2b490d81583f03f6ae268dab1aaa8b67f9f3718f
1 //! The raw form of a `Map`, allowing untyped access.
3 //! All relevant details are in the `RawMap` struct.
5 use core
::any
::{Any
, TypeId
};
6 use core
::borrow
::Borrow
;
7 use std
::collections
::hash_map
::{self, HashMap
};
8 use core
::convert
::TryInto
;
10 use core
::hash
::{Hasher
, BuildHasherDefault
};
11 use core
::ops
::{Index
, IndexMut
};
13 use crate::any
::UncheckedAnyExt
;
20 impl Hasher
for TypeIdHasher
{
22 fn write(&mut self, bytes
: &[u8]) {
23 // This expects to receive exactly one 64-bit value, and there’s no realistic chance of
24 // that changing, but I don’t want to depend on something that isn’t expressly part of the
25 // contract for safety. But I’m OK with release builds putting everything in one bucket
26 // if it *did* change (and debug builds panicking).
27 debug_assert_eq!(bytes
.len(), 8);
28 let _
= bytes
.try_into()
29 .map(|array
| self.value
= u64::from_ne_bytes(array
));
33 fn finish(&self) -> u64 { self.value
}
38 fn verify_hashing_with(type_id
: TypeId
) {
39 let mut hasher
= TypeIdHasher
::default();
40 type_id
.hash(&mut hasher
);
41 // SAFETY: u64 is valid for all bit patterns.
42 assert_eq!(hasher
.finish(), unsafe { core
::mem
::transmute
::<TypeId
, u64>(type_id
) });
44 // Pick a variety of types, just to demonstrate it’s all sane. Normal, zero-sized, unsized, &c.
45 verify_hashing_with(TypeId
::of
::<usize>());
46 verify_hashing_with(TypeId
::of
::<()>());
47 verify_hashing_with(TypeId
::of
::<str>());
48 verify_hashing_with(TypeId
::of
::<&str>());
49 verify_hashing_with(TypeId
::of
::<Vec
<u8>>());
52 /// The raw, underlying form of a `Map`.
54 /// At its essence, this is a wrapper around `HashMap<TypeId, Box<Any>>`, with the portions that
55 /// would be memory-unsafe removed or marked unsafe. Normal people are expected to use the safe
56 /// `Map` interface instead, but there is the occasional use for this such as iteration over the
57 /// contents of an `Map`. However, because you will then be dealing with `Any` trait objects, it
58 /// doesn’t tend to be so very useful. Still, if you need it, it’s here.
60 pub struct RawMap
<A
: ?Sized
+ UncheckedAnyExt
= dyn Any
> {
61 inner
: HashMap
<TypeId
, Box
<A
>, BuildHasherDefault
<TypeIdHasher
>>,
64 // #[derive(Clone)] would want A to implement Clone, but in reality it’s only Box<A> that can.
65 impl<A
: ?Sized
+ UncheckedAnyExt
> Clone
for RawMap
<A
> where Box
<A
>: Clone
{
67 fn clone(&self) -> RawMap
<A
> {
69 inner
: self.inner
.clone(),
74 impl_common_methods
! {
76 new() => HashMap
::with_hasher(Default
::default());
77 with_capacity(capacity
) => HashMap
::with_capacity_and_hasher(capacity
, Default
::default());
80 /// `RawMap` iterator.
82 pub struct Iter
<'a
, A
: ?Sized
+ UncheckedAnyExt
> {
83 inner
: hash_map
::Iter
<'a
, TypeId
, Box
<A
>>,
85 impl<'a
, A
: ?Sized
+ UncheckedAnyExt
> Iterator
for Iter
<'a
, A
> {
87 #[inline] fn next(&mut self) -> Option<&'a A> { self.inner.next().map(|x| &**x.1) }
88 #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
90 impl<'a
, A
: ?Sized
+ UncheckedAnyExt
> ExactSizeIterator
for Iter
<'a
, A
> {
91 #[inline] fn len(&self) -> usize { self.inner.len() }
94 /// `RawMap` mutable iterator.
95 pub struct IterMut
<'a
, A
: ?Sized
+ UncheckedAnyExt
> {
96 inner
: hash_map
::IterMut
<'a
, TypeId
, Box
<A
>>,
98 impl<'a
, A
: ?Sized
+ UncheckedAnyExt
> Iterator
for IterMut
<'a
, A
> {
99 type Item
= &'a
mut A
;
100 #[inline] fn next(&mut self) -> Option<&'a mut A> { self.inner.next().map(|x| &mut **x.1) }
101 #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
103 impl<'a
, A
: ?Sized
+ UncheckedAnyExt
> ExactSizeIterator
for IterMut
<'a
, A
> {
104 #[inline] fn len(&self) -> usize { self.inner.len() }
107 /// `RawMap` move iterator.
