irregex — the irregular-expression engine
Copyright 2026 The Billy Company
This product includes software developed at The Billy Company
(https://billylives.com/).
This product bundles the following third-party components, which carry their
own licenses and copyright notices. Those notices are reproduced with the
component and are not superseded by the Apache License, Version 2.0 above.
* PCRE2 — Perl-Compatible Regular Expressions (vendor/pcre2/)
BSD-3-Clause WITH PCRE2-exception
Copyright (c) 1997-2024 University of Cambridge
Copyright (c) 2009-2024 Zoltan Herczeg
The backend behind `-P`. See vendor/pcre2/LICENCE.md for the full text.
* libsais — linear-time suffix array construction (vendor/libsais/)
Apache-2.0
Copyright (c) 2021-2025 Ilya Grebnov
The suffix sort under the FM-index. See vendor/libsais/LICENSE for the
full text.
* WHATWG Encoding Standard index tables (tools/whatwg/index-*.txt,
tools/whatwg/encodings.json)
CC0-1.0 (public-domain dedication)
Sourced from https://encoding.spec.whatwg.org/ — used to generate the
legacy-encoding decode tables.
* Unicode Character Database, version 16.0.0 (tools/ucd/*.txt)
Unicode License v3
Copyright (c) 2024 Unicode, Inc. Unicode and the Unicode Logo are
registered trademarks of Unicode, Inc. in the U.S. and other countries.
Pinned upstream data files from https://www.unicode.org/Public/16.0.0/ucd/
(emoji-data.txt from .../ucd/emoji/, DerivedGeneralCategory.txt from
.../ucd/extracted/) — used to generate the Unicode property, case-folding,
script, emoji-property, and property-alias tables.
See tools/ucd/LICENSE.txt for the full copyright and permission notice, and
tools/ucd/README.md for the per-file pin and what each one lowers into.
* ripgrep integration-test corpus, mined
(the exact face package's bench/conformance/rgsuite/spec.json)
Unlicense OR MIT
Copyright (c) 2015 Andrew Gallant
Test names, arguments, and haystack bytes mechanically extracted from
ripgrep's own `rgtest!` suite (https://github.com/BurntSushi/ripgrep) so
that ripgrep — not a hardcoded expectation — is the correctness oracle for
this engine's `rg` drop-in parity. Some haystacks are Project Gutenberg
public-domain texts carried through from that suite. The implementation is
an independent reimplementation; only this test corpus is derived.
Algorithms and interface conventions implemented from published descriptions
rather than from borrowed source — among them Aho–Corasick (1975), Hyperscan's
Teddy prefilter, Cox's trigram-index construction, and ripgrep's CLI and
ignore-file conventions — carry no obligation here. They are credited where
they are used, in the module headers and in research/*/PRIOR_ART.md.