@eslint-community/regexpp

What is @eslint-community/regexpp?

@eslint-community/regexpp is a utility library for parsing, analyzing, and transforming regular expressions. It is particularly useful for developers who need to work with regular expressions in a programmatic way, such as in linting tools, code editors, or other development tools.

What are @eslint-community/regexpp's main functionalities?

Parsing Regular Expressions

This feature allows you to parse a regular expression string into an Abstract Syntax Tree (AST). The AST can then be analyzed or transformed as needed.

const { parseRegExpLiteral } = require('@eslint-community/regexpp');
const ast = parseRegExpLiteral('/abc/');
console.log(JSON.stringify(ast, null, 2));

Validating Regular Expressions

This feature allows you to validate a regular expression string. If the regex is invalid, an error will be thrown, which can be caught and handled.

const { validateRegExpLiteral } = require('@eslint-community/regexpp');
try {
  validateRegExpLiteral('/abc/');
  console.log('Valid regex');
} catch (e) {
  console.error('Invalid regex', e.message);
}

Traversing AST

This feature allows you to traverse the AST of a regular expression. You can define visitor functions that will be called for specific types of nodes in the AST.

const { parseRegExpLiteral, visitRegExpAST } = require('@eslint-community/regexpp');
const ast = parseRegExpLiteral('/abc/');
visitRegExpAST(ast, {
  onCharacterClassEnter(node) {
    console.log('Character class:', node);
  }
});

Other packages similar to @eslint-community/regexpp

regexp-tree

regexp-tree is a similar library that provides tools for parsing, transforming, and analyzing regular expressions. It offers a more extensive set of transformations and optimizations compared to @eslint-community/regexpp.

regex-parser

regex-parser is a simpler library that focuses on parsing regular expressions into ASTs. It is less feature-rich compared to @eslint-community/regexpp but can be useful for basic parsing needs.

regexgen

regexgen is a library that generates regular expressions from a set of strings. While it does not offer parsing or validation, it is useful for creating regex patterns programmatically, which can complement the features of @eslint-community/regexpp.

README

@eslint-community/regexpp

A regular expression parser for ECMAScript.

💿 Installation

$ npm install @eslint-community/regexpp

• require Node@^12.0.0 || ^14.0.0 || >=16.0.0.

📖 Usage

import {
    AST,
    RegExpParser,
    RegExpValidator,
    RegExpVisitor,
    parseRegExpLiteral,
    validateRegExpLiteral,
    visitRegExpAST
} from "@eslint-community/regexpp"

parseRegExpLiteral(source, options?)

Parse a given regular expression literal then make AST object.

This is equivalent to new RegExpParser(options).parseLiteral(source).

• Parameters:
  • source (string | RegExp) The source code to parse.
  • options? (RegExpParser.Options) The options to parse.
• Return:
  • The AST of the regular expression.

validateRegExpLiteral(source, options?)

Validate a given regular expression literal.

This is equivalent to new RegExpValidator(options).validateLiteral(source).

• Parameters:
  • source (string) The source code to validate.
  • options? (RegExpValidator.Options) The options to validate.

visitRegExpAST(ast, handlers)

Visit each node of a given AST.

This is equivalent to new RegExpVisitor(handlers).visit(ast).

• Parameters:
  • ast (AST.Node) The AST to visit.
  • handlers (RegExpVisitor.Handlers) The callbacks.

RegExpParser

new RegExpParser(options?)

• Parameters:
  • options? (RegExpParser.Options) The options to parse.

parser.parseLiteral(source, start?, end?)

Parse a regular expression literal.

• Parameters:
  • source (string) The source code to parse. E.g. "/abc/g".
  • start? (number) The start index in the source code. Default is 0.
  • end? (number) The end index in the source code. Default is source.length.
• Return:
  • The AST of the regular expression.

parser.parsePattern(source, start?, end?, flags?)

Parse a regular expression pattern.

• Parameters:
  • source (string) The source code to parse. E.g. "abc".
  • start? (number) The start index in the source code. Default is 0.
  • end? (number) The end index in the source code. Default is source.length.
  • flags? ({ unicode?: boolean, unicodeSets?: boolean }) The flags to enable Unicode mode, and Unicode Set mode.
• Return:
  • The AST of the regular expression pattern.

parser.parseFlags(source, start?, end?)

Parse a regular expression flags.

• Parameters:
  • source (string) The source code to parse. E.g. "gim".
  • start? (number) The start index in the source code. Default is 0.
  • end? (number) The end index in the source code. Default is source.length.
• Return:
  • The AST of the regular expression flags.

RegExpValidator

new RegExpValidator(options)

• Parameters:
  • options (RegExpValidator.Options) The options to validate.

validator.validateLiteral(source, start, end)

Validate a regular expression literal.

• Parameters:
  • source (string) The source code to validate.
  • start? (number) The start index in the source code. Default is 0.
  • end? (number) The end index in the source code. Default is source.length.

validator.validatePattern(source, start, end, flags)

Validate a regular expression pattern.

• Parameters:
  • source (string) The source code to validate.
  • start? (number) The start index in the source code. Default is 0.
  • end? (number) The end index in the source code. Default is source.length.
  • flags? ({ unicode?: boolean, unicodeSets?: boolean }) The flags to enable Unicode mode, and Unicode Set mode.

validator.validateFlags(source, start, end)

Validate a regular expression flags.

• Parameters:
  • source (string) The source code to validate.
  • start? (number) The start index in the source code. Default is 0.
  • end? (number) The end index in the source code. Default is source.length.

RegExpVisitor

new RegExpVisitor(handlers)

• Parameters:
  • handlers (RegExpVisitor.Handlers) The callbacks.

visitor.visit(ast)

Validate a regular expression literal.

• Parameters:
  • ast (AST.Node) The AST to visit.

📰 Changelog

• GitHub Releases

🍻 Contributing

Welcome contributing!

Please use GitHub's Issues/PRs.

Development Tools

• npm test runs tests and measures coverage.
• npm run build compiles TypeScript source code to index.js, index.js.map, and index.d.ts.
• npm run clean removes the temporary files which are created by npm test and npm run build.
• npm run lint runs ESLint.
• npm run update:test updates test fixtures.
• npm run update:ids updates src/unicode/ids.ts.
• npm run watch runs tests with --watch option.