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< title > pair</ title >
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< a accesskey = "p" href = "deduce_sequence.html" >< img src = "../../../../../../doc/html/images/prev.png" alt = "Prev" ></ a >< a accesskey = "u" href = "../support.html" >< img src = "../../../../../../doc/html/images/up.png" alt = "Up" ></ a >< a accesskey = "h" href = "../../index.html" >< img src = "../../../../../../doc/html/images/home.png" alt = "Home" ></ a >< a accesskey = "n" href = "../iterator.html" >< img src = "../../../../../../doc/html/images/next.png" alt = "Next" ></ a >
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< div class = "section" lang = "en" >
< div class = "titlepage" >< div >< div >< h3 class = "title" >
< a name = "fusion.support.pair" ></ a >< a href = "pair.html" title = "pair" > pair</ a ></ h3 ></ div ></ div ></ div >
< a name = "fusion.support.pair.description" ></ a >< h4 >
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< a name = "id466114" ></ a >
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< a href = "pair.html#fusion.support.pair.description" > Description</ a >
</ h4 >
< p >
Fusion < tt class = "computeroutput" >< span class = "identifier" > pair</ span ></ tt > type is a half
runtime pair. A half runtime pair is similar to a < a href = "../adapted/std__pair.html" title = "std::pair" >< tt class = "computeroutput" >< span class = "identifier" > std</ span >< span class = "special" > ::</ span >< span class = "identifier" > pair</ span ></ tt ></ a > ,
but, unlike < a href = "../adapted/std__pair.html" title = "std::pair" >< tt class = "computeroutput" >< span class = "identifier" > std</ span >< span class = "special" > ::</ span >< span class = "identifier" > pair</ span ></ tt ></ a > ,
the first type does not have data. It is used as elements in < span class = "underline" > _map</ span > _s,
for example.
</ p >
< a name = "fusion.support.pair.synopsis" ></ a >< h4 >
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< a name = "id466219" ></ a >
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< a href = "pair.html#fusion.support.pair.synopsis" > Synopsis</ a >
</ h4 >
< pre class = "programlisting" >
< span class = "keyword" > template</ span > < span class = "special" > < </ span >< span class = "keyword" > typename</ span > < span class = "identifier" > First</ span >< span class = "special" > ,</ span > < span class = "keyword" > typename</ span > < span class = "identifier" > Second</ span >< span class = "special" > > </ span >
< span class = "keyword" > struct</ span > < span class = "identifier" > pair</ span >< span class = "special" > ;</ span >
< span class = "keyword" > namespace</ span > < span class = "identifier" > result_of</ span >
< span class = "special" > {</ span >
< span class = "keyword" > template</ span > < span class = "special" > < </ span >< span class = "keyword" > typename</ span > < span class = "identifier" > First</ span >< span class = "special" > ,</ span > < span class = "keyword" > typename</ span > < span class = "identifier" > Second</ span >< span class = "special" > > </ span >
< span class = "keyword" > struct</ span > < span class = "identifier" > first</ span >< span class = "special" > ;</ span >
< span class = "keyword" > template</ span > < span class = "special" > < </ span >< span class = "keyword" > typename</ span > < span class = "identifier" > First</ span >< span class = "special" > ,</ span > < span class = "keyword" > typename</ span > < span class = "identifier" > Second</ span >< span class = "special" > > </ span >
< span class = "keyword" > struct</ span > < span class = "identifier" > second</ span >< span class = "special" > ;</ span >
< span class = "keyword" > template</ span > < span class = "special" > < </ span >< span class = "keyword" > typename</ span > < span class = "identifier" > First</ span >< span class = "special" > ,</ span > < span class = "keyword" > typename</ span > < span class = "identifier" > Second</ span >< span class = "special" > > </ span >
< span class = "keyword" > struct</ span > < span class = "identifier" > make_pair</ span >< span class = "special" > ;</ span >
< span class = "special" > }</ span >
< span class = "keyword" > template</ span > < span class = "special" > < </ span >< span class = "keyword" > typename</ span > < span class = "identifier" > First</ span >< span class = "special" > ,</ span > < span class = "keyword" > typename</ span > < span class = "identifier" > Second</ span >< span class = "special" > > </ span >
< span class = "keyword" > typename</ span > < span class = "identifier" > result_of</ span >< span class = "special" > ::</ span >< span class = "identifier" > make_pair</ span >< span class = "special" > < </ span >< span class = "identifier" > First</ span >< span class = "special" > ,</ span >< span class = "identifier" > Second</ span >< span class = "special" > > ::</ span >< span class = "identifier" > type</ span >
< span class = "identifier" > make_pair</ span >< span class = "special" > (</ span >< span class = "identifier" > Second</ span > < span class = "keyword" > const</ span > < span class = "special" > & );</ span >
</ pre >
< a name = "fusion.support.pair.template_parameters" ></ a >< h4 >
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< a name = "id466662" ></ a >
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< a href = "pair.html#fusion.support.pair.template_parameters" > Template parameters</ a >
</ h4 >
< div class = "informaltable" >< table class = "table" >
< colgroup >
< col >
< col >
</ colgroup >
< thead >< tr >
< th >
< p >
Parameter
</ p >
</ th >
< th >
< p >
Description
</ p >
</ th >
</ tr ></ thead >
< tbody >
< tr >
< td >
< p >
First
</ p >
</ td >
< td >
< p >
The first type. This is purely a type. No data is held.
