# File lib/rake.rb, line 874
874:     def calculate_exclude_regexp
875:       ignores = []
876:       @exclude_patterns.each do |pat|
877:         case pat
878:         when Regexp
879:           ignores << pat
880:         when /[*.]/
881:           Dir[pat].each do |p| ignores << p end
882:         else
883:           ignores << Regexp.quote(pat)
884:         end
885:       end
886:       if ignores.empty?
887:         @exclude_re = /^$/
888:       else
889:         re_str = ignores.collect { |p| "(" + p.to_s + ")" }.join("|")
890:         @exclude_re = Regexp.new(re_str)
891:       end
892:     end