diff --git a/CHANGELOG.md b/CHANGELOG.md index 214ba6b..1be2128 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -24,8 +24,14 @@ - Implemented `Default` on `Map` (not just on `RawMap`). -- The implementation of `Into>` for `Map` has been - replaced with the more general `From>` for `RawMap`. +- Removed the `anymap::raw` wrapper layer around `std::collections::hash_map`, + in favour of exposing the raw `HashMap` directly. I think there was a reason + I did it that seven years ago, but I think that reason may have dissolved by + now, and I can’t think of it and I don’t like the particular safe + `as_mut`/unsafe insert approach that I used. Because of the hashbrown stuff, + I have retained `anymap::RawMap` is an alias, and `anymap::raw_hash_map` too. + The end result of this is that raw access can finally access things that have + stabilised since Rust 1.7.0, and we’ll no longer need to play catch-up. - Worked around the spurious `where_clauses_object_safety` future-compatibility lint that has been raised since mid-2018. If you put `#![allow(where_clauses_object_safety)]` on your binary crates for this reason, you can remove it. diff --git a/src/lib.rs b/src/lib.rs index d4f227a..beef1bd 100644 --- a/src/lib.rs +++ b/src/lib.rs @@ -7,6 +7,8 @@ #![cfg_attr(not(feature = "std"), no_std)] use core::any::{Any, TypeId}; +use core::convert::TryInto; +use core::hash::{Hasher, BuildHasherDefault}; use core::marker::PhantomData; #[cfg(not(any(feature = "std", feature = "hashbrown")))] @@ -18,10 +20,34 @@ extern crate alloc; #[cfg(not(feature = "std"))] use alloc::boxed::Box; -use raw::RawMap; use any::{UncheckedAnyExt, IntoBox}; pub use any::CloneAny; +#[cfg(all(feature = "std", not(feature = "hashbrown")))] +/// A re-export of [`std::collections::hash_map`] for raw access. +/// +/// If the `hashbrown` feature gets enabled, this will become an export of `hashbrown::hash_map`. +/// +/// As with [`RawMap`][crate::RawMap], this is exposed for compatibility reasons, since features +/// are supposed to be additive. This *is* imperfect, since the two modules are incompatible in a +/// few places (e.g. hashbrown’s entry types have an extra generic parameter), but it’s close, and +/// much too useful to give up the whole concept. +pub use std::collections::hash_map as raw_hash_map; + +#[cfg(feature = "hashbrown")] +/// A re-export of [`hashbrown::hash_map`] for raw access. +/// +/// If the `hashbrown` feature was disabled, this would become an export of +/// `std::collections::hash_map`. +/// +/// As with [`RawMap`][crate::RawMap], this is exposed for compatibility reasons, since features +/// are supposed to be additive. This *is* imperfect, since the two modules are incompatible in a +/// few places (e.g. hashbrown’s entry types have an extra generic parameter), but it’s close, and +/// much too useful to give up the whole concept. +pub use hashbrown::hash_map as raw_hash_map; + +use self::raw_hash_map::HashMap; + macro_rules! impl_common_methods { ( field: $t:ident.$field:ident; @@ -104,7 +130,17 @@ macro_rules! impl_common_methods { } mod any; -pub mod raw; + +/// Raw access to the underlying `HashMap`. +/// +/// This is a public type alias because the underlying `HashMap` could be +/// `std::collections::HashMap` or `hashbrown::HashMap`, depending on the crate features enabled. +/// For that reason, you should refer to this type as `anymap::RawMap` rather than +/// `std::collections::HashMap` to avoid breakage if something else in your crate tree enables +/// hashbrown. +/// +/// See also [`raw_hash_map`], an export of the corresponding `hash_map` module. +pub type RawMap = HashMap, BuildHasherDefault>; /// A collection containing zero or one values for any given type and allowing convenient, /// type-safe access to those values. @@ -176,8 +212,8 @@ pub type AnyMap = Map; impl_common_methods! { field: