UnaryExpr

# File lib/rexml/parsers/xpathparser.rb, line 474
      def UnaryExpr path, parsed
        path =~ /^(\-*)/
        path = $'
        if $1 and (($1.size % 2) != 0)
          mult = -1
        else
          mult = 1
        end
        parsed << :neg if mult < 0

        n = []
        path = UnionExpr( path, n )
        parsed.concat( n )
        path
      end