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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! A pointer type for heap allocation.
//!
//! `Box<T, A>` is similar to
//! [`std::boxed::Box<T>`](https://doc.rust-lang.org/nightly/std/boxed/struct.Box.html),
//! but pointers are associated with a specific allocator, allowing boxed pointers
//! in different heaps.
use core::borrow;
use core::cmp::Ordering;
use core::fmt;
use core::hash::{Hash, Hasher};
use core::iter::FusedIterator;
use core::marker::PhantomData;
use core::mem;
use core::ops::{Deref, DerefMut};
use core::ptr::{self, NonNull};
use alloc::{Alloc, Layout, handle_alloc_error};
#[cfg(feature = "std")]
use alloc::Global;
use raw_vec::RawVec;
#[cfg(not(feature = "nonnull_cast"))]
use ::NonNullCast;
/// A pointer type for heap allocation.
global_alloc! {
pub struct Box<T: ?Sized, A: Alloc> {
ptr: NonNull<T>,
marker: PhantomData<T>,
pub(crate) a: A,
}
}
impl<T, A: Alloc> Box<T, A> {
/// Allocates memory in the given allocator and then places `x` into it.
///
/// This doesn't actually allocate if `T` is zero-sized.
///
/// # Examples
///
/// ```
/// # #[macro_use]
/// extern crate allocator_api;
/// # test_using_global! {
/// use allocator_api::{Box, Global};
/// # fn main() {
/// let five = Box::new_in(5, Global);
/// # }
/// # }
/// ```
#[inline(always)]
pub fn new_in(x: T, a: A) -> Box<T, A> {
let mut a = a;
let layout = Layout::for_value(&x);
let size = layout.size();
let ptr = if size == 0 {
NonNull::dangling()
} else {
unsafe {
let ptr = a.alloc(layout).unwrap_or_else(|_| { handle_alloc_error(layout) });
ptr::write(ptr.as_ptr() as *mut T, x);
ptr.cast()
}
};
Box {
ptr: ptr,
marker: PhantomData,
a: a,
}
}
}
#[cfg(feature = "std")]
impl<T> Box<T> {
/// Allocates memory on the heap and then places `x` into it.
///
/// This doesn't actually allocate if `T` is zero-sized.
///
/// # Examples
///
/// ```
/// extern crate allocator_api;
/// use allocator_api::Box;
/// # fn main() {
/// let five = Box::new(5);
/// # }
/// ```
#[inline(always)]
pub fn new(x: T) -> Box<T> {
Box::new_in(x, Global)
}
}
#[cfg(feature = "std")]
impl<T: ?Sized> Box<T> {
/// Constructs a box from a raw pointer.
///
/// After calling this function, the raw pointer is owned by the
/// resulting `Box`. Specifically, the `Box` destructor will call
/// the destructor of `T` and free the allocated memory. Since the
/// way `Box` allocates and releases memory is unspecified, the
/// only valid pointer to pass to this function is the one taken
/// from another `Box` via the [`Box::into_raw`] function.
///
/// This function is unsafe because improper use may lead to
/// memory problems. For example, a double-free may occur if the
/// function is called twice on the same raw pointer.
///
/// [`Box::into_raw`]: struct.Box.html#method.into_raw
///
/// # Examples
///
/// ```
/// extern crate allocator_api;
/// use allocator_api::Box;
/// # fn main() {
/// let x = Box::new(5);
/// let ptr = Box::into_raw(x);
/// let x = unsafe { Box::from_raw(ptr) };
/// # }
/// ```
#[inline]
pub unsafe fn from_raw(raw: *mut T) -> Self {
Box::from_raw_in(raw, Global)
}
}
impl<T: ?Sized, A: Alloc> Box<T, A> {
/// Constructs a box from a raw pointer in the given allocator.
///
/// This is similar to the [`Box::from_raw`] function, but assumes
/// the pointer was allocated with the given allocator.
///
/// This function is unsafe because improper use may lead to
/// memory problems. For example, specifying the wrong allocator
/// may corrupt the allocator state.
