-#![unstable(feature = "raw_vec_internals", reason = "implementation detail", issue = "0")]
+#![unstable(feature = "raw_vec_internals", reason = "implementation detail", issue = "none")]
#![doc(hidden)]
use core::cmp;
use core::ptr::{self, NonNull, Unique};
use core::slice;
-use crate::alloc::{Alloc, Layout, Global, AllocErr, handle_alloc_error};
-use crate::collections::TryReserveError::{self, *};
+use crate::alloc::{handle_alloc_error, Alloc, AllocErr, Global, Layout};
use crate::boxed::Box;
+use crate::collections::TryReserveError::{self, *};
#[cfg(test)]
mod tests;
/// involved. This type is excellent for building your own data structures like Vec and VecDeque.
/// In particular:
///
-/// * Produces Unique::empty() on zero-sized types
-/// * Produces Unique::empty() on zero-length allocations
-/// * Catches all overflows in capacity computations (promotes them to "capacity overflow" panics)
-/// * Guards against 32-bit systems allocating more than isize::MAX bytes
-/// * Guards against overflowing your length
-/// * Aborts on OOM or calls handle_alloc_error as applicable
-/// * Avoids freeing Unique::empty()
-/// * Contains a ptr::Unique and thus endows the user with all related benefits
+/// * Produces `Unique::empty()` on zero-sized types.
+/// * Produces `Unique::empty()` on zero-length allocations.
+/// * Catches all overflows in capacity computations (promotes them to "capacity overflow" panics).
+/// * Guards against 32-bit systems allocating more than isize::MAX bytes.
+/// * Guards against overflowing your length.
+/// * Aborts on OOM or calls `handle_alloc_error` as applicable.
+/// * Avoids freeing `Unique::empty()`.
+/// * Contains a `ptr::Unique` and thus endows the user with all related benefits.
///
/// This type does not in anyway inspect the memory that it manages. When dropped it *will*
-/// free its memory, but it *won't* try to Drop its contents. It is up to the user of RawVec
-/// to handle the actual things *stored* inside of a RawVec.
+/// free its memory, but it *won't* try to drop its contents. It is up to the user of `RawVec`
+/// to handle the actual things *stored* inside of a `RawVec`.
///
-/// Note that a RawVec always forces its capacity to be usize::MAX for zero-sized types.
-/// This enables you to use capacity growing logic catch the overflows in your length
+/// Note that a `RawVec` always forces its capacity to be `usize::MAX` for zero-sized types.
+/// This enables you to use capacity-growing logic catch the overflows in your length
/// that might occur with zero-sized types.
///
-/// However this means that you need to be careful when round-tripping this type
-/// with a `Box<[T]>`: `capacity()` won't yield the len. However `with_capacity`,
-/// `shrink_to_fit`, and `from_box` will actually set RawVec's private capacity
+/// The above means that you need to be careful when round-tripping this type with a
+/// `Box<[T]>`, since `capacity()` won't yield the length. However, `with_capacity`,
+/// `shrink_to_fit`, and `from_box` will actually set `RawVec`'s private capacity
/// field. This allows zero-sized types to not be special-cased by consumers of
/// this type.
#[allow(missing_debug_implementations)]
}
impl<T, A: Alloc> RawVec<T, A> {
- /// Like `new` but parameterized over the choice of allocator for
- /// the returned RawVec.
+ /// Like `new`, but parameterized over the choice of allocator for
+ /// the returned `RawVec`.
pub const fn new_in(a: A) -> Self {
- // !0 is usize::MAX. This branch should be stripped at compile time.
- // FIXME(mark-i-m): use this line when `if`s are allowed in `const`
- //let cap = if mem::size_of::<T>() == 0 { !0 } else { 0 };
-
- // Unique::empty() doubles as "unallocated" and "zero-sized allocation"
- RawVec {
- ptr: Unique::empty(),
- // FIXME(mark-i-m): use `cap` when ifs are allowed in const
- cap: [0, !0][(mem::size_of::<T>() == 0) as usize],
- a,
- }
+ let cap = if mem::size_of::<T>() == 0 { core::usize::MAX } else { 0 };
+
+ // `Unique::empty()` doubles as "unallocated" and "zero-sized allocation".
