has_key

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Returns the result type of has_key.

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template<
    typename Seq,
    typename Key>
struct has_key
{
    typedef unspecified type;
};

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Table 1.29. Parameters

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Table 1.29. Parameters

=======

Table 1.33. Parameters

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Table 1.33. Parameters

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Table 1.33. Parameters

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Table 1.33. Parameters

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Table 1.33. Parameters

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Parameter	Requirement	Description
`Seq`	A model of Forward Sequence	Argument sequence
`Key`	Any type	Key type

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Expression =======

Expression >>>>>>> .merge-right.r57125 Semantics

result_of::has_key<Seq, Key>::type

Return type: An MPL Integral Constant.

Semantics: Returns mpl::true_ if Seq contains an element with key type Key, returns mpl::false_ otherwise.

Header

#include <boost/fusion/sequence/intrinsic/has_key.hpp>
#include <boost/fusion/include/has_key.hpp>

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typedef map<pair<int, char>, pair<char, char>, pair<double, char> > mymap;
BOOST_MPL_ASSERT((result_of::has_key<mymap, int>));
BOOST_MPL_ASSERT_NOT((result_of::has_key<mymap, void*>));