Map.raw; - new() => RawMap::new(); - with_capacity(capacity) => RawMap::with_capacity(capacity); + new() => RawMap::with_hasher(Default::default()); + with_capacity(capacity) => RawMap::with_capacity_and_hasher(capacity, Default::default()); } impl Map { @@ -227,57 +263,121 @@ impl Map { #[inline] pub fn entry>(&mut self) -> Entry { match self.raw.entry(TypeId::of::()) { - raw::Entry::Occupied(e) => Entry::Occupied(OccupiedEntry { + raw_hash_map::Entry::Occupied(e) => Entry::Occupied(OccupiedEntry { inner: e, type_: PhantomData, }), - raw::Entry::Vacant(e) => Entry::Vacant(VacantEntry { + raw_hash_map::Entry::Vacant(e) => Entry::Vacant(VacantEntry { inner: e, type_: PhantomData, }), } } + + /// Get access to the raw hash map that backs this. + /// + /// This will seldom be useful, but it’s conceivable that you could wish to iterate over all + /// the items in the collection, and this lets you do that. + /// + /// To improve compatibility with Cargo features, interact with this map through the names + /// [`anymap::RawMap`][RawMap] and [`anymap::raw_hash_map`][raw_hash_map], rather than through + /// `std::collections::{HashMap, hash_map}` or `hashbrown::{HashMap, hash_map}`, for anything + /// beyond self methods. Otherwise, if you use std and another crate in the tree enables + /// hashbrown, your code will break. + #[inline] + pub fn as_raw(&self) -> &RawMap { + &self.raw + } + + /// Get mutable access to the raw hash map that backs this. + /// + /// This will seldom be useful, but it’s conceivable that you could wish to iterate over all + /// the items in the collection mutably, or drain or something, or *possibly* even batch + /// insert, and this lets you do that. + /// + /// To improve compatibility with Cargo features, interact with this map through the names + /// [`anymap::RawMap`][RawMap] and [`anymap::raw_hash_map`][raw_hash_map], rather than through + /// `std::collections::{HashMap, hash_map}` or `hashbrown::{HashMap, hash_map}`, for anything + /// beyond self methods. Otherwise, if you use std and another crate in the tree enables + /// hashbrown, your code will break. + /// + /// # Safety + /// + /// If you insert any values to the raw map, the key (a `TypeId`) must match the value’s type, + /// or *undefined behaviour* will occur when you access those values. + /// + /// (*Removing* entries is perfectly safe.) + #[inline] + pub unsafe fn as_raw_mut(&mut self) -> &mut RawMap { + &mut self.raw + } + + /// Convert this into the raw hash map that backs this. + /// + /// This will seldom be useful, but it’s conceivable that you could wish to consume all the + /// items in the collection and do *something* with some or all of them, and this lets you do + /// that, without the `unsafe` that `.as_raw_mut().drain()` would require. + /// + /// To improve compatibility with Cargo features, interact with this map through the names + /// [`anymap::RawMap`][RawMap] and [`anymap::raw_hash_map`][raw_hash_map], rather than through + /// `std::collections::{HashMap, hash_map}` or `hashbrown::{HashMap, hash_map}`, for anything + /// beyond self methods. Otherwise, if you use std and another crate in the tree enables + /// hashbrown, your code will break. + #[inline] + pub fn into_raw(self) -> RawMap { + self.raw + } + + /// Construct a map from a collection of raw values. + /// + /// You know what? I can’t immediately think of any legitimate use for this, especially because + /// of the requirement of the `BuildHasherDefault` generic in the map. + /// + /// Perhaps this will be most practical as `unsafe { Map::from_raw(iter.collect()) }`, iter + /// being an iterator over `(TypeId, Box)` pairs. Eh, this method provides symmetry with + /// `into_raw`, so I don’t care if literally no one ever uses it. I’m not even going to write a + /// test for it, it’s so trivial. + /// + /// To improve compatibility with Cargo features, interact with this map through the names + /// [`anymap::RawMap`][RawMap] and [`anymap::raw_hash_map`][raw_hash_map], rather than through + /// `std::collections::{HashMap, hash_map}` or `hashbrown::{HashMap, hash_map}`, for anything + /// beyond self methods. Otherwise, if you use std and another crate in the tree enables + /// hashbrown, your code will break. + /// + /// # Safety + /// + /// For all entries in the raw map, the key (a `TypeId`) must match the value’s type, + /// or *undefined behaviour* will occur when you access that entry. + #[inline] + pub unsafe fn from_raw(raw: RawMap) -> Map { + Self { raw } + } } impl Extend> for Map { #[inline] fn extend>>(&mut self, iter: T) { for item in iter { - let _ = unsafe { self.raw.insert(item.type_id(), item) }; + let _ = self.raw.insert(item.type_id(), item); } } } -impl AsRef> for Map { - #[inline] - fn as_ref(&self) -> &RawMap { - &self.raw - } -} - -impl AsMut> for Map { - #[inline] - fn as_mut(&mut self) -> &mut RawMap { - &mut self.raw - } -} - -impl From> for RawMap { - #[inline] - fn from(map: Map) -> RawMap { - map.raw - } -} - /// A view into a single occupied location in an `Map`. pub struct OccupiedEntry<'a, A: ?Sized + UncheckedAnyExt, V: 'a> { - inner: raw::OccupiedEntry<'a, A>, + #[cfg(all(feature = "std", not(feature = "hashbrown")))] + inner: raw_hash_map::OccupiedEntry<'a, TypeId, Box>, + #[cfg(feature = "hashbrown")] + inner: raw_hash_map::OccupiedEntry<'a, TypeId, Box, BuildHasherDefault>, type_: PhantomData, } /// A view into a single empty location in an `Map`. pub struct VacantEntry<'a, A: ?Sized + UncheckedAnyExt, V: 'a> { - inner: raw::VacantEntry<'a, A>, + #[cfg(all(feature = "std", not(feature = "hashbrown")))] + inner: raw_hash_map::VacantEntry<'a, TypeId, Box>, + #[cfg(feature = "hashbrown")] + inner: raw_hash_map::VacantEntry<'a, TypeId, Box, BuildHasherDefault>, type_: PhantomData, } @@ -353,6 +453,35 @@ impl<'a, A: ?Sized + UncheckedAnyExt, V: IntoBox> VacantEntry<'a, A, V> { } } +/// A hasher designed to eke a little more speed out, given `TypeId`’s known characteristics. +/// +/// Specifically, this is a no-op hasher that expects to be fed a u64’s worth of +/// randomly-distributed bits. It works well for `TypeId` (eliminating start-up time, so that my +/// get_missing benchmark is ~30ns rather than ~900ns, and being a good deal faster after that, so +/// that my insert_and_get_on_260_types benchmark is ~12μs instead of ~21.5μs), but will +/// panic in debug mode and always emit zeros in release mode for any other sorts of inputs, so +/// yeah, don’t use it! 😀 +#[derive(Default)] +pub struct TypeIdHasher { + value: u64, +} + +impl Hasher for TypeIdHasher { + #[inline] + fn write(&mut self, bytes: &[u8]) { + // This expects to receive exactly one 64-bit value, and there’s no realistic chance of + // that changing, but I don’t want to depend on something that isn’t expressly part of the + // contract for safety. But I’m OK with release builds putting everything in one bucket + // if it *did* change (and debug builds panicking). + debug_assert_eq!(bytes.len(), 8); + let _ = bytes.try_into() + .map(|array| self.value = u64::from_ne_bytes(array)); + } + + #[inline] + fn finish(&self) -> u64 { self.value } +} + #[cfg(test)] mod tests { use super::*; @@ -487,4 +616,23 @@ mod tests { assert_debug::>(); assert_debug::>(); } + + #[test] + fn type_id_hasher() { + #[cfg(not(feature = "std"))] + use alloc::vec::Vec; + use core::hash::Hash; + fn verify_hashing_with(type_id: TypeId) { + let mut hasher = TypeIdHasher::default(); + type_id.hash(&mut hasher); + // SAFETY: u64 is valid for all bit patterns. + assert_eq!