rerejs
v0.2.1
Published
Re-implementation of ECMA-262 (JavaScript) RegExp
Downloads
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Readme
ReRE.js
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 (
(?<foo>...)
and\k<foo>
), 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.
Getting Started
Install ReRE.js as dependency:
$ npm install rerejs
Then, you can start:
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: the explanation of
src/canonicalize.ts
. - docs/vm.md: the explanation for the VM using ReRE.js on matching.
License
ReRE.js is licensed under MIT license.
(C) 2020 TSUYUSATO "MakeNowJust" Kitsune