Add util::span

libs/util/include/psemek/util/span.hpp

@@ -0,0 +1,57 @@
+#pragma once
+
+#include <iterator>
+#include <array>
+
+namespace psemek::util
+{
+
+	template <typename T>
+	struct span
+	{
+		using value_type = std::remove_cv_t<T>;
+		using size_type = std::size_t;
+		using difference_type = std::ptrdiff_t;
+		using pointer = T *;
+		using const_pointer = const T *;
+		using reference = T &;
+		using const_reference = const T &;
+		using iterator = pointer;
+		using reverse_iterator = std::reverse_iterator<iterator>;
+
+		T * p_begin = nullptr;
+		T * p_end = nullptr;
+
+		span() = default;
+		span(span const &) = default;
+		span(span &&) = default;
+
+		span(T * begin, T * end)
+			: p_begin{begin}
+			, p_end{end}
+		{}
+
+		template <std::size_t N>
+		span(T (&a)[N])
+			: p_begin{a}
+			, p_end{a + N}
+		{}
+
+		template <std::size_t N>
+		span(std::array<T, N> & a)
+			: p_begin{a.data()}
+			, p_end{a.data() + N}
+		{}
+
+		T * begin() const { return p_begin; }
+		T * end() const { return p_end; }
+
+		difference_type size() const { return p_end - p_begin; }
+
+		reverse_iterator rbegin() const { return reverse_iterator(p_end); }
+		reverse_iterator rend() const { return reverse_iterator(p_begin); }
+
+		T & operator[] (size_type i) const { return p_begin[i]; }
+	};
+
+}