@babel/regjsgen

What is @babel/regjsgen?

@babel/regjsgen is a utility library that generates regular expressions from abstract syntax trees (ASTs) produced by the @babel/parser. It is particularly useful for transforming and generating regex patterns programmatically.

What are @babel/regjsgen's main functionalities?

Generate Regular Expressions from AST

This feature allows you to generate a regular expression from an abstract syntax tree (AST). The AST can be created manually or obtained from a parser like @babel/parser.

const regjsgen = require('@babel/regjsgen');
const ast = {
  type: 'RegExpLiteral',
  pattern: 'abc',
  flags: ''
};
const regex = regjsgen.generate(ast);
console.log(regex); // Output: /abc/

Support for Complex Patterns

This feature supports generating complex regular expression patterns, including groups, alternations, and quantifiers, from their corresponding AST representations.

const regjsgen = require('@babel/regjsgen');
const ast = {
  type: 'RegExpLiteral',
  pattern: '(a|b)*c',
  flags: 'g'
};
const regex = regjsgen.generate(ast);
console.log(regex); // Output: /(a|b)*c/g

Other packages similar to @babel/regjsgen

regexgen

regexgen is a library that generates regular expressions from a list of strings. Unlike @babel/regjsgen, which generates regex from ASTs, regexgen focuses on creating optimized regex patterns from string inputs.

regexp-tree

regexp-tree is a toolkit for working with regular expressions, including parsing, transforming, and generating regex patterns. It provides a more comprehensive set of tools compared to @babel/regjsgen, which focuses solely on generation from ASTs.

README

regjsgen

This is a fork of bnjmnt4n/regjsgen with some additional patches. The end goal is to merge these patches upstream.

• be866435 feat: support modifiers proposal (bnjmnt4n/regjsgen#28)

Generate regular expressions from regjsparser’s AST.

Installation

npm i regjsgen

API

regjsgen.generate(ast)

This function accepts an abstract syntax tree representing a regular expression (see regjsparser), and returns the generated regular expression string.

const regjsparser = require('regjsparser');
const regjsgen = require('regjsgen');

// Generate an AST with `regjsparser`.
let ast = regjsparser.parse(regex);

// Modify AST
// …

// Generate `RegExp` string with `regjsgen`.
let regex = regjsgen.generate(ast);

Support

Tested in Node.js 10, 12, 14, and 16.
Compatible with regjsparser v0.7.0’s AST.