#pragma once
#if __cplusplus < 202002L
// Components for manipulating non-owning sequences of objects -*- C++ -*-

// Copyright (C) 2019-2024 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file span
 *  This is a Standard C++ Library header.
 */

//
// P0122 span library
// Contributed by ThePhD
//

#ifndef _GLIBCXX_SPAN
#define _GLIBCXX_SPAN 1

#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif
#include <bits/ranges_base.h>
#include <array>
#include <cstddef>
#include <debug/debug.h>
#ifdef ARDUINO_ARCH_SAM
//SAM架构将byte定义在内置头文件中，标准库中未定义
#include <Arduino.h>
#endif
#ifdef __cpp_lib_span // C++ >= 20 && concepts
namespace std _GLIBCXX_VISIBILITY(default)
{
	_GLIBCXX_BEGIN_NAMESPACE_VERSION

	_GLIBCXX17_INLINE constexpr size_t dynamic_extent = static_cast<size_t>(-1);

	template <typename _Type, size_t _Extent>
	class span;

	namespace __detail
	{
		template <typename _Tp>
		_CSL_Struct17Concept(__is_span, _GLIBCXX17_INLINE, false, );

		template <typename _Tp, size_t _Num>
		_CSL_Struct17Concept(__is_span, _GLIBCXX17_INLINE, true, <span<_Tp, _Num>>);

		template <typename _Tp>
		_CSL_Struct17Concept(__is_std_array, _GLIBCXX17_INLINE, false, );

		template <typename _Tp, size_t _Num>
		_CSL_Struct17Concept(__is_std_array, _GLIBCXX17_INLINE, true, <std::array<_Tp, _Num>>);

		template <size_t _Extent>
		class __extent_storage
		{
		public:
			constexpr __extent_storage(size_t) noexcept
			{
			}

			static constexpr size_t
			_M_extent() noexcept
			{
				return _Extent;
			}
		};

		template <>
		class __extent_storage<dynamic_extent>
		{
		public:
			constexpr __extent_storage(size_t __extent) noexcept
				: _M_extent_value(__extent)
			{
			}

			constexpr size_t
			_M_extent() const noexcept
			{
				return this->_M_extent_value;
			}

		private:
			size_t _M_extent_value;
		};
	} // namespace __detail

	template <typename _Type, size_t _Extent = dynamic_extent>
	class span // 不采用GCC的explicit重载构造，因为C++20之前都不支持且必要性不大
	{
		template <size_t _Offset, size_t _Count>
		static constexpr size_t
		_S_subspan_extent()
		{
			if _GLIBCXX17_CONSTEXPR (_Count != dynamic_extent)
				return _Count;
			else if _GLIBCXX17_CONSTEXPR (extent != dynamic_extent)
				return _Extent - _Offset;
			else
				return dynamic_extent;
		}

		// _GLIBCXX_RESOLVE_LIB_DEFECTS
		// 3255. span's array constructor is too strict
		template <typename _Tp, size_t _ArrayExtent, typename = enable_if_t<_Extent == dynamic_extent || _ArrayExtent == _Extent>>
		using __is_compatible_array = __is_array_convertible<_Type, _Tp>;

		template <typename _Ref>
		using __is_compatible_ref = __is_array_convertible<_Type, remove_reference_t<_Ref>>;

		// Nested type so that _Type is not an associated class of iterator.
		struct __iter_tag;

	public:
		// member types
		using element_type = _Type;
		using value_type = remove_cv_t<_Type>;
		using size_type = size_t;
		using difference_type = ptrdiff_t;
		using pointer = _Type *;
		using const_pointer = const _Type *;
		using reference = element_type &;
		using const_reference = const element_type &;
		using iterator = __gnu_cxx::__normal_iterator<pointer, __iter_tag>;
		using reverse_iterator = std::reverse_iterator<iterator>;
#if __cplusplus > 202002L
		using const_iterator = std::const_iterator<iterator>;
		using const_reverse_iterator = std::const_iterator<reverse_iterator>;
#endif

