def scan

      # remove private comment
      remaining_code = remove_private_comments(@body)

      # continuation lines are united to one line
      remaining_code = united_to_one_line(remaining_code)

      # semicolons are replaced to line feed
      remaining_code = semicolon_to_linefeed(remaining_code)

      # collect comment for file entity
      whole_comment, remaining_code = collect_first_comment(remaining_code)
      @top_level.comment = whole_comment

      # String "remaining_code" is converted to Array "remaining_lines"
      remaining_lines = remaining_code.split("\n")

      # "module" or "program" parts are parsed (new)
      #
      level_depth = 0
      block_searching_flag = nil
      block_searching_lines = []
      pre_comment = []
      module_program_trailing = ""
      module_program_name = ""
      other_block_level_depth = 0
      other_block_searching_flag = nil
      remaining_lines.collect!{|line|
        if !block_searching_flag && !other_block_searching_flag
          if line =~ /^\s*?module\s+(\w+)\s*?(!.*?)?$/i
            block_searching_flag = :module
            block_searching_lines << line
            module_program_name = $1
            module_program_trailing = find_comments($2)
            next false
          elsif line =~ /^\s*?program\s+(\w+)\s*?(!.*?)?$/i ||
                 line =~ /^\s*?\w/ && !block_start?(line)
            block_searching_flag = :program
            block_searching_lines << line
            module_program_name = $1 || ""
            module_program_trailing = find_comments($2)
            next false

          elsif block_start?(line)
            other_block_searching_flag = true
            next line

          elsif line =~ /^\s*?!\s?(.*)/
            pre_comment << line
            next line
          else
            pre_comment = []
            next line
          end
        elsif other_block_searching_flag
          other_block_level_depth += 1 if block_start?(line)
          other_block_level_depth -= 1 if block_end?(line)
          if other_block_level_depth < 0
            other_block_level_depth = 0
            other_block_searching_flag = nil
          end
          next line
        end

        block_searching_lines << line
        level_depth += 1 if block_start?(line)
        level_depth -= 1 if block_end?(line)
        if level_depth >= 0
          next false
        end

        # "module_program_code" is formatted.
        # ":nodoc:" flag is checked.
        #
        module_program_code = block_searching_lines.join("\n")
        module_program_code = remove_empty_head_lines(module_program_code)
        if module_program_trailing =~ /^:nodoc:/
          # next loop to search next block
          level_depth = 0
          block_searching_flag = false
          block_searching_lines = []
          pre_comment = []
          next false
        end

        # NormalClass is created, and added to @top_level
        #
        if block_searching_flag == :module
          module_name = module_program_name
          module_code = module_program_code
          module_trailing = module_program_trailing
          progress "m"
          @stats.num_modules += 1
          f9x_module = @top_level.add_module NormalClass, module_name
          f9x_module.record_location @top_level

          f9x_comment = COMMENTS_ARE_UPPER ? 
            find_comments(pre_comment.join("\n"))  + "\n" + module_trailing :
              module_trailing + "\n" + find_comments(module_code.sub(/^.*$\n/i, ''))
          f9x_module.comment = f9x_comment
          parse_program_or_module(f9x_module, module_code)

          TopLevel.all_files.each do |name, toplevel|
            if toplevel.include_includes?(module_name, @options.ignore_case)
              if !toplevel.include_requires?(@file_name, @options.ignore_case)
                toplevel.add_require(Require.new(@file_name, ""))
              end
            end
            toplevel.each_classmodule{|m|
              if m.include_includes?(module_name, @options.ignore_case)
                if !m.include_requires?(@file_name, @options.ignore_case)
                  m.add_require(Require.new(@file_name, ""))
                end
              end
            }
          end
        elsif block_searching_flag == :program
          program_name = module_program_name
          program_code = module_program_code
          program_trailing = module_program_trailing
          progress "p"
          program_comment = COMMENTS_ARE_UPPER ? 
            find_comments(pre_comment.join("\n")) + "\n" + program_trailing : 
              program_trailing + "\n" + find_comments(program_code.sub(/^.*$\n/i, ''))
          program_comment = "\n\n= <i>Program</i> <tt>#{program_name}</tt>\n\n" \
                            + program_comment
          @top_level.comment << program_comment
          parse_program_or_module(@top_level, program_code, :private)
        end

        # next loop to search next block
        level_depth = 0
        block_searching_flag = false
        block_searching_lines = []
        pre_comment = []
        next false
      }

      remaining_lines.delete_if{ |line|
        line == false
      }

      # External subprograms and functions are parsed
      #
      parse_program_or_module(@top_level, remaining_lines.join("\n"),
                              :public, true)

