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c731157395
Add `vec::Drain{,Filter}::keep_rest`
This PR adds `keep_rest` methods to `vec::Drain` and `vec::DrainFilter` under `drain_keep_rest` feature gate:
```rust
// mod alloc::vec
impl<T, A: Allocator> Drain<'_, T, A> {
pub fn keep_rest(self);
}
impl<T, F, A: Allocator> DrainFilter<'_, T, F, A>
where
F: FnMut(&mut T) -> bool,
{
pub fn keep_rest(self);
}
```
Both these methods cancel draining of elements that were not yet yielded from the iterators. While this needs more testing & documentation, I want at least start the discussion. This may be a potential way out of the "should `DrainFilter` exhaust itself on drop?" argument.
91 lines
2.3 KiB
Rust
91 lines
2.3 KiB
Rust
#![feature(allocator_api)]
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#![feature(alloc_layout_extra)]
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#![feature(assert_matches)]
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#![feature(box_syntax)]
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#![feature(cow_is_borrowed)]
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#![feature(const_box)]
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#![feature(const_convert)]
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#![feature(const_cow_is_borrowed)]
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#![feature(const_heap)]
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#![feature(const_mut_refs)]
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#![feature(const_nonnull_slice_from_raw_parts)]
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#![feature(const_ptr_write)]
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#![feature(const_try)]
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#![feature(core_intrinsics)]
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#![feature(drain_filter)]
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#![feature(exact_size_is_empty)]
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#![feature(new_uninit)]
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#![feature(pattern)]
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#![feature(trusted_len)]
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#![feature(try_reserve_kind)]
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#![feature(unboxed_closures)]
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#![feature(associated_type_bounds)]
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#![feature(binary_heap_into_iter_sorted)]
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#![feature(binary_heap_drain_sorted)]
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#![feature(slice_ptr_get)]
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#![feature(binary_heap_retain)]
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#![feature(binary_heap_as_slice)]
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#![feature(inplace_iteration)]
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#![feature(iter_advance_by)]
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#![feature(iter_next_chunk)]
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#![feature(round_char_boundary)]
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#![feature(slice_group_by)]
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#![feature(slice_partition_dedup)]
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#![feature(string_remove_matches)]
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#![feature(const_btree_new)]
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#![feature(const_default_impls)]
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#![feature(const_trait_impl)]
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#![feature(const_str_from_utf8)]
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#![feature(nonnull_slice_from_raw_parts)]
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#![feature(panic_update_hook)]
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#![feature(pointer_is_aligned)]
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#![feature(slice_flatten)]
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#![feature(thin_box)]
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#![feature(bench_black_box)]
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#![feature(strict_provenance)]
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#![feature(once_cell)]
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#![feature(drain_keep_rest)]
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use std::collections::hash_map::DefaultHasher;
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use std::hash::{Hash, Hasher};
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mod arc;
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mod borrow;
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mod boxed;
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mod btree_set_hash;
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mod c_str;
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mod const_fns;
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mod cow_str;
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mod fmt;
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mod heap;
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mod linked_list;
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mod rc;
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mod slice;
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mod str;
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mod string;
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mod thin_box;
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mod vec;
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mod vec_deque;
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fn hash<T: Hash>(t: &T) -> u64 {
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let mut s = DefaultHasher::new();
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t.hash(&mut s);
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s.finish()
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}
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// FIXME: Instantiated functions with i128 in the signature is not supported in Emscripten.
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// See https://github.com/kripken/emscripten-fastcomp/issues/169
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#[cfg(not(target_os = "emscripten"))]
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#[test]
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fn test_boxed_hasher() {
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let ordinary_hash = hash(&5u32);
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let mut hasher_1 = Box::new(DefaultHasher::new());
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5u32.hash(&mut hasher_1);
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assert_eq!(ordinary_hash, hasher_1.finish());
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let mut hasher_2 = Box::new(DefaultHasher::new()) as Box<dyn Hasher>;
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5u32.hash(&mut hasher_2);
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assert_eq!(ordinary_hash, hasher_2.finish());
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}
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