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fe692bf9 FG |
1 | use core::hash::{BuildHasher, Hash}; |
2 | ||
3 | use super::{Equivalent, IndexMap}; | |
4 | ||
5 | pub struct PrivateMarker {} | |
6 | ||
7 | /// Opt-in mutable access to keys. | |
8 | /// | |
9 | /// These methods expose `&mut K`, mutable references to the key as it is stored | |
10 | /// in the map. | |
11 | /// You are allowed to modify the keys in the hashmap **if the modification | |
12 | /// does not change the key’s hash and equality**. | |
13 | /// | |
14 | /// If keys are modified erroneously, you can no longer look them up. | |
15 | /// This is sound (memory safe) but a logical error hazard (just like | |
16 | /// implementing PartialEq, Eq, or Hash incorrectly would be). | |
17 | /// | |
18 | /// `use` this trait to enable its methods for `IndexMap`. | |
19 | pub trait MutableKeys { | |
20 | type Key; | |
21 | type Value; | |
22 | ||
23 | /// Return item index, mutable reference to key and value | |
24 | fn get_full_mut2<Q: ?Sized>( | |
25 | &mut self, | |
26 | key: &Q, | |
27 | ) -> Option<(usize, &mut Self::Key, &mut Self::Value)> | |
28 | where | |
29 | Q: Hash + Equivalent<Self::Key>; | |
30 | ||
31 | /// Scan through each key-value pair in the map and keep those where the | |
32 | /// closure `keep` returns `true`. | |
33 | /// | |
34 | /// The elements are visited in order, and remaining elements keep their | |
35 | /// order. | |
36 | /// | |
37 | /// Computes in **O(n)** time (average). | |
38 | fn retain2<F>(&mut self, keep: F) | |
39 | where | |
40 | F: FnMut(&mut Self::Key, &mut Self::Value) -> bool; | |
41 | ||
42 | /// This method is not useful in itself – it is there to “seal” the trait | |
43 | /// for external implementation, so that we can add methods without | |
44 | /// causing breaking changes. | |
45 | fn __private_marker(&self) -> PrivateMarker; | |
46 | } | |
47 | ||
48 | /// Opt-in mutable access to keys. | |
49 | /// | |
50 | /// See [`MutableKeys`](trait.MutableKeys.html) for more information. | |
51 | impl<K, V, S> MutableKeys for IndexMap<K, V, S> | |
52 | where | |
53 | K: Eq + Hash, | |
54 | S: BuildHasher, | |
55 | { | |
56 | type Key = K; | |
57 | type Value = V; | |
58 | fn get_full_mut2<Q: ?Sized>(&mut self, key: &Q) -> Option<(usize, &mut K, &mut V)> | |
59 | where | |
60 | Q: Hash + Equivalent<K>, | |
61 | { | |
62 | self.get_full_mut2_impl(key) | |
63 | } | |
64 | ||
65 | fn retain2<F>(&mut self, keep: F) | |
66 | where | |
67 | F: FnMut(&mut K, &mut V) -> bool, | |
68 | { | |
69 | self.retain_mut(keep) | |
70 | } | |
71 | ||
72 | fn __private_marker(&self) -> PrivateMarker { | |
73 | PrivateMarker {} | |
74 | } | |
75 | } |