Description

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A metafunction that establishes the conceptual classification of a particular Sequence or Iterator (see Iterator Concepts and Sequence Concepts).

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Synopsis

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Synopsis

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namespace traits
{
    template <typename T>
    struct category_of
    {
        typedef unspecified type;
    };
}

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Parameters

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Parameters

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Expression =======

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

typedef traits::category_of<T>::type category;

Return type:

The return type is derived from one of:

namespace boost { namespace fusion
{
    struct incrementable_sequence_tag {};

    struct single_pass_sequence_tag
        : incrementable_sequence_tag {};

    struct forward_traversal_tag
        : single_pass_sequence_tag {};

    struct bidirectional_traversal_tag
        : forward_traversal_tag {};

    struct random_access_traversal_tag
        : bidirectional_traversal_tag {};
}}

And optionally from:

namespace boost { namespace fusion
{
    struct associative_tag {};
}}

Semantics: Establishes the conceptual classification of a particular Sequence or Iterator.

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Header

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Header

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#include <boost/fusion/support/category_of.hpp>
#include <boost/fusion/include/category_of.hpp>

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Example

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Example

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using boost::is_base_of;
typedef traits::category_of<list<> >::type list_category;
typedef traits::category_of<vector<> >::type vector_category;
BOOST_MPL_ASSERT(( is_base_of<forward_traversal_tag, list_category> ));
BOOST_MPL_ASSERT(( is_base_of<random_access_traversal_tag, vector_category> ));