package aho-corasick

ocaml-aho-corasick

Find many literal patterns in one pass over a byte string. Pure OCaml, with no runtime dependencies beyond the standard library.

Supports overlapping matches, lazy iteration, leftmost-longest selection, replacement, ASCII case folding, and streaming across chunk boundaries.

Install

Requires OCaml 4.14 or newer and Dune 3.14 or newer.

Until v0.1.1 is published to opam, install from this checkout:

opam install .

After publication:

opam install aho-corasick

Add (libraries aho-corasick) to your executable or library's Dune stanza.

Quick start

let matcher = Aho_corasick.build [ "he"; "she"; "his"; "hers" ]
let matches = Aho_corasick.find_all matcher "ushers"
(* she: 1..4, he: 2..4, hers: 2..6 *)

let words = Aho_corasick.build [ "cat"; "dog" ]
let replaced =
  Aho_corasick.replace_all words ~f:(fun _ -> "[pet]") "cat and dog"
(* "[pet] and [pet]" *)

Each match has a pattern index into the original pattern list, a start byte offset, and an exclusive stop byte offset. Build once and reuse the immutable matcher.

find_all and find_iter include overlaps. find_leftmost_longest and replace_all choose non-overlapping matches, preferring the longest match at the earliest position. mem stops at the first match.

Matching uses bytes, including for UTF-8. ~ignore_case:true folds ASCII letters only. Empty pattern lists are allowed; empty strings as patterns raise Invalid_argument.

Documentation

• Usage and streaming examples
• Match rules and performance
• Compatibility and differential testing
• Reproducible benchmarks and published results
• Building and testing
• Release procedure and changelog
• Website and API reference

License

MIT.