# File lib/hike/index.rb, line 162
      def build_pattern_for(basename)
        extname = basename.extname
        aliases = find_aliases_for(extname)

        if aliases.any?
          basename = basename.basename(extname)
          aliases  = [extname] + aliases
          aliases_pattern = aliases.map { |e| Regexp.escape(e) }.join("|")
          basename_re = Regexp.escape(basename.to_s) + "(?:#{aliases_pattern})"
        else
          basename_re = Regexp.escape(basename.to_s)
        end

        extension_pattern = extensions.map { |e| Regexp.escape(e) }.join("|")
        /^#{basename_re}(?:#{extension_pattern})*$/
      end