https://github.com/rhaeguard/rgx

a tiny regex engine written in go
https://github.com/rhaeguard/rgx

golang regex regex-engine regex-util

Last synced: about 2 months ago
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a tiny regex engine written in go

• Host: GitHub
• URL: https://github.com/rhaeguard/rgx
• Owner: rhaeguard
• License: mit
• Created: 2023-08-20T20:31:40.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2023-10-13T22:24:42.000Z (about 1 year ago)
• Last Synced: 2023-10-15T13:29:11.758Z (about 1 year ago)
• Topics: golang, regex, regex-engine, regex-util
• Language: Go
• Homepage:
• Size: 108 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# rgx

![](https://github.com/rhaeguard/rgx/actions/workflows/go.yml/badge.svg)

A very simple regex engine written in go. This library is experimental, use it at your own risk!

read the [article](https://rhaeguard.github.io/posts/regex).

### to add the dependency:

```shell

go get github.com/rhaeguard/rgx

```

### how to use: 

```go

import "github.com/rhaeguard/rgx"

pattern, err := rgx.Compile(regexString)

if err != nil {

	// error handling

}

results := pattern.FindMatches(content)

if results.Matches {

	groupMatchString := results.Groups["group-name"]

}

```

### todo

- [x] `^` beginning of the string

- [x] `$` end of the string

- [x] `.` any single character/wildcard

- [x] bracket notation

  - [x] `[ ]` bracket notation/ranges

  - [x] `[^ ]` bracket negation notation

  - [x] better handling of the bracket expressions: e.g., `[ab-exy12]`

  - [x] special characters in the bracket

    - [x] support escape character

- [x] quantifiers

  - [x] `*` none or more times

  - [x] `+` one or more times

  - [x] `?` optional

  - [x] `{m,n}` more than or equal to `m` and less than equal to `n` times

- [x] capturing group

  - [x] `( )` capturing group or subexpression

  - [x] `\n` backreference, e.g, `(dog)\1` where `n` is in `[0, 9]`

  - [x] `\k` named backreference, e.g, `(?dog)\k`

  - [x] extracting the string that matches with the regex

- [x] `\` escape character

  - [x] support special characters - context dependant

- [x] better error handling in the API

- [x] ability to work on multi-line strings (tested on [Alice in Wonderland](./lib_testdata) text corpus)

  - [x] `.` should not match the newline - `\n`

  - [x] `$` should match the newline - `\n`

  - [x] multiple full matches

## notes

- `\` escape turns any next character into a literal, no special combinations such as `\d` for digits, `\b` for backspace, etc. are allowed

- numeric groups `\n` only support single digit references, so `\10` will be interpreted as the first capture group followed by a literal `0`

## credits

- [Alice in Wonderland, Lewis Carroll, Project Guttenberg](https://www.gutenberg.org/ebooks/11)