Where is xmlscan/scanner as used in xsd4r

[Paul Fraser]

'xmlscanner.rb' (which is part of the in built xsd code) has the
following require(s)

require 'xsd/xmlparser'
require 'xmlscan/scanner'

Where is xmlscan/scanner?

Also, can anyone suggest the best (and/or fastest) scanner to use with
the inbuilt xsd code?

Thanks
Paul Fraser