+ RawVec { ptr: Unique::empty(), cap, a }
}
- /// Like `with_capacity` but parameterized over the choice of
- /// allocator for the returned RawVec.
+ /// Like `with_capacity`, but parameterized over the choice of
+ /// allocator for the returned `RawVec`.
#[inline]
pub fn with_capacity_in(capacity: usize, a: A) -> Self {
RawVec::allocate_in(capacity, false, a)
}
- /// Like `with_capacity_zeroed` but parameterized over the choice
- /// of allocator for the returned RawVec.
+ /// Like `with_capacity_zeroed`, but parameterized over the choice
+ /// of allocator for the returned `RawVec`.
#[inline]
pub fn with_capacity_zeroed_in(capacity: usize, a: A) -> Self {
RawVec::allocate_in(capacity, true, a)
let alloc_size = capacity.checked_mul(elem_size).unwrap_or_else(|| capacity_overflow());
alloc_guard(alloc_size).unwrap_or_else(|_| capacity_overflow());
- // handles ZSTs and `capacity = 0` alike
+ // Handles ZSTs and `capacity == 0` alike.
let ptr = if alloc_size == 0 {
NonNull::<T>::dangling()
} else {
let align = mem::align_of::<T>();
let layout = Layout::from_size_align(alloc_size, align).unwrap();
- let result = if zeroed {
- a.alloc_zeroed(layout)
- } else {
- a.alloc(layout)
- };
+ let result = if zeroed { a.alloc_zeroed(layout) } else { a.alloc(layout) };
match result {
Ok(ptr) => ptr.cast(),
Err(_) => handle_alloc_error(layout),
}
};
- RawVec {
- ptr: ptr.into(),
- cap: capacity,
- a,
- }
+ RawVec { ptr: ptr.into(), cap: capacity, a }
}
}
}
impl<T> RawVec<T, Global> {
- /// Creates the biggest possible RawVec (on the system heap)
- /// without allocating. If T has positive size, then this makes a
- /// RawVec with capacity 0. If T has 0 size, then it makes a
- /// RawVec with capacity `usize::MAX`. Useful for implementing
+ /// HACK(Centril): This exists because `#[unstable]` `const fn`s needn't conform
+ /// to `min_const_fn` and so they cannot be called in `min_const_fn`s either.
+ ///
+ /// If you change `RawVec<T>::new` or dependencies, please take care to not
+ /// introduce anything that would truly violate `min_const_fn`.
+ ///
+ /// NOTE: We could avoid this hack and check conformance with some
+ /// `#[rustc_force_min_const_fn]` attribute which requires conformance
+ /// with `min_const_fn` but does not necessarily allow calling it in
+ /// `stable(...) const fn` / user code not enabling `foo` when
+ /// `#[rustc_const_unstable(feature = "foo", ..)]` is present.
+ pub const NEW: Self = Self::new();
+
+ /// Creates the biggest possible `RawVec` (on the system heap)
+ /// without allocating. If `T` has positive size, then this makes a
+ /// `RawVec` with capacity `0`. If `T` is zero-sized, then it makes a
+ /// `RawVec` with capacity `usize::MAX`. Useful for implementing
/// delayed allocation.
pub const fn new() -> Self {
Self::new_in(Global)
}
- /// Creates a RawVec (on the system heap) with exactly the
+ /// Creates a `RawVec` (on the system heap) with exactly the
/// capacity and alignment requirements for a `[T; capacity]`. This is
- /// equivalent to calling RawVec::new when `capacity` is 0 or T is
+ /// equivalent to calling `RawVec::new` when `capacity` is `0` or `T` is
/// zero-sized. Note that if `T` is zero-sized this means you will
- /// *not* get a RawVec with the requested capacity!
+ /// *not* get a `RawVec` with the requested capacity.
///
/// # Panics
///
///
/// # Aborts
///
- /// Aborts on OOM
+ /// Aborts on OOM.
