parsey/interp.js

A parser for context-free grammars

const valuators = {};

valuators.multiply  = (a, b) => a * b;
valuators.add       = (a, b) => a + b;
valuators.divide    = (a, b) => a / b;
valuators.subtract  = (a, b) => a - b;
valuators.number    = (n) => parseInt(n);
valuators.group     = (n) => n;

valuators.factor    = (op, n) => parseInt(op) || parseInt(n);
valuators.prod      = (a, b, c, d) => (a * b) || a * c || b * d || a;
valuators.sum       = (a, op, b) => a + (b || 0);
valuators.exp       = (a, _, b) => Math.pow(a, b) || a;

module.exports.valueOf = (exprType, values) => {
  return valuators[exprType].apply(null, values);
};