</ p >
</ td >
</ tr >
< tr >
< td >
< p >
Second
</ p >
</ td >
< td >
< p >
The second type. This contains data.
</ p >
</ td >
</ tr >
</ tbody >
</ table ></ div >
< div class = "variablelist" >
< p class = "title" >< b > Notation</ b ></ p >
< dl >
< dt >< span class = "term" >< tt class = "computeroutput" >< span class = "identifier" > P</ span ></ tt ></ span ></ dt >
< dd >< p >
Fusion pair type
</ p ></ dd >
< dt >< span class = "term" >< tt class = "computeroutput" >< span class = "identifier" > p</ span ></ tt > ,
< tt class = "computeroutput" >< span class = "identifier" > p2</ span ></ tt ></ span ></ dt >
< dd >< p >
Fusion pairs
</ p ></ dd >
< dt >< span class = "term" >< tt class = "computeroutput" >< span class = "identifier" > F</ span ></ tt > ,
< tt class = "computeroutput" >< span class = "identifier" > S</ span ></ tt ></ span ></ dt >
< dd >< p >
Arbitrary types
</ p ></ dd >
< dt >< span class = "term" >< tt class = "computeroutput" >< span class = "identifier" > s</ span ></ tt ></ span ></ dt >
< dd >< p >
Value of type < tt class = "computeroutput" >< span class = "identifier" > S</ span ></ tt >
</ p ></ dd >
< dt >< span class = "term" >< tt class = "computeroutput" >< span class = "identifier" > o</ span ></ tt ></ span ></ dt >
< dd >< p >
Output stream
</ p ></ dd >
< dt >< span class = "term" >< tt class = "computeroutput" >< span class = "identifier" > i</ span ></ tt ></ span ></ dt >
< dd >< p >
Input stream
</ p ></ dd >
</ dl >
</ div >
< a name = "fusion.support.pair.expression_semantics" ></ a >< h4 >
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< a name = "id466942" ></ a >
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< a href = "pair.html#fusion.support.pair.expression_semantics" > Expression Semantics</ a >
</ h4 >
< div class = "informaltable" >< table class = "table" >
< colgroup >
< col >
< col >
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< col >
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</ colgroup >
< thead >< tr >
< th >
< p >
Expression
</ p >
</ th >
< th >
< p >
Semantics
</ p >
</ th >
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< td class = "auto-generated" > </ td >
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</ tr ></ thead >
< tbody >
< tr >
< td >
< p >
< tt class = "computeroutput" >< span class = "identifier" > P</ span >< span class = "special" > ::</ span >< span class = "identifier" > first_type</ span ></ tt >
</ p >
</ td >
< td >
< p >
The type of the first template parameter, < tt class = "computeroutput" >< span class = "identifier" > F</ span ></ tt > ,
equivalent to < tt class = "computeroutput" >< span class = "identifier" > result_of</ span >< span class = "special" > ::</ span >< span class = "identifier" > first</ span >< span class = "special" > < </ span >< span class = "identifier" > P</ span >< span class = "special" > > ::</ span >< span class = "identifier" > type</ span ></ tt > .
</ p >
</ td >
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< td class = "auto-generated" > </ td >
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</ tr >
< tr >
< td >
< p >
< tt class = "computeroutput" >< span class = "identifier" > P</ span >< span class = "special" > ::</ span >< span class = "identifier" > second_type</ span ></ tt >
</ p >
</ td >
< td >
< p >
The type of the second template parameter, < tt class = "computeroutput" >< span class = "identifier" > S</ span ></ tt > ,
equivalent to < tt class = "computeroutput" >< span class = "identifier" > result_of</ span >< span class = "special" > ::</ span >< span class = "identifier" > second</ span >< span class = "special" > < </ span >< span class = "identifier" > P</ span >< span class = "special" > > ::</ span >< span class = "identifier" > type</ span ></ tt > .
</ p >
</ td >
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< td class = "auto-generated" > </ td >
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</ tr >
< tr >
< td >
< p >
< tt class = "computeroutput" >< span class = "identifier" > P</ span >< span class = "special" > ()</ span ></ tt >
</ p >
</ td >
< td >
< p >
Default construction.
