Selbstreferenzielle Typen mittels Pin und Pointer-Fixierung

use std::marker::PhantomPinned;
use std::pin::Pin;
 
pub struct SelfReferential {
    value: String,
    pointer: *const String,
    _marker: PhantomPinned,
}
 
impl SelfReferential {
    pub fn new(val: &str) -> Self {
        Self {
            value: val.to_string(),
            pointer: std::ptr::null(),
            _marker: PhantomPinned,
        }
    }
 
    pub fn init(self: Pin<&mut Self>) {
        let val_ptr = &self.value as *const String;
        unsafe {
            let this = self.get_unchecked_mut();
            this.pointer = val_ptr;
        }
    }
 
    pub fn get_referred_value(&self) -> Option<&str> {
        if self.pointer.is_null() {
            None
        } else {
            unsafe { Some(&*self.pointer) }
        }
    }
}