refactor: moving Drain into drain.rs
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157
library/alloc/src/vec/drain.rs
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157
library/alloc/src/vec/drain.rs
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@ -0,0 +1,157 @@
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use crate::alloc::{Allocator, Global};
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use core::iter::{
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FusedIterator, TrustedLen,
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};
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use core::mem::{self};
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use core::ptr::{self, NonNull};
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use core::slice::{self};
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use core::fmt;
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use super::{Vec};
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/// A draining iterator for `Vec<T>`.
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///
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/// This `struct` is created by [`Vec::drain`].
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/// See its documentation for more.
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///
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/// # Example
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///
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/// ```
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/// let mut v = vec![0, 1, 2];
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/// let iter: std::vec::Drain<_> = v.drain(..);
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/// ```
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#[stable(feature = "drain", since = "1.6.0")]
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pub struct Drain<
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'a,
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T: 'a,
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#[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + 'a = Global,
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> {
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/// Index of tail to preserve
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pub(super) tail_start: usize,
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/// Length of tail
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pub(super) tail_len: usize,
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/// Current remaining range to remove
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pub(super) iter: slice::Iter<'a, T>,
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pub(super) vec: NonNull<Vec<T, A>>,
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}
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#[stable(feature = "collection_debug", since = "1.17.0")]
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impl<T: fmt::Debug, A: Allocator> fmt::Debug for Drain<'_, T, A> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_tuple("Drain").field(&self.iter.as_slice()).finish()
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}
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}
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impl<'a, T, A: Allocator> Drain<'a, T, A> {
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/// Returns the remaining items of this iterator as a slice.
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///
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/// # Examples
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///
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/// ```
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/// let mut vec = vec!['a', 'b', 'c'];
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/// let mut drain = vec.drain(..);
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/// assert_eq!(drain.as_slice(), &['a', 'b', 'c']);
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/// let _ = drain.next().unwrap();
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/// assert_eq!(drain.as_slice(), &['b', 'c']);
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/// ```
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#[stable(feature = "vec_drain_as_slice", since = "1.46.0")]
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pub fn as_slice(&self) -> &[T] {
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self.iter.as_slice()
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}
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/// Returns a reference to the underlying allocator.
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#[unstable(feature = "allocator_api", issue = "32838")]
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#[inline]
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pub fn allocator(&self) -> &A {
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unsafe { self.vec.as_ref().allocator() }
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}
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}
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#[stable(feature = "vec_drain_as_slice", since = "1.46.0")]
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impl<'a, T, A: Allocator> AsRef<[T]> for Drain<'a, T, A> {
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fn as_ref(&self) -> &[T] {
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self.as_slice()
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}
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}
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#[stable(feature = "drain", since = "1.6.0")]
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unsafe impl<T: Sync, A: Sync + Allocator> Sync for Drain<'_, T, A> {}
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#[stable(feature = "drain", since = "1.6.0")]
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unsafe impl<T: Send, A: Send + Allocator> Send for Drain<'_, T, A> {}
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#[stable(feature = "drain", since = "1.6.0")]
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impl<T, A: Allocator> Iterator for Drain<'_, T, A> {
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type Item = T;
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#[inline]
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fn next(&mut self) -> Option<T> {
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self.iter.next().map(|elt| unsafe { ptr::read(elt as *const _) })
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}
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fn size_hint(&self) -> (usize, Option<usize>) {
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self.iter.size_hint()
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}
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}
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#[stable(feature = "drain", since = "1.6.0")]
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impl<T, A: Allocator> DoubleEndedIterator for Drain<'_, T, A> {
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#[inline]
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fn next_back(&mut self) -> Option<T> {
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self.iter.next_back().map(|elt| unsafe { ptr::read(elt as *const _) })
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}
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}
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#[stable(feature = "drain", since = "1.6.0")]
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impl<T, A: Allocator> Drop for Drain<'_, T, A> {
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fn drop(&mut self) {
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/// Continues dropping the remaining elements in the `Drain`, then moves back the
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/// un-`Drain`ed elements to restore the original `Vec`.
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struct DropGuard<'r, 'a, T, A: Allocator>(&'r mut Drain<'a, T, A>);
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impl<'r, 'a, T, A: Allocator> Drop for DropGuard<'r, 'a, T, A> {
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fn drop(&mut self) {
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// Continue the same loop we have below. If the loop already finished, this does
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// nothing.
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self.0.for_each(drop);
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if self.0.tail_len > 0 {
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unsafe {
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let source_vec = self.0.vec.as_mut();
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// memmove back untouched tail, update to new length
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let start = source_vec.len();
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let tail = self.0.tail_start;
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if tail != start {
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let src = source_vec.as_ptr().add(tail);
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let dst = source_vec.as_mut_ptr().add(start);
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ptr::copy(src, dst, self.0.tail_len);
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}
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source_vec.set_len(start + self.0.tail_len);
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}
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}
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}
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}
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// exhaust self first
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while let Some(item) = self.next() {
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let guard = DropGuard(self);
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drop(item);
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mem::forget(guard);
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}
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// Drop a `DropGuard` to move back the non-drained tail of `self`.
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DropGuard(self);
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}
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}
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#[stable(feature = "drain", since = "1.6.0")]
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impl<T, A: Allocator> ExactSizeIterator for Drain<'_, T, A> {
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fn is_empty(&self) -> bool {
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self.iter.is_empty()
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}
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}
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#[unstable(feature = "trusted_len", issue = "37572")]
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unsafe impl<T, A: Allocator> TrustedLen for Drain<'_, T, A> {}
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#[stable(feature = "fused", since = "1.26.0")]
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impl<T, A: Allocator> FusedIterator for Drain<'_, T, A> {}
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@ -84,6 +84,11 @@ pub use self::splice::Splice;
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mod splice;
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#[stable(feature = "drain", since = "1.6.0")]
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pub use self::drain::Drain;
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mod drain;
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/// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'.
