Class iterator

opt_utils/include/open_ptrack/opt_utils/json.h:287–303

	{
	public:
		class iterator : public std::iterator<std::input_iterator_tag, Node>
		{
		public:
			iterator(Node **o) : p(o) {}
			iterator(const iterator &it) : p(it.p) {}

			iterator &operator++() { ++p; return *this; }
			iterator operator++(int) { iterator tmp(*this); operator++(); return tmp; }

			bool operator==(const iterator &rhs) { return p == rhs.p; }
			bool operator!=(const iterator &rhs) { return p != rhs.p; }

			Node &operator*() { return **p; }

		private:
			Node **p;
		};
		class const_iterator : public std::iterator<std::input_iterator_tag, const Node>
		{
		public: