1 #![cfg(feature = "use_std")]
2
3 use std::collections::HashMap;
4 use std::hash::Hash;
5 use std::iter::Iterator;
6
7 /// Return a `HashMap` of keys mapped to a list of their corresponding values.
8 ///
9 /// See [`.into_group_map()`](crate::Itertools::into_group_map)
10 /// for more information.
into_group_map<I, K, V>(iter: I) -> HashMap<K, Vec<V>> where I: Iterator<Item = (K, V)>, K: Hash + Eq,11 pub fn into_group_map<I, K, V>(iter: I) -> HashMap<K, Vec<V>>
12 where
13 I: Iterator<Item = (K, V)>,
14 K: Hash + Eq,
15 {
16 let mut lookup = HashMap::new();
17
18 iter.for_each(|(key, val)| {
19 lookup.entry(key).or_insert_with(Vec::new).push(val);
20 });
21
22 lookup
23 }
24
into_group_map_by<I, K, V, F>(iter: I, mut f: F) -> HashMap<K, Vec<V>> where I: Iterator<Item = V>, K: Hash + Eq, F: FnMut(&V) -> K,25 pub fn into_group_map_by<I, K, V, F>(iter: I, mut f: F) -> HashMap<K, Vec<V>>
26 where
27 I: Iterator<Item = V>,
28 K: Hash + Eq,
29 F: FnMut(&V) -> K,
30 {
31 into_group_map(iter.map(|v| (f(&v), v)))
32 }
33