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https://github.com/makenowjust/rerejs
Re-implementation of ECMA-262 (JavaScript) RegExp
https://github.com/makenowjust/rerejs
ecmascript javascript regexp
Last synced: 3 months ago
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Re-implementation of ECMA-262 (JavaScript) RegExp
- Host: GitHub
- URL: https://github.com/makenowjust/rerejs
- Owner: makenowjust
- License: mit
- Created: 2020-03-08T15:49:00.000Z (almost 5 years ago)
- Default Branch: main
- Last Pushed: 2024-11-09T10:00:57.000Z (3 months ago)
- Last Synced: 2024-11-09T11:16:52.833Z (3 months ago)
- Topics: ecmascript, javascript, regexp
- Language: TypeScript
- Homepage:
- Size: 2.14 MB
- Stars: 27
- Watchers: 3
- Forks: 1
- Open Issues: 15
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# ReRE.js
Re-implementation of ECMA-262 (JavaScript) RegExp.
[](https://codecov.io/gh/MakeNowJust/rerejs)
[](https://github.com/MakeNowJust/rerejs/actions)
[](https://www.npmjs.com/package/rerejs)
## About
ReRE.js is a framework for processing [ECMA-262][] (JavaScript standard) `RegExp`.
It provides:
- **parser** which constructs AST nodes from a `RegExp` pattern string,
- **engine** which executes `RegExp` matching against an input string, and
- **ponyfill** (or **shim**) which is complete and full-featured alternative of `RegExp` class.
ReRE.js supports the latest `RegExp` features:
- look-behind assertion (`(?<=...)`),
- named capture group, named back reference (`(?...)` and `\k`), and
- Unicode property class (`\p{ASCII}`).
Moreover, ReRE.js supports ["Additional ECMAScript Features for Web Browsers"][] for `RegExp`.
It means robust, so it can parse some terrible real-world `RegExp` patterns correctly.
[ECMA-262]: https://www.ecma-international.org/ecma-262/10.0/index.html
["Additional ECMAScript Features for Web Browsers"]: https://www.ecma-international.org/ecma-262/10.0/index.html#sec-regular-expressions-patterns
## Getting Started
Install ReRE.js as dependency:
```console
$ npm install rerejs
```
Then, you can start:
```javascript
import {
// A parser for `RegExp` pattern.
Parser,
// A compiler for parsed `RegExp` pattern node.
Compiler,
// A ponyfill of `RegExp`.
RegExpCompat
} from './index';
/*
* Usage of `Parser`.
*/
// `new Parser` with parsing pattern source and flags,
// then call `parse` method to execute parsing.
const parser = new Parser('a+', 'u');
const pattern = parser.parse();
console.log(pattern);
// => {
// type: 'Pattern',
// flagSet: {
// global: false,
// ignoreCase: false,
// multiline: false,
// unicode: true,
// dotAll: false,
// sticky: false
// },
// captureParens: 0,
// names: Map(0) {},
// child: {
// type: 'Some',
// nonGreedy: false,
// child: { type: 'Char', value: 97, raw: 'a', range: [ 0, 1 ] },
// range: [ 0, 2 ]
// },
// range: [ 0, 2 ]
// }
/*
* Usage of `Compiler`.
*/
// `new Compiler` with pattern node, then call `compile` to get `program`.
const compiler = new Compiler(pattern);
const program = compiler.compile();
// `program` is compiled regular expression pattern.
// To execute matching, invoke `exec` method.
// Note that `program` is not `RegExpCompat` instance,
// and `exec` method result is not the same as `RegExp.prototype.exec`.
console.log(program.exec('bbaaabb'));
// => Match [
// 0 [0:0] => '',
// ]
/*
* Usage of `RegExpCompat`.
*/
// You cau use `RegExpCompat` like `RegExp` very.
const re = new RegExpCompat('a+', 'u');
console.log(re.exec('bbaaabb'));
// => [ 'aaa', index: 2, input: 'bbaaabb', groups: undefined ]
// Also, you can pass `RegExpCompat` instance to
// `String.prototype.match`, `String.prototype.replace`
// and other methods accepts `RegExp` instance.
console.log('bbaaabb'.match(re));
// => [ 'aaa', index: 2, input: 'bbaaabb', groups: undefined ]
console.log('bbaaabb'.replace(re, 'ccc'));
// => bbcccbb
// You can write `global.RegExp = RegExpCompat;`,
// however it does not work as you expected because
// it does not override `RegExp` literals construction.
```
## Contributing
ReRE.js is *alpha quality* project for now, so there are many bugs and problems.
If you found something, please open an issue.
Especially such reports are needed:
- "There is a different behavior between the browser and ReRE.js."
- "`RegExp` matching goes on infinite-loop. VM Bug?"
- "A typo in comment or error message is found."
Pull Requests are also welcome.
However I concentrate improving ReRE.js ECMA-262 compatibility for now.
So, I cannot accept a feature request as soon.
Notably, it is out of targets of this project that extending `RegExp` syntax.
(e.g. support `x` flag like `Perl` regular expression)
## Documents for Developer
There are few documents for now. Sorry.
- [docs/canonicalize.md](docs/canonicalize.md): the explanation of `src/canonicalize.ts`.
- [docs/vm.md](docs/vm.md): the explanation for the VM using ReRE.js on matching.
## License
ReRE.js is licensed under MIT license.
(C) 2020-2022 TSUYUSATO "[MakeNowJust][]" Kitsune
[MakeNowJust]: https://github.com/MakeNowJust