binarySearch
Perform a binary search of Arcs encoded as a packed array
Return
the index of the Arc having the target label, or if no Arc has the matching label, -1 - idx), where idx is the index of the Arc with the next highest label, or the total number of arcs if the target label exceeds the maximum.
Parameters
fst
the FST from which to read
arc
the starting arc; sibling arcs greater than this will be searched. Usually the first arc in the array.
targetLabel
the label to search for
Throws
IOException
when the FST reader does