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< em > s</ em >< sub > 1</ sub > ,< em > s</ em >< sub > 2</ sub > ,...< em > s</ em >< sub > n</ sub > ,...< tt class = "literal" >< span class = "pre" > in</ span ></ tt > .</ td >
</ tr >
</ tbody >
</ table >
</ div >
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< div class = "section" id = "id462" >
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< h3 >< a class = "subsection-title" href = "#example" name = "example" > Example</ a ></ h3 >
< pre class = "literal-block" >
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typedef < a href = "./transform.html" class = "identifier" > transform</ a > <
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< a href = "./range-c.html" class = "identifier" > range_c</ a > < int,0,10>
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, < a href = "./plus.html" class = "identifier" > plus</ a > < < a href = "./placeholders.html" class = "identifier" > _1</ a > ,< a href = "./int.html" class = "identifier" > int_</ a > < 7> >
, < a href = "./back-inserter.html" class = "identifier" > back_inserter</ a > < vector0<> >
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> ::type r1;
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typedef < a href = "./transform.html" class = "identifier" > transform</ a > < r1, < a href = "./minus.html" class = "identifier" > minus</ a > < < a href = "./placeholders.html" class = "identifier" > _1</ a > ,< a href = "./int.html" class = "identifier" > int_</ a > < 2> > > ::type r2;
typedef < a href = "./reverse-transform.html" class = "identifier" > reverse_transform</ a > <
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r2
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, < a href = "./minus.html" class = "identifier" > minus</ a > < < a href = "./placeholders.html" class = "identifier" > _1</ a > ,5>
, < a href = "./front-inserter.html" class = "identifier" > front_inserter</ a > < vector0<> >
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> ::type r3;
< a href = "./assert.html" class = "identifier" > BOOST_MPL_ASSERT</ a > (( < a href = "./equal.html" class = "identifier" > equal</ a > < r1, < a href = "./range-c.html" class = "identifier" > range_c</ a > < int,7,17> > ));
< a href = "./assert.html" class = "identifier" > BOOST_MPL_ASSERT</ a > (( < a href = "./equal.html" class = "identifier" > equal</ a > < r2, < a href = "./range-c.html" class = "identifier" > range_c</ a > < int,5,15> > ));
< a href = "./assert.html" class = "identifier" > BOOST_MPL_ASSERT</ a > (( < a href = "./equal.html" class = "identifier" > equal</ a > < r3, < a href = "./range-c.html" class = "identifier" > range_c</ a > < int,0,10> > ));
</ pre >
</ div >
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< div class = "section" id = "id463" >
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< h3 >< a class = "subsection-title" href = "#models" name = "models" > Models</ a ></ h3 >
< ul class = "simple" >
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< li >< a class = "reference internal" href = "./transform.html" > transform</ a ></ li >
< li >< a class = "reference internal" href = "./remove.html" > remove</ a ></ li >
< li >< a class = "reference internal" href = "./replace.html" > replace</ a ></ li >
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</ ul >
</ div >
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< div class = "section" id = "id464" >
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< h3 >< a class = "subsection-title" href = "#see-also" name = "see-also" > See also</ a ></ h3 >
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< p >< a class = "reference internal" href = "./transformation-algorithms.html" > Transformation Algorithms</ a > , < a class = "reference internal" href = "./inserter.html" > Inserter</ a ></ p >
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</ div >
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< div class = "footer-separator" ></ div >
< table class = "footer" >< tr class = "footer" >< td class = "header-group navigation-bar" >< span class = "navigation-group" >< a href = "./inserter.html" class = "navigation-link" > Prev</ a > < a href = "./inserters.html" class = "navigation-link" > Next</ a ></ span >< span class = "navigation-group-separator" > | </ span >< span class = "navigation-group" >< a href = "./inserter.html" class = "navigation-link" > Back</ a > Along</ span >< span class = "navigation-group-separator" > | </ span >< span class = "navigation-group" >< a href = "./algorithms-concepts.html" class = "navigation-link" > Up</ a > < a href = "../refmanual.html" class = "navigation-link" > Home</ a ></ span >< span class = "navigation-group-separator" > | </ span >< span class = "navigation-group" >< a href = "./refmanual_toc.html" class = "navigation-link" > Full TOC</ a ></ span ></ td >
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< td >< div class = "copyright-footer" >< div class = "copyright" > Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</ div >
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at < a class = "reference external" href = "http://www.boost.org/LICENSE_1_0.txt" target = "_top" > http://www.boost.org/LICENSE_1_0.txt</ a > )</ div ></ td ></ tr ></ table ></ body >
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