intrusive linked list example

intrusive_list.cpp

#include <iostream>
#include <cstring>
#include <string>

struct list_head {
	struct list_head *next, *prev;
};

#define INIT_LIST_HEAD(ptr) do { \
    (ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)

#ifndef container_of
#define container_of(ptr, type, member) __extension__ ({	\
    const __typeof__( ((type *)0)->member ) *__mptr = (ptr); \
    (type *)( (char *)__mptr - offsetof(type,member) );})
#endif

#define list_entry(ptr, type, member)	container_of(ptr, type, member)

void __list_add(struct list_head * add,
	struct list_head * prev,
	struct list_head * next)
{
	next->prev = add;
	add->next = next;
	add->prev = prev;
	prev->next = add;
}

void list_add_tail(struct list_head *add, struct list_head *head)
{
	__list_add(add, head->prev, head);
}

#define list_for_each(pos, head) \
	for (pos = (head)->next; pos != (head); pos = pos->next)

struct PhoneBook {
    struct list_head people_head;
    int npages;
};

struct Person {
    struct list_head people_list;
    char *name;
};

int main(int argc, char *argv[])

{
    list_head *p = (list_head*)0;
    PhoneBook *book = new PhoneBook();
    book->npages = 300;
    INIT_LIST_HEAD(&book->people_head);

    Person *person = new Person();
    INIT_LIST_HEAD(&person->people_list);
    person->name = new char[80];
    memcpy(person->name, "John Doe", sizeof("John Doe"));

    list_add_tail(&person->people_list, &book->people_head);

    Person *somebody;
    list_for_each(p, &book->people_head) {
        somebody = list_entry(p, Person, people_list);
        std::cout << somebody->name << std::endl;
    }

    return 0;
}