gplib/include/gp/iterator.hpp

#pragma once
#include <stddef.h>
#include <stdint.h>

enum class iterator_type_t{
	contiguous_iterator,
	non_contiguous_iterator,
	lazy_iterator
};

template<typename T>
struct pointer_iterator final
{
	T* data;
	typedef T value_type;
	typedef std::size_t difference_type;
	static constexpr iterator_type_t iterator_type = iterator_type_t::contiguous_iterator;

	constexpr pointer_iterator(const pointer_iterator& oth)
	: data{oth.data}
	{}

	constexpr pointer_iterator(T* ptr)
	: data{ptr}
	{}

	constexpr operator T&()
	{
		return *data;
	}

	constexpr T& operator*(){
		return *data;
	}

	constexpr pointer_iterator operator++()
	{
		return pointer_iterator{++data};
	}

	constexpr pointer_iterator operator++(int)
	{
		return pointer_iterator{data++};
	}

	constexpr pointer_iterator operator--()
	{
		return pointer_iterator{--data};
	}

	constexpr pointer_iterator operator--(int)
	{
		return pointer_iterator{data--};
	}

	constexpr pointer_iterator operator+(const std::size_t offset)
	{
		return pointer_iterator{data+offset};
	}

	constexpr pointer_iterator operator+(const int offset)
	{
		return pointer_iterator{data+offset};
	}

	constexpr pointer_iterator operator-(const std::size_t offset)
	{
		return pointer_iterator{data-offset};
	}

	constexpr pointer_iterator operator-(const int offset)
	{
		return pointer_iterator{data-offset};
	}

	constexpr difference_type operator-(const pointer_iterator& oth) const
	{
		return (T*)data-(T*)oth.data;
	}

	constexpr bool operator==(const pointer_iterator& oth)
	{
		return data==oth.data;
	}

	constexpr bool operator!=(pointer_iterator& oth)
	{
		return data!=oth.data;
	}

	constexpr bool before_or_equal(const pointer_iterator& oth)
	{
		return reinterpret_cast<std::intptr_t>(data) <= reinterpret_cast<std::intptr_t>(oth.data);
	}

	constexpr bool operator<=(const pointer_iterator& oth)
	{
		return before_or_equal(oth);
	}
};