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.

### Documentation

https://docs.rs/aho-corasick/.

### Example

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:

use aho_corasick::{Automaton, AcAutomaton, Match};
let aut = AcAutomaton::new(vec!["apple", "maple"]);
let mut it = aut.find("I like maple apples.");
assert_eq!(it.next(), Some(Match {
pati: 1,
start: 7,
end: 12,
}));
assert_eq!(it.next(), Some(Match {
pati: 0,
start: 13,
end: 18,
}));
assert_eq!(it.next(), None);

### Alternatives

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.