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use super::{OwnedAlloc, UninitAlloc};
use std::fmt;
pub enum MaybeUninitAlloc<T>
where
T: ?Sized,
{
Init(OwnedAlloc<T>),
Uninit(UninitAlloc<T>),
}
impl<T> MaybeUninitAlloc<T> {
pub fn or_init<F>(self, init: F) -> OwnedAlloc<T>
where
F: FnOnce() -> T,
{
match self {
MaybeUninitAlloc::Init(ptr) => ptr,
MaybeUninitAlloc::Uninit(ptr) => ptr.init(init()),
}
}
}
impl<T> MaybeUninitAlloc<T>
where
T: ?Sized,
{
pub unsafe fn or_init_in_place<F>(self, init: F) -> OwnedAlloc<T>
where
F: FnOnce(&mut T),
{
match self {
MaybeUninitAlloc::Init(ptr) => ptr,
MaybeUninitAlloc::Uninit(ptr) => ptr.init_in_place(init),
}
}
pub fn is_initialized(&self) -> bool {
match self {
MaybeUninitAlloc::Init(_) => true,
MaybeUninitAlloc::Uninit(_) => false,
}
}
pub fn is_uninitialized(&self) -> bool {
match self {
MaybeUninitAlloc::Init(_) => true,
MaybeUninitAlloc::Uninit(_) => false,
}
}
pub fn drop_in_place(self) -> UninitAlloc<T> {
match self {
MaybeUninitAlloc::Init(ptr) => ptr.drop_in_place(),
MaybeUninitAlloc::Uninit(ptr) => ptr,
}
}
pub fn init_as_ok(self) -> Result<OwnedAlloc<T>, UninitAlloc<T>> {
match self {
MaybeUninitAlloc::Init(ptr) => Ok(ptr),
MaybeUninitAlloc::Uninit(ptr) => Err(ptr),
}
}
pub fn uninit_as_ok(self) -> Result<UninitAlloc<T>, OwnedAlloc<T>> {
match self {
MaybeUninitAlloc::Init(ptr) => Err(ptr),
MaybeUninitAlloc::Uninit(ptr) => Ok(ptr),
}
}
pub fn modify<F, A>(&mut self, visit: F) -> Option<A>
where
F: FnOnce(&mut T) -> A,
{
match self {
MaybeUninitAlloc::Init(ptr) => Some(visit(&mut **ptr)),
MaybeUninitAlloc::Uninit(_) => None,
}
}
}
impl<T> From<T> for MaybeUninitAlloc<T> {
fn from(val: T) -> Self {
MaybeUninitAlloc::Init(OwnedAlloc::new(val))
}
}
impl<T> From<OwnedAlloc<T>> for MaybeUninitAlloc<T>
where
T: ?Sized,
{
fn from(alloc: OwnedAlloc<T>) -> Self {
MaybeUninitAlloc::Init(alloc)
}
}
impl<T> From<UninitAlloc<T>> for MaybeUninitAlloc<T>
where
T: ?Sized,
{
fn from(alloc: UninitAlloc<T>) -> Self {
MaybeUninitAlloc::Uninit(alloc)
}
}
impl<T> fmt::Debug for MaybeUninitAlloc<T>
where
T: ?Sized,
{
fn fmt(&self, fmtr: &mut fmt::Formatter) -> fmt::Result {
match self {
MaybeUninitAlloc::Init(ptr) => write!(fmtr, "Init({:?})", ptr),
MaybeUninitAlloc::Uninit(ptr) => write!(fmtr, "Uninit({:?})", ptr),
}
}
}
#[cfg(test)]
mod test {
use super::{super::UninitAlloc, MaybeUninitAlloc};
#[test]
fn or_init_is_noop_if_initialized() {
let init = MaybeUninitAlloc::from(90);
assert_eq!(*init.or_init(|| 50), 90);
}
#[test]
fn or_init_calls_if_uninit() {
let init = MaybeUninitAlloc::from(UninitAlloc::new());
assert_eq!(*init.or_init(|| 50), 50);
}
#[test]
fn modifies() {
let mut init = MaybeUninitAlloc::from(20);
assert!(init.modify(|addr| *addr = 2).is_some());
assert_eq!(*init.init_as_ok().unwrap(), 2);
}
}