get_trait/
entry.rs

1//! Entry API for maps.
2use get::GetMut;
3
4/// A trait for getting an entry at a given key.
5pub trait GetEntry<'a>: GetMut {
6    /// The type of an occupied entry.
7    type Occupied: OccupiedEntry<'a, Self>;
8
9    /// The type of a vacant entry.
10    type Vacant: VacantEntry<'a, Self>;
11
12    /// Gets the entry.
13    fn entry(&'a mut self, key: Self::Key) -> Entry<'a, Self>;
14}
15
16/// An entry at a given key.
17pub enum Entry<'a, T: ?Sized + GetEntry<'a>> {
18    /// An entry with a value.
19    Occupied(T::Occupied),
20
21    /// An entry without a value.
22    Vacant(T::Vacant),
23}
24impl<'a, T: ?Sized + GetEntry<'a>> Entry<'a, T> {
25    /// Gets this entry's value, inserting the given default value if the entry is empty.
26    pub fn or_insert(self, default: T::Value) -> &'a mut T::Value {
27        match self {
28            Entry::Occupied(entry) => entry.into_mut(),
29            Entry::Vacant(entry) => entry.insert(default),
30        }
31    }
32    /// Similar to `or_insert`, using a closure to create the value if necessary.
33    pub fn or_insert_with<F: FnOnce() -> T::Value>(self, default: F) -> &'a mut T::Value {
34        match self {
35            Entry::Occupied(entry) => entry.into_mut(),
36            Entry::Vacant(entry) => entry.insert(default()),
37        }
38    }
39}
40
41/// A trait for an entry with a value.
42pub trait OccupiedEntry<'a, T: ?Sized + GetEntry<'a>> {
43    /// Gets a reference to the key at this entry.
44    fn key(&self) -> &T::Key;
45
46    /// Gets a reference to the value at this entry.
47    fn get(&self) -> &T::Value;
48
49    /// Gets a mutable reference to the value at this entry.
50    fn get_mut(&mut self) -> &mut T::Value;
51
52    /// Inserts the given value into this entry, returning the old value.
53    fn insert(&mut self, value: T::Value) -> T::Value;
54
55    /// Consumes this entry handle, yielding a mutable reference to its value.
56    fn into_mut(self) -> &'a mut T::Value;
57
58    /// Removes this entry, returning both its key and value.
59    fn remove_entry(self) -> (T::Key, T::Value);
60}
61
62/// A trait for an entry without a value.
63pub trait VacantEntry<'a, T: ?Sized + GetEntry<'a>> {
64    /// Gets a reference to the key at this entry.
65    fn key(&self) -> &T::Key;
66
67    /// Consumes this entry, yielding back the key instead of inserting.
68    fn into_key(self) -> T::Key;
69
70    /// Inserts a value into this entry, yielding a mutable reference to its value.
71    fn insert(self, value: T::Value) -> &'a mut T::Value;
72}
get_trait/entry.rs

get_trait/
entry.rs
