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Diffstat (limited to 'rust/alloc/vec/extract_if.rs')
-rw-r--r-- | rust/alloc/vec/extract_if.rs | 115 |
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 f314a51d4d3d..000000000000 --- 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); - } - } -} |