map_ext/
lib.rs

1#![cfg_attr( features = "unstable"
2           , feature(augmented_assignments, op_assign_traits) )]
3
4//! Extensions to `std::collections::HashMap` and `std::collections::BTreeMap`.
5
6/// Trait adding an `update` method to maps, allowing their entries to be
7/// updated.
8pub trait Update<K, V> {
9    /// Update the entry for the given key by applying a function to the value.
10    ///
11    /// If there is an entry in the map corresponding to `key`, updates the
12    /// value by applying the function `f` to it. Otherwise, if there is
13    /// no entry, does nothing.
14    ///
15    /// # Arguments
16    ///   - `key`: the key to the entry to update
17    ///   - `f`: a function taking `&mut V` to update the entry's value
18    ///
19    fn update<F>(&mut self, key: &K, f: F)
20    where F: FnOnce(&mut V);
21}
22
23/// Trait adding an `update_or` method to maps, allowing their entries to be
24/// updated with a default value.
25pub trait UpdateOr<K, V> {
26    /// Update the entry for given key, or insert a default.
27    ///
28    /// If there is an entry in the map corresponding to `key`, updates the
29    /// value by applying the function `f` to it. Otherwise, if there is
30    /// no entry, inserts the default value into the map for that key.
31    ///
32    /// # Arguments
33    ///   - `key`: the key to the entry to update
34    ///   - `f`: a function taking `&mut V` to update the entry's value
35    ///   - `default`: a default value to insert if there is no existing value
36    ///
37    fn update_or<F>(&mut self, key: &K, f: F, default: V)
38    where F: FnOnce(&mut V);
39}
40
41pub mod btree_map;
42pub use self::btree_map::*;
43
44pub mod hash_map;
45pub use self::hash_map::*;
46
47#[cfg(test)]
48mod tests {
49    #[test]
50    fn it_works() {
51    }
52}
map_ext/lib.rs

map_ext/
lib.rs
