initial commit

oscar64/include/opp/span.h

@@ -0,0 +1,169 @@
+#ifndef OPP_SPAN_H
+#define OPP_SPAN_H
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <opp/utility.h>
+
+namespace opp
+{
+static const size_t	dynamic_extent	=	0xffff;
+
+template <class T, int N = dynamic_extent>
+class span
+{
+protected:
+	T		*	_data;
+	size_t		_size;
+public:
+	span(void)
+		: _data(nullptr), _size(0)
+		{}
+
+	span(T * data, size_t size)
+		: _data(data), _size(size)
+		{}
+
+	span(T * data)
+		: _data(data), _size(N)
+		{}
+
+	span(opp::array<T, N> & arr)
+		: _data(arr.data()), _size(N)
+		{}
+
+	span(opp::vector<T> & vec)
+		: _data(vec.data()), _size(vec.size())
+		{}
+
+	span(const opp::array<T, N> & arr)
+		: _data(arr.data()), _size(N)
+		{}
+
+	span(const opp::vector<T> & vec)
+		: _data(vec.data()), _size(vec.size())
+		{}
+
+	constexpr size_t size(void) const
+	{
+		if constexpr (N == dynamic_extent)
+			return _size;
+		else
+			return N;
+	}
+
+	T & operator[](int i) 
+		{return _data[i];}
+
+	const T & operator[](int i) const
+		{return _data[i];}
+
+	T * begin(void)
+	{
+		return _data;
+	}
+
+	const T * begin(void) const
+	{
+		return _data;
+	}
+
+	const T * cbegin(void) const
+	{
+		return _data;
+	}
+
+	T * end(void)
+	{
+		return _data + size();
+	}
+
+	const T * end(void) const
+	{
+		return _data + size();
+	}
+
+	const T * cend(void) const
+	{
+		return _data + size();
+	}
+
+	T & back(void)
+	{
+		return _data[size() - 1];
+	}
+
+	const T & back(void) const
+	{
+		return _data[size() - 1];
+	}
+
+	T & front(void)
+	{
+		return _data[0];
+	}
+
+	const T & front(void) const
+	{
+		return _data[0];
+	}
+
+	T * data(void)
+	{
+		return _data;
+	}
+
+	const T * data(void) const
+	{
+		return _data;
+	}
+
+	template< int Offset, int Count = dynamic_extent >
+	constexpr auto subspan() const
+	{
+		if constexpr (Count == dynamic_extent)
+		{
+			if constexpr (N == dynamic_extent)
+				return opp::span<T>(_data + Offset, _size - Offset);
+			else
+				return opp::span<T, (N - Offset)>(_data + Offset);
+		}
+		else
+			return opp::span<T, Count>(_data + Offset);
+	}
+
+	constexpr auto subspan(size_t offset, size_t count = dynamic_extent)
+	{
+		if (count == dynamic_extent)
+			return opp::span<T>(_data + offset, size() - offset);
+		else
+			return opp::span<T>(_data + offset, count);
+	}
+
+	template< int Count >
+	constexpr auto first() const
+	{
+		return opp::span<T, Count>(_data);
+	}
+
+	constexpr auto first( size_t count ) const
+	{
+		return opp::span<T>(_data, count);
+	}
+
+	template< int Count >
+	constexpr auto last() const
+	{
+		return opp::span<T, Count>(_data + size() - Count);
+	}
+
+	constexpr auto last( size_t count ) const
+	{
+		return opp::span<T>(_data + size() - count, count);
+	}
+};
+	
+}
+
+
+#endif