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use core::fmt;
use core::iter::FusedIterator;
use core::marker::PhantomData;
use core::mem::{self, size_of, ManuallyDrop};
use core::ptr::{self, NonNull};
use core::slice::{self};
use crate::stable::addr;
use super::{Allocator, Global, RawVec};
#[cfg(not(no_global_oom_handling))]
use super::Vec;
/// 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();
/// ```
pub struct IntoIter<T, 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,
}
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']);
/// ```
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');
/// ```
pub fn as_mut_slice(&mut self) -> &mut [T] {
unsafe { &mut *self.as_raw_mut_slice() }
}
/// Returns a reference to the underlying allocator.
#[inline(always)]
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())
}
}
impl<T, A: Allocator> AsRef<[T]> for IntoIter<T, A> {
fn as_ref(&self) -> &[T] {
self.as_slice()
}
}
unsafe impl<T: Send, A: Allocator + Send> Send for IntoIter<T, A> {}
unsafe impl<T: Sync, A: Allocator + Sync> Sync for IntoIter<T, A> {}
impl<T, A: Allocator> Iterator for IntoIter<T, A> {
type Item = T;
#[inline(always)]
fn next(&mut self) -> Option<T> {
if self.ptr == self.end {
None
} else if 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 = self.ptr.cast::<u8>().wrapping_add(1).cast();
// Make up a value of this ZST.
Some(unsafe { mem::zeroed() })
} else {
let old = self.ptr;
self.ptr = unsafe { self.ptr.add(1) };
Some(unsafe { ptr::read(old) })
}
}
#[inline(always)]
fn size_hint(&self) -> (usize, Option<usize>) {
let exact = if size_of::<T>() == 0 {
addr(self.end).wrapping_sub(addr(self.ptr))
} else {
unsafe { self.end.offset_from(self.ptr) as usize }
};
(exact, Some(exact))
}
#[inline(always)]
fn count(self) -> usize {
self.len()
}
}
impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> {
#[inline(always)]
fn next_back(&mut self) -> Option<T> {
if self.end == self.ptr {
None
} else if size_of::<T>() == 0 {
// See above for why 'ptr.offset' isn't used
self.end = self.end.cast::<u8>().wrapping_add(1).cast();
// Make up a value of this ZST.
Some(unsafe { mem::zeroed() })
} else {
self.end = unsafe { self.end.sub(1) };
Some(unsafe { ptr::read(self.end) })
}
}
}
impl<T, A: Allocator> ExactSizeIterator for IntoIter<T, A> {}
impl<T, A: Allocator> FusedIterator for IntoIter<T, A> {}
#[doc(hidden)]
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
impl<T: Copy> NonDrop for T {}
#[cfg(not(no_global_oom_handling))]
impl<T: Clone, A: Allocator + Clone> Clone for IntoIter<T, A> {
fn clone(&self) -> Self {
let mut vec = Vec::<T, A>::with_capacity_in(self.len(), (*self.alloc).clone());
vec.extend(self.as_slice().iter().cloned());
vec.into_iter()
}
}
impl<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
}
}