简单实现了容器forward_list 对应迭代器：foward_list_iterator 以及find和advance算法，主要想搞清楚他们是怎么在一起运行的

//
// Created by jiaming pan on 6/6/20.
//

#ifndef FORWARD_LIST_FORWARD_LIST_H
#define FORWARD_LIST_FORWARD_LIST_H

#include <memory>
#include <iostream>
namespace my{
    template <typename T>
     struct node{
        T val;
        struct node * next;
    } ;
    template <typename T>
    struct __forward_list_iterator{
        typedef __forward_list_iterator self;
        typedef std::forward_iterator_tag iterator_category;
        typedef T value_type;
        typedef T* pointer;
        typedef T& reference;
        typedef ptrdiff_t difference_type;
        typedef node<T> * node_type;
        node_type node_;
        explicit __forward_list_iterator(node_type node){
            node_ =  node;
        }
         __forward_list_iterator(const self & self_){
            node_ =  self_.node_;
        }
        reference operator*() const  {
            return node_->val;
        }
        self& operator++() {
            node_ = node_->next;
            return  *this;
        }
        bool operator ==(const self & comp) const{
            return  this->node_ == comp.node_;
        }
        bool operator !=(const self & comp) const{
            return  this->node_ != comp.node_;
        }
        self operator++(int)  {
           self tmp = *this;
            ++*this;
            return tmp;
        }
    };
    template <typename T>
    class forward_list {
    public:
        using Node = node<T>;
        forward_list() {
            rear_ = new Node;
            head_ = rear_;
        };
        typedef __forward_list_iterator<T>  iterator;
        void insert_back(T value){
            rear_->val = value;
            auto tmp  = new Node;
            rear_->next = tmp;
            rear_ = tmp;
        }
        iterator begin() const {
            return iterator(head_);
        }
        iterator end() const{
            return iterator(rear_);
        }
    private:
        Node * head_;
        Node * rear_;
    };

    template <typename iteratorT,typename elementT>
    iteratorT find(iteratorT iteratorBegin,iteratorT iteratorEnd,const elementT & target){
        for( auto & item = iteratorBegin; item != iteratorEnd; item ++){
           if(*item == target) return item;
        }
    }

    template <typename iteratorT,typename distT>
    void doAdvance(iteratorT& iter , distT dist,std::forward_iterator_tag){
        std::cout << "doAdvance forward_iterator_tag" <<std::endl;
        while(dist -- ){
            ++iter;
        }

    }

    template <typename iteratorT,typename distT>
    void doAdvance(iteratorT& iter , distT dist,std::random_access_iterator_tag){
        std::cout << "doAdvance random_access_iterator_tag" <<std::endl;
        iter += dist;
    }

    template <typename iteratorT>
    struct  iterator_traits{
        typedef typename iteratorT::iterator_category iterator_category;
     };
    template <typename iteratorT>
    struct  iterator_traits<iteratorT *>{
        typedef typename std::random_access_iterator_tag iterator_category;
    };

    template <typename iteratorT>
    struct  iterator_traits<const iteratorT *>{
        typedef typename std::random_access_iterator_tag iterator_category;
    };


    template <typename iteratorT,typename distT>
    void advance(iteratorT& iter , distT dist){

   //     doAdvance(iter,dist,typename iteratorT::iterator_category());并不能接收普通指针，因为普通指针内没有定义iterator_category
        doAdvance(iter,dist,typename iterator_traits<iteratorT>::iterator_category());
    }




}


#endif //FORWARD_LIST_FORWARD_LIST_H