(hasher.finish(), unsafe { core::mem::transmute::(type_id) }); + } + // Pick a variety of types, just to demonstrate it’s all sane. Normal, zero-sized, unsized, &c. + verify_hashing_with(TypeId::of::()); + verify_hashing_with(TypeId::of::<()>()); + verify_hashing_with(TypeId::of::()); + verify_hashing_with(TypeId::of::<&str>()); + verify_hashing_with(TypeId::of::>()); + } } diff --git a/src/raw.rs b/src/raw.rs deleted file mode 100644 index 081edd4..0000000 --- a/src/raw.rs +++ /dev/null @@ -1,371 +0,0 @@ -//! The raw form of a `Map`, allowing untyped access. -//! -//! All relevant details are in the `RawMap` struct. - -use core::any::{Any, TypeId}; -use core::borrow::Borrow; -#[cfg(all(feature = "std", not(feature = "hashbrown")))] -use std::collections::hash_map::{self, HashMap}; -#[cfg(feature = "hashbrown")] -use hashbrown::hash_map::{self, HashMap}; -#[cfg(not(feature = "std"))] -use alloc::boxed::Box; -use core::convert::TryInto; -use core::hash::Hash; -use core::hash::{Hasher, BuildHasherDefault}; -use core::ops::{Index, IndexMut}; - -use crate::any::UncheckedAnyExt; - -#[derive(Default)] -struct TypeIdHasher { - value: u64, -} - -impl Hasher for TypeIdHasher { - #[inline] - fn write(&mut self, bytes: &[u8]) { - // This expects to receive exactly one 64-bit value, and there’s no realistic chance of - // that changing, but I don’t want to depend on something that isn’t expressly part of the - // contract for safety. But I’m OK with release builds putting everything in one bucket - // if it *did* change (and debug builds panicking). - debug_assert_eq!(bytes.len(), 8); - let _ = bytes.try_into() - .map(|array| self.value = u64::from_ne_bytes(array)); - } - - #[inline] - fn finish(&self) -> u64 { self.value } -} - -#[test] -fn type_id_hasher() { - #[cfg(not(feature = "std"))] - use alloc::vec::Vec; - fn verify_hashing_with(type_id: TypeId) { - let mut hasher = TypeIdHasher::default(); - type_id.hash(&mut hasher); - // SAFETY: u64 is valid for all bit patterns. - assert_eq!(hasher.finish(), unsafe { core::mem::transmute::(type_id) }); - } - // Pick a variety of types, just to demonstrate it’s all sane. Normal, zero-sized, unsized, &c. - verify_hashing_with(TypeId::of::()); - verify_hashing_with(TypeId::of::<()>()); - verify_hashing_with(TypeId::of::()); - verify_hashing_with(TypeId::of::<&str>()); - verify_hashing_with(TypeId::of::>()); -} - -/// The raw, underlying form of a `Map`. -/// -/// At its essence, this is a wrapper around `HashMap>`, with the portions that -/// would be memory-unsafe removed or marked unsafe. Normal people are expected to use the safe -/// `Map` interface instead, but there is the occasional use for this such as iteration over the -/// contents of an `Map`. However, because you will then be dealing with `Any` trait objects, it -/// doesn’t tend to be so very useful. Still, if you need it, it’s here. -#[derive(Debug)] -pub struct RawMap { - inner: HashMap, BuildHasherDefault>, -} - -// #[derive(Clone)] would want A to implement Clone, but in reality it’s only Box that can. -impl Clone for RawMap where Box: Clone { - #[inline] - fn clone(&self) -> RawMap { - RawMap { - inner: self.inner.clone(), - } - } -} - -impl_common_methods! { - field: RawMap.inner; - new() => HashMap::with_hasher(Default::default()); - with_capacity(capacity) => HashMap::with_capacity_and_hasher(capacity, Default::default()); -} - -/// `RawMap` iterator. -#[derive(Clone)] -pub struct Iter<'a, A: ?Sized + UncheckedAnyExt> { - inner: hash_map::Iter<'a, TypeId, Box>, -} -impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for Iter<'a, A> { - type Item = &'a A; - #[inline] fn next(&mut self) -> Option<&'a A> { self.inner.next().map(|x| &**x.1) } - #[inline] fn size_hint(&self) -> (usize, Option) { self.inner.size_hint() } -} -impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for Iter<'a, A> { - #[inline] fn len(&self) -> usize { self.inner.len() } -} - -/// `RawMap` mutable iterator. -pub struct IterMut<'a, A: ?Sized + UncheckedAnyExt> { - inner: hash_map::IterMut<'a, TypeId, Box>, -} -impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for IterMut<'a, A> { - type Item = &'a mut A; - #[inline] fn