108 pub struct IntoIter
<A
: ?Sized
+ UncheckedAnyExt
> {
109 inner
: hash_map
::IntoIter
<TypeId
, Box
<A
>>,
111 impl<A
: ?Sized
+ UncheckedAnyExt
> Iterator
for IntoIter
<A
> {
113 #[inline] fn next(&mut self) -> Option<Box<A>> { self.inner.next().map(|x| x.1) }
114 #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
116 impl<A
: ?Sized
+ UncheckedAnyExt
> ExactSizeIterator
for IntoIter
<A
> {
117 #[inline] fn len(&self) -> usize { self.inner.len() }
120 /// `RawMap` drain iterator.
121 pub struct Drain
<'a
, A
: ?Sized
+ UncheckedAnyExt
> {
122 inner
: hash_map
::Drain
<'a
, TypeId
, Box
<A
>>,
124 impl<'a
, A
: ?Sized
+ UncheckedAnyExt
> Iterator
for Drain
<'a
, A
> {
126 #[inline] fn next(&mut self) -> Option<Box<A>> { self.inner.next().map(|x| x.1) }
127 #[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
129 impl<'a
, A
: ?Sized
+ UncheckedAnyExt
> ExactSizeIterator
for Drain
<'a
, A
> {
130 #[inline] fn len(&self) -> usize { self.inner.len() }
133 impl<A
: ?Sized
+ UncheckedAnyExt
> RawMap
<A
> {
134 /// An iterator visiting all entries in arbitrary order.
136 /// Iterator element type is `&Any`.
138 pub fn iter(&self) -> Iter
<A
> {
140 inner
: self.inner
.iter(),
144 /// An iterator visiting all entries in arbitrary order.
146 /// Iterator element type is `&mut Any`.
148 pub fn iter_mut(&mut self) -> IterMut
<A
> {
150 inner
: self.inner
.iter_mut(),
154 /// Clears the map, returning all items as an iterator.
156 /// Iterator element type is `Box<Any>`.
158 /// Keeps the allocated memory for reuse.
160 pub fn drain(&mut self) -> Drain
<A
> {
162 inner
: self.inner
.drain(),
166 /// Gets the entry for the given type in the collection for in-place manipulation.
168 pub fn entry(&mut self, key
: TypeId
) -> Entry
<A
> {
169 match self.inner
.entry(key
) {
170 hash_map
::Entry
::Occupied(e
) => Entry
::Occupied(OccupiedEntry
{
173 hash_map
::Entry
::Vacant(e
) => Entry
::Vacant(VacantEntry
{
179 /// Returns a reference to the value corresponding to the key.
181 /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
182 /// form *must* match those for the key type.
184 pub fn get
<Q
: ?Sized
>(&self, k
: &Q
) -> Option
<&A
>
185 where TypeId
: Borrow
<Q
>, Q
: Hash
+ Eq
{
186 self.inner
.get(k
).map(|x
| &**x
)
189 /// Returns true if the map contains a value for the specified key.
191 /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
192 /// form *must* match those for the key type.
194 pub fn contains_key
<Q
: ?Sized
>(&self, k
: &Q
) -> bool
195 where TypeId
: Borrow
<Q
>, Q
: Hash
+ Eq
{
196 self.inner
.contains_key(k
)
199 /// Returns a mutable reference to the value corresponding to the key.
201 /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
202 /// form *must* match those for the key type.
204 pub fn get_mut
<Q
: ?Sized
>(&mut self, k
: &Q
) -> Option
<&mut A
>
205 where TypeId
: Borrow
<Q
>, Q
: Hash
+ Eq
{
206 self.inner
.get_mut(k
).map(|x
| &mut **x
)
209 /// Inserts a key-value pair from the map. If the key already had a value present in the map,
210 /// that value is returned. Otherwise, `None` is returned.
214 /// `key` and the type ID of `value` must match, or *undefined behaviour* occurs.
216 pub unsafe fn insert(&mut self, key
: TypeId
, value
: Box
<A
>) -> Option
<Box
<A
>> {
217 self.inner
.insert(key
, value
)
220 /// Removes a key from the map, returning the value at the key if the key was previously in the
223 /// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
224 /// form *must* match those for the key type.
