projects / ceph.git / blame
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1 | // Boost.Geometry (aka GGL, Generic Geometry Library) |
| 2 | ||
| 3 | // Copyright (c) 2007-2015 Barend Gehrels, Amsterdam, the Netherlands. | |
| 4 | // Copyright (c) 2008-2015 Bruno Lalande, Paris, France. | |
| 5 | // Copyright (c) 2009-2015 Mateusz Loskot, London, UK. | |
| 6 | ||
| 7 | // This file was modified by Oracle on 2015. | |
| 8 | // Modifications copyright (c) 2015, Oracle and/or its affiliates. | |
| 9 | ||
| 10 | // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle | |
| 11 | ||
| 12 | // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library | |
| 13 | // (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands. | |
| 14 | ||
| 15 | // Use, modification and distribution is subject to the Boost Software License, | |
| 16 | // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at | |
| 17 | // http://www.boost.org/LICENSE_1_0.txt) | |
| 18 | ||
| 19 | #ifndef BOOST_GEOMETRY_UTIL_COMPRESS_VARIANT_HPP | |
| 20 | #define BOOST_GEOMETRY_UTIL_COMPRESS_VARIANT_HPP | |
| 21 | ||
| 22 | ||
| 23 | #include <boost/mpl/equal_to.hpp> | |
| 24 | #include <boost/mpl/fold.hpp> | |
| 25 | #include <boost/mpl/front.hpp> | |
| 26 | #include <boost/mpl/if.hpp> | |
| 27 | #include <boost/mpl/insert.hpp> | |
| 28 | #include <boost/mpl/int.hpp> | |
| 29 | #include <boost/mpl/set.hpp> | |
| 30 | #include <boost/mpl/size.hpp> | |
| 31 | #include <boost/mpl/vector.hpp> | |
| 32 | #include <boost/variant/variant_fwd.hpp> | |
| 33 | ||
| 34 | ||
| 35 | namespace boost { namespace geometry | |
| 36 | { | |
| 37 | ||
| 38 | ||
| 39 | namespace detail | |
| 40 | { | |
| 41 | ||
| 42 | template <typename Variant> | |
| 43 | struct unique_types: | |
| 44 | boost::mpl::fold< | |
| 45 | typename boost::mpl::reverse_fold< | |
| 46 | typename Variant::types, | |
| 47 | boost::mpl::set<>, | |
| 48 | boost::mpl::insert< | |
| 49 | boost::mpl::placeholders::_1, | |
| 50 | boost::mpl::placeholders::_2 | |
| 51 | > | |
| 52 | >::type, | |
| 53 | boost::mpl::vector<>, | |
| 54 | boost::mpl::push_back | |
| 55 | < | |
| 56 | boost::mpl::placeholders::_1, boost::mpl::placeholders::_2 | |
| 57 | > | |
| 58 | > | |
| 59 | {}; | |
| 60 | ||
| 61 | template <typename Types> | |
| 62 | struct variant_or_single: | |
| 63 | boost::mpl::if_< | |
| 64 | boost::mpl::equal_to< | |
| 65 | boost::mpl::size<Types>, | |
| 66 | boost::mpl::int_<1> | |
| 67 | >, | |
| 68 | typename boost::mpl::front<Types>::type, | |
| 69 | typename make_variant_over<Types>::type | |
| 70 | > | |
| 71 | {}; | |
| 72 | ||
| 73 | } // namespace detail | |
| 74 | ||
| 75 | ||
| 76 | /*! | |
| 77 | \brief Meta-function that takes a boost::variant type and tries to minimize | |
| 78 | it by doing the following: | |
| 79 | - if there's any duplicate types, remove them | |
| 80 | - if the result is a variant of one type, turn it into just that type | |
| 81 | \ingroup utility | |
| 82 | \par Example | |
| 83 | \code | |
| 84 | typedef variant<int, float, int, long> variant_type; | |
| 85 | typedef compress_variant<variant_type>::type compressed; | |
| 86 | typedef boost::mpl::vector<int, float, long> result_types; | |
| 87 | BOOST_MPL_ASSERT(( boost::mpl::equal<compressed::types, result_types> )); | |
| 88 | ||
| 89 | typedef variant<int, int, int> one_type_variant_type; | |
| 90 | typedef compress_variant<one_type_variant_type>::type single_type; | |
| 91 | BOOST_MPL_ASSERT(( boost::equals<single_type, int> )); | |
| 92 | \endcode | |
| 93 | */ | |
| 94 | ||
| 95 | template <typename Variant> | |
| 96 | struct compress_variant: | |
| 97 | detail::variant_or_single< | |
| 98 | typename detail::unique_types<Variant>::type | |
| 99 | > | |
| 100 | {}; | |
| 101 | ||
| 102 | ||
| 103 | }} // namespace boost::geometry | |
| 104 | ||
| 105 | ||
| 106 | #endif // BOOST_GEOMETRY_UTIL_COMPRESS_VARIANT_HPP |