How to compose/re-use rules?

[mspoulsen]

Hi,

In jison you can compose rules from other rules like this:

AMOUNT                     \d+([\d,]*\d+)?(.\d+)?
CHIPS                     '('\s*(\W)({AMOUNT})\s+\w+\s*')'

Is there a way to do this in moo so I can re-use complicated rules like in this case amount?

Thanks!

[nathan]

You can just write a template function that interpolates RegExps, e.g.:

function reg(strings, ...pieces) {
  return new RegExp(strings.raw.map((r, i) => r + (pieces[i] === undefined ? '' : '(?:' + pieces[i].source + ')')).join(''))
}
const AMOUNT = /\d+([\d,]*\d+)?(.\d+)?/
const CHIPS = reg`\(\s*(\W)(${AMOUNT})\s+\w+\s*\)`