Boost C++ Libraries

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prior

Description

Returns the type of the previous iterator in a sequence.

Synopsis

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

Table 1.14. Parameters

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

Expression Semantics

result_of::prior<I>::type

Return type: A model of the same iterator concept as I.

Semantics: Returns an iterator to the previous element in the sequence before I.

Header

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

Example

typedef vector<int,double> vec;
typedef result_of::next<result_of::begin<vec>::type>::type second;

BOOST_MPL_ASSERT((boost::is_same<result_of::value_of<second>::type, double>));

typedef result_of::prior<second>::type first;
BOOST_MPL_ASSERT((boost::is_same<result_of::value_of<first>::type, int>));