		// member constants
		static constexpr size_t extent = _Extent;

		// constructors, copy and assignment

		template <typename = std::enable_if_t<_Extent == dynamic_extent || _Extent == 0>>
		constexpr span() noexcept
			: _M_ptr(nullptr), _M_extent(0)
		{
		}

		template <typename _It, enable_if_t<contiguous_iterator<_It> _CSL_Parentheses11 && __is_compatible_ref<iter_reference_t<_It>>::value && extent != dynamic_extent, bool> = true>
		constexpr explicit span(_It __first, size_type __count) noexcept
			: _M_ptr(std::to_address(__first)), _M_extent(__count)
		{
			__glibcxx_assert(__count == _Extent);
			__glibcxx_requires_valid_range(__first, __first + __count);
		}
		template <typename _It, enable_if_t<contiguous_iterator<_It> _CSL_Parentheses11 && __is_compatible_ref<iter_reference_t<_It>>::value && extent == dynamic_extent, bool> = true>
		constexpr span(_It __first, size_type __count) noexcept
			: _M_ptr(std::to_address(__first)), _M_extent(__count)
		{
			__glibcxx_requires_valid_range(__first, __first + __count);
		}

		template <typename _It, typename _End, enable_if_t<contiguous_iterator<_It> _CSL_Parentheses11 && sized_sentinel_for<_End, _It> _CSL_Parentheses11 && __is_compatible_ref<iter_reference_t<_It>>::value && !is_convertible_v<_End, size_type> _CSL_Parentheses11 && extent != dynamic_extent, bool> = true> // 这里使用 enable_if_t<...,bool> = true 而不是 typename = enable_if_t<...> 是因为后者无法重载
		constexpr explicit span(_It __first, _End __last) noexcept(noexcept(__last - __first)) : _M_ptr(std::to_address(__first)), _M_extent(static_cast<size_type>(__last - __first))
		{
			__glibcxx_assert((__last - __first) == _Extent);
			__glibcxx_requires_valid_range(__first, __last);
		}
		template <typename _It, typename _End, enable_if_t<contiguous_iterator<_It> _CSL_Parentheses11 && sized_sentinel_for<_End, _It> _CSL_Parentheses11 && __is_compatible_ref<iter_reference_t<_It>>::value && !is_convertible_v<_End, size_type> _CSL_Parentheses11 && extent == dynamic_extent, bool> = true>
		constexpr span(_It __first, _End __last) noexcept(noexcept(__last - __first)) : _M_ptr(std::to_address(__first)), _M_extent(static_cast<size_type>(__last - __first))
		{
			__glibcxx_requires_valid_range(__first, __last);
		}

		template <size_t _ArrayExtent>
		constexpr span(type_identity_t<enable_if_t<_Extent == dynamic_extent || _ArrayExtent == _Extent, element_type>> (&__arr)[_ArrayExtent]) noexcept
			: span(static_cast<pointer>(__arr), _ArrayExtent)
		{
		}

		template <typename _Tp, size_t _ArrayExtent>
		constexpr span(array<enable_if_t<__is_compatible_array<_Tp, _ArrayExtent>::value, _Tp>, _ArrayExtent> &__arr) noexcept
			: span(static_cast<pointer>(__arr.data()), _ArrayExtent)
		{
		}

		template <typename _Tp, size_t _ArrayExtent>
		constexpr span(const array<enable_if_t<__is_compatible_array<const _Tp, _ArrayExtent>::value, _Tp>, _ArrayExtent> &__arr) noexcept
			: span(static_cast<pointer>(__arr.data()), _ArrayExtent)
		{
		}

