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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); -        } -    } -}  |