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Diffstat (limited to 'boost/spirit/home/x3/support/unused.hpp')
-rw-r--r-- | boost/spirit/home/x3/support/unused.hpp | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/boost/spirit/home/x3/support/unused.hpp b/boost/spirit/home/x3/support/unused.hpp new file mode 100644 index 0000000000..cf42d13098 --- /dev/null +++ b/boost/spirit/home/x3/support/unused.hpp @@ -0,0 +1,93 @@ +/*============================================================================= + Copyright (c) 2001-2014 Joel de Guzman + Copyright (c) 2001-2011 Hartmut Kaiser + + Distributed under the Boost Software License, Version 1.0. (See accompanying + file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) +==============================================================================*/ +#if !defined(BOOST_SPIRIT_X3_UNUSED_APRIL_16_2006_0616PM) +#define BOOST_SPIRIT_X3_UNUSED_APRIL_16_2006_0616PM + +#if defined(_MSC_VER) +#pragma once +#endif + +#include <ostream> +#include <istream> +#include <boost/mpl/identity.hpp> + +#if defined(BOOST_MSVC) +# pragma warning(push) +# pragma warning(disable: 4522) // multiple assignment operators specified warning +#endif + +/////////////////////////////////////////////////////////////////////////////// +namespace boost { namespace spirit { namespace x3 +{ + struct unused_type + { + unused_type() + { + } + + template <typename T> + unused_type(T const&) + { + } + + template <typename T> + unused_type const& + operator=(T const&) const + { + return *this; + } + + template <typename T> + unused_type& + operator=(T const&) + { + return *this; + } + + unused_type const& + operator=(unused_type const&) const + { + return *this; + } + + unused_type& + operator=(unused_type const&) + { + return *this; + } + + // unused_type can also masquerade as an empty context (see context.hpp) + + template <typename ID> + struct get_result : mpl::identity<unused_type> {}; + + template <typename ID> + unused_type get(ID) const + { + return unused_type(); + } + }; + + unused_type const unused = unused_type(); + + inline std::ostream& operator<<(std::ostream& out, unused_type const&) + { + return out; + } + + inline std::istream& operator>>(std::istream& in, unused_type&) + { + return in; + } +}}} + +#if defined(BOOST_MSVC) +# pragma warning(pop) +#endif + +#endif |