#![feature(arbitrary_self_types)]

use std::marker::PhantomData;
use std::ptr::NonNull;

#[allow(non_camel_case_types)]
type gpointer = *mut std::ffi::c_void;

pub struct GList {
    pub data: gpointer,
    pub next: *mut GList,
    pub prev: *mut GList,
}

impl GList {
    pub fn iter<T>(self: *mut Self) -> GListIter<T> {
        GListIter {
            glist: NonNull::new(self),
            _marker: PhantomData,
        }
    }
}

pub struct GListIter<T> {
    glist: Option<NonNull<GList>>,
    _marker: PhantomData<T>,
}

impl<T> Iterator for GListIter<T> {
    type Item = *mut T;

    fn next(&mut self) -> Option<Self::Item> {
        self.glist.map(|current| {
            self.glist = NonNull::new(unsafe { (*current.as_ptr()).next });

            unsafe { (*current.as_ptr()).data as *mut T }
        })
    }
}