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use std::any::Any;
use std::borrow::{Borrow, BorrowMut};
use std::marker::{PhantomData, Unsize};
use std::mem;
use std::ops::{CoerceUnsized, Deref, DerefMut, InPlace, Placer};
use std::ops::Place as StdPlace;
use std::ptr::Unique;
use super::{Allocator, Error, Block};
pub struct AllocBox<'a, T: 'a + ?Sized, A: 'a + ?Sized + Allocator> {
item: Unique<T>,
size: usize,
align: usize,
allocator: &'a A,
}
impl<'a, T: ?Sized, A: ?Sized + Allocator> AllocBox<'a, T, A> {
pub fn take(self) -> T where T: Sized {
let val = unsafe { ::std::ptr::read(*self.item) };
let block = Block::new(*self.item as *mut u8, self.size, self.align);
unsafe { self.allocator.deallocate_raw(block) };
mem::forget(self);
val
}
pub unsafe fn as_block(&self) -> Block {
Block::new(*self.item as *mut u8, self.size, self.align)
}
}
impl<'a, T: ?Sized, A: ?Sized + Allocator> Deref for AllocBox<'a, T, A> {
type Target = T;
fn deref(&self) -> &T {
unsafe { self.item.get() }
}
}
impl<'a, T: ?Sized, A: ?Sized + Allocator> DerefMut for AllocBox<'a, T, A> {
fn deref_mut(&mut self) -> &mut T {
unsafe { self.item.get_mut() }
}
}
impl<'a, T: ?Sized + Unsize<U>, U: ?Sized, A: ?Sized + Allocator> CoerceUnsized<AllocBox<'a, U, A>> for AllocBox<'a, T, A> {}
impl<'a, A: ?Sized + Allocator> AllocBox<'a, Any, A> {
pub fn downcast<T: Any>(self) -> Result<AllocBox<'a, T, A>, AllocBox<'a, Any, A>> {
use std::raw::TraitObject;
if self.is::<T>() {
let obj: TraitObject = unsafe { mem::transmute::<*mut Any, TraitObject>(*self.item) };
let new_allocated = AllocBox {
item: unsafe { Unique::new(obj.data as *mut T) },
size: self.size,
align: self.align,
allocator: self.allocator,
};
mem::forget(self);
Ok(new_allocated)
} else {
Err(self)
}
}
}
impl<'a, T: ?Sized, A: ?Sized + Allocator> Borrow<T> for AllocBox<'a, T, A> {
fn borrow(&self) -> &T {
&**self
}
}
impl<'a, T: ?Sized, A: ?Sized + Allocator> BorrowMut<T> for AllocBox<'a, T, A> {
fn borrow_mut(&mut self) -> &mut T {
&mut **self
}
}
impl<'a, T: ?Sized, A: ?Sized + Allocator> Drop for AllocBox<'a, T, A> {
#[inline]
fn drop(&mut self) {
use std::intrinsics::drop_in_place;
unsafe {
drop_in_place(*self.item);
self.allocator.deallocate_raw(Block::new(*self.item as *mut u8, self.size, self.align));
}
}
}
pub fn make_place<A: ?Sized + Allocator, T>(alloc: &A) -> Result<Place<T, A>, super::Error> {
let (size, align) = (mem::size_of::<T>(), mem::align_of::<T>());
match unsafe { alloc.allocate_raw(size, align) } {
Ok(block) => {
Ok(Place {
allocator: alloc,
block: block,
_marker: PhantomData,
})
}
Err(e) => Err(e),
}
}
pub struct Place<'a, T: 'a, A: 'a + ?Sized + Allocator> {
allocator: &'a A,
block: Block<'a>,
_marker: PhantomData<T>,
}
impl<'a, T: 'a, A: 'a + ?Sized + Allocator> Placer<T> for Place<'a, T, A> {
type Place = Self;
fn make_place(self) -> Self {
self
}
}
impl<'a, T: 'a, A: 'a + ?Sized + Allocator> InPlace<T> for Place<'a, T, A> {
type Owner = AllocBox<'a, T, A>;
unsafe fn finalize(self) -> Self::Owner {
let allocated = AllocBox {
item: Unique::new(self.block.ptr() as *mut T),
size: self.block.size(),
align: self.block.align(),
allocator: self.allocator,
};
mem::forget(self);
allocated
}
}
impl<'a, T: 'a, A: 'a + ?Sized + Allocator> StdPlace<T> for Place<'a, T, A> {
fn pointer(&mut self) -> *mut T {
self.block.ptr() as *mut T
}
}
impl<'a, T: 'a, A: 'a + ?Sized + Allocator> Drop for Place<'a, T, A> {
#[inline]
fn drop(&mut self) {
unsafe {
self.allocator.deallocate_raw(mem::replace(&mut self.block, Block::empty()));
}
}
}