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0.4.1 Dec 27, 2023
0.4.0 Dec 27, 2023

#731 in Data structures

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155 downloads per month
Used in ilex

Apache-2.0

160KB
3K SLoC

twie

twie [twaɪ] - Fast, compressed prefix tries.

This crate provides a Trie type that implements an associative container with slice-like keys. It has the following properties.

  • Most one-shot operations are worst-case O(n), where n is the length of the key in bytes. This may require at most 2n tree hops, but the internal representation tries to minimize this where possible.

  • Finding all prefixes of a string that are in the trie is also O(n). These prefixes are provided in order.

  • Building a trie out of, e.g., an iterator is quadratic.

  • Subtries of the whole trie (i.e. all entries with some particular prefix) can be operated on like regular tries (insertion is only supported from the root, unfortunately).

  • Memory for storing keys is shared.

  • The trie's internal indexing type is configurable, which allows trading off maximum key size for shrinking the size of tree nodes, and thus, memory usage.

let words = Trie::<str, i32>::from([
  ("poise", 0),
  ("poison", 1),
  ("poisonous", 2),
  ("poison #9", 3),
]);

assert_eq!(
  words.prefixes("poisonous snake").map(|(k, _)| k).collect::<Vec<_>>(),
  ["poison", "poisonous"],
)

Dependencies

~1MB
~12K SLoC