scan

# File lib/erb.rb, line 454
        def scan
          new_line = true
          stag_reg = /(.*?)(<%%|<%=|<%#|<%-|<%|\n|\z)/
          etag_reg = /(.*?)(%%>|-%>|%>|\n|\z)/
          scanner = StringScanner.new(@src)
          while ! scanner.eos?
            if new_line && @stag.nil? && scanner.scan(/[ \t]*<%-/)
              yield('<%')
              new_line = false
              next
            end
            scanner.scan(@stag ? etag_reg : stag_reg)
            text = scanner[1]
            elem = scanner[2]
            new_line = (elem == "\n")
            yield(text) unless text.empty?
            if elem == '-%>'
              yield('%>')
              if scanner.scan(/(\n|\z)/)
                yield(:cr)
                new_line = true
              end
            elsif elem == '<%-'
              yield('<%')
            else
              yield(elem) unless elem.empty?
            end
          end
        end