def united_to_one_line(f90src)
      return "" unless f90src
      lines = f90src.split("\n")
      previous_continuing = false
      now_continuing = false
      body = ""
      lines.each{ |line|
        words = line.split("")
        next if words.empty? && previous_continuing
        commentout = false
        brank_flag = true ; brank_char = ""
        squote = false    ; dquote = false
        ignore = false
        words.collect! { |char|
          if previous_continuing && brank_flag
            now_continuing = true
            ignore         = true
            case char
            when "!"                       ; break
            when " " ; brank_char << char  ; next ""
            when "&"
              brank_flag = false
              now_continuing = false
              next ""
            else 
              brank_flag     = false
              now_continuing = false
              ignore         = false
              next brank_char + char
            end
          end
          ignore = false

          if now_continuing
            next ""
          elsif !(squote) && !(dquote) && !(commentout)
            case char
            when "!" ; commentout = true     ; next char
            when "\""; dquote = true         ; next char
            when "\'"; squote = true         ; next char
            when "&" ; now_continuing = true ; next ""
            else next char
            end
          elsif commentout
            next char
          elsif squote
            case char
            when "\'"; squote = false ; next char
            else next char
            end
          elsif dquote
            case char
            when "\""; dquote = false ; next char
            else next char
            end
          end
        }
        if !ignore && !previous_continuing || !brank_flag
          if previous_continuing
            body << words.join("")
          else
            body << "\n" + words.join("")
          end
        end
        previous_continuing = now_continuing ? true : nil
        now_continuing = nil
      }
      return body
    end
def united_to_one_line(f90src)
      return "" unless f90src
      lines = f90src.split("\n")
      previous_continuing = false
      now_continuing = false
      body = ""
      lines.each{ |line|
        words = line.split("")
        next if words.empty? && previous_continuing
        commentout = false
        brank_flag = true ; brank_char = ""
        squote = false    ; dquote = false
        ignore = false
        words.collect! { |char|
          if previous_continuing && brank_flag
            now_continuing = true
            ignore         = true
            case char
            when "!"                       ; break
            when " " ; brank_char << char  ; next ""
            when "&"
              brank_flag = false
              now_continuing = false
              next ""
            else 
              brank_flag     = false
              now_continuing = false
              ignore         = false
              next brank_char + char
            end
          end
          ignore = false

          if now_continuing
            next ""
          elsif !(squote) && !(dquote) && !(commentout)
            case char
            when "!" ; commentout = true     ; next char
            when "\""; dquote = true         ; next char
            when "\'"; squote = true         ; next char
            when "&" ; now_continuing = true ; next ""
            else next char
            end
          elsif commentout
            next char
          elsif squote
            case char
            when "\'"; squote = false ; next char
            else next char
            end
          elsif dquote
            case char
            when "\""; dquote = false ; next char
            else next char
            end
          end
        }
        if !ignore && !previous_continuing || !brank_flag
          if previous_continuing
            body << words.join("")
          else
            body << "\n" + words.join("")
          end
        end
        previous_continuing = now_continuing ? true : nil
        now_continuing = nil
      }
      return body
    end
Continuous lines are united.

 Comments in continuous lines are removed.