ometa L {
  start    = jedynki:j -> ['start', j],
  jedynki  = dwojki:d '1' -> ['jedynki', d, '1']
             | '1' -> '1',
  dwojki   = start:s '2' -> ['start', s,  '2'] | '2' -> '2'
}

L.matchAll('2121', 'start')

ometa L2 {
  number   = digit+,
  addExpr  = addExpr '+' mulExpr
           | addExpr '-' mulExpr
           | mulExpr,
  mulExpr  = mulExpr '*' primExpr
           | mulExpr '/' primExpr
           | primExpr,
  primExpr = '(' expr ')'
           | number,
  expr     = addExpr
}

L2.matchAll('6*(4+2)', 'expr')


ometa CalcParser {
  digit    = ^digit:d                 -> d.digitValue(),
  number   = number:n digit:d         -> (n * 10 + d)
           | digit,
  addExpr  = addExpr:x '+' mulExpr:y  -> ['add', x, y]
           | addExpr:x '-' mulExpr:y  -> ['sub', x, y]
           | mulExpr,
  mulExpr  = mulExpr:x '*' primExpr:y -> ['mul', x, y]
           | mulExpr:x '/' primExpr:y -> ['div', x, y]
           | primExpr,
  primExpr = '(' expr:x ')'           -> x
           | number:n                 -> ['num', n],
  expr     = addExpr
}

tree = CalcParser.matchAll('6*(4+3)', 'expr')



ometa L3 {
  x    = expr:e -> ['expr', e],
  expr  = x:xq '+' digit:d -> ['x' , xq, '+', d]
             | digit:d -> d.digitValue()
}

L3.matchAll('4+2+3', 'x') [expr, 4]