</ p >
</ td >
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< td class = "auto-generated" > </ td >
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</ tr >
< tr >
< td >
< p >
< tt class = "computeroutput" >< span class = "identifier" > P</ span >< span class = "special" > (</ span >< span class = "identifier" > s</ span >< span class = "special" > )</ span ></ tt >
</ p >
</ td >
< td >
< p >
Construct a pair given value for the second type, < tt class = "computeroutput" >< span class = "identifier" > s</ span ></ tt > .
</ p >
</ td >
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< td class = "auto-generated" > </ td >
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</ tr >
< tr >
< td >
< p >
< tt class = "computeroutput" >< span class = "identifier" > P</ span >< span class = "special" > (</ span >< span class = "identifier" > p2</ span >< span class = "special" > )</ span ></ tt >
</ p >
</ td >
< td >
< p >
Copy constructs a pair from another pair, < tt class = "computeroutput" >< span class = "identifier" > p2</ span ></ tt > .
</ p >
</ td >
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< td class = "auto-generated" > </ td >
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</ tr >
< tr >
< td >
< p >
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< tt class = "computeroutput" >< span class = "identifier" > p</ span >< span class = "special" > .</ span >< span class = "identifier" > second</ span ></ tt >
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</ p >
</ td >
< td >
< p >
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Get the data from < tt class = "computeroutput" >< span class = "identifier" > p1</ span >< span class = "special" > .]]</ span > < span class = "special" > [[</ span ></ tt > p
= p2< tt class = "computeroutput" >< span class = "special" > ]</ span > < span class = "special" > [</ span >< span class = "identifier" > Assigns</ span > < span class = "identifier" > a</ span >
< span class = "identifier" > pair</ span >< span class = "special" > ,</ span >
</ tt > p1< tt class = "computeroutput" >< span class = "special" > ,</ span > < span class = "identifier" > from</ span >
< span class = "identifier" > another</ span > < span class = "identifier" > pair</ span >< span class = "special" > ,</ span > </ tt > p2< tt class = "computeroutput" >< span class = "special" > .]]</ span >
< span class = "special" > [[</ span >< span class = "identifier" > make_pair</ span >< span class = "special" > < </ span >< span class = "identifier" > F</ span >< span class = "special" > > (</ span >< span class = "identifier" > s</ span >< span class = "special" > )]</ span > < span class = "special" > [</ span >< span class = "identifier" > Make</ span > < span class = "identifier" > a</ span >
< span class = "identifier" > pair</ span > < span class = "identifier" > given</ span >
< span class = "identifier" > the</ span > < span class = "identifier" > first</ span >
< span class = "identifier" > type</ span >< span class = "special" > ,</ span >
</ tt > F< tt class = "computeroutput" >< span class = "special" > ,</ span > < span class = "keyword" > and</ span >
< span class = "identifier" > a</ span > < span class = "identifier" > value</ span >
< span class = "keyword" > for</ span > < span class = "identifier" > the</ span >
< span class = "identifier" > second</ span > < span class = "identifier" > type</ span >< span class = "special" > ,</ span > </ tt > s< tt class = "computeroutput" >< span class = "special" > .</ span >
< span class = "identifier" > The</ span > < span class = "identifier" > second</ span >
< span class = "identifier" > type</ span > < span class = "identifier" > assumes</ span >
< span class = "identifier" > the</ span > < span class = "identifier" > type</ span >
< span class = "identifier" > of</ span > </ tt > s< tt class = "computeroutput" >< span class = "special" > ]]</ span >
< span class = "special" > [[</ span ></ tt > o << p< tt class = "computeroutput" >< span class = "special" > ]</ span > < span class = "special" > [</ span >< span class = "identifier" > Output</ span > </ tt > p< tt class = "computeroutput" > < span class = "identifier" > to</ span >
< span class = "identifier" > output</ span > < span class = "identifier" > stream</ span >< span class = "special" > ,</ span > </ tt > o< tt class = "computeroutput" >< span class = "special" > .]]</ span >
< span class = "special" > [[</ span ></ tt > i >> p< tt class = "computeroutput" >< span class = "special" > ]</ span > < span class = "special" > [</ span >< span class = "identifier" > Input</ span > </ tt > p< tt class = "computeroutput" > < span class = "identifier" > from</ span >
< span class = "identifier" > input</ span > < span class = "identifier" > stream</ span >< span class = "special" > ,</ span > </ tt > i< tt class = "computeroutput" >< span class = "special" > .]]</ span >
< span class = "special" > [[</ span ></ tt > p == p2< tt class = "computeroutput" >< span class = "special" > ]</ span >
< span class = "special" > [</ span >< span class = "identifier" > Tests</ span >
< span class = "identifier" > two</ span > < span class = "identifier" > pairs</ span >
< span class = "keyword" > for</ span > < span class = "identifier" > equality</ span >< span class = "special" > .]]</ span > < span class = "special" > [[</ span ></ tt > p
!= p2`
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</ p >
</ td >
< td >
< p >
Tests two pairs for inequality.
