vendor/itertools-0.7.8/src/group_map.rs

   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()`](../trait.Itertools.html#method.into_group_map)
  10 /// for more information.
  11 pub fn into_group_map<I, K, V>(iter: I) -> HashMap<K, Vec<V>>
  12     where I: Iterator<Item=(K, V)>,
  13           K: Hash + Eq,
  14 {
  15     let mut lookup = HashMap::new();
  16
  17     for (key, val) in iter {
  18         lookup.entry(key).or_insert(Vec::new()).push(val);
  19     }
  20
  21     lookup
  22 }