REMLINE analogue

[tsh73]

(resurfaced at
justbasiccom.proboards.com/thread/685/using-line-numbers
)
As you probably know, REMLINE.BAS is original program from Microsoft
disigned to remove unused line numbers
(really handy then converting some older BASIC with line numbers to JB)

Original program called REMLINE.BAS, my copy size 12 318 bytes, 398 lines
Starts with LOOONG comment (41 lines!)
'
'   Microsoft RemLine - Line Number Removal Utility
'   Copyright (C) Microsoft Corporation 1985-1990
'
'   REMLINE.BAS is a program to remove line numbers from Microsoft Basic
'   Programs. It removes only those line numbers that are not the object
'   of one of the following statements: GOSUB, RETURN, GOTO, THEN, ELSE,
'   RESUME, RESTORE, or RUN.
'

And indeed it needs some heavy adapting to JB
I pretty sure someone already did that - but I apparently do not have it.

Here is code from www.qb64.net adapted to JB
(it is much smaller, 92 lines, 3064 bytes.)
Under the code attribution is written

Code courtesy of Pete from the Network 54 Qbasic Forum

While testing, I found one problem with it:
it does not supports things like
ON ME(J) GOSUB 770,720,640
- so on this case, it preserved first number (770) but deleted other two.
Anyway JB does not support this construction either, so if you encounter this, you will have to rewrite it somehow.

Here it is
Since it attempts to rewrite source program, having backup is a wise move.
'from
'http://www.qb64.net/wiki/index-php/Line_number/
'   Code courtesy of Pete from the Network 54 Qbasic Forum
'adaptation to JB by tsh73, may 2021
CLS
REDIM linenumber(100000)
PRINT "This Program removes unnecessary line numbers.": PRINT
INPUT "Name of file: "; filename$: PRINT
OPEN filename$ FOR INPUT AS #1
   DO UNTIL EOF(#1)
       LINE INPUT #1, a$
       REM Get rid of quotes and REM statements.
       DO while 1
           IF INSTR(a$, CHR$(34)) <> 0 THEN
               IF INSTR(a$, CHR$(34), INSTR(a$, CHR$(34)) + 1 ) = 0 THEN EXIT DO: REM Mismatched quotes. Illegal code.
               a$ = MID$(a$, 1, INSTR(a$, CHR$(34)) - 1) + MID$(a$, INSTR(a$, CHR$(34), INSTR(a$, CHR$(34)) + 1) + 1)
           ELSE
               EXIT DO
           END IF
       LOOP
       IF INSTR( upper$(a$), "REM ") <> 0 THEN a$ = MID$(a$, 1, INSTR( upper$(a$), "REM "))
       IF INSTR( upper$(a$), "' ") <> 0 THEN a$ = MID$(a$, 1, INSTR(a$, "' "))
       DO while 1
           flag = 0
           REM Break down compound statements and get line numbers.
           IF INSTR(a$, "GOTO ") <> 0 THEN flag = 1: n = INSTR(a$, "GOTO ") + 5: GOSUB [tracknumber]
           IF INSTR(a$, "GOSUB ") <> 0 THEN flag = 1: n = INSTR(a$, "GOSUB ") + 6: GOSUB [tracknumber]
           IF INSTR(a$, "THEN ") <> 0 THEN flag = 1: n = INSTR(a$, "THEN ") + 5: GOSUB [tracknumber]
           IF INSTR(a$, "ELSE ") <> 0 THEN flag = 1: n = INSTR(a$, "ELSE ") + 5: GOSUB [tracknumber]
           IF INSTR(a$, "RUN ") <> 0 THEN flag = 1: n = INSTR(a$, "RUN ") + 4: GOSUB [tracknumber]
           IF INSTR(a$, "RESUME ") <> 0 THEN flag = 1: n = INSTR(a$, "RESUME ") + 7: GOSUB [tracknumber]
           IF INSTR(a$, "RETURN ") <> 0 THEN flag = 1: n = INSTR(a$, "RETURN ") + 7: GOSUB [tracknumber]
           IF flag = 0 THEN EXIT DO ELSE a$ = MID$(a$, n)
       LOOP
   LOOP
   PRINT "Number of line-numbered statements kept:"; count
CLOSE #1
OPEN filename$ FOR INPUT AS #1
OPEN "filename.tmp" FOR OUTPUT AS #2
   DO UNTIL EOF(#1)
       LINE INPUT #1, a$
       flag = 0
       IF VAL(MID$(a$, 1, 1)) <> 0 THEN
           FOR i = 1 TO count
               IF VAL(a$) = linenumber(i) THEN flag = 1: EXIT FOR
           NEXT
           IF flag = 0 THEN a$ = MID$(a$, INSTR(a$, " ") + 1)
       END IF
       PRINT #2, a$
   LOOP
CLOSE #1
CLOSE #2
run "notepad.exe filename.tmp"
PRINT
PRINT "Back up original file as .org and give edited file original file name? [Y/N]"
DO while 1
   'b$ =  upper$(INKEY$)
   b$ =  upper$(input$(1))
   SELECT CASE b$
   'CASE CHR$(27): SYSTEM  'does not provide ESC
   CASE "N"
       'ON ERROR GOTO [resnxt]
       'KILL "filename.tmp"
       'ON ERROR GOTO 0
       call tryKill "filename.tmp"
       PRINT
       PRINT "Temporary "+ CHR$(34) + "filename.tmp" + CHR$(34) + " was removed and no changes were made to original file."
       PRINT
       PRINT "Press any key to end."
       EXIT DO
   CASE "Y"
       'ON ERROR GOTO [resnxt]
       'KILL MID$(filename$, 1, INSTR(filename$, ".") - 1) + ".org"
       'ON ERROR GOTO 0
       call tryKill MID$(filename$, 1, INSTR(filename$, ".") - 1) + ".org"
       NAME filename$ AS MID$(filename$, 1, INSTR(filename$, ".") - 1) + ".org"
       NAME "filename.tmp" AS filename$
       PRINT : PRINT "File conversion completed. Press any key to end."
       EXIT DO
   END SELECT
LOOP
'SLEEP
'SYSTEM
end

[tracknumber]
DO while 1
   count = count + 1
   linenumber(count) = VAL(MID$(a$, n))
   IF INSTR(a$, "ON") <> 0 AND INSTR