Merge remote-tracking branch 'Kernel/master'

Kernel/include_std/iterator

@@ -0,0 +1,138 @@
+/*
+	This file is part of Fennix Kernel.
+
+	Fennix Kernel 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 of
+	the License, or (at your option) any later version.
+
+	Fennix Kernel 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.
+
+	You should have received a copy of the GNU General Public License
+	along with Fennix Kernel. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+namespace std
+{
+	struct input_iterator_tag
+	{
+	};
+
+	struct output_iterator_tag
+	{
+	};
+
+	struct forward_iterator_tag : public input_iterator_tag
+	{
+	};
+
+	struct bidirectional_iterator_tag : public forward_iterator_tag
+	{
+	};
+
+	struct random_access_iterator_tag : public bidirectional_iterator_tag
+	{
+	};
+
+	struct contiguous_iterator_tag : public random_access_iterator_tag
+	{
+	};
+
+	template <class Iter>
+	struct iterator_traits
+	{
+	public:
+		using difference_type = typename Iter::difference_type;
+		using value_type = typename Iter::value_type;
+		using pointer = typename Iter::pointer;
+		using reference = typename Iter::reference;
+		using iterator_category = typename Iter::iterator_category;
+	};
+
+	template <class InputIt>
+	constexpr typename std::iterator_traits<InputIt>::difference_type __do_distance(InputIt first, InputIt last, std::input_iterator_tag)
+	{
+		typename std::iterator_traits<InputIt>::difference_type result = 0;
+		while (first != last)
+		{
+			++first;
+			++result;
+		}
+		return result;
+	}
+
+	template <class InputIt>
+	constexpr typename std::iterator_traits<InputIt>::difference_type __do_distance(InputIt first, InputIt last, std::random_access_iterator_tag)
+	{
+		return last - first;
+	}
+
+	template <class InputIt>
+	constexpr typename std::iterator_traits<InputIt>::difference_type distance(InputIt first, InputIt last)
+	{
+		return __do_distance(first, last, typename std::iterator_traits<InputIt>::iterator_category());
+	}
+
+	template <class InputIt>
+	void __do_advance(InputIt &it, typename std::iterator_traits<InputIt>::difference_type n, std::input_iterator_tag)
+	{
+		while (n > 0)
+		{
+			--n;
+			++it;
+		}
+	}
+
+	template <class InputIt>
+	void __do_advance(InputIt &it, typename std::iterator_traits<InputIt>::difference_type n, std::bidirectional_iterator_tag)
+	{
+		while (n > 0)
+		{
+			--n;
+			++it;
+		}
+		while (n < 0)
+		{
+			++n;
+			--it;
+		}
+	}
+
+	template <class InputIt>
+	void __do_advance(InputIt &it, typename std::iterator_traits<InputIt>::difference_type n, std::random_access_iterator_tag)
+	{
+		it += n;
+	}
+
+	template <class InputIt, class Distance>
+	constexpr void advance(InputIt &it, Distance n)
+	{
+		__do_advance(it, typename std::iterator_traits<InputIt>::difference_type(n),
+					 typename std::iterator_traits<InputIt>::iterator_category());
+	}
+
+	template <class BidirIt>
+	constexpr BidirIt prev(BidirIt it, typename std::iterator_traits<BidirIt>::difference_type n = 1)
+	{
+		std::advance(it, -n);
+		return it;
+	}
+
+	template <class InputIt>
+	constexpr InputIt next(InputIt it, typename std::iterator_traits<InputIt>::difference_type n = 1)
+	{
+		std::advance(it, n);
+		return it;
+	}
+
+	struct default_sentinel_t
+	{
+	};
+
+	inline constexpr default_sentinel_t default_sentinel{};
+}