226 pub fn remove
<Q
: ?Sized
>(&mut self, k
: &Q
) -> Option
<Box
<A
>>
227 where TypeId
: Borrow
<Q
>, Q
: Hash
+ Eq
{
233 impl<A
: ?Sized
+ UncheckedAnyExt
, Q
> Index
<Q
> for RawMap
<A
> where TypeId
: Borrow
<Q
>, Q
: Eq
+ Hash
{
237 fn index(&self, index
: Q
) -> &A
{
238 self.get(&index
).expect("no entry found for key")
242 impl<A
: ?Sized
+ UncheckedAnyExt
, Q
> IndexMut
<Q
> for RawMap
<A
> where TypeId
: Borrow
<Q
>, Q
: Eq
+ Hash
{
244 fn index_mut(&mut self, index
: Q
) -> &mut A
{
245 self.get_mut(&index
).expect("no entry found for key")
249 impl<A
: ?Sized
+ UncheckedAnyExt
> IntoIterator
for RawMap
<A
> {
251 type IntoIter
= IntoIter
<A
>;
254 fn into_iter(self) -> IntoIter
<A
> {
256 inner
: self.inner
.into_iter(),
261 /// A view into a single occupied location in a `RawMap`.
262 pub struct OccupiedEntry
<'a
, A
: ?Sized
+ UncheckedAnyExt
> {
263 inner
: hash_map
::OccupiedEntry
<'a
, TypeId
, Box
<A
>>,
266 /// A view into a single empty location in a `RawMap`.
267 pub struct VacantEntry
<'a
, A
: ?Sized
+ UncheckedAnyExt
> {
268 inner
: hash_map
::VacantEntry
<'a
, TypeId
, Box
<A
>>,
271 /// A view into a single location in a `RawMap`, which may be vacant or occupied.
272 pub enum Entry
<'a
, A
: ?Sized
+ UncheckedAnyExt
> {
273 /// An occupied Entry
274 Occupied(OccupiedEntry
<'a
, A
>),
276 Vacant(VacantEntry
<'a
, A
>),
279 impl<'a
, A
: ?Sized
+ UncheckedAnyExt
> Entry
<'a
, A
> {
280 /// Ensures a value is in the entry by inserting the default if empty, and returns
281 /// a mutable reference to the value in the entry.
285 /// The type ID of `default` must match the entry’s key, or *undefined behaviour* occurs.
287 pub unsafe fn or_insert(self, default: Box
<A
>) -> &'a
mut A
{
289 Entry
::Occupied(inner
) => inner
.into_mut(),
290 Entry
::Vacant(inner
) => inner
.insert(default),
294 /// Ensures a value is in the entry by inserting the result of the default function if empty,
295 /// and returns a mutable reference to the value in the entry.
299 /// The type ID of the value returned by `default` must match the entry’s key,
300 /// or *undefined behaviour* occurs.
302 pub unsafe fn or_insert_with
<F
: FnOnce() -> Box
<A
>>(self, default: F
) -> &'a
mut A
{
304 Entry
::Occupied(inner
) => inner
.into_mut(),
305 Entry
::Vacant(inner
) => inner
.insert(default()),
310 impl<'a
, A
: ?Sized
+ UncheckedAnyExt
> OccupiedEntry
<'a
, A
> {
311 /// Gets a reference to the value in the entry.
313 pub fn get(&self) -> &A
{
317 /// Gets a mutable reference to the value in the entry.
319 pub fn get_mut(&mut self) -> &mut A
{
320 &mut **self.inner
.get_mut()
323 /// Converts the OccupiedEntry into a mutable reference to the value in the entry
324 /// with a lifetime bound to the collection itself.
326 pub fn into_mut(self) -> &'a
mut A
{
327 &mut **self.inner
.into_mut()
330 /// Sets the value of the entry, and returns the entry's old value.
334 /// The type ID of `value` must match the entry’s key, or *undefined behaviour* occurs.
336 pub unsafe fn insert(&mut self, value
: Box
<A
>) -> Box
<A
> {
337 self.inner
.insert(value
)
340 /// Takes the value out of the entry, and returns it.
342 pub fn remove(self) -> Box
<A
> {
347 impl<'a
, A
: ?Sized
+ UncheckedAnyExt
> VacantEntry
<'a
, A
> {
348 /// Sets the value of the entry with the VacantEntry's key,
349 /// and returns a mutable reference to it.
353 /// The type ID of `value` must match the entry’s key, or *undefined behaviour* occurs.
355 pub unsafe fn insert(self, value
: Box
<A
>) -> &'a
mut A
{
356 &mut **self.inner
.insert(value
)