M_history Module

redo(3f) - [M_history] Fortran-based Input History Editor
(LICENSE:MIT)

subroutine redo(inputline,r)

  character(len=*) :: inputline
  character(len=1),intent(in),optional :: r

the redo(3f) routine lets you recall, list, save, and modify previously
entered program input. Built-in help is included.

The redo(3f) input history editor is a simple-to-use input history
editor interface modeled on the CDC NOS command REDO. It uses a
line editor model that means no special escape characters or control
characters are required. Typically, only a few minutes are required
to master usage.

When using redo(3f) input lines are usually first read into a character
variable and then passed to the routine. The returned string can then
be parsed or read from with an internal READ(3f). So, for example,
if you have an existing READ(3f) such as

   READ(*,101) A,I,K

replace it with something similar to

  USE M_HISTORY,ONLY : REDO
  CHARACTER(LEN=255) :: LINE ! make variable big enough to read a line
        :
        :
  READ(*,'(A)') LINE   ! read line into character variable
  CALL REDO(LINE)      ! pass line to REDO(3f). This is a no-op except
                       ! for storing the line into the input history
                       ! unless the input line is the "r" command
  READ(LINE,101)A,I,K  ! read from variable like you did from file

  inputline    line to record into history buffer file or to edit.

  r            Optional character to use as command to invoke editing.
               Defaults to 'r'.

When prompted for an input line by your program you may at any time
enter "r" on a line by itself, or a line beginning with "r r_command"
and you will enter the command history edit mode. Now you can recall
and edit previous input or compose an input line using the editor
commands.

By default, you will be editing the last line you entered, shifted
one character to the right by an exclamation character.

The character you respond with in column one controls what happens next.

o If you enter "?" while in command edit mode, help is displayed.

o If the last input line is not the desired line to edit,
  select the line to edit by entering its line number or by
  using the /,l,u, and d commands (see below for details) to find the desired input line.
o Next enter an editing directive (c,m) to edit the selected line. The
  "change" command will change all occurrences of an old string to a
  new string ...

   c/old/new/

o or the "modify" command can be used with the special characters # & and ^ ...
    o A # under a character will delete a character.
    o An "&" (ampersand) will cause the character above it to be replaced with a space.
    o  To insert a string enter ^string#.
    o Otherwise, enter a character under one in the currently displayed command and it will replace it.
    o hit RETURN to start another edit of the line
o Once the change is executed you will be prompted for another edit
  directive
o You will stay in edit mode until you enter a return on a
  blank line to feed your line to your program; or enter "." or
  "q" (which means cancel changes and return a blank line).

A detailed summary of the main edit-mode commands follows. In the
descriptions, N stands for a number ...

                          For the "c" directive the second character
                          becomes the delimiter. Traditionally one
                          usually uses a delimiter of / unless the
                          string you are editing contains /.

 mmod_string    If the first character of your entry is m or blank,
          o REPLACE a string by entering a replacement character under it
          o LEAVE a character alone by leaving a space under it
          o DELETE a character by putting a # character under it
          o BLANK OUT a character by putting an & under it
          o INSERT A STRING by entering ^STRING#

   The "modify" directive takes a little practice but this single
   directive accommodates positionally deleting, replacing, and
   inserting text. it is hardest using "modify" to put the strings
   "&" and "#" into your lines. to put a # or & character into a
   string use the 'c' command instead or ^&# or ^##.

 ;N N N N ...  Append specified lines to current line

    w FILENAME   write entire command history to specified file
    r FILENAME   replace command history with file contents
    a FILENAME   append lines from file onto command history

   program demo_redo
   use M_history, only : redo
   implicit none
   character(len=1024) ::  line
   integer             :: ios
   integer             :: cstat
   character(len=256)  :: sstat
   write(*,'(a)')                                             &
   & 'REDO(3f) COMMAND INPUT EDITOR',                         &
   & 'enter "r" or "r r_command" on the input line to go',    &
   & 'into history edit mode. Once in history edit mode you', &
   & 'may enter "?" to get some help. Enter "quit" to exit',  &
   & 'the program.'
   do
      write(*,'(a)',advance='no')'>->'    ! write prompt
      read(*,'(a)',iostat=ios) line       ! read new input line
      ! if "r", edit and return a line from the history editor
      call redo(line) ! store into history if not "r".
      if(line == 'quit')stop ! exit program if user enters "quit"
      ! now call user code to process new line of data
      ! As an example, call the system shell
      call execute_command_line(trim(line),cmdstat=cstat,cmdmsg=sstat)
   enddo
   end program demo_redo

The example program is basically a loop that reads a command from
standard input and then executes it as a subshell unless the "r"
command is entered.

Now, we will enter an echo(1) command followed by a few other lines
of input. Then we recall the echo(1) command and use a few of the
features of redo(3) to change and then re-execute the command.

   >echo This isss a Test
   This isss a Test
   >date
   Sun May 31 23:54:09 EDT 2009
   >pwd
   /cygdrive/c/urbanjs/MYCYGWIN/DISKA/public_html/public/CLONE/REDO
   >r                            ! enter edit mode
   00001 echo This isss a Test   ! last commands are displayed
   00002 date
   00003 pwd
   !pwd
   >1                            ! go to first line in history
   !echo This isss a Test
                ##   t           ! delete and replace characters
   !echo This is a test          ! insert a string
                   ^new #
   !echo This is a new test
   c/test/TEST/                  ! change a substring
   !echo This is a new TEST
                      &          | replace character with spaces
   !echo This is a newTEST
                                 ! a blank line ends editing
   This is a newTEST
   >quit

John S. Urban, 1988,2009,2011,2015 (last change: Nov 2019)

MIT