next(&mut self) -> Option<&'a mut A> { self.inner.next().map(|x| &mut **x.1) } - #[inline] fn size_hint(&self) -> (usize, Option) { self.inner.size_hint() } -} -impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for IterMut<'a, A> { - #[inline] fn len(&self) -> usize { self.inner.len() } -} - -/// `RawMap` move iterator. -pub struct IntoIter { - inner: hash_map::IntoIter>, -} -impl Iterator for IntoIter { - type Item = Box; - #[inline] fn next(&mut self) -> Option> { self.inner.next().map(|x| x.1) } - #[inline] fn size_hint(&self) -> (usize, Option) { self.inner.size_hint() } -} -impl ExactSizeIterator for IntoIter { - #[inline] fn len(&self) -> usize { self.inner.len() } -} - -/// `RawMap` drain iterator. -pub struct Drain<'a, A: ?Sized + UncheckedAnyExt> { - inner: hash_map::Drain<'a, TypeId, Box>, -} -impl<'a, A: ?Sized + UncheckedAnyExt> Iterator for Drain<'a, A> { - type Item = Box; - #[inline] fn next(&mut self) -> Option> { self.inner.next().map(|x| x.1) } - #[inline] fn size_hint(&self) -> (usize, Option) { self.inner.size_hint() } -} -impl<'a, A: ?Sized + UncheckedAnyExt> ExactSizeIterator for Drain<'a, A> { - #[inline] fn len(&self) -> usize { self.inner.len() } -} - -impl RawMap { - /// An iterator visiting all entries in arbitrary order. - /// - /// Iterator element type is `&Any`. - #[inline] - pub fn iter(&self) -> Iter { - Iter { - inner: self.inner.iter(), - } - } - - /// An iterator visiting all entries in arbitrary order. - /// - /// Iterator element type is `&mut Any`. - #[inline] - pub fn iter_mut(&mut self) -> IterMut { - IterMut { - inner: self.inner.iter_mut(), - } - } - - /// Clears the map, returning all items as an iterator. - /// - /// Iterator element type is `Box`. - /// - /// Keeps the allocated memory for reuse. - #[inline] - pub fn drain(&mut self) -> Drain { - Drain { - inner: self.inner.drain(), - } - } - - /// Gets the entry for the given type in the collection for in-place manipulation. - #[inline] - pub fn entry(&mut self, key: TypeId) -> Entry { - match self.inner.entry(key) { - hash_map::Entry::Occupied(e) => Entry::Occupied(OccupiedEntry { - inner: e, - }), - hash_map::Entry::Vacant(e) => Entry::Vacant(VacantEntry { - inner: e, - }), - } - } - - /// Returns a reference to the value corresponding to the key. - /// - /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed - /// form *must* match those for the key type. - #[inline] - pub fn get(&self, k: &Q) -> Option<&A> - where TypeId: Borrow, Q: Hash + Eq { - self.inner.get(k).map(|x| &**x) - } - - /// Returns true if the map contains a value for the specified key. - /// - /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed - /// form *must* match those for the key type. - #[inline] - pub fn contains_key(&self, k: &Q) -> bool - where TypeId: Borrow, Q: Hash + Eq { - self.inner.contains_key(k) - } - - /// Returns a mutable reference to the value corresponding to the key. - /// - /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed - /// form *must* match those for the key type. - #[inline] - pub fn get_mut(&mut self, k: &Q) -> Option<&mut A> - where TypeId: Borrow, Q: Hash + Eq { - self.inner.get_mut(k).map(|x| &mut **x) - } - - /// Inserts a key-value pair from the map. If the key already had a value present in the map, - /// that value is returned. Otherwise, `None` is returned. - /// - /// # Safety - /// - /// `key` and the type ID of `value` must match, or *undefined behaviour* occurs. - #[inline] - pub unsafe fn insert(&mut self, key: TypeId, value: Box) -> Option> { - self.inner.insert(key, value) - } - - /// Removes a key from the map, returning the value at the key if the key was previously in the - /// map. - /// - /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed - /// form *must* match those for the key type. - #[inline] - pub fn remove(&mut self, k: &Q) -> Option> - where TypeId: Borrow, Q: Hash + Eq { - self.inner.remove(k) - } - -} - -impl Index for RawMap where TypeId: Borrow, Q: Eq + Hash { - type Output = A; - - #[inline] - fn index(&self, index: Q) -> &A { - self.get(&index).expect("no entry found for key") - } -} - -impl IndexMut for RawMap where TypeId: Borrow, Q: Eq + Hash { - #[inline] - fn index_mut(&mut self, index: Q) -> &mut A { - self.get_mut(&index).expect("no entry found for key") - } -} - -impl IntoIterator for RawMap { - type Item = Box; - type IntoIter = IntoIter; - - #[inline] - fn into_iter(self) -> IntoIter { - IntoIter { - inner: self.inner.into_iter(), - } - } -} - -/// A view into a single occupied location in a `RawMap`. -pub struct OccupiedEntry<'a, A: ?Sized + UncheckedAnyExt> { - #[cfg(all(feature = "std", not(feature = "hashbrown")))] - inner: hash_map::OccupiedEntry<'a, TypeId, Box>, - #[cfg(feature = "hashbrown")] - inner: hash_map::OccupiedEntry<'a, TypeId, Box, BuildHasherDefault>, -} - -/// A view into a single empty location in a `RawMap`. -pub struct VacantEntry<'a, A: ?Sized + UncheckedAnyExt> { - #[cfg(all(feature = "std", not(feature = "hashbrown")))] - inner: hash_map::VacantEntry<'a, TypeId, Box>, - #[cfg(feature = "hashbrown")] - inner: hash_map::VacantEntry<'a, TypeId, Box, BuildHasherDefault>, -} - -/// A view into a single location in a `RawMap`, which may be vacant or occupied. -pub enum Entry<'a, A: ?Sized + UncheckedAnyExt> { - /// An occupied Entry - Occupied(OccupiedEntry<'a, A>), - /// A vacant Entry - Vacant(VacantEntry<'a, A>), -} - -impl<'a, A: ?Sized + UncheckedAnyExt> Entry<'a, A> { - /// Ensures a value is in the entry by inserting the default if empty, and returns - /// a mutable reference to the value in the entry. - /// - /// # Safety - /// - /// The type ID of `default` must match the entry’s key, or *undefined behaviour* occurs. - #[inline] - pub unsafe fn or_insert(self, default: Box) -> &'a mut A { - match self { - Entry::Occupied(inner) => inner.into_mut(), - Entry::Vacant(inner) => inner.insert(default), - } - } - - /// Ensures a value is in the entry by inserting the result of the default function if empty, - /// and returns a mutable reference to the value in the entry. - /// - /// # Safety - /// - /// The type ID of the value returned by `default` must match the entry’s key, - /// or *undefined behaviour* occurs. - #[inline] - pub unsafe fn or_insert_with Box>(self, default: F) -> &'a mut A { - match self { - Entry::Occupied(inner) => inner.into_mut(), - Entry::Vacant(inner) => inner.insert(default()), - } - } -} - -impl<'a, A: ?Sized + UncheckedAnyExt> OccupiedEntry<'a, A> { - /// Gets a reference to the value in the entry. - #[inline] - pub fn get(&self) -> &A { - &**self.inner.get() - } - - /// Gets a mutable reference to the value in the entry. - #[inline] - pub fn get_mut(&mut self) -> &mut A { - &mut **self.inner.get_mut() - } - - /// Converts the OccupiedEntry into a mutable reference to the value in the entry - /// with a lifetime bound to the collection itself. - #[inline] - pub fn into_mut(self) -> &'a mut A { - &mut **self.inner.into_mut() - } - - /// Sets the value of the entry, and returns the entry's old value. - /// - /// # Safety - /// - /// The type ID of `value` must match the entry’s key, or *undefined behaviour* occurs. - #[inline] - pub unsafe fn insert(&mut self, value: Box) -> Box { - self.inner.insert(value) - } - - /// Takes the value out of the entry, and returns it. - #[inline] - pub fn remove(self) -> Box { - self.inner.remove() - } -} - -impl<'a, A: ?Sized + UncheckedAnyExt> VacantEntry<'a, A> { - /// Sets the value of the entry with the VacantEntry's key, - /// and returns a mutable reference to it. - /// - /// # Safety - /// - /// The type ID of `value` must match the entry’s key, or *undefined behaviour* occurs. - #[inline] - pub unsafe fn insert(self, value: Box) -> &'a mut A { - &mut **self.inner.insert(value) - } -}