line_iterator_view.cpp

class line_iterator_view {
	const char *line_beg;
	const char *line_end;
	const char *current;
	const char *current_eol;

	// Передвигает наш итератор на след. позицию.
	void advance_to_next_eol()
	{
		current_eol = strchr(current, '\n');
		if (!current_eol) {
			current_eol = line_end;
		}
	}

public:
	class line {
		const char *beg, *end_;
	public:
		line(const char *b, const char *e) : beg(b), end_(e)
		{}
		const char *begin()
		{
			return beg;
		}

		const char *end()
		{
			return end_;
		}
	};
	line_iterator_view() : line_beg(nullptr), line_end(nullptr),
		current(nullptr), current_eol(nullptr)
	{}

	line_iterator_view(const char *line_beg, const char *line_end)
		: line_beg(line_beg), line_end(line_end), current(line_beg),
		current_eol(current)
	{
		assert(line_end > line_beg);
		advance_to_next_eol();
	}

	line operator *()
	{
		return { current, current_eol };
	}

	line_iterator_view &operator ++()
	{
		if (current_eol >= line_end) {
			current = current_eol = nullptr;
			return *this;
		}
		current = ++current_eol;
		advance_to_next_eol();
		return *this;
	}

	bool operator ==(const line_iterator_view &v) const
	{
		return this->current == v.current &&
			this->current_eol == v.current_eol;
	}

	bool operator !=(const line_iterator_view &v) const
	{
		return !this->operator==(v);
	}
};

class line_iterator_pair {
	line_iterator_view iter;
public:
	line_iterator_pair(const char *line_beg, const char *line_end)
		: iter(line_beg, line_end)
	{}

	line_iterator_view &begin()
	{
		return iter;
	}

	static line_iterator_view end()
	{
		return {};
	}
};

line_iterator_pair make_line_iterator_range(const char *line_beg,
	const char *line_end)
{
	return { line_beg, line_end };
}