///
/// [`Box::into_raw`]: struct.Box.html#method.into_raw
///
/// # Examples
///
/// ```
/// # #[macro_use]
/// extern crate allocator_api;
/// # test_using_global! {
/// use allocator_api::{Box, Global};
/// # fn main() {
/// let x = Box::new_in(5, Global);
/// let ptr = Box::into_raw(x);
/// let x = unsafe { Box::from_raw_in(ptr, Global) };
/// # }
/// # }
/// ```
#[inline]
pub unsafe fn from_raw_in(raw: *mut T, a: A) -> Self {
Box {
ptr: NonNull::new_unchecked(raw),
marker: PhantomData,
a: a,
}
}
/// Consumes the `Box`, returning the wrapped raw pointer.
///
/// After calling this function, the caller is responsible for the
/// memory previously managed by the `Box`. In particular, the
/// caller should properly destroy `T` and release the memory. The
/// proper way to do so is to convert the raw pointer back into a
/// `Box` with the [`Box::from_raw`] or the [`Box::from_raw_in`]
/// functions, with the appropriate allocator.
///
/// Note: this is an associated function, which means that you have
/// to call it as `Box::into_raw(b)` instead of `b.into_raw()`. This
/// is so that there is no conflict with a method on the inner type.
///
/// [`Box::from_raw`]: struct.Box.html#method.from_raw
///
/// # Examples
///
/// ```
/// # #[macro_use]
/// extern crate allocator_api;
/// # test_using_global! {
/// use allocator_api::Box;
/// # fn main() {
/// let x = Box::new(5);
/// let ptr = Box::into_raw(x);
/// # }
/// # }
/// ```
#[inline]
pub fn into_raw(b: Box<T, A>) -> *mut T {
let ptr = b.ptr.as_ptr();
mem::forget(b);
ptr
}
/// Consumes and leaks the `Box`, returning a mutable reference,
/// `&'a mut T`. Here, the lifetime `'a` may be chosen to be `'static`.
///
/// This function is mainly useful for data that lives for the remainder of
/// the program's life. Dropping the returned reference will cause a memory
/// leak. If this is not acceptable, the reference should first be wrapped
/// with the [`Box::from_raw`] function producing a `Box`. This `Box` can
/// then be dropped which will properly destroy `T` and release the
/// allocated memory.
///
/// Note: this is an associated function, which means that you have
/// to call it as `Box::leak(b)` instead of `b.leak()`. This
/// is so that there is no conflict with a method on the inner type.
///
/// [`Box::from_raw`]: struct.Box.html#method.from_raw
///
/// # Examples
///
/// Simple usage:
///
/// ```
/// # #[macro_use]
/// extern crate allocator_api;
/// # test_using_global! {
/// use allocator_api::Box;
/// fn main() {
/// let x = Box::new(41);
/// let static_ref: &'static mut usize = Box::leak(x);
/// *static_ref += 1;
/// assert_eq!(*static_ref, 42);
/// }
/// # }
/// ```
///
/// Unsized data:
///
/// ```
/// # #[macro_use]
/// extern crate allocator_api;
/// # test_using_global! {
/// # use std::ptr;
/// use allocator_api::{Box, RawVec};
/// struct MyVec<T> {
/// buf: RawVec<T>,
/// len: usize,
/// }
///
/// impl<T> MyVec<T> {
/// pub fn push(&mut self, elem: T) {
/// if self.len == self.buf.cap() { self.buf.double(); }
/// // double would have aborted or panicked if the len exceeded
/// // `isize::MAX` so this is safe to do unchecked now.
/// unsafe {
/// ptr::write(self.buf.ptr().offset(self.len as isize), elem);
/// }
/// self.len += 1;
/// }
/// }
/// fn main() {
/// //let x = vec![1, 2, 3].into_boxed_slice();
/// let mut v = MyVec { buf: RawVec::new(), len: 0 };
/// v.push(1);
/// v.push(2);
/// v.push(3);
/// v.buf.shrink_to_fit(v.len);
/// let x = unsafe { v.buf.into_box() };
/// let static_ref = Box::leak(x);
/// static_ref[0] = 4;
/// assert_eq!(*static_ref, [4, 2, 3]);
/// }
/// # }
/// ```
#[inline]
pub fn leak<'a>(b: Box<T, A>) -> &'a mut T
where
T: 'a // Technically not needed, but kept to be explicit.
