regexpp

What is regexpp?

The regexpp npm package is a library for parsing and manipulating regular expressions in JavaScript. It provides a detailed regular expression parser with a visitor interface for traversing abstract syntax trees, and utilities for working with regular expressions.

What are regexpp's main functionalities?

Regular Expression Parser

This feature allows you to parse a regular expression literal into an abstract syntax tree (AST), which can then be traversed or manipulated.

const { parseRegExpLiteral } = require('regexpp');
const ast = parseRegExpLiteral('/abc/g');

RegExp Visitor

This feature provides a visitor interface to traverse the AST nodes of a parsed regular expression, allowing you to perform operations on individual nodes.

const { RegExpParser, visitRegExpAST } = require('regexpp');
const parser = new RegExpParser();
const ast = parser.parsePattern('a|b');
visitRegExpAST(ast, {
  onCharacterEnter(node) {
    console.log(node.value);
  }
});

RegExp Validator

This feature allows you to validate a regular expression pattern for syntax errors, which is useful for ensuring patterns are correct before using them.

const { RegExpValidator } = require('regexpp');
const validator = new RegExpValidator();
try {
  validator.validatePattern('(?<name>a)');
} catch (error) {
  console.error(error.message);
}

Other packages similar to regexpp

ret

The 'ret' package is a regular expression parser that tokenizes regex strings. It is similar to regexpp in that it provides a way to parse regular expressions, but it does not offer the same visitor interface for traversing the AST.

regexp-tree

The 'regexp-tree' package provides a regular expression parser, transformer, and optimizer. It is similar to regexpp in parsing capabilities but also includes optimization features for regular expressions, which regexpp does not have.

README

regexpp

A regular expression parser for ECMAScript.

💿 Installation

$ npm install regexpp

• require Node.js 8 or newer.

📖 Usage

import {
    AST,
    RegExpParser,
    RegExpValidator,
    RegExpVisitor,
    parseRegExpLiteral,
    validateRegExpLiteral,
    visitRegExpAST
} from "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?, uFlag?)

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.
  • uFlag? (boolean) The flag to enable Unicode 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, uFlag)

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.
  • uFlag? (boolean) The flag to enable Unicode 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.