variantlist.cpp

/*********************************************************
	  File Name: variantlist.cpp
	  Author: Abby Cin
	  Mail: abbytsing@gmail.com
	  Created Time: Sat 17 Jun 2017 09:18:19 AM CST
**********************************************************/

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

namespace nm
{
template<typename T, typename... Rest>
class variant_list {
private:
	struct Node {
		variant<T, Rest...> data;
		Node *next;
		template<typename U>
		Node(U &&u, Node *nxt) : data(std::forward<U>(u)), next(nxt)
		{
		}
	};

public:
	class iterator {
	public:
		iterator(Node *n) : data_(n)
		{
		}

		iterator(const iterator &rhs)
		{
			data_ = rhs.data_;
		}

		iterator &operator=(const iterator &rhs)
		{
			if (this != &rhs) {
				data_ = rhs.data_;
			}
			return *this;
		}

		iterator &operator++()
		{
			data_ = data_->next;
			return *this;
		}

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

		bool operator!=(const iterator &rhs)
		{
			return !(*this == rhs);
		}

		variant<T, Rest...> *operator->()
		{
			return &data_->data;
		}

		variant<T, Rest...> &operator*()
		{
			return data_->data;
		}

	private:
		Node *data_;
	};

public:
	variant_list() : root_(nullptr)
	{
	}
	~variant_list()
	{
		this->clear();
	}

	template<typename U>
	void push(U &&u)
	{
		if (root_ == nullptr) {
			root_ = new Node(std::forward<U>(u), nullptr);
			tail_ = root_;
		} else {
			auto tmp = new Node(std::forward<U>(u), nullptr);
			tail_->next = tmp;
			tail_ = tmp;
		}
	}

	iterator begin()
	{
		return iterator(root_);
	}

	iterator end()
	{
		return iterator(nullptr);
	}

	void clear()
	{
		Node *tmp = nullptr;
		while (root_) {
			tmp = root_->next;
			delete root_;
			root_ = tmp;
		}
		root_ = tail_ = nullptr;
	}

private:
	Node *root_;
	Node *tail_;
};
}

int main()
{
	nm::variant_list<int, double, std::string> l;
	l.push(233);
	l.push(3809.929);
	l.push("ha??");
	for (auto &x : l) {
		std::cout << x << '\n';
	}
}