{
unsafe { &mut *Box::into_raw(b) }
}
}
impl<T: ?Sized, A: Alloc> Drop for Box<T, A> {
fn drop(&mut self) {
unsafe {
let value = self.ptr.as_ref();
if mem::size_of_val(value) != 0 {
let layout = Layout::for_value(value);
self.a.dealloc(self.ptr.cast(), layout);
}
}
}
}
impl<T: Default, A: Alloc + Default> Default for Box<T, A> {
/// Creates a `Box<T>`, with the `Default` value for T.
fn default() -> Box<T, A> {
Box::new_in(Default::default(), Default::default())
}
}
impl<T, A: Alloc + Default> Default for Box<[T], A> {
fn default() -> Box<[T], A> {
let a = A::default();
let b = Box::<[T; 0], A>::new_in([], a);
let raw = b.ptr.as_ptr();
let a = unsafe { ptr::read(&b.a) };
mem::forget(b);
unsafe { Box::from_raw_in(raw, a) }
}
}
impl<T: Clone, A: Alloc + Clone> Clone for Box<T, A> {
/// Returns a new box with a `clone()` of this box's contents.
///
/// # Examples
///
/// ```
/// # #[macro_use]
/// extern crate allocator_api;
/// # test_using_global! {
/// use allocator_api::Box;
/// # fn main() {
/// let x = Box::new(5);
/// let y = x.clone();
/// # }
/// # }
/// ```
#[inline]
fn clone(&self) -> Box<T, A> {
Box::new_in((**self).clone(), self.a.clone())
}
/// Copies `source`'s contents into `self` without creating a new allocation.
///
/// # Examples
///
/// ```
/// # #[macro_use]
/// extern crate allocator_api;
/// # test_using_global! {
/// use allocator_api::Box;
/// # fn main() {
/// let x = Box::new(5);
/// let mut y = Box::new(10);
///
/// y.clone_from(&x);
///
/// assert_eq!(*y, 5);
/// # }
/// # }
/// ```
#[inline]
fn clone_from(&mut self, source: &Box<T, A>) {
(**self).clone_from(&(**source));
}
}
impl<T: ?Sized + PartialEq, A: Alloc> PartialEq for Box<T, A> {
#[inline]
fn eq(&self, other: &Box<T, A>) -> bool {
PartialEq::eq(&**self, &**other)
}
#[inline]
fn ne(&self, other: &Box<T, A>) -> bool {
PartialEq::ne(&**self, &**other)
}
}
impl<T: ?Sized + PartialOrd, A: Alloc> PartialOrd for Box<T, A> {
#[inline]
fn partial_cmp(&self, other: &Box<T, A>) -> Option<Ordering> {
PartialOrd::partial_cmp(&**self, &**other)
}
#[inline]
fn lt(&self, other: &Box<T, A>) -> bool {
PartialOrd::lt(&**self, &**other)
}
#[inline]
fn le(&self, other: &Box<T, A>) -> bool {
PartialOrd::le(&**self, &**other)
}
#[inline]
fn ge(&self, other: &Box<T, A>) -> bool {
PartialOrd::ge(&**self, &**other)
}
#[inline]
fn gt(&self, other: &Box<T, A>) -> bool {
PartialOrd::gt(&**self, &**other)
}
}
impl<T: ?Sized + Ord, A: Alloc> Ord for Box<T, A> {
#[inline]
fn cmp(&self, other: &Box<T, A>) -> Ordering {
Ord::cmp(&**self, &**other)
}
}
impl<T: ?Sized + Eq, A: Alloc> Eq for Box<T, A> {}
impl<T: ?Sized + Hash, A: Alloc> Hash for Box<T, A> {
fn hash<H: Hasher>(&self, state: &mut H) {
(**self).hash(state);
}
}
impl<T: ?Sized + Hasher, A: Alloc> Hasher for Box<T, A> {
fn finish(&self) -> u64 {
(**self).finish()
}
fn write(&mut self, bytes: &[u8]) {
(**self).write(bytes)
}
fn write_u8(&mut self, i: u8) {
(**self).write_u8(i)
}
fn write_u16(&mut self, i: u16) {
(**self).write_u16(i)
}
fn write_u32(&mut self, i: u32) {
(**self).write_u32(i)
}
fn write_u64(&mut self, i: u64) {
(**self).write_u64(i)
}
fn write_u128(&mut self, i: u128) {
(**self).write_u128(i)
}
fn write_usize(&mut self, i: usize) {
(**self).write_usize(i)
}
fn write_i8(&mut self, i: i8) {
(**self).write_i8(i)
}
fn write_i16(&mut self, i: i16) {
(**self).write_i16(i)
