This crate provides an implementation of the Aho-Corasick algorithm. Its intended use case is for fast substring matching, particularly when matching multiple substrings in a search text. This is achieved by compiling the substrings into a finite state machine.
This implementation provides optimal algorithmic time complexity. Construction
of the finite state machine is O(p) where p is the length of the substrings
concatenated. Matching against search text is O(n + p + m), where n is
the length of the search text and m is the number of matches.
Dual-licensed under MIT or the UNLICENSE.
https://docs.rs/aho-corasick/.
The documentation contains several examples, and there is a more complete
example as a full program in examples/dict-search.rs.
Here is a quick example showing simple substring matching:
```rust use aho_corasick::{Automaton, AcAutomaton, Match};
let aut = AcAutomaton::new(vec!["apple", "maple"]); let mut it = aut.find("I like maple apples."); asserteq!(it.next(), Some(Match { pati: 1, start: 7, end: 12, })); asserteq!(it.next(), Some(Match { pati: 0, start: 13, end: 18, })); assert_eq!(it.next(), None); ```
Aho-Corasick is useful for matching multiple substrings against many long
strings. If your long string is fixed, then you might consider building a
suffix array
of the search text (which takes O(n) time). Matches can then be found in
O(plogn) time.