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

The regular expression parser for ECMAScript.

💿 Installation

$ npm install regexpp

• require Node.js 6.5.0 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.