summaryrefslogtreecommitdiffstats
path: root/rust/alloc/vec/extract_if.rs
diff options
context:
space:
mode:
Diffstat (limited to 'rust/alloc/vec/extract_if.rs')
-rw-r--r--rust/alloc/vec/extract_if.rs115
1 files changed, 0 insertions, 115 deletions
diff --git a/rust/alloc/vec/extract_if.rs b/rust/alloc/vec/extract_if.rs
deleted file mode 100644
index f314a51d4d..0000000000
--- a/rust/alloc/vec/extract_if.rs
+++ /dev/null
@@ -1,115 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-use crate::alloc::{Allocator, Global};
-use core::ptr;
-use core::slice;
-
-use super::Vec;
-
-/// An iterator which uses a closure to determine if an element should be removed.
-///
-/// This struct is created by [`Vec::extract_if`].
-/// See its documentation for more.
-///
-/// # Example
-///
-/// ```
-/// #![feature(extract_if)]
-///
-/// let mut v = vec![0, 1, 2];
-/// let iter: std::vec::ExtractIf<'_, _, _> = v.extract_if(|x| *x % 2 == 0);
-/// ```
-#[unstable(feature = "extract_if", reason = "recently added", issue = "43244")]
-#[derive(Debug)]
-#[must_use = "iterators are lazy and do nothing unless consumed"]
-pub struct ExtractIf<
- 'a,
- T,
- F,
- #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
-> where
- F: FnMut(&mut T) -> bool,
-{
- pub(super) vec: &'a mut Vec<T, A>,
- /// The index of the item that will be inspected by the next call to `next`.
- pub(super) idx: usize,
- /// The number of items that have been drained (removed) thus far.
- pub(super) del: usize,
- /// The original length of `vec` prior to draining.
- pub(super) old_len: usize,
- /// The filter test predicate.
- pub(super) pred: F,
-}
-
-impl<T, F, A: Allocator> ExtractIf<'_, T, F, A>
-where
- F: FnMut(&mut T) -> bool,
-{
- /// Returns a reference to the underlying allocator.
- #[unstable(feature = "allocator_api", issue = "32838")]
- #[inline]
- pub fn allocator(&self) -> &A {
- self.vec.allocator()
- }
-}
-
-#[unstable(feature = "extract_if", reason = "recently added", issue = "43244")]
-impl<T, F, A: Allocator> Iterator for ExtractIf<'_, T, F, A>
-where
- F: FnMut(&mut T) -> bool,
-{
- type Item = T;
-
- fn next(&mut self) -> Option<T> {
- unsafe {
- while self.idx < self.old_len {
- let i = self.idx;
- let v = slice::from_raw_parts_mut(self.vec.as_mut_ptr(), self.old_len);
- let drained = (self.pred)(&mut v[i]);
- // Update the index *after* the predicate is called. If the index
- // is updated prior and the predicate panics, the element at this
- // index would be leaked.
- self.idx += 1;
- if drained {
- self.del += 1;
- return Some(ptr::read(&v[i]));
- } else if self.del > 0 {
- let del = self.del;
- let src: *const T = &v[i];
- let dst: *mut T = &mut v[i - del];
- ptr::copy_nonoverlapping(src, dst, 1);
- }
- }
- None
- }
- }
-
- fn size_hint(&self) -> (usize, Option<usize>) {
- (0, Some(self.old_len - self.idx))
- }
-}
-
-#[unstable(feature = "extract_if", reason = "recently added", issue = "43244")]
-impl<T, F, A: Allocator> Drop for ExtractIf<'_, T, F, A>
-where
- F: FnMut(&mut T) -> bool,
-{
- fn drop(&mut self) {
- unsafe {
- if self.idx < self.old_len && self.del > 0 {
- // This is a pretty messed up state, and there isn't really an
- // obviously right thing to do. We don't want to keep trying
- // to execute `pred`, so we just backshift all the unprocessed
- // elements and tell the vec that they still exist. The backshift
- // is required to prevent a double-drop of the last successfully
- // drained item prior to a panic in the predicate.
- let ptr = self.vec.as_mut_ptr();
- let src = ptr.add(self.idx);
- let dst = src.sub(self.del);
- let tail_len = self.old_len - self.idx;
- src.copy_to(dst, tail_len);
- }
- self.vec.set_len(self.old_len - self.del);
- }
- }
-}