Gruffalo

• Gruffalo

Based on the RNGLR algorithm described in the paper Right Nulled GLR Parsers (Elizabeth Scott & Adrian Johnstone, ACM, 2006).

RNGLR parsers accept any context-free grammar, while still being (nearly?) as fast as LR parsers (e.g. yacc).

Maitreya

• maitreya en GitHub

Maitreya is a generalized LR parser generator written in javascript.

Features

• Accept GLR grammars, not limited to LR(k) grammars.
• Support incremental (not yet) / streaming parsing.
• Can do both scanner less parsing and token based parsing.
• Can build grammar on the fly by using parser combinators.
• Support both interpretation and code genearation.

Example

import {defineGrammar, def, ref, many1, regex, choice} from 'maitreya/grammar';
import {GLRParser} from 'maitreya/interpret';

let grammar = defineGrammar(() => {
  def('exp', [ref('num')], ([num]) => num);
  def('exp', [ref('exp'), ref('op'), ref('exp')], ([lhs, op, rhs]) => op(lhs, rhs));
  def('num', [many1(regex(/^[0-9]/))], ([digits]) => Number(digits.join('')));
  def('op', [choice('+', '-')], ([op]) => {
    return {
      ['+'](lhs, rhs) { return lhs + rhs; },
      ['-'](lhs, rhs) { return lhs - rhs; }
    }[op];
  });
});

let parser = new GLRParser(grammar);
parser.feed('3+2-5');
console.log(parser.results);

Look at the API Reference