纯C语言(C89)实现简单链表

起因

工作很少接触纯C项目，业余写着玩玩，不断雕琢

目标

纯C实现简单链表，提供方便易用泛型接口，避免依赖

实现

完全封装，隐藏结构体细节，不支持栈创建
拷贝存储，轻微性能代价换来易用性

list.h

#ifndef LIST_H
#define LIST_H
#include <stddef.h>

typedef struct ListItem_ ListItem;
typedef struct List_ List;
List* list_new();
void list_free(List* l);

size_t list_length(List* l);
ListItem* list_head(List* l);
ListItem* list_tail(List* l);

ListItem* list_next(ListItem* e);
size_t list_data(ListItem* e, void** data);

int list_insert_next(List* l, ListItem* e, void* data_in, size_t size);
int list_remove_next(List* l, ListItem* e);

#endif // LIST_H

list.c

#include "list.h"
#include <stdlib.h>
#include <string.h>

typedef unsigned char byte;

typedef struct ListItem_ {
    struct ListItem_* next;
    byte* data;
    size_t size;
} ListItem;

typedef struct List_ {
    size_t count;
    ListItem* head;
    ListItem* tail;
} List;

List* list_new() {
    List* l = calloc(1, sizeof(List));
    return l;
}

void list_free(List* l) {
    while (list_length(l) > 0) {
        list_remove_next(l, 0);
    }
}

size_t list_length(List* l) {
    return l->count;
}

ListItem* list_head(List* l) {
    return l->head;
}

ListItem* list_tail(List* l) {
    return l->tail;
}

ListItem* list_next(ListItem* e) {
    return e->next;
}

size_t list_data(ListItem* e, void** data) {
    if (!e) return 0;
    *data = e->data;
    return e->size;
}

int list_insert_next(List* l, ListItem* e, void* data_in, size_t size) {
    ListItem* e_new = calloc(1, sizeof(ListItem));
    if (!e_new) return -1;
    e_new->data = calloc(size, sizeof(byte));
    if (e_new->data) {
        memcpy(e_new->data, data_in, size);
        e_new->size = size;
    } else {
        free(e_new);
        return -1;
    }
    if (l->count == 0) {
        if (e) return -1;
        l->head = e_new;
        l->tail = e_new;
    } else if (e) {
        e_new->next = e->next;
        e->next = e_new;
        if (!e_new->next) 
            l->tail = e_new;
    } else {
        e_new->next = l->head;
        l->head = e_new;    
    }
    l->count ++;
    return 0;
}

int list_remove_next(List* l, ListItem* e) {
    ListItem* e_next;
    if (l->count == 0) return -1;
    if (e) {
        if (!e->next) return -1;
        e_next = e->next;
        e->next = e_next->next;
    } else {
        e_next = l->head;
        l->head = e_next->next;
        if (l->count == 1) l->tail = 0;
    }
    free(e_next->data);
    free(e_next);
    l->count --;
    return 0;
}

测试

#include <stdio.h>
#include <stdlib.h>
#include "list.h"

int main(int argc, char *argv[]) {
    List* l = list_new();
    ListItem* it;
    size_t l_len = 0;
    int i, x, y, *p, n;
    for (i=0; i<10; i++) {
        list_insert_next(l,0,&i,sizeof(i));
    }
    l_len = list_length(l);
    printf("l_len:%d \n", l_len);
    while (list_length(l) > 0) {
        if (!list_remove_next(l,0)) {
            n = list_data(list_head(l), &p);
            if (n) printf("list_head:%d size:%d \t", *p, n);
            n = list_data(list_tail(l), &p);
            if (n) printf("list_tail:%d size:%d \n", *p, n);        
        }
    }
    list_free(l);
    return 0;
}

l_len:10
list_head:8 size:4      list_tail:0 size:4
list_head:7 size:4      list_tail:0 size:4
list_head:6 size:4      list_tail:0 size:4
list_head:5 size:4      list_tail:0 size:4
list_head:4 size:4      list_tail:0 size:4
list_head:3 size:4      list_tail:0 size:4
list_head:2 size:4      list_tail:0 size:4
list_head:1 size:4      list_tail:0 size:4
list_head:0 size:4      list_tail:0 size:4