		template <typename _Range, enable_if_t<!__detail::__is_span<remove_cvref_t<_Range>> _CSL_Parentheses11 && !__detail::__is_std_array<remove_cvref_t<_Range>> _CSL_Parentheses11 && !is_array_v<remove_cvref_t<_Range>> _CSL_Parentheses11 && ranges::contiguous_range<_Range> _CSL_Parentheses11 && ranges::sized_range<_Range> _CSL_Parentheses11 && (ranges::borrowed_range<_Range> _CSL_Parentheses11 || is_const_v<element_type> _CSL_Parentheses11) && __is_compatible_ref<ranges::range_reference_t<_Range>>::value && extent != dynamic_extent, bool> = true>
		constexpr explicit span(_Range &&__range) noexcept(noexcept(ranges::data(__range)) && noexcept(ranges::size(__range)))
			: span(ranges::data(__range), ranges::size(__range))
		{
			__glibcxx_assert(ranges::size(__range) == extent);
		}
		template <typename _Range, enable_if_t<!__detail::__is_span<remove_cvref_t<_Range>> _CSL_Parentheses11 && !__detail::__is_std_array<remove_cvref_t<_Range>> _CSL_Parentheses11 && !is_array_v<remove_cvref_t<_Range>> _CSL_Parentheses11 && ranges::contiguous_range<_Range> _CSL_Parentheses11 && ranges::sized_range<_Range> _CSL_Parentheses11 && (ranges::borrowed_range<_Range> _CSL_Parentheses11 || is_const_v<element_type> _CSL_Parentheses11) && __is_compatible_ref<ranges::range_reference_t<_Range>>::value && extent == dynamic_extent, bool> = true>
		constexpr span(_Range &&__range) noexcept(noexcept(ranges::data(__range)) && noexcept(ranges::size(__range)))
			: span(ranges::data(__range), ranges::size(__range))
		{
		}

		constexpr span(const span &) noexcept = default;

		template <typename _OType, size_t _OExtent, enable_if_t<(_Extent == dynamic_extent || _OExtent == dynamic_extent || _Extent == _OExtent) && __is_array_convertible<_Type, _OType>::value && extent != dynamic_extent && _OExtent == dynamic_extent, bool> = true>
		constexpr explicit span(const span<_OType, _OExtent> &__s) noexcept
			: _M_extent(__s.size()), _M_ptr(__s.data())
		{
#if __cpp_if_constexpr // C++11不允许constexpr函数中有if
			if constexpr (extent != dynamic_extent)
			{
				__glibcxx_assert(__s.size() == extent);
			}
#endif
		}
		template <typename _OType, size_t _OExtent, enable_if_t<(_Extent == dynamic_extent || _OExtent == dynamic_extent || _Extent == _OExtent) && __is_array_convertible<_Type, _OType>::value && (extent == dynamic_extent || _OExtent != dynamic_extent), bool> = true>
		constexpr span(const span<_OType, _OExtent> &__s) noexcept
			: _M_extent(__s.size()), _M_ptr(__s.data())
		{
#if __cpp_if_constexpr // C++11不允许constexpr函数中有if
			if constexpr (extent != dynamic_extent)
			{
				__glibcxx_assert(__s.size() == extent);
			}
#endif
		}

		~span() noexcept = default;

		_GLIBCXX17_CONSTEXPR span &
		operator=(const span &) noexcept = default;

		// observers

		[[nodiscard]]
		constexpr size_type
		size() const noexcept
		{
			return this->_M_extent._M_extent();
		}

		[[nodiscard]]
		constexpr size_type
		size_bytes() const noexcept
		{
			return this->_M_extent._M_extent() * sizeof(element_type);
		}

		[[nodiscard]]
		constexpr bool
		empty() const noexcept
		{
			return size() == 0;
		}

		// element access

		[[nodiscard]]
		constexpr reference
		front() const noexcept
		{
			__glibcxx_assert(!empty());
			return *this->_M_ptr;
		}

		[[nodiscard]]
		constexpr reference
		back() const noexcept
		{
			__glibcxx_assert(!empty());
			return *(this->_M_ptr + (size() - 1));
		}

