list_unlink.c

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/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   list_unlink.c                                      :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: unite <marvin@42.fr>                       +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2020/07/18 22:16:54 by unite             #+#    #+#             */
/*   Updated: 2020/09/07 22:48:41 by unite            ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */
 
#include "list.h"
 
static void *list_unlink_inner(t_list *alst, size_t index)
{
    t_link  *link;
    void    *content;
 
    if (index < alst->size / 2)
    {
        link = alst->head;
        while (index-- > 0)
            link = link->next;
    }
    else
    {
        link = alst->tail;
        while (++index < alst->size)
            link = link->prev;
    }
    link->prev->next = link->next;
    link->next->prev = link->prev;
    content = link->content;
    free(link);
    alst->size--;
    return (content);
}
 
void    *list_unlink(t_list *alst, size_t index)
{
    if (index >= alst->size)
    {
        ds_exit_set(EINVAL);
        return (NULL);
    }
    else if (index == 0)
        return (list_unlink_first(alst));
    else if (index + 1 == alst->size)
        return (list_unlink_last(alst));
    else
        return (list_unlink_inner(alst, index));
}