c语言实现迭代器iterator

1. iterator.h

#ifndef _ITERATOR_H
#define _ITERATOR_H

typedef void *iterator_t;
typedef void (*iterator_next_t)(iterator_t *p_iter);
typedef void (*iterator_prev_t)(iterator_t *p_iter);
typedef int (*compare_t)(iterator_t it1, iterator_t it2);
typedef void (*swap_t)(iterator_t it1, iterator_t it2);
typedef int (*visit_t)(void *p_arg, iterator_t it);

typedef struct _iterator_if{
iterator_next_t pfn_next; //调用迭代器后移的函数指针，相当于p1++
iterator_prev_t pfn_prev; //调用迭代器前移的函数指针，相当于p2--
}iterator_if_t;

void iterator_if_init(iterator_if_t *p_if, iterator_next_t pfn_next, iterator_prev_t pfn_prev);
void iterator_next(iterator_if_t *p_if, iterator_t *p_iter); //迭代器后移函数，相当于++
void iterator_prev(iterator_if_t *p_if, iterator_t *p_iter); //迭代器前移函数，相当于--
//void iterator_if_get(iterator_if_t *p_if);
void iter_sort(iterator_if_t *p_if, iterator_t begin, iterator_t end, compare_t compare, swap_t swap);
void iter_foreach(iterator_if_t *p_if, iterator_t begin, iterator_t end, visit_t visit, void *p_arg);
#endif

2. iterator.c

#include "iterator.h"

void iterator_if_init(iterator_if_t *p_if, iterator_next_t pfn_next, iterator_prev_t pfn_prev)
{
    p_if->pfn_next = pfn_next;
    p_if->pfn_prev = pfn_prev;
}

void iterator_next(iterator_if_t *p_if, iterator_t *p_iter)
{
    p_if->pfn_next(p_iter);
}

void iterator_prev(iterator_if_t *p_if, iterator_t *p_iter)
{
    p_if->pfn_prev(p_iter);
}

/**
 * @breif 冒泡排序算法函数
 */
void iter_sort(iterator_if_t *p_if, iterator_t begin, iterator_t end, compare_t compare, swap_t swap)
{
    int flag = 1; // flag = 1，表示指针的内容未交换
    iterator_t it1 = begin; // it1指向需要排序的首元素
    iterator_t it2 = end;   // it2指向需要排序的最后一个元素之后

    iterator_t it_next;
    if (begin == end) 
    {
        return;
    }

    while (it2 != begin)
    {
        it1 = begin;
        flag = 1;
        while(it1 != it2)
        {
            it_next = it1; //暂存
            iterator_next(p_if, &it_next); // it_next为it1的下一个元素
            if(it_next == it2) break;
            if(compare(it1, it_next) > 0)
            {
                swap(it1, it_next); //交换内容
                flag = 0; // flag = 0，表示指针的内容已交换
            }
            it1 = it_next; // it1的下一个元素
        }
        if(flag) return; //没有交换，表示已经有序，则直接返回
        iterator_prev(p_if, &it2); // it2向前移
    }
}

void iter_foreach(iterator_if_t *p_if, iterator_t begin, iterator_t end, visit_t visit, void *p_arg)
{
    iterator_t it = begin;
    while(it != end)
    {
        if (visit(p_arg, it) < 0) 
        { //若返回值为负值，表示用户终止了遍历
            return;
        }
        iterator_next(p_if, &it);//让迭代器向后移动
    }
}

3. demo

#include <stdio.h>
#include "dlist.h"
#include "iterator.h"

#define ITERATOR_FOREATCH_EN    1

typedef struct _dlist_int
{
    dlist_node_t node;
    int data;
}dlist_int_t;

static void __dlist_iterator_next(iterator_t *p_iter) //让迭代器指向容器的下一个数据
{
    *p_iter = ((dlist_node_t *)*p_iter)->p_next;
}

static void __dlist_iterator_prev(iterator_t *p_iter) //让迭代器指向容器的上一个数据
{
    *p_iter = ((dlist_node_t *)*p_iter)->p_prev;
}

int list_node_process(void *p_arg, dlist_node_t *p_node)
{
    printf("%d ", ((dlist_int_t *)p_node) -> data);
    return 0;
}

static int __visit(void *p_arg, iterator_t it)
{
    printf("%d ", ((dlist_int_t *)it)->data);
    return 0;
}

static int __compare(iterator_t it1, iterator_t it2)
{
    return ((dlist_int_t *)it1) -> data - ((dlist_int_t *)it2) -> data;
}

static void __swap(iterator_t it1, iterator_t it2)
{
    int data = ((dlist_int_t *)it2) -> data;
    ((dlist_int_t *)it2) -> data = ((dlist_int_t *)it1) -> data;
    ((dlist_int_t *)it1) -> data = data;
}

int main(void)
{
    iterator_if_t iterator_if;
    dlist_head_t head; //定义链表头结点
    dlist_int_t node[5]; //定义5个结点空间
    int i;

    dlist_init(&head);

    for (i = 0; i < 5; i++) 
    { //将5个结点添加至链表尾部
        node[i].data = 5 - i; // 使值的顺序为 5~1
        dlist_add_tail(&head, &(node[i].node));
    }
    iterator_if_init(&iterator_if, __dlist_iterator_next, __dlist_iterator_prev);

    printf("
Before bubble sort:
");
#if (ITERATOR_FOREATCH_EN)
    iter_foreach(&iterator_if,dlist_begin_get(&head), dlist_end_get(&head), __visit, NULL);
#else
    dlist_foreach(&head, list_node_process, NULL); //打印排序前的情况
#endif

    iter_sort(&iterator_if, dlist_begin_get(&head), dlist_end_get(&head), __compare, __swap);

    printf("
After bubble sort:
");

#if (ITERATOR_FOREATCH_EN)
    iter_foreach(&iterator_if,dlist_begin_get(&head), dlist_end_get(&head), __visit, NULL);
#else 
    dlist_foreach (&head, list_node_process, NULL); //打印排序后的情况
#endif

    return 0;
}