}
fn write_i32(&mut self, i: i32) {
(**self).write_i32(i)
}
fn write_i64(&mut self, i: i64) {
(**self).write_i64(i)
}
fn write_i128(&mut self, i: i128) {
(**self).write_i128(i)
}
fn write_isize(&mut self, i: isize) {
(**self).write_isize(i)
}
}
impl<T, A: Alloc + Default> From<T> for Box<T, A> {
fn from(t: T) -> Self {
Box::new_in(t, Default::default())
}
}
impl<'a, T: Copy, A: Alloc + Default> From<&'a [T]> for Box<[T], A> {
fn from(slice: &'a [T]) -> Box<[T], A> {
let a = Default::default();
let mut boxed = unsafe { RawVec::with_capacity_in(slice.len(), a).into_box() };
boxed.copy_from_slice(slice);
boxed
}
}
impl<T: fmt::Display + ?Sized, A: Alloc> fmt::Display for Box<T, A> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Display::fmt(&**self, f)
}
}
impl<T: fmt::Debug + ?Sized, A: Alloc> fmt::Debug for Box<T, A> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(&**self, f)
}
}
impl<T: ?Sized, A: Alloc> fmt::Pointer for Box<T, A> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
// It's not possible to extract the inner Uniq directly from the Box,
// instead we cast it to a *const which aliases the Unique
let ptr: *const T = &**self;
fmt::Pointer::fmt(&ptr, f)
}
}
impl<T: ?Sized, A: Alloc> Deref for Box<T, A> {
type Target = T;
fn deref(&self) -> &T {
unsafe { self.ptr.as_ref() }
}
}
impl<T: ?Sized, A: Alloc> DerefMut for Box<T, A> {
fn deref_mut(&mut self) -> &mut T {
unsafe { self.ptr.as_mut() }
}
}
impl<I: Iterator + ?Sized, A: Alloc> Iterator for Box<I, A> {
type Item = I::Item;
fn next(&mut self) -> Option<I::Item> {
(**self).next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
(**self).size_hint()
}
fn nth(&mut self, n: usize) -> Option<I::Item> {
(**self).nth(n)
}
}
impl<I: DoubleEndedIterator + ?Sized, A: Alloc> DoubleEndedIterator for Box<I, A> {
fn next_back(&mut self) -> Option<I::Item> {
(**self).next_back()
}
}
impl<I: ExactSizeIterator + ?Sized, A: Alloc> ExactSizeIterator for Box<I, A> {
fn len(&self) -> usize {
(**self).len()
}
}
impl<I: FusedIterator + ?Sized, A: Alloc> FusedIterator for Box<I, A> {}
impl<T: Clone, A: Alloc + Clone> Clone for Box<[T], A> {
fn clone(&self) -> Self {
let mut new = BoxBuilder {
data: RawVec::with_capacity_in(self.len(), self.a.clone()),
len: 0,
};
let mut target = new.data.ptr();
for item in self.iter() {
unsafe {
ptr::write(target, item.clone());
target = target.offset(1);
};
new.len += 1;
}
return unsafe { new.into_box() };
// Helper type for responding to panics correctly.
struct BoxBuilder<T, A: Alloc> {
data: RawVec<T, A>,
len: usize,
}
impl<T, A: Alloc> BoxBuilder<T, A> {
unsafe fn into_box(self) -> Box<[T], A> {
let raw = ptr::read(&self.data);
mem::forget(self);
raw.into_box()
}
}
impl<T, A: Alloc> Drop for BoxBuilder<T, A> {
fn drop(&mut self) {
let mut data = self.data.ptr();
let max = unsafe { data.offset(self.len as isize) };
while data != max {
unsafe {
ptr::read(data);
data = data.offset(1);
}
}
}
}
}
}
impl<T: ?Sized, A: Alloc> borrow::Borrow<T> for Box<T, A> {
fn borrow(&self) -> &T {
&**self
}
}
impl<T: ?Sized, A: Alloc> borrow::BorrowMut<T> for Box<T, A> {
fn borrow_mut(&mut self) -> &mut T {
&mut **self
}
}
impl<T: ?Sized, A: Alloc> AsRef<T> for Box<T, A> {
fn as_ref(&self) -> &T {
&**self
}
}
impl<T: ?Sized, A: Alloc> AsMut<T> for Box<T, A> {
fn as_mut(&mut self) -> &mut T {
&mut **self
}
}