      @top_level
    end
def scan

      # remove private comment
      remaining_code = remove_private_comments(@body)

      # continuation lines are united to one line
      remaining_code = united_to_one_line(remaining_code)

      # semicolons are replaced to line feed
      remaining_code = semicolon_to_linefeed(remaining_code)

      # collect comment for file entity
      whole_comment, remaining_code = collect_first_comment(remaining_code)
      @top_level.comment = whole_comment

      # String "remaining_code" is converted to Array "remaining_lines"
      remaining_lines = remaining_code.split("\n")

      # "module" or "program" parts are parsed (new)
      #
      level_depth = 0
      block_searching_flag = nil
      block_searching_lines = []
      pre_comment = []
      module_program_trailing = ""
      module_program_name = ""
      other_block_level_depth = 0
      other_block_searching_flag = nil
      remaining_lines.collect!{|line|
        if !block_searching_flag && !other_block_searching_flag
          if line =~ /^\s*?module\s+(\w+)\s*?(!.*?)?$/i
            block_searching_flag = :module
            block_searching_lines << line
            module_program_name = $1
            module_program_trailing = find_comments($2)
            next false
          elsif line =~ /^\s*?program\s+(\w+)\s*?(!.*?)?$/i ||
                 line =~ /^\s*?\w/ && !block_start?(line)
            block_searching_flag = :program
            block_searching_lines << line
            module_program_name = $1 || ""
            module_program_trailing = find_comments($2)
            next false

          elsif block_start?(line)
            other_block_searching_flag = true
            next line

          elsif line =~ /^\s*?!\s?(.*)/
            pre_comment << line
            next line
          else
            pre_comment = []
            next line
          end
        elsif other_block_searching_flag
          other_block_level_depth += 1 if block_start?(line)
          other_block_level_depth -= 1 if block_end?(line)
          if other_block_level_depth < 0
            other_block_level_depth = 0
            other_block_searching_flag = nil
          end
          next line
        end

        block_searching_lines << line
        level_depth += 1 if block_start?(line)
        level_depth -= 1 if block_end?(line)
        if level_depth >= 0
          next false
        end

        # "module_program_code" is formatted.
        # ":nodoc:" flag is checked.
        #
        module_program_code = block_searching_lines.join("\n")
        module_program_code = remove_empty_head_lines(module_program_code)
        if module_program_trailing =~ /^:nodoc:/
          # next loop to search next block
          level_depth = 0
          block_searching_flag = false
          block_searching_lines = []
          pre_comment = []
          next false
        end

        # NormalClass is created, and added to @top_level
        #
        if block_searching_flag == :module
          module_name = module_program_name
          module_code = module_program_code
          module_trailing = module_program_trailing
          progress "m"
          @stats.num_modules += 1
          f9x_module = @top_level.add_module NormalClass, module_name
          f9x_module.record_location @top_level

          f9x_comment = COMMENTS_ARE_UPPER ? 
            find_comments(pre_comment.join("\n"))  + "\n" + module_trailing :
              module_trailing + "\n" + find_comments(module_code.sub(/^.*$\n/i, ''))
          f9x_module.comment = f9x_comment
          parse_program_or_module(f9x_module, module_code)

          TopLevel.all_files.each do |name, toplevel|
            if toplevel.include_includes?(module_name, @options.ignore_case)
              if !toplevel.include_requires?(@file_name, @options.ignore_case)
                toplevel.add_require(Require.new(@file_name, ""))
              end
            end
            toplevel.each_classmodule{|m|
              if m.include_includes?(module_name, @options.ignore_case)
                if !m.include_requires?(@file_name, @options.ignore_case)
                  m.add_require(Require.new(@file_name, ""))
                end
              end
            }
          end
        elsif block_searching_flag == :program
          program_name = module_program_name
          program_code = module_program_code
          program_trailing = module_program_trailing
          progress "p"
          program_comment = COMMENTS_ARE_UPPER ? 
            find_comments(pre_comment.join("\n")) + "\n" + program_trailing : 
              program_trailing + "\n" + find_comments(program_code.sub(/^.*$\n/i, ''))
          program_comment = "\n\n= <i>Program</i> <tt>#{program_name}</tt>\n\n" \
                            + program_comment
          @top_level.comment << program_comment
          parse_program_or_module(@top_level, program_code, :private)
        end

        # next loop to search next block
        level_depth = 0
        block_searching_flag = false
        block_searching_lines = []
        pre_comment = []
        next false
      }

      remaining_lines.delete_if{ |line|
        line == false
      }

      # External subprograms and functions are parsed
      #
      parse_program_or_module(@top_level, remaining_lines.join("\n"),
                              :public, true)

      @top_level
    end
prepare to parse a Fortran 95 file
 define code constructs