#include <iostream>
#include "CirclePoints.h"

int main() {
	CirclePoints circlePoints1(3, 4); //окружность. радиус равен 3, кол-во точек 4
	std::cout << "Points (1): ";
	for (auto a : circlePoints1) { //прямой итератор
		std::cout << "(" << a.x << "; " << a.y << "), "; //вывод координат точек в научной записи
	}
	std::cout << std::endl << "Reversed points (1): ";
	for (auto a = circlePoints1.end()--; a != circlePoints1.begin(); a--) { //обратный итератор
		std::cout << "(" << (*a).x << "; " << (*a).y << "), ";
	}
	CirclePoints circlePoints2(2, 8); //окружность. радиус равен 2, кол-во точек 8
	std::cout << std::endl << "Points (2): ";
	for (auto a : circlePoints2) { //прямой итератор
		std::cout << "(" << a.x << "; " << a.y << "), ";
	}
	return 0;
}









#include <iterator>
#include <math.h>

struct Point {
	double x, y;
};

class CirclePoints {
private:
	double radius;
	int k; //количество точек, равномерно распределённых вдоль окружности
public:
	CirclePoints(double radius, int k): radius(radius), k(k) {
	}
	double getRadius() {
		return radius;
	}
	void setRadius(double radius) {
		this->radius = radius;
	}
	int getK() {
		return k;
	}
	void setK(int k) {
		this->k = k;
	}
	class PointsIterator: public std::iterator<std::bidirectional_iterator_tag, int, ptrdiff_t, Point*, Point> {
	private:
		bool isDefault = true;
		CirclePoints& circlePoints;
		int currentPoint; //номер данной точки [0; k)
		void next() {
			isDefault = ++currentPoint == circlePoints.k;
		}
		void previous() {
			isDefault = --currentPoint == -1;
		}
	public:
		PointsIterator(CirclePoints& circlePoints, bool isDefault): isDefault(false), circlePoints(circlePoints) {
			currentPoint = isDefault ? circlePoints.k : -1;
		}
		bool operator == (PointsIterator other) {
			return (isDefault && other.isDefault) || (currentPoint == other.currentPoint);
		}
		bool operator != (PointsIterator other) {
			return !(*this == other);
		}
		Point operator * () {
			if (isDefault) {
				throw "not initialized iterator";
			}
			if (currentPoint == -1) {
				next();
			} else if (currentPoint == circlePoints.k) {
				previous();
			}
			double alpha = 360.0 * (double) currentPoint / (double) circlePoints.k * std::acos(-1) / 180.0; //угол относительно начальной точки (перевод в радианы)
			Point point;
			point.x = circlePoints.radius * std::cos(alpha);
			point.y = circlePoints.radius * std::sin(alpha);
			return point;
		}
		PointsIterator& operator ++ () {
			if (isDefault) {
				throw "not initialized iterator";
			}
			next();
			return *this;
		}
		PointsIterator& operator ++ (int) {
			PointsIterator& tmp = *this;
			operator++();
			return tmp;
		}
		PointsIterator& operator -- () {
			if (isDefault) {
				throw "not initialized iterator";
			}
			previous();
			return *this;
		}
		PointsIterator& operator -- (int) {
			PointsIterator& tmp = *this;
			operator--();
			return tmp;
		}
	};
	PointsIterator begin() {
		return PointsIterator(*this, false);
	}
	PointsIterator end() {
		return PointsIterator(*this, true);
	}
};