LCOM1920-T5G03

#include <lcom/lcf.h>

#include "list.h"

struct list_node{

    list_node_t *p, *n;

    void *val;

};

list_node_t* (list_node_ctor)(list_node_t *p, list_node_t *n, void *val){

    list_node_t *ret = malloc(sizeof(list_node_t));

    if(ret == NULL) return NULL;

    ret->p = p;

    ret->n = n;

    ret->val = val;

    return ret;

}

void (list_node_dtor)(list_node_t *p){

    free(p);

}

list_node_t* (list_node_next)(const list_node_t *p){ return p->n; }

list_node_t* (list_node_prev)(const list_node_t *p){ return p->p; }

void**       (list_node_val )(list_node_t *p){ return &p->val; }

struct list{

    list_node_t *begin_;

    list_node_t *end_;

    size_t sz;

};

list_t* (list_ctor)(void){

    list_t *ret = malloc(sizeof(list_t));

    if(ret == NULL) return NULL;

    ret->sz = 0;

    ret->begin_ = NULL; ret->end_ = NULL;

    ret->begin_ = list_node_ctor(NULL, NULL, NULL);

    ret->end_   = list_node_ctor(NULL, NULL, NULL);

    if(ret->begin_ == NULL || ret->end_ == NULL){

        list_dtor(ret);

        return NULL;

    }

    ret->begin_->n = ret->end_  ;

    ret->end_  ->p = ret->begin_;

    return ret;

}

int (list_dtor)(list_t *l){

    if(l == NULL) return 0;

    if(list_size(l) > 0) return 1;

    list_node_dtor(l->begin_);

    list_node_dtor(l->end_);

    free(l);

    return 0;

}

list_node_t* (list_begin )(      list_t *l){ return l->begin_->n; }

list_node_t* (list_end   )(      list_t *l){ return l->end_; }

size_t       (list_size  )(const list_t *l){ return l->sz; }

list_node_t* (list_insert)(list_t *l, list_node_t *position, void *val){

    list_node_t *node = list_node_ctor(position->p, position, val);

    position->p->n = node;

    position->p    = node;

    ++l->sz;

    return node;

}

void*        (list_erase )(list_t *l, list_node_t *position){

    position->p->n = position->n;

    position->n->p = position->p;

    void *ret = position->val;

    list_node_dtor(position);

    --l->sz;

    return ret;

}