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author | Lauren Budorick <lauren@mapbox.com> | 2017-04-27 15:56:55 -0700 |
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committer | GitHub <noreply@github.com> | 2017-04-27 15:56:55 -0700 |
commit | f6e79d70735361438655f279c8699a786d25458c (patch) | |
tree | cc01ae7aba097bae4aa84beb12ac6b8f34f4d51a /include/mbgl/util/indexed_tuple.hpp | |
parent | 839ad87f37a4880804fb4c79157d998ac59954b5 (diff) | |
download | qtlocation-mapboxgl-f6e79d70735361438655f279c8699a786d25458c.tar.gz |
[core] Render fill-extrusion layers (#8431)
Diffstat (limited to 'include/mbgl/util/indexed_tuple.hpp')
-rw-r--r-- | include/mbgl/util/indexed_tuple.hpp | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/include/mbgl/util/indexed_tuple.hpp b/include/mbgl/util/indexed_tuple.hpp new file mode 100644 index 0000000000..a414639530 --- /dev/null +++ b/include/mbgl/util/indexed_tuple.hpp @@ -0,0 +1,56 @@ +#pragma once + +#include <mbgl/util/type_list.hpp> + +#include <type_traits> +#include <tuple> + +namespace mbgl { + +template <class T, class... Ts> +struct TypeIndex; + +template <class T, class... Ts> +struct TypeIndex<T, T, Ts...> : std::integral_constant<std::size_t, 0> {}; + +template <class T, class U, class... Ts> +struct TypeIndex<T, U, Ts...> : std::integral_constant<std::size_t, 1 + TypeIndex<T, Ts...>::value> {}; + +template <class...> class IndexedTuple; + +// A tuple of Ts, where individual members can be accessed via `t.get<I>()` for I ∈ Is. +// +// See https://github.com/mapbox/cpp/blob/master/C%2B%2B%20Structural%20Metaprogramming.md +// for motivation. +// +template <class... Is, class... Ts> +class IndexedTuple<TypeList<Is...>, TypeList<Ts...>> : public std::tuple<Ts...> { +public: + static_assert(sizeof...(Is) == sizeof...(Ts), "IndexedTuple size mismatch"); + + using std::tuple<Ts...>::tuple; + + template <class I> + static constexpr std::size_t Index = TypeIndex<I, Is...>::value; + + template <class I> + auto& get() { + return std::get<Index<I>>(*this); + } + + template <class I> + const auto& get() const { + return std::get<Index<I>>(*this); + } + + template <class... Js, class... Us> + IndexedTuple<TypeList<Is..., Js...>, TypeList<Ts..., Us...>> + concat(const IndexedTuple<TypeList<Js...>, TypeList<Us...>>& other) const { + return IndexedTuple<TypeList<Is..., Js...>, TypeList<Ts..., Us...>> { + get<Is>()..., + other.template get<Js>()... + }; + } +}; + +} // namespace mbgl |