#[inline]
pub fn with_capacity(capacity: usize) -> Self {
RawVec::allocate_in(capacity, false, Global)
}
- /// Like `with_capacity` but guarantees the buffer is zeroed.
+ /// Like `with_capacity`, but guarantees the buffer is zeroed.
#[inline]
pub fn with_capacity_zeroed(capacity: usize) -> Self {
RawVec::allocate_in(capacity, true, Global)
}
impl<T, A: Alloc> RawVec<T, A> {
- /// Reconstitutes a RawVec from a pointer, capacity, and allocator.
+ /// Reconstitutes a `RawVec` from a pointer, capacity, and allocator.
///
/// # Undefined Behavior
///
- /// The ptr must be allocated (via the given allocator `a`), and with the given capacity. The
- /// capacity cannot exceed `isize::MAX` (only a concern on 32-bit systems).
- /// If the ptr and capacity come from a RawVec created via `a`, then this is guaranteed.
+ /// The `ptr` must be allocated (via the given allocator `a`), and with the given `capacity`.
+ /// The `capacity` cannot exceed `isize::MAX` (only a concern on 32-bit systems).
+ /// If the `ptr` and `capacity` come from a `RawVec` created via `a`, then this is guaranteed.
pub unsafe fn from_raw_parts_in(ptr: *mut T, capacity: usize, a: A) -> Self {
- RawVec {
- ptr: Unique::new_unchecked(ptr),
- cap: capacity,
- a,
- }
+ RawVec { ptr: Unique::new_unchecked(ptr), cap: capacity, a }
}
}
impl<T> RawVec<T, Global> {
- /// Reconstitutes a RawVec from a pointer, capacity.
+ /// Reconstitutes a `RawVec` from a pointer and capacity.
///
/// # Undefined Behavior
///
- /// The ptr must be allocated (on the system heap), and with the given capacity. The
- /// capacity cannot exceed `isize::MAX` (only a concern on 32-bit systems).
- /// If the ptr and capacity come from a RawVec, then this is guaranteed.
+ /// The `ptr` must be allocated (on the system heap), and with the given `capacity`.
+ /// The `capacity` cannot exceed `isize::MAX` (only a concern on 32-bit systems).
+ /// If the `ptr` and `capacity` come from a `RawVec`, then this is guaranteed.
pub unsafe fn from_raw_parts(ptr: *mut T, capacity: usize) -> Self {
- RawVec {
- ptr: Unique::new_unchecked(ptr),
- cap: capacity,
- a: Global,
- }
+ RawVec { ptr: Unique::new_unchecked(ptr), cap: capacity, a: Global }
}
/// Converts a `Box<[T]>` into a `RawVec<T>`.
impl<T, A: Alloc> RawVec<T, A> {
/// Gets a raw pointer to the start of the allocation. Note that this is
- /// Unique::empty() if `capacity = 0` or T is zero-sized. In the former case, you must
+ /// `Unique::empty()` if `capacity == 0` or `T` is zero-sized. In the former case, you must
/// be careful.
pub fn ptr(&self) -> *mut T {
self.ptr.as_ptr()
/// This will always be `usize::MAX` if `T` is zero-sized.
#[inline(always)]
pub fn capacity(&self) -> usize {
- if mem::size_of::<T>() == 0 {
- !0
- } else {
- self.cap
- }
+ if mem::size_of::<T>() == 0 { !0 } else { self.cap }
}
- /// Returns a shared reference to the allocator backing this RawVec.
+ /// Returns a shared reference to the allocator backing this `RawVec`.
pub fn alloc(&self) -> &A {
&self.a
}
- /// Returns a mutable reference to the allocator backing this RawVec.
+ /// Returns a mutable reference to the allocator backing this `RawVec`.
pub fn alloc_mut(&mut self) -> &mut A {
&mut self.a
}
///
/// # Panics
///
- /// * Panics if T is zero-sized on the assumption that you managed to exhaust
+ /// * Panics if `T` is zero-sized on the assumption that you managed to exhaust
/// all `usize::MAX` slots in your imaginary buffer.