		[[nodiscard]]
		constexpr reference
		operator[](size_type __idx) const noexcept
		{
			__glibcxx_assert(__idx < size());
			return *(this->_M_ptr + __idx);
		}

#if __cpp_lib_span >= 202311L // >= C++26
		[[nodiscard]]
		constexpr reference
		at(size_type __idx) const
		{
			if (__idx >= size())
				__throw_out_of_range_fmt(__N("span::at(%zu) out-of-range for span "
											 "of size %zu"),
										 __idx, this->size());
			return *(this->_M_ptr + __idx);
		}
#endif

		[[nodiscard]]
		constexpr pointer
		data() const noexcept
		{
			return this->_M_ptr;
		}

		// iterator support

		[[nodiscard]]
		constexpr iterator
		begin() const noexcept
		{
			return iterator(this->_M_ptr);
		}

		[[nodiscard]]
		constexpr iterator
		end() const noexcept
		{
			return iterator(this->_M_ptr + this->size());
		}

		[[nodiscard]]
		constexpr reverse_iterator
		rbegin() const noexcept
		{
			return reverse_iterator(this->end());
		}

		[[nodiscard]]
		constexpr reverse_iterator
		rend() const noexcept
		{
			return reverse_iterator(this->begin());
		}

#if __cplusplus > 202002L
		[[nodiscard]]
		constexpr const_iterator
		cbegin() const noexcept
		{
			return begin();
		}

		[[nodiscard]]
		constexpr const_iterator
		cend() const noexcept
		{
			return end();
		}

		[[nodiscard]]
		constexpr const_reverse_iterator
		crbegin() const noexcept
		{
			return rbegin();
		}

		[[nodiscard]]
		constexpr const_reverse_iterator
		crend() const noexcept
		{
			return rend();
		}
#endif

		// subviews

		template <size_t _Count>
		[[nodiscard]]
		constexpr span<element_type, _Count>
		first() const noexcept
		{
			if _GLIBCXX17_CONSTEXPR (_Extent == dynamic_extent)
				__glibcxx_assert(_Count <= size());
			else
				_GLIBCXX17_STATIC_ASSERT(_Count <= extent);
			using _Sp = span<element_type, _Count>;
			return _Sp{this->data(), _Count};
		}

		[[nodiscard]]
		constexpr span<element_type, dynamic_extent>
		first(size_type __count) const noexcept
		{
			__glibcxx_assert(__count <= size());
			return {this->data(), __count};
		}

		template <size_t _Count>
		[[nodiscard]]
		constexpr span<element_type, _Count>
		last() const noexcept
		{
			if _GLIBCXX17_CONSTEXPR (_Extent == dynamic_extent)
				__glibcxx_assert(_Count <= size());
			else
				_GLIBCXX17_STATIC_ASSERT(_Count <= extent);
			using _Sp = span<element_type, _Count>;
			return _Sp{this->data() + (this->size() - _Count), _Count};
		}

		[[nodiscard]]
		constexpr span<element_type, dynamic_extent>
		last(size_type __count) const noexcept
		{
			__glibcxx_assert(__count <= size());
			return {this->data() + (this->size() - __count), __count};
		}

		template <size_t _Offset, size_t _Count = dynamic_extent>
		[[nodiscard]]
		constexpr auto
		subspan() const noexcept
			-> span<element_type, _S_subspan_extent<_Offset, _Count>()>
		{
			if _GLIBCXX17_CONSTEXPR (_Extent == dynamic_extent)
			{
				__glibcxx_assert(_Offset <= size());
			}
			else
				_GLIBCXX17_STATIC_ASSERT(_Offset <= extent);

			using _Sp = span<element_type, _S_subspan_extent<_Offset, _Count>()>;

			if _GLIBCXX17_CONSTEXPR (_Count == dynamic_extent)
				return _Sp{this->data() + _Offset, this->size() - _Offset};
			else
			{
				if _GLIBCXX17_CONSTEXPR (_Extent == dynamic_extent)
				{
					__glibcxx_assert(_Count <= size());
					__glibcxx_assert(_Count <= (size() - _Offset));
				}
				else
				{
					_GLIBCXX17_STATIC_ASSERT(_Count <= extent);
					_GLIBCXX17_STATIC_ASSERT(_Count <= (extent - _Offset));
				}
				return _Sp{this->data() + _Offset, _Count};
			}
		}

