367 строки
12 KiB
Rust
367 строки
12 KiB
Rust
// SPDX-License-Identifier: Apache-2.0 OR MIT
|
|
|
|
#[cfg(not(no_global_oom_handling))]
|
|
use super::AsVecIntoIter;
|
|
use crate::alloc::{Allocator, Global};
|
|
use crate::raw_vec::RawVec;
|
|
use core::fmt;
|
|
use core::intrinsics::arith_offset;
|
|
use core::iter::{
|
|
FusedIterator, InPlaceIterable, SourceIter, TrustedLen, TrustedRandomAccessNoCoerce,
|
|
};
|
|
use core::marker::PhantomData;
|
|
use core::mem::{self, ManuallyDrop};
|
|
#[cfg(not(no_global_oom_handling))]
|
|
use core::ops::Deref;
|
|
use core::ptr::{self, NonNull};
|
|
use core::slice::{self};
|
|
|
|
/// An iterator that moves out of a vector.
|
|
///
|
|
/// This `struct` is created by the `into_iter` method on [`Vec`](super::Vec)
|
|
/// (provided by the [`IntoIterator`] trait).
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```
|
|
/// let v = vec![0, 1, 2];
|
|
/// let iter: std::vec::IntoIter<_> = v.into_iter();
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
#[rustc_insignificant_dtor]
|
|
pub struct IntoIter<
|
|
T,
|
|
#[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
|
|
> {
|
|
pub(super) buf: NonNull<T>,
|
|
pub(super) phantom: PhantomData<T>,
|
|
pub(super) cap: usize,
|
|
// the drop impl reconstructs a RawVec from buf, cap and alloc
|
|
// to avoid dropping the allocator twice we need to wrap it into ManuallyDrop
|
|
pub(super) alloc: ManuallyDrop<A>,
|
|
pub(super) ptr: *const T,
|
|
pub(super) end: *const T,
|
|
}
|
|
|
|
#[stable(feature = "vec_intoiter_debug", since = "1.13.0")]
|
|
impl<T: fmt::Debug, A: Allocator> fmt::Debug for IntoIter<T, A> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
f.debug_tuple("IntoIter").field(&self.as_slice()).finish()
|
|
}
|
|
}
|
|
|
|
impl<T, A: Allocator> IntoIter<T, A> {
|
|
/// Returns the remaining items of this iterator as a slice.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// let vec = vec!['a', 'b', 'c'];
|
|
/// let mut into_iter = vec.into_iter();
|
|
/// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
|
|
/// let _ = into_iter.next().unwrap();
|
|
/// assert_eq!(into_iter.as_slice(), &['b', 'c']);
|
|
/// ```
|
|
#[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")]
|
|
pub fn as_slice(&self) -> &[T] {
|
|
unsafe { slice::from_raw_parts(self.ptr, self.len()) }
|
|
}
|
|
|
|
/// Returns the remaining items of this iterator as a mutable slice.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// let vec = vec!['a', 'b', 'c'];
|
|
/// let mut into_iter = vec.into_iter();
|
|
/// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
|
|
/// into_iter.as_mut_slice()[2] = 'z';
|
|
/// assert_eq!(into_iter.next().unwrap(), 'a');
|
|
/// assert_eq!(into_iter.next().unwrap(), 'b');
|
|
/// assert_eq!(into_iter.next().unwrap(), 'z');
|
|
/// ```
|
|
#[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")]
|
|
pub fn as_mut_slice(&mut self) -> &mut [T] {
|
|
unsafe { &mut *self.as_raw_mut_slice() }
|
|
}
|
|
|
|
/// Returns a reference to the underlying allocator.
|
|
#[unstable(feature = "allocator_api", issue = "32838")]
|
|
#[inline]
|
|
pub fn allocator(&self) -> &A {
|
|
&self.alloc
|
|
}
|
|
|
|
fn as_raw_mut_slice(&mut self) -> *mut [T] {
|
|
ptr::slice_from_raw_parts_mut(self.ptr as *mut T, self.len())
|
|
}
|
|
|
|
/// Drops remaining elements and relinquishes the backing allocation.
|
|
///
|
|
/// This is roughly equivalent to the following, but more efficient
|
|
///
|
|
/// ```
|
|
/// # let mut into_iter = Vec::<u8>::with_capacity(10).into_iter();
|
|
/// (&mut into_iter).for_each(core::mem::drop);
|
|
/// unsafe { core::ptr::write(&mut into_iter, Vec::new().into_iter()); }
|
|
/// ```
|
|
///
|
|
/// This method is used by in-place iteration, refer to the vec::in_place_collect
|
|
/// documentation for an overview.
|
|
#[cfg(not(no_global_oom_handling))]
|
|
pub(super) fn forget_allocation_drop_remaining(&mut self) {
|
|
let remaining = self.as_raw_mut_slice();
|
|
|
|
// overwrite the individual fields instead of creating a new
|
|
// struct and then overwriting &mut self.
