// Boost.Geometry (aka GGL, Generic Geometry Library)
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// Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
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// Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
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// Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
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// This file was modified by Oracle on 2020.
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// Modifications copyright (c) 2020, Oracle and/or its affiliates.
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// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
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// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
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// (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
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// Use, modification and distribution is subject to the Boost Software License,
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// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_GEOMETRY_CORE_TAG_CAST_HPP
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#define BOOST_GEOMETRY_CORE_TAG_CAST_HPP
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#include <type_traits>
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namespace boost { namespace geometry
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{
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/*!
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\brief Metafunction defining a type being either the specified tag, or one
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of the specified basetags if the type inherits from them.
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\details Tags can inherit each other. A multi_point inherits, for example,
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both the multi_tag and the pointlike_tag. Often behaviour can be shared
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between different geometry types. A tag, found by the metafunction tag,
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can be casted to a more basic tag, and then dispatched by that tag.
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\ingroup core
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\tparam Tag The tag to be casted to one of the base tags
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\tparam BaseTags Base tags
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\qbk{[include reference/core/tag_cast.qbk]}
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*/
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template <typename Tag, typename ...BaseTags>
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struct tag_cast
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{
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typedef Tag type;
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};
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#ifndef DOXYGEN_NO_SPECIALIZATIONS
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template <typename Tag, typename BaseTag, typename ...BaseTags>
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struct tag_cast<Tag, BaseTag, BaseTags...>
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{
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typedef std::conditional_t
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<
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std::is_base_of<BaseTag, Tag>::value,
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BaseTag,
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typename tag_cast
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<
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Tag, BaseTags...
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>::type
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> type;
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};
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#endif // DOXYGEN_NO_SPECIALIZATIONS
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_CORE_TAG_CAST_HPP
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