/// * Panics on 32-bit platforms if the requested capacity exceeds
/// `isize::MAX` bytes.
unsafe {
let elem_size = mem::size_of::<T>();
- // since we set the capacity to usize::MAX when elem_size is
- // 0, getting to here necessarily means the RawVec is overfull.
+ // Since we set the capacity to `usize::MAX` when `elem_size` is
+ // 0, getting to here necessarily means the `RawVec` is overfull.
assert!(elem_size != 0, "capacity overflow");
let (new_cap, uniq) = match self.current_layout() {
Some(cur) => {
// Since we guarantee that we never allocate more than
- // isize::MAX bytes, `elem_size * self.cap <= isize::MAX` as
+ // `isize::MAX` bytes, `elem_size * self.cap <= isize::MAX` as
// a precondition, so this can't overflow. Additionally the
// alignment will never be too large as to "not be
// satisfiable", so `Layout::from_size_align` will always
// return `Some`.
//
- // tl;dr; we bypass runtime checks due to dynamic assertions
+ // TL;DR, we bypass runtime checks due to dynamic assertions
// in this module, allowing us to use
// `from_size_align_unchecked`.
let new_cap = 2 * self.cap;
let new_size = new_cap * elem_size;
alloc_guard(new_size).unwrap_or_else(|_| capacity_overflow());
- let ptr_res = self.a.realloc(NonNull::from(self.ptr).cast(),
- cur,
- new_size);
+ let ptr_res = self.a.realloc(NonNull::from(self.ptr).cast(), cur, new_size);
match ptr_res {
Ok(ptr) => (new_cap, ptr.cast().into()),
- Err(_) => handle_alloc_error(
- Layout::from_size_align_unchecked(new_size, cur.align())
- ),
+ Err(_) => handle_alloc_error(Layout::from_size_align_unchecked(
+ new_size,
+ cur.align(),
+ )),
}
}
None => {
- // skip to 4 because tiny Vec's are dumb; but not if that
- // would cause overflow
+ // Skip to 4 because tiny `Vec`'s are dumb; but not if that
+ // would cause overflow.
let new_cap = if elem_size > (!0) / 8 { 1 } else { 4 };
match self.a.alloc_array::<T>(new_cap) {
Ok(ptr) => (new_cap, ptr.into()),
///
/// # Panics
///
- /// * Panics if T is zero-sized on the assumption that you managed to exhaust
+ /// * Panics if `T` is zero-sized on the assumption that you managed to exhaust
/// all `usize::MAX` slots in your imaginary buffer.
/// * Panics on 32-bit platforms if the requested capacity exceeds
/// `isize::MAX` bytes.
None => return false, // nothing to double
};
- // since we set the capacity to usize::MAX when elem_size is
- // 0, getting to here necessarily means the RawVec is overfull.
+ // Since we set the capacity to `usize::MAX` when `elem_size` is
+ // 0, getting to here necessarily means the `RawVec` is overfull.
assert!(elem_size != 0, "capacity overflow");
- // Since we guarantee that we never allocate more than isize::MAX
+ // Since we guarantee that we never allocate more than `isize::MAX`
// bytes, `elem_size * self.cap <= isize::MAX` as a precondition, so
// this can't overflow.
//
- // Similarly like with `double` above we can go straight to
+ // Similarly to with `double` above, we can go straight to
// `Layout::from_size_align_unchecked` as we know this won't
// overflow and the alignment is sufficiently small.
let new_cap = 2 * self.cap;
self.cap = new_cap;
true
}
- Err(_) => {
- false
- }
+ Err(_) => false,
}
}
}
/// The same as `reserve_exact`, but returns on errors instead of panicking or aborting.
- pub fn try_reserve_exact(&mut self, used_capacity: usize, needed_extra_capacity: usize)
- -> Result<(), TryReserveError> {
-
+ pub fn try_reserve_exact(
+ &mut self,
+ used_capacity: usize,
+ needed_extra_capacity: usize,
+ ) -> Result<(), TryReserveError> {
self.reserve_internal(used_capacity, needed_extra_capacity, Fallible, Exact)
}
///
/// # Aborts
///
- /// Aborts on OOM
+ /// Aborts on OOM.
pub fn reserve_exact(&mut self, used_capacity: usize, needed_extra_capacity: usize) {
match self.reserve_internal(used_capacity, needed_extra_capacity, Infallible, Exact) {
Err(CapacityOverflow) => capacity_overflow(),
Err(AllocError { .. }) => unreachable!(),
Ok(()) => { /* yay */ }
- }
- }
+ }
+ }
/// Calculates the buffer's new size given that it'll hold `used_capacity +
/// needed_extra_capacity` elements. This logic is used in amortized reserve methods.