</ p >
</ td >
</ tr >
</ tbody >
</ table ></ div >
< a name = "fusion.support.pair.header" ></ a >< h4 >
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< a name = "id467922" ></ a >
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< a href = "pair.html#fusion.support.pair.header" > Header</ a >
</ h4 >
< pre class = "programlisting" >
< span class = "preprocessor" > #include</ span > < span class = "special" > < </ span >< span class = "identifier" > boost</ span >< span class = "special" > /</ span >< span class = "identifier" > fusion</ span >< span class = "special" > /</ span >< span class = "identifier" > support</ span >< span class = "special" > /</ span >< span class = "identifier" > pair</ span >< span class = "special" > .</ span >< span class = "identifier" > hpp</ span >< span class = "special" > > </ span >
< span class = "preprocessor" > #include</ span > < span class = "special" > < </ span >< span class = "identifier" > boost</ span >< span class = "special" > /</ span >< span class = "identifier" > fusion</ span >< span class = "special" > /</ span >< span class = "identifier" > include</ span >< span class = "special" > /</ span >< span class = "identifier" > pair</ span >< span class = "special" > .</ span >< span class = "identifier" > hpp</ span >< span class = "special" > > </ span >
</ pre >
< a name = "fusion.support.pair.example" ></ a >< h4 >
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< a name = "id468079" ></ a >
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< a href = "pair.html#fusion.support.pair.example" > Example</ a >
</ h4 >
< pre class = "programlisting" >
< span class = "identifier" > pair</ span >< span class = "special" > < </ span >< span class = "keyword" > int</ span >< span class = "special" > ,</ span > < span class = "keyword" > char</ span >< span class = "special" > > </ span > < span class = "identifier" > p</ span >< span class = "special" > (</ span >< span class = "char" > 'X'</ span >< span class = "special" > );</ span >
< span class = "identifier" > std</ span >< span class = "special" > ::</ span >< span class = "identifier" > cout</ span > < span class = "special" > << </ span > < span class = "identifier" > p</ span > < span class = "special" > << </ span > < span class = "identifier" > std</ span >< span class = "special" > ::</ span >< span class = "identifier" > endl</ span >< span class = "special" > ;</ span >
< span class = "identifier" > std</ span >< span class = "special" > ::</ span >< span class = "identifier" > cout</ span > < span class = "special" > << </ span > < span class = "identifier" > make_pair</ span >< span class = "special" > < </ span >< span class = "keyword" > int</ span >< span class = "special" > > (</ span >< span class = "char" > 'X'</ span >< span class = "special" > )</ span > < span class = "special" > << </ span > < span class = "identifier" > std</ span >< span class = "special" > ::</ span >< span class = "identifier" > endl</ span >< span class = "special" > ;</ span >
< span class = "identifier" > assert</ span >< span class = "special" > ((</ span >< span class = "identifier" > p</ span > < span class = "special" > ==</ span > < span class = "identifier" > make_pair</ span >< span class = "special" > < </ span >< span class = "keyword" > int</ span >< span class = "special" > > (</ span >< span class = "char" > 'X'</ span >< span class = "special" > )));</ span >
</ pre >
</ div >
< table xmlns:rev = "http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width = "100%" >< tr >
< td align = "left" ></ td >
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< td align = "right" >< div class = "copyright-footer" > Copyright © 2001-2007 Joel de Guzman, Dan Marsden, Tobias
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Schwinger< p >
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at < a href = "http://www.boost.org/LICENSE_1_0.txt" target = "_top" > http://www.boost.org/LICENSE_1_0.txt</ a > )
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</ p >
</ div ></ td >
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</ tr ></ table >
< hr >
< div class = "spirit-nav" >
< a accesskey = "p" href = "deduce_sequence.html" >< img src = "../../../../../../doc/html/images/prev.png" alt = "Prev" ></ a >< a accesskey = "u" href = "../support.html" >< img src = "../../../../../../doc/html/images/up.png" alt = "Up" ></ a >< a accesskey = "h" href = "../../index.html" >< img src = "../../../../../../doc/html/images/home.png" alt = "Home" ></ a >< a accesskey = "n" href = "../iterator.html" >< img src = "../../../../../../doc/html/images/next.png" alt = "Next" ></ a >
</ div >
</ body >
</ html >
