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https://github.com/srackham/pcre2
A V library for processing PCRE regular expressions
https://github.com/srackham/pcre2
pcre2 regex regular-expressions vlang vlang-module
Last synced: about 1 month ago
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A V library for processing PCRE regular expressions
- Host: GitHub
- URL: https://github.com/srackham/pcre2
- Owner: srackham
- License: mit
- Created: 2022-10-05T09:11:54.000Z (about 2 years ago)
- Default Branch: master
- Last Pushed: 2023-12-02T07:11:39.000Z (about 1 year ago)
- Last Synced: 2024-08-04T01:05:20.289Z (5 months ago)
- Topics: pcre2, regex, regular-expressions, vlang, vlang-module
- Language: V
- Homepage:
- Size: 124 KB
- Stars: 4
- Watchers: 1
- Forks: 1
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-v - pcre2 - Library for processing PCRE regular expressions. (Libraries / Text processing)
README
# pcre2
**NOTE**: This release is graded alpha and is likely to experience API
changes up until the 1.0 release.
## Overview
A V library module for processing [Perl Compatible Regular Expressions (PCRE)](https://en.wikipedia.org/wiki/Perl_Compatible_Regular_Expressions) using the [PCRE2 library](https://www.pcre.org/).
- The `pcre2` module is a wrapper for the PCRE2 8-bit runtime library.
- Regex `find_*` methods search a `subject` string for regular expression matches.
- Regex `replace_*` methods return a string in which matches in the `subject`
string are replaced by a replacement string or the result of a replacement function.
- Regex `*_all_*` methods process all matches; `*_one_*` methods process the first match.
- The Regex `replace_*_extended` methods support the PCRE2 extended replacements string syntax (see `PCRE2_SUBSTITUTE_EXTENDED` in the [pcre2api](https://www.pcre.org/current/doc/html/pcre2api.html) man page).
- Currently there are no extraction methods for named subpatterns.
- The [pcre module](https://github.com/vlang/pcre) (which uses the older PCRE library) was the inspiration and starting point for this project;
the [Go regex package](https://pkg.go.dev/regexp) also influenced the project.
## Documentation
- [pcre2 module documentation](https://srackham.github.io/pcre2/pcre2.html).
- [PCRE regular expressions syntax](https://www.pcre.org/current/doc/html/pcre2syntax.html).
- [Github repository](https://github.com/srackham/pcre2)
## Examples
```v
import srackham.pcre2
fn main() {
// Match words starting with `d` or `n`.
r := pcre2.must_compile(r'\b([dn].*?)\b')
subject := 'Lorem nisi dis diam a cras placerat natoque'
// Extract array of all matched strings.
a := r.find_all(subject)
println(a) // ['nisi', 'dis', 'diam', 'natoque']
// Quote matched words.
s1 := r.replace_all(subject, '"$1"')
println(s1) // 'Lorem "nisi" "dis" "diam" a cras placerat "natoque"'
// Replace all matched strings with upper case.
s2 := r.replace_all_fn(subject, fn (m string) string {
return m.to_upper()
})
println(s2) // 'Lorem NISI DIS DIAM a cras placerat NATOQUE'
// Replace all matched strings with upper case (PCRE2 extended replacement syntax).
s3 := r.replace_all_extended(subject, r'\U$1')
println(s3) // 'Lorem NISI DIS DIAM a cras placerat NATOQUE'
}
```
For more examples see inside the [examples directory](https://github.com/srackham/pcre2/tree/master/examples) and take a look at the [module tests](https://github.com/srackham/pcre2/blob/master/pcre2_test.v).
## Dependencies
Install the PCRE2 library:
**Arch Linux and Manjaro**: `pacman -S pcre2`
**Debian and Ubuntu**: `apt install libpcre2-dev`
**Fedora**: `yum install pcre2-devel`
**macOS**: `brew install pcre2`
**Windows** †: `pacman.exe -S mingw-w64-x86_64-pcre2`
† Uses the [MSYS2](https://www.msys2.org/) package management tools.
## Installation
v install srackham.pcre2
Test the installation by running:
v test $HOME/.vmodules/srackham/pcre2
Example installation and test workflows for Ubuntu, macOS and Windows can be found in the Github Actions [workflow file](https://github.com/srackham/pcre2/blob/master/.github/workflows/ci.yml).
## Performance
Complex patterns can cause PCRE2 resource exhaustion. `find_*` library functions respond to such errors by raising a panic. The solution is to simplify the offending pattern. Unlike, for example, the Go regexp package, PCRE2 does not have linear-time performance and while they may not trigger a panic, pathalogical patterns can exhibit slow performance. See the PCRE2 [pcre2perform man page](https://www.pcre.org/current/doc/html/pcre2perform.html).