Boost C++ Libraries

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value_of

Description

Returns the type stored at the position of an iterator.

Synopsis

template<
    typename I
    >
struct value_of
{
    typedef unspecified type;
};

Table 1.12. Parameters

Parameter	Requirement	Description
`I`	Model of Forward Iterator	Operation's argument

Expression Semantics

result_of::value_of<I>::type

Return type: Any type

Semantics: Returns the type stored in a sequence at iterator position I.

Header

#include <boost/fusion/iterator/value_of.hpp>
#include <boost/fusion/include/value_of.hpp>

Example

typedef vector<int,int&,const int&> vec;
typedef result_of::begin<vec>::type first;
typedef result_of::next<first>::type second;
typedef result_of::next<second>::type third;

BOOST_MPL_ASSERT((boost::is_same<result_of::value_of<first>::type, int>));
BOOST_MPL_ASSERT((boost::is_same<result_of::value_of<second>::type, int&>));
BOOST_MPL_ASSERT((boost::is_same<result_of::value_of<third>::type, const int&>));