|
|
// this creates less assembly
|
|
self.cap = 0;
|
|
self.buf = unsafe { NonNull::new_unchecked(RawVec::NEW.ptr()) };
|
|
self.ptr = self.buf.as_ptr();
|
|
self.end = self.buf.as_ptr();
|
|
|
|
unsafe {
|
|
ptr::drop_in_place(remaining);
|
|
}
|
|
}
|
|
|
|
/// Forgets to Drop the remaining elements while still allowing the backing allocation to be freed.
|
|
#[allow(dead_code)]
|
|
pub(crate) fn forget_remaining_elements(&mut self) {
|
|
self.ptr = self.end;
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "vec_intoiter_as_ref", since = "1.46.0")]
|
|
impl<T, A: Allocator> AsRef<[T]> for IntoIter<T, A> {
|
|
fn as_ref(&self) -> &[T] {
|
|
self.as_slice()
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
unsafe impl<T: Send, A: Allocator + Send> Send for IntoIter<T, A> {}
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
unsafe impl<T: Sync, A: Allocator + Sync> Sync for IntoIter<T, A> {}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T, A: Allocator> Iterator for IntoIter<T, A> {
|
|
type Item = T;
|
|
|
|
#[inline]
|
|
fn next(&mut self) -> Option<T> {
|
|
if self.ptr as *const _ == self.end {
|
|
None
|
|
} else if mem::size_of::<T>() == 0 {
|
|
// purposefully don't use 'ptr.offset' because for
|
|
// vectors with 0-size elements this would return the
|
|
// same pointer.
|
|
self.ptr = unsafe { arith_offset(self.ptr as *const i8, 1) as *mut T };
|
|
|
|
// Make up a value of this ZST.
|
|
Some(unsafe { mem::zeroed() })
|
|
} else {
|
|
let old = self.ptr;
|
|
self.ptr = unsafe { self.ptr.offset(1) };
|
|
|
|
Some(unsafe { ptr::read(old) })
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
fn size_hint(&self) -> (usize, Option<usize>) {
|
|
let exact = if mem::size_of::<T>() == 0 {
|
|
self.end.addr().wrapping_sub(self.ptr.addr())
|
|
} else {
|
|
unsafe { self.end.sub_ptr(self.ptr) }
|
|
};
|
|
(exact, Some(exact))
|
|
}
|
|
|
|
#[inline]
|
|
fn advance_by(&mut self, n: usize) -> Result<(), usize> {
|
|
let step_size = self.len().min(n);
|
|
let to_drop = ptr::slice_from_raw_parts_mut(self.ptr as *mut T, step_size);
|
|
if mem::size_of::<T>() == 0 {
|
|
// SAFETY: due to unchecked casts of unsigned amounts to signed offsets the wraparound
|
|
// effectively results in unsigned pointers representing positions 0..usize::MAX,
|
|
// which is valid for ZSTs.
|
|
self.ptr = unsafe { arith_offset(self.ptr as *const i8, step_size as isize) as *mut T }
|
|
} else {
|
|
// SAFETY: the min() above ensures that step_size is in bounds
|
|
self.ptr = unsafe { self.ptr.add(step_size) };
|
|
}
|
|
// SAFETY: the min() above ensures that step_size is in bounds
|
|
unsafe {
|
|
ptr::drop_in_place(to_drop);
|
|
}
|
|
if step_size < n {
|
|
return Err(step_size);
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
#[inline]
|
|
fn count(self) -> usize {
|
|
self.len()
|
|
}
|
|
|
|
unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> Self::Item
|
|
where
|
|
Self: TrustedRandomAccessNoCoerce,
|
|
{
|
|
// SAFETY: the caller must guarantee that `i` is in bounds of the
|
|
// `Vec<T>`, so `i` cannot overflow an `isize`, and the `self.ptr.add(i)`
|
|
// is guaranteed to pointer to an element of the `Vec<T>` and
|
|
// thus guaranteed to be valid to dereference.
|
|
//
|
|
// Also note the implementation of `Self: TrustedRandomAccess` requires
|
|
// that `T: Copy` so reading elements from the buffer doesn't invalidate
|
|
// them for `Drop`.
|
|
unsafe {
|
|
if mem::size_of::<T>() == 0 { mem::zeroed() } else { ptr::read(self.ptr.add(i)) }
|
|
}
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> {
|
|
#[inline]
|
|
fn next_back(&mut self) -> Option<T> {
|
|
if self.end == self.ptr {
|
|
None
|
|
} else if mem::size_of::<T>() == 0 {
|
|
// See above for why 'ptr.offset' isn't used
|
|
self.end = unsafe { arith_offset(self.end as *const i8, -1) as *mut T };
|
|
|
|
// Make up a value of this ZST.
