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.
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")
orimport ... from "pegjs"
withrequire("peggy")
orimport ... from "peggy"
as appropriate. - Any scripts that use the
pegjs
cli should now usepeggy
instead. - That's it!
- 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 โ 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
Online version is the easiest way to generate a parser. Just enter your grammar, try parsing few inputs, and download generated parser code.
Full documentation is available at peggyjs.org.
- Project website
- Wiki
- Source code
- Issue tracker
- Discussions
- Browser Benchmark Suite
- Browser Test Suite
Peggy was originally developed by David Majda (@dmajda). It is currently maintained by Joe Hildebrand (@hildjj).
You are welcome to contribute code. Unless your contribution is really trivial you should get in touch with us first โ this can prevent wasted effort on both sides.