18 releases (9 breaking)
0.10.1 | Sep 2, 2024 |
---|---|
0.10.0 | May 29, 2024 |
0.9.1 | Apr 2, 2024 |
0.9.0 | Feb 26, 2024 |
0.1.3 | May 26, 2020 |
#56 in Text processing
714,206 downloads per month
Used in 331 crates
(217 directly)
1.5MB
38K
SLoC
regress - REGex in Rust with EcmaScript Syntax
oh no why
Introduction
regress is a backtracking regular expression engine implemented in Rust, which targets JavaScript regular expression syntax. See the crate documentation for more.
It's fast, Unicode-aware, has few dependencies, and has a big test suite. It makes fewer guarantees than the regex
crate but it enables more syntactic features, such as backreferences and lookaround assertions.
Fun Tools
The regress-tool
binary can be used for some fun.
You can see how things get compiled with the dump-phases
cli flag:
> cargo run 'x{3,4}' 'i' --dump-phases
You can run a little benchmark too, for example:
> cargo run --release -- 'abcd' 'i' --bench ~/3200.txt
Want to contribute?
This was my first Rust program so no doubt there is room for improvement.
There's lots of stuff still missing, maybe you want to contribute?
Currently Missing Features
- An API for replacing a string while substituting in capture groups (e.g. with
$1
) - An API for escaping a string to make it a literal
- Implementing
std::str::pattern::Pattern
Missing Performance Optimizations
- Anchored matches like
^abc
still perform a string search. We should compute whether the whole regex is anchored, and optimize matching if so. - Non-greedy loops like
.*?
will eagerly compute their maximum match. This doesn't affect correctness but it does mean they may match more than they should. - Pure literal searches should use Boyer-Moore or etc.
- There are lots of vectorization opportunities.
Dependencies
~2MB
~30K SLoC