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use std::ops::{Deref, DerefMut};
use std::sync::atomic::*;
struct NABufferData<T> {
data: T,
refs: AtomicUsize,
}
impl<T> NABufferData<T> {
fn new(data: T) -> Self {
Self {
data: data,
refs: AtomicUsize::new(1),
}
}
fn inc_refs(obj: &mut Self) {
obj.refs.fetch_add(1, Ordering::SeqCst);
}
fn dec_refs(obj: &mut Self) {
if obj.refs.fetch_sub(1, Ordering::SeqCst) == 0 {
std::mem::forget(obj);
}
}
fn get_num_refs(obj: &Self) -> usize {
obj.refs.load(Ordering::Relaxed)
}
fn get_read_ptr(obj: &Self) -> &T {
&obj.data
}
fn get_write_ptr(obj: &mut Self) -> Option<&mut T> {
Some(&mut obj.data)
}
}
pub struct NABufferRef<T> {
ptr: *mut NABufferData<T>,
}
impl<T> NABufferRef<T> {
pub fn new(val: T) -> Self {
let bdata = NABufferData::new(val);
let nbox: Box<_> = Box::new(bdata);
Self { ptr: Box::into_raw(nbox) }
}
pub fn get_num_refs(&self) -> usize {
unsafe {
NABufferData::get_num_refs(self.ptr.as_mut().unwrap())
}
}
pub fn as_ref(&self) -> &T {
unsafe {
NABufferData::get_read_ptr(self.ptr.as_mut().unwrap())
}
}
pub fn as_mut(&mut self) -> Option<&mut T> {
unsafe {
NABufferData::get_write_ptr(self.ptr.as_mut().unwrap())
}
}
}
impl<T> Deref for NABufferRef<T> {
type Target = T;
fn deref(&self) -> &T { self.as_ref() }
}
impl<T> DerefMut for NABufferRef<T> {
fn deref_mut(&mut self) -> &mut T { self.as_mut().unwrap() }
}
impl<T> Clone for NABufferRef<T> {
fn clone(&self) -> Self {
unsafe {
NABufferData::inc_refs(self.ptr.as_mut().unwrap());
}
Self { ptr: self.ptr }
}
}
impl<T> Drop for NABufferRef<T> {
fn drop(&mut self) {
unsafe {
NABufferData::dec_refs(self.ptr.as_mut().unwrap());
}
}
}
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