Peggy

Peggy is a simple parser generator for JavaScript that produces fast parsers with excellent error reporting. You can use it to process complex data or computer languages and build transformers, interpreters, compilers and other tools easily.

Peggy is the successor of PEG.js.

Migrating from PEG.js

Peggy version 1.x.x is API compatible with the most recent PEG.js release. Follow these steps to upgrade:

Uninstall pegjs (and @types/pegjs if you're using the DefinitelyTyped type definitions - we now include type definitions as part of peggy itself).
Replace all require("pegjs") or import ... from "pegjs" with require("peggy") or import ... from "peggy" as appropriate.
Any scripts that use the pegjs cli should now use peggy instead.
That's it!

Features

Simple and expressive grammar syntax
Integrates both lexical and syntactical analysis
Parsers have excellent error reporting out of the box
Based on parsing expression grammar formalism — more powerful than traditional LL(k) and LR(k) parsers
Usable from your browser, from the command line, or via JavaScript API
Source map support

Getting Started

Online version is the easiest way to generate a parser. Just enter your grammar, try parsing few inputs, and download generated parser code.

Documentation

Full documentation is available at peggyjs.org.

Development

Peggy was originally developed by David Majda (@dmajda). It is currently maintained by Joe Hildebrand (@hildjj).