/// Returns `(new_capacity, new_alloc_size)`.
- fn amortized_new_size(&self, used_capacity: usize, needed_extra_capacity: usize)
- -> Result<usize, TryReserveError> {
-
- // Nothing we can really do about these checks :(
- let required_cap = used_capacity.checked_add(needed_extra_capacity)
- .ok_or(CapacityOverflow)?;
+ fn amortized_new_size(
+ &self,
+ used_capacity: usize,
+ needed_extra_capacity: usize,
+ ) -> Result<usize, TryReserveError> {
+ // Nothing we can really do about these checks, sadly.
+ let required_cap =
+ used_capacity.checked_add(needed_extra_capacity).ok_or(CapacityOverflow)?;
// Cannot overflow, because `cap <= isize::MAX`, and type of `cap` is `usize`.
let double_cap = self.cap * 2;
// `double_cap` guarantees exponential growth.
}
/// The same as `reserve`, but returns on errors instead of panicking or aborting.
- pub fn try_reserve(&mut self, used_capacity: usize, needed_extra_capacity: usize)
- -> Result<(), TryReserveError> {
+ pub fn try_reserve(
+ &mut self,
+ used_capacity: usize,
+ needed_extra_capacity: usize,
+ ) -> Result<(), TryReserveError> {
self.reserve_internal(used_capacity, needed_extra_capacity, Fallible, Amortized)
}
///
/// # Aborts
///
- /// Aborts on OOM
+ /// Aborts on OOM.
///
/// # Examples
///
return false;
}
- let new_cap = self.amortized_new_size(used_capacity, needed_extra_capacity)
+ let new_cap = self
+ .amortized_new_size(used_capacity, needed_extra_capacity)
.unwrap_or_else(|_| capacity_overflow());
// Here, `cap < used_capacity + needed_extra_capacity <= new_cap`
// (regardless of whether `self.cap - used_capacity` wrapped).
- // Therefore we can safely call grow_in_place.
+ // Therefore, we can safely call `grow_in_place`.
let new_layout = Layout::new::<T>().repeat(new_cap).unwrap().0;
// FIXME: may crash and burn on over-reserve
alloc_guard(new_layout.size()).unwrap_or_else(|_| capacity_overflow());
match self.a.grow_in_place(
- NonNull::from(self.ptr).cast(), old_layout, new_layout.size(),
+ NonNull::from(self.ptr).cast(),
+ old_layout,
+ new_layout.size(),
) {
Ok(_) => {
self.cap = new_cap;
true
}
- Err(_) => {
- false
- }
+ Err(_) => false,
}
}
}
return;
}
- // This check is my waterloo; it's the only thing Vec wouldn't have to do.
+ // This check is my waterloo; it's the only thing `Vec` wouldn't have to do.
assert!(self.cap >= amount, "Tried to shrink to a larger capacity");
if amount == 0 {
// We want to create a new zero-length vector within the
- // same allocator. We use ptr::write to avoid an
+ // same allocator. We use `ptr::write` to avoid an
// erroneous attempt to drop the contents, and we use
- // ptr::read to sidestep condition against destructuring
+ // `ptr::read` to sidestep condition against destructuring
// types that implement Drop.
unsafe {
//
// We also know that `self.cap` is greater than `amount`, and
// consequently we don't need runtime checks for creating either
- // layout
+ // layout.
