classA class useful for tracking the position in the input token stream that corresponds to the head of the sequence passed to a parser. The['a]
cursor :int ->
object
..end
#cursor
class type is used in the X
module defined below.val position_ : int
The current position
method advance : 'a -> < advance : 'b; position : int; .. > as 'b
c#advance i
to construct a new object corresponding to the
new input position after reading an input symbol i
.method position : int