33 lines
758 B
Rust
33 lines
758 B
Rust
#![cfg(feature = "use_std")]
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use std::collections::HashMap;
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use std::hash::Hash;
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use std::iter::Iterator;
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/// Return a `HashMap` of keys mapped to a list of their corresponding values.
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///
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/// See [`.into_group_map()`](crate::Itertools::into_group_map)
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/// for more information.
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pub fn into_group_map<I, K, V>(iter: I) -> HashMap<K, Vec<V>>
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where
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I: Iterator<Item = (K, V)>,
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K: Hash + Eq,
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{
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let mut lookup = HashMap::new();
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iter.for_each(|(key, val)| {
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lookup.entry(key).or_insert_with(Vec::new).push(val);
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});
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lookup
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}
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pub fn into_group_map_by<I, K, V, F>(iter: I, mut f: F) -> HashMap<K, Vec<V>>
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where
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I: Iterator<Item = V>,
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K: Hash + Eq,
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F: FnMut(&V) -> K,
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{
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into_group_map(iter.map(|v| (f(&v), v)))
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}
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