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< title > The MPL Reference Manual: fold< / title >
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< 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 = "./iteration-algorithms.html" class = "navigation-link" > Iteration Algorithms< / a > / < a href = "./fold.html" class = "navigation-link" > fold< / a > < / td >
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< div class = "section" id = "fold" >
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< h1 > < a class = "toc-backref" href = "./iteration-algorithms.html#id1469" > fold< / a > < / h1 >
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< div class = "section" id = "id493" >
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< h3 > < a class = "subsection-title" href = "#synopsis" name = "synopsis" > Synopsis< / a > < / h3 >
< pre class = "literal-block" >
template<
typename Sequence
, typename State
, typename ForwardOp
>
struct < a href = "./fold.html" class = "identifier" > fold< / a >
{
typedef < em > unspecified< / em > type;
};
< / pre >
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< h3 > < a class = "subsection-title" href = "#description" name = "description" > Description< / a > < / h3 >
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< p > Returns the result of the successive application of binary < tt class = "literal" > < span class = "pre" > ForwardOp< / span > < / tt > to the
result of the previous < tt class = "literal" > < span class = "pre" > ForwardOp< / span > < / tt > invocation (< tt class = "literal" > < span class = "pre" > State< / span > < / tt > if it's the first call)
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and every element of the sequence in the range [< tt class = "literal" > < span class = "pre" > < a href = "./begin.html" class = "identifier" > begin< / a > < Sequence> ::type< / span > < / tt > , < tt class = "literal" > < span class = "pre" > < a href = "./end.html" class = "identifier" > end< / a > < Sequence> ::type< / span > < / tt > ) in order.< / p >
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< div class = "section" id = "id495" >
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< h3 > < a class = "subsection-title" href = "#header" name = "header" > Header< / a > < / h3 >
< pre class = "literal-block" >
#include < < a href = "../../../../boost/mpl/fold.hpp" class = "header" > boost/mpl/fold.hpp< / a > >
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< div class = "section" id = "id496" >
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< h3 > < a class = "subsection-title" href = "#parameters" name = "parameters" > Parameters< / a > < / h3 >
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< colgroup >
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< tr > < th class = "head" > Parameter< / th >
< th class = "head" > Requirement< / th >
< th class = "head" > Description< / th >
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< / tr >
< / thead >
< tbody valign = "top" >
< tr > < td > < tt class = "literal" > < span class = "pre" > Sequence< / 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 > A sequence to iterate.< / td >
< / tr >
< tr > < td > < tt class = "literal" > < span class = "pre" > State< / span > < / tt > < / td >
< td > Any type< / td >
< td > The initial state for the first < tt class = "literal" > < span class = "pre" > ForwardOp< / span > < / tt >
application.< / td >
< / tr >
< tr > < td > < tt class = "literal" > < span class = "pre" > ForwardOp< / span > < / tt > < / td >
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< td > Binary < a class = "reference internal" href = "./lambda-expression.html" > Lambda Expression< / a > < / td >
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< td > The operation to be executed on forward
traversal.< / td >
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< / tbody >
< / table >
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< h3 > < a class = "subsection-title" href = "#expression-semantics" name = "expression-semantics" > Expression semantics< / a > < / h3 >
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< p > For any < a class = "reference internal" href = "./forward-sequence.html" > Forward Sequence< / a > < tt class = "literal" > < span class = "pre" > s< / span > < / tt > , binary < a class = "reference internal" href = "./lambda-expression.html" > Lambda Expression< / a > < tt class = "literal" > < span class = "pre" > op< / span > < / tt > , and arbitrary type < tt class = "literal" > < span class = "pre" > state< / span > < / tt > :< / p >
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< pre class = "literal-block" >
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typedef < a href = "./fold.html" class = "identifier" > fold< / a > < s,state,op> ::type t;
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< / 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" / >
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< tr class = "field" > < th class = "field-name" > Return type:< / th > < td class = "field-body" > < p class = "first" > A type.< / p >
< / td >
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< / tr >
< tr class = "field" > < th class = "field-name" > Semantics:< / th > < td class = "field-body" > < p class = "first" > Equivalent to< / p >
< pre class = "last literal-block" >
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typedef < a href = "./iter-fold.html" class = "identifier" > iter_fold< / a > <
s
, state
, apply_wrap2< < a href = "./lambda.html" class = "identifier" > lambda< / a > < op> ::type, < a href = "./placeholders.html" class = "identifier" > _1< / a > , < a href = "./deref.html" class = "identifier" > deref< / a > < < a href = "./placeholders.html" class = "identifier" > _2< / a > > >
> ::type t;
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< / pre >
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< h3 > < a class = "subsection-title" href = "#complexity" name = "complexity" > Complexity< / a > < / h3 >
< p > Linear. Exactly < tt class = "literal" > < span class = "pre" > < a href = "./size.html" class = "identifier" > size< / a > < s> ::value< / span > < / tt > applications of < tt class = "literal" > < span class = "pre" > op< / span > < / tt > .< / p >
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< div class = "section" id = "id499" >
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< h3 > < a class = "subsection-title" href = "#example" name = "example" > Example< / a > < / h3 >
< pre class = "literal-block" >
typedef < a href = "./vector.html" class = "identifier" > vector< / a > < long,float,short,double,float,long,long double> types;
typedef < a href = "./fold.html" class = "identifier" > fold< / a > <
types
, < a href = "./int.html" class = "identifier" > int_< / a > < 0>
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, < a href = "./if.html" class = "identifier" > if_< / a > < is_float< < a href = "./placeholders.html" class = "identifier" > _2< / a > > ,< a href = "./next.html" class = "identifier" > next< / a > < < a href = "./placeholders.html" class = "identifier" > _1< / a > > ,< a href = "./placeholders.html" class = "identifier" > _1< / a > >
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> ::type number_of_floats;
< a href = "./assert-relation.html" class = "identifier" > BOOST_MPL_ASSERT_RELATION< / a > ( number_of_floats::value, ==, 4 );
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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 = "./algorithms.html" > Algorithms< / a > , < a class = "reference internal" href = "./accumulate.html" > accumulate< / a > , < a class = "reference internal" href = "./reverse-fold.html" > reverse_fold< / a > , < a class = "reference internal" href = "./iter-fold.html" > iter_fold< / a > , < a class = "reference internal" href = "./reverse-iter-fold.html" > reverse_iter_fold< / a > , < a class = "reference internal" href = "./copy.html" > copy< / a > , < a class = "reference internal" href = "./copy-if.html" > copy_if< / a > < / p >
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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
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