|
|
Some(unsafe { mem::zeroed() })
|
|
} else {
|
|
self.end = unsafe { self.end.offset(-1) };
|
|
|
|
Some(unsafe { ptr::read(self.end) })
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
fn advance_back_by(&mut self, n: usize) -> Result<(), usize> {
|
|
let step_size = self.len().min(n);
|
|
if mem::size_of::<T>() == 0 {
|
|
// SAFETY: same as for advance_by()
|
|
self.end = unsafe {
|
|
arith_offset(self.end as *const i8, step_size.wrapping_neg() as isize) as *mut T
|
|
}
|
|
} else {
|
|
// SAFETY: same as for advance_by()
|
|
self.end = unsafe { self.end.offset(step_size.wrapping_neg() as isize) };
|
|
}
|
|
let to_drop = ptr::slice_from_raw_parts_mut(self.end as *mut T, step_size);
|
|
// SAFETY: same as for advance_by()
|
|
unsafe {
|
|
ptr::drop_in_place(to_drop);
|
|
}
|
|
if step_size < n {
|
|
return Err(step_size);
|
|
}
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T, A: Allocator> ExactSizeIterator for IntoIter<T, A> {
|
|
fn is_empty(&self) -> bool {
|
|
self.ptr == self.end
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "fused", since = "1.26.0")]
|
|
impl<T, A: Allocator> FusedIterator for IntoIter<T, A> {}
|
|
|
|
#[unstable(feature = "trusted_len", issue = "37572")]
|
|
unsafe impl<T, A: Allocator> TrustedLen for IntoIter<T, A> {}
|
|
|
|
#[doc(hidden)]
|
|
#[unstable(issue = "none", feature = "std_internals")]
|
|
#[rustc_unsafe_specialization_marker]
|
|
pub trait NonDrop {}
|
|
|
|
// T: Copy as approximation for !Drop since get_unchecked does not advance self.ptr
|
|
// and thus we can't implement drop-handling
|
|
#[unstable(issue = "none", feature = "std_internals")]
|
|
impl<T: Copy> NonDrop for T {}
|
|
|
|
#[doc(hidden)]
|
|
#[unstable(issue = "none", feature = "std_internals")]
|
|
// TrustedRandomAccess (without NoCoerce) must not be implemented because
|
|
// subtypes/supertypes of `T` might not be `NonDrop`
|
|
unsafe impl<T, A: Allocator> TrustedRandomAccessNoCoerce for IntoIter<T, A>
|
|
where
|
|
T: NonDrop,
|
|
{
|
|
const MAY_HAVE_SIDE_EFFECT: bool = false;
|
|
}
|
|
|
|
#[cfg(not(no_global_oom_handling))]
|
|
#[stable(feature = "vec_into_iter_clone", since = "1.8.0")]
|
|
impl<T: Clone, A: Allocator + Clone> Clone for IntoIter<T, A> {
|
|
#[cfg(not(test))]
|
|
fn clone(&self) -> Self {
|
|
self.as_slice().to_vec_in(self.alloc.deref().clone()).into_iter()
|
|
}
|
|
#[cfg(test)]
|
|
fn clone(&self) -> Self {
|
|
crate::slice::to_vec(self.as_slice(), self.alloc.deref().clone()).into_iter()
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
unsafe impl<#[may_dangle] T, A: Allocator> Drop for IntoIter<T, A> {
|
|
fn drop(&mut self) {
|
|
struct DropGuard<'a, T, A: Allocator>(&'a mut IntoIter<T, A>);
|
|
|
|
impl<T, A: Allocator> Drop for DropGuard<'_, T, A> {
|
|
fn drop(&mut self) {
|
|
unsafe {
|
|
// `IntoIter::alloc` is not used anymore after this and will be dropped by RawVec
|
|
let alloc = ManuallyDrop::take(&mut self.0.alloc);
|
|
// RawVec handles deallocation
|
|
let _ = RawVec::from_raw_parts_in(self.0.buf.as_ptr(), self.0.cap, alloc);
|
|
}
|
|
}
|
|
}
|
|
|
|
let guard = DropGuard(self);
|
|
// destroy the remaining elements
|
|
unsafe {
|
|
ptr::drop_in_place(guard.0.as_raw_mut_slice());
|
|
}
|
|
// now `guard` will be dropped and do the rest
|
|
}
|
|
}
|
|
|
|
// In addition to the SAFETY invariants of the following three unsafe traits
|
|
// also refer to the vec::in_place_collect module documentation to get an overview
|
|
#[unstable(issue = "none", feature = "inplace_iteration")]
|
|
#[doc(hidden)]
|
|
unsafe impl<T, A: Allocator> InPlaceIterable for IntoIter<T, A> {}
|
|
|
|
#[unstable(issue = "none", feature = "inplace_iteration")]
|
|
#[doc(hidden)]
|
|
unsafe impl<T, A: Allocator> SourceIter for IntoIter<T, A> {
|
|
type Source = Self;
|
|
|
|
#[inline]
|
|
unsafe fn as_inner(&mut self) -> &mut Self::Source {
|
|
self
|
|
}
|
|
}
|
|
|
|
#[cfg(not(no_global_oom_handling))]
|
|
unsafe impl<T> AsVecIntoIter for IntoIter<T> {
|
|
type Item = T;
|
|
|
|
fn as_into_iter(&mut self) -> &mut IntoIter<Self::Item> {
|
|
self
|
|
}
|
|
}
|