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///
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/// # Examples
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@ -3320,150 +3325,3 @@ impl<T> AsIntoIter for IntoIter<T> {
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self
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}
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}
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/// A draining iterator for `Vec<T>`.
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///
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/// This `struct` is created by [`Vec::drain`].
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/// See its documentation for more.
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///
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/// # Example
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///
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/// ```
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/// let mut v = vec![0, 1, 2];
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/// let iter: std::vec::Drain<_> = v.drain(..);
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/// ```
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#[stable(feature = "drain", since = "1.6.0")]
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pub struct Drain<
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'a,
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T: 'a,
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#[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + 'a = Global,
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> {
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/// Index of tail to preserve
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tail_start: usize,
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/// Length of tail
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tail_len: usize,
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/// Current remaining range to remove
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iter: slice::Iter<'a, T>,
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vec: NonNull<Vec<T, A>>,
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}
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#[stable(feature = "collection_debug", since = "1.17.0")]
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impl<T: fmt::Debug, A: Allocator> fmt::Debug for Drain<'_, T, A> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_tuple("Drain").field(&self.iter.as_slice()).finish()
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}
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}
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impl<'a, T, A: Allocator> Drain<'a, T, A> {
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/// Returns the remaining items of this iterator as a slice.
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///
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/// # Examples
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///
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/// ```
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/// let mut vec = vec!['a', 'b', 'c'];
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/// let mut drain = vec.drain(..);
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/// assert_eq!(drain.as_slice(), &['a', 'b', 'c']);
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/// let _ = drain.next().unwrap();
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/// assert_eq!(drain.as_slice(), &['b', 'c']);
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/// ```
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#[stable(feature = "vec_drain_as_slice", since = "1.46.0")]
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pub fn as_slice(&self) -> &[T] {
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self.iter.as_slice()
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}
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/// Returns a reference to the underlying allocator.
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#[unstable(feature = "allocator_api", issue = "32838")]
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#[inline]
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pub fn allocator(&self) -> &A {
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unsafe { self.vec.as_ref().allocator() }
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}
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}
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#[stable(feature = "vec_drain_as_slice", since = "1.46.0")]
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impl<'a, T, A: Allocator> AsRef<[T]> for Drain<'a, T, A> {
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fn as_ref(&self) -> &[T] {
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self.as_slice()
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}
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}
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#[stable(feature = "drain", since = "1.6.0")]
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unsafe impl<T: Sync, A: Sync + Allocator> Sync for Drain<'_, T, A> {}
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#[stable(feature = "drain", since = "1.6.0")]
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unsafe impl<T: Send, A: Send + Allocator> Send for Drain<'_, T, A> {}
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#[stable(feature = "drain", since = "1.6.0")]
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impl<T, A: Allocator> Iterator for Drain<'_, T, A> {
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type Item = T;
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#[inline]
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fn next(&mut self) -> Option<T> {
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self.iter.next().map(|elt| unsafe { ptr::read(elt as *const _) })
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}
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fn size_hint(&self) -> (usize, Option<usize>) {
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self.iter.size_hint()
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}
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}
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#[stable(feature = "drain", since = "1.6.0")]
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impl<T, A: Allocator> DoubleEndedIterator for Drain<'_, T, A> {
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#[inline]
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fn next_back(&mut self) -> Option<T> {
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self.iter.next_back().map(|elt| unsafe { ptr::read(elt as *const _) })
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}
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}
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#[stable(feature = "drain", since = "1.6.0")]
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impl<T, A: Allocator> Drop for Drain<'_, T, A> {
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fn drop(&mut self) {
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/// Continues dropping the remaining elements in the `Drain`, then moves back the
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/// un-`Drain`ed elements to restore the original `Vec`.
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struct DropGuard<'r, 'a, T, A: Allocator>(&'r mut Drain<'a, T, A>);
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impl<'r, 'a, T, A: Allocator> Drop for DropGuard<'r, 'a, T, A> {
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fn drop(&mut self) {
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// Continue the same loop we have below. If the loop already finished, this does
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// nothing.
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self.0.for_each(drop);
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if self.0.tail_len > 0 {
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unsafe {
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let source_vec = self.0.vec.as_mut();
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// memmove back untouched tail, update to new length
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let start = source_vec.len();
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let tail = self.0.tail_start;
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if tail != start {
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let src = source_vec.as_ptr().add(tail);
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let dst = source_vec.as_mut_ptr().add(start);
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ptr::copy(src, dst, self.0.tail_len);
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}
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source_vec.set_len(start + self.0.tail_len);
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}
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}
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}
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}
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// exhaust self first
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while let Some(item) = self.next() {
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let guard = DropGuard(self);
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drop(item);
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mem::forget(guard);
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}
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// Drop a `DropGuard` to move back the non-drained tail of `self`.
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DropGuard(self);
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}
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}
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#[stable(feature = "drain", since = "1.6.0")]
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impl<T, A: Allocator> ExactSizeIterator for Drain<'_, T, A> {
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fn is_empty(&self) -> bool {
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self.iter.is_empty()
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}
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}
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#[unstable(feature = "trusted_len", issue = "37572")]
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unsafe impl<T, A: Allocator> TrustedLen for Drain<'_, T, A> {}
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#[stable(feature = "fused", since = "1.26.0")]
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impl<T, A: Allocator> FusedIterator for Drain<'_, T, A> {}
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