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62 lines
2.2 KiB
C++
62 lines
2.2 KiB
C++
#pragma once
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#include <boost/range/counting_range.hpp>
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#include <boost/range/adaptor/transformed.hpp>
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#include <type_traits>
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namespace collections
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{
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namespace internal
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{
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template <typename ResultType, typename CountingType, typename BeginType, typename EndType>
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auto rangeImpl(BeginType begin, EndType end)
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{
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if constexpr (std::is_same_v<ResultType, CountingType>)
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return boost::counting_range<CountingType>(static_cast<CountingType>(begin), static_cast<CountingType>(end));
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else
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return boost::counting_range<CountingType>(static_cast<CountingType>(begin), static_cast<CountingType>(end))
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| boost::adaptors::transformed([](CountingType x) { return static_cast<ResultType>(x); });
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}
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}
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/// For loop adaptor which is used to iterate through a half-closed interval [begin, end).
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/// The parameters `begin` and `end` can have any integral or enum types.
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template <typename BeginType, typename EndType>
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requires((std::is_integral_v<BeginType> || std::is_enum_v<BeginType>) &&
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(std::is_integral_v<EndType> || std::is_enum_v<EndType>) &&
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(!std::is_enum_v<BeginType> || !std::is_enum_v<EndType> || std::is_same_v<BeginType, EndType>))
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inline auto range(BeginType begin, EndType end)
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{
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if constexpr (std::is_integral_v<BeginType> && std::is_integral_v<EndType>)
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{
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using CommonType = std::common_type_t<BeginType, EndType>;
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return internal::rangeImpl<CommonType, CommonType>(begin, end);
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}
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else if constexpr (std::is_enum_v<BeginType>)
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{
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return internal::rangeImpl<BeginType, std::underlying_type_t<BeginType>>(begin, end);
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}
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else
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{
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return internal::rangeImpl<EndType, std::underlying_type_t<EndType>>(begin, end);
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}
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}
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/// For loop adaptor which is used to iterate through a half-closed interval [0, end).
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/// The parameter `end` can have any integral or enum type.
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/// The same as range(0, end).
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template <typename Type>
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requires(std::is_integral_v<Type> || std::is_enum_v<Type>)
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inline auto range(Type end)
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{
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if constexpr (std::is_integral_v<Type>)
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return internal::rangeImpl<Type, Type>(0, end);
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else
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return internal::rangeImpl<Type, std::underlying_type_t<Type>>(0, end);
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}
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}
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