'Record whether or not this rule parsed the input at this position
successfully.'

def memoize(self, input, ruleIndex, ruleStartIndex, success):

    if success:
        stopTokenIndex = (input.index() - 1)
    else:
        stopTokenIndex = self.MEMO_RULE_FAILED
    if (ruleIndex in self._state.ruleMemo):
        self._state.ruleMemo[ruleIndex][ruleStartIndex] = stopTokenIndex
