# Regex translation sources and notices

The JS-to-ripgrep candidate translator adapts the following analysis techniques to this project's byte-preserving reads and JavaScript final verification. These projects are references, not runtime dependencies. Unicode membership comes from the running JavaScript engine rather than copied Unicode tables.

| Project | Technique used here | Source license |
| --- | --- | --- |
| [regexpu-core](https://github.com/mathiasbynens/regexpu-core) | Separate scalar sets from class strings; apply scoped flags before lowering a set | MIT |
| [refa](https://github.com/RunDevelopment/refa/tree/8d20d94232b1adb043c29810046c060ca1664bf1) | Normalized character intervals and bounded finite languages | MIT |
| [regex-syntax](https://github.com/rust-lang/regex/blob/master/regex-syntax/src/hir/literal.rs) | Budget literal expansion; retain necessary prefixes and suffixes without dropping alternatives | MIT OR Apache-2.0 |
| [RE2](https://github.com/google/re2/blob/main/re2/prefilter.cc) | Necessary AND/OR literal conditions for file prefiltering | BSD-3-Clause |
| [Vectorscan](https://github.com/VectorCamp/vectorscan/blob/develop/src/parser/prefilter.cpp) | Widen unsupported assertions and backreferences while retaining regular constraints | BSD-3-Clause |

Production implementations live in `src/core/character-set.ts`, `src/core/search-analysis.ts`, `src/core/case-fold.ts`, `src/pi/rg-regex.ts`, and `src/pi/rg-process.ts`. In particular, this project does not copy an automaton engine, a Unicode version table, or upstream match semantics into its final verifier.

## MIT reference projects

regexpu-core: Copyright Mathias Bynens <https://mathiasbynens.be/>

refa: Copyright (c) 2020 Michael Schmidt

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## Test262 regression witnesses

`src/testing/regex-translation-corpus.ts` adapts selected patterns and witnesses from [Test262](https://github.com/tc39/test262). Each fixture identifies its upstream test file. The local assertions check candidate-line inclusion and final JS results rather than reproducing the Test262 harness.

Copyright 2022 Igalia S.L. All rights reserved.

Copyright (C) 2017 the V8 project authors. All rights reserved.

Copyright 2025 Mathias Bynens. All rights reserved.

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