		[[nodiscard]]
		constexpr span<element_type, dynamic_extent>
		subspan(size_type __offset, size_type __count = dynamic_extent) const
			noexcept
		{
			__glibcxx_assert(__offset <= size());
			if (__count == dynamic_extent)
				__count = this->size() - __offset;
			else
			{
				__glibcxx_assert(__count <= size());
				__glibcxx_assert(__offset + __count <= size());
			}
			return {this->data() + __offset, __count};
		}

	private:
		pointer _M_ptr;
		[[no_unique_address]] __detail::__extent_storage<extent> _M_extent;
	};
#ifdef __cpp_deduction_guides
	// deduction guides

	template <typename _Type, size_t _ArrayExtent>
	span(_Type (&)[_ArrayExtent]) -> span<_Type, _ArrayExtent>;

	template <typename _Type, size_t _ArrayExtent>
	span(array<_Type, _ArrayExtent> &) -> span<_Type, _ArrayExtent>;

	template <typename _Type, size_t _ArrayExtent>
	span(const array<_Type, _ArrayExtent> &)
		-> span<const _Type, _ArrayExtent>;

	template <typename _Iter, typename _End>
	span(_Iter, _End)
		-> span<enable_if_t<contiguous_iterator<_Iter> _CSL_Parentheses11, remove_reference_t<iter_reference_t<_Iter>>>>;

	template <typename _Range>
	span(_Range &&)
		-> span<enable_if_t<ranges::contiguous_range<_Range> _CSL_Parentheses11, remove_reference_t<ranges::range_reference_t<_Range &>>>>;
#endif
	template <typename _Type, size_t _Extent>
	[[nodiscard]]
	inline span<const byte, _Extent == dynamic_extent
								? dynamic_extent
								: _Extent * sizeof(_Type)>
	as_bytes(span<_Type, _Extent> __sp) noexcept
	{
		auto data = reinterpret_cast<const byte *>(__sp.data());
		auto size = __sp.size_bytes();
		constexpr auto extent = _Extent == dynamic_extent
									? dynamic_extent
									: _Extent * sizeof(_Type);
		return span<const byte, extent>{data, size};
	}

	template <typename _Type, size_t _Extent>
	inline span<enable_if_t<!is_const_v<_Type> _CSL_Parentheses11, byte>, _Extent == dynamic_extent
																			  ? dynamic_extent
																			  : _Extent * sizeof(_Type)>
	as_writable_bytes [[nodiscard]] (span<_Type, _Extent> __sp) noexcept
	{
		auto data = reinterpret_cast<byte *>(__sp.data());
		auto size = __sp.size_bytes();
		constexpr auto extent = _Extent == dynamic_extent
									? dynamic_extent
									: _Extent * sizeof(_Type);
		return span<byte, extent>{data, size};
	}

	namespace ranges
	{
		// Opt-in to borrowed_range concept
		template <typename _ElementType, size_t _Extent>
		_CSL_Struct17Concept(enable_borrowed_range, _GLIBCXX17_INLINE, true, <span<_ElementType, _Extent>>);

		// Opt-in to view concept
		template <typename _ElementType, size_t _Extent>
		_CSL_Struct17Concept(enable_view, _GLIBCXX17_INLINE, true, <span<_ElementType, _Extent>>);
	}
	_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // __cpp_lib_span
#endif // _GLIBCXX_SPAN
#else
#include_next <span>
#endif