Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for an old version of Boost. Click here to view this page for the latest version.


// Boost.Bimap
// Copyright (c) 2006-2007 Matias Capeletto
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at

/// \file tags/support/value_type_of.hpp
/// \brief Consistent way to access the value type of a tagged or untagged type.


#if defined(_MSC_VER)
#pragma once

#include <boost/config.hpp>

#include <boost/bimap/tags/tagged.hpp>

/** \struct boost::bimaps::tags::support::value_type_of
\brief Metafunction to work with tagged and untagged type uniformly

template< class Type >
struct value_type_of
    typedef {UntaggedType} type;

If the type is tagged this metafunction returns Type::value_type, and if it is not
tagged it return the same type. This allows to work consistenly with tagged and
untagged types.

See also tagged, tag_of.


namespace boost {
namespace bimaps {
namespace tags {
namespace support {

// value_type_of metafunction

template< class Type >
struct value_type_of
    typedef Type type;

template< class Type, class Tag >
struct value_type_of< tagged< Type, Tag > >
    typedef Type type;

} // namespace support
} // namespace tags
} // namespace bimaps
} // namespace boost