indexmap/set/
mutable.rs

1use core::hash::{BuildHasher, Hash};
2
3use super::{Equivalent, IndexSet};
4use crate::map::MutableKeys;
5
6/// Opt-in mutable access to [`IndexSet`] values.
7///
8/// These methods expose `&mut T`, mutable references to the value as it is stored
9/// in the set.
10/// You are allowed to modify the values in the set **if the modification
11/// does not change the value’s hash and equality**.
12///
13/// If values are modified erroneously, you can no longer look them up.
14/// This is sound (memory safe) but a logical error hazard (just like
15/// implementing `PartialEq`, `Eq`, or `Hash` incorrectly would be).
16///
17/// `use` this trait to enable its methods for `IndexSet`.
18///
19/// This trait is sealed and cannot be implemented for types outside this crate.
20pub trait MutableValues: private::Sealed {
21    type Value;
22
23    /// Return item index and mutable reference to the value
24    ///
25    /// Computes in **O(1)** time (average).
26    fn get_full_mut2<Q>(&mut self, value: &Q) -> Option<(usize, &mut Self::Value)>
27    where
28        Q: ?Sized + Hash + Equivalent<Self::Value>;
29
30    /// Return mutable reference to the value at an index.
31    ///
32    /// Valid indices are `0 <= index < self.len()`.
33    ///
34    /// Computes in **O(1)** time.
35    fn get_index_mut2(&mut self, index: usize) -> Option<&mut Self::Value>;
36
37    /// Scan through each value in the set and keep those where the
38    /// closure `keep` returns `true`.
39    ///
40    /// The values are visited in order, and remaining values keep their order.
41    ///
42    /// Computes in **O(n)** time (average).
43    fn retain2<F>(&mut self, keep: F)
44    where
45        F: FnMut(&mut Self::Value) -> bool;
46}
47
48/// Opt-in mutable access to [`IndexSet`] values.
49///
50/// See [`MutableValues`] for more information.
51impl<T, S> MutableValues for IndexSet<T, S>
52where
53    S: BuildHasher,
54{
55    type Value = T;
56
57    fn get_full_mut2<Q>(&mut self, value: &Q) -> Option<(usize, &mut T)>
58    where
59        Q: ?Sized + Hash + Equivalent<T>,
60    {
61        match self.map.get_full_mut2(value) {
62            Some((index, value, ())) => Some((index, value)),
63            None => None,
64        }
65    }
66
67    fn get_index_mut2(&mut self, index: usize) -> Option<&mut T> {
68        match self.map.get_index_mut2(index) {
69            Some((value, ())) => Some(value),
70            None => None,
71        }
72    }
73
74    fn retain2<F>(&mut self, mut keep: F)
75    where
76        F: FnMut(&mut T) -> bool,
77    {
78        self.map.retain2(move |value, ()| keep(value));
79    }
80}
81
82mod private {
83    pub trait Sealed {}
84
85    impl<T, S> Sealed for super::IndexSet<T, S> {}
86}
indexmap/set/mutable.rs

indexmap/set/
mutable.rs