let old_size = elem_size * self.cap;
let new_size = elem_size * amount;
let align = mem::align_of::<T>();
let old_layout = Layout::from_size_align_unchecked(old_size, align);
- match self.a.realloc(NonNull::from(self.ptr).cast(),
- old_layout,
- new_size) {
+ match self.a.realloc(NonNull::from(self.ptr).cast(), old_layout, new_size) {
Ok(p) => self.ptr = p.cast().into(),
- Err(_) => handle_alloc_error(
- Layout::from_size_align_unchecked(new_size, align)
- ),
+ Err(_) => {
+ handle_alloc_error(Layout::from_size_align_unchecked(new_size, align))
+ }
}
}
self.cap = amount;
return Ok(());
}
- // Nothing we can really do about these checks :(
+ // Nothing we can really do about these checks, sadly.
let new_cap = match strategy {
- Exact => used_capacity.checked_add(needed_extra_capacity).ok_or(CapacityOverflow)?,
+ Exact => {
+ used_capacity.checked_add(needed_extra_capacity).ok_or(CapacityOverflow)?
+ }
Amortized => self.amortized_new_size(used_capacity, needed_extra_capacity)?,
};
let new_layout = Layout::array::<T>(new_cap).map_err(|_| CapacityOverflow)?;
let ptr = match (res, fallibility) {
(Err(AllocErr), Infallible) => handle_alloc_error(new_layout),
- (Err(AllocErr), Fallible) => return Err(TryReserveError::AllocError {
- layout: new_layout,
- non_exhaustive: (),
- }),
+ (Err(AllocErr), Fallible) => {
+ return Err(TryReserveError::AllocError {
+ layout: new_layout,
+ non_exhaustive: (),
+ });
+ }
(Ok(ptr), _) => ptr,
};
Ok(())
}
}
-
}
impl<T> RawVec<T, Global> {
/// Converts the entire buffer into `Box<[T]>`.
///
/// Note that this will correctly reconstitute any `cap` changes
- /// that may have been performed. (see description of type for details)
+ /// that may have been performed. (See description of type for details.)
///
/// # Undefined Behavior
///
/// the rules around uninitialized boxed values are not finalized yet,
/// but until they are, it is advisable to avoid them.
pub unsafe fn into_box(self) -> Box<[T]> {
- // NOTE: not calling `capacity()` here, actually using the real `cap` field!
+ // NOTE: not calling `capacity()` here; actually using the real `cap` field!
let slice = slice::from_raw_parts_mut(self.ptr(), self.cap);
let output: Box<[T]> = Box::from_raw(slice);
mem::forget(self);
}
impl<T, A: Alloc> RawVec<T, A> {
- /// Frees the memory owned by the RawVec *without* trying to Drop its contents.
+ /// Frees the memory owned by the `RawVec` *without* trying to drop its contents.
pub unsafe fn dealloc_buffer(&mut self) {
let elem_size = mem::size_of::<T>();
if elem_size != 0 {
}
unsafe impl<#[may_dangle] T, A: Alloc> Drop for RawVec<T, A> {
- /// Frees the memory owned by the RawVec *without* trying to Drop its contents.
+ /// Frees the memory owned by the `RawVec` *without* trying to drop its contents.
fn drop(&mut self) {
- unsafe { self.dealloc_buffer(); }
+ unsafe {
+ self.dealloc_buffer();
+ }
}
}
-
-
// We need to guarantee the following:
-// * We don't ever allocate `> isize::MAX` byte-size objects
-// * We don't overflow `usize::MAX` and actually allocate too little
+// * We don't ever allocate `> isize::MAX` byte-size objects.
+// * We don't overflow `usize::MAX` and actually allocate too little.
//
// On 64-bit we just need to check for overflow since trying to allocate
// `> isize::MAX` bytes will surely fail. On 32-bit and 16-bit we need to add
// an extra guard for this in case we're running on a platform which can use
-// all 4GB in user-space. e.g., PAE or x32
+// all 4GB in user-space, e.g., PAE or x32.
#[inline]
fn alloc_guard(alloc_size: usize) -> Result<(), TryReserveError> {
// ensure that the code generation related to these panics is minimal as there's
// only one location which panics rather than a bunch throughout the module.
fn capacity_overflow() -> ! {
- panic!("capacity overflow")
+ panic!("capacity overflow");
}
projects / rust.git / blobdiff