// worst-case scenario for the grammar below

nines = "9999999999"
for (var i = 0; i < 12; i += 1)
  nines += nines


ometa M {
  digit  = '0' -> 'a' | '1' -> 'b' | '2' -> 'c' | '3' -> 'd' | '4' -> 'e' |
           '5' -> 'f' | '6' -> 'g' | '7' -> 'h' | '8' -> 'i' | '9' -> 'j',
  digits = digit*
}
start = (new Date()).getTime()
M.matchAll(nines, "digits")
t1 = (new Date()).getTime() - start
// firefox 3.5.7 on alex's mbp: 16803 15776 15301
// safari 4.0.4 on alex's mpb: 3761 3777 3760
// chrome 4.0.249.49 on alex's mbp: 2998 2925 3012


// here we create a subgrammar of M that overrides the digit rule w/ a version that uses a jumptable
N = M.delegated()
N.digit = function() {
  var $elf = this
  var x = $elf._apply('anything')
  var f = ({
     '0': function() { return 'a' },
     '1': function() { return 'b' },
     '2': function() { return 'c' },
     '3': function() { return 'd' },
     '4': function() { return 'e' },
     '5': function() { return 'f' },
     '6': function() { return 'g' },
     '7': function() { return 'h' },
     '8': function() { return 'i' },
     '9': function() { return 'j' }
    })[x]
  if (!f)
    throw fail
  return f()
}
start = (new Date()).getTime()
N.matchAll(nines, "digits")
t2 = (new Date()).getTime() - start
// firefox 3.5.7 on alex's mbp: 1479 2557 1399
// safari 4.0.4 on alex's mpb: 342 385 479
// chrome 4.0.249.49 on alex's mbp: 516 429 450


// here we create a subgrammar of M that overrides the digit rule w/ a version that uses a jumptable
O = M.delegated()
O.digit = function() {
  var $elf = this
  return (function() {
    switch ($elf._apply('anything')) {
      case '0': return 'a';
      case '1': return 'b';
      case '2': return 'c';
      case '3': return 'd';
      case '4': return 'e';
      case '5': return 'f';
      case '6': return 'g';
      case '7': return 'h';
      case '8': return 'i';
      case '9': return 'j';
      default:  throw fail
    }
   })()
}
start = (new Date()).getTime()
O.matchAll(nines, "digits")
t3 = (new Date()).getTime() - start
// firefox 3.5.7 on alex's mbp: 867 875 869
// safari 4.0.4 on alex's mpb: 245 274 224
// chrome 4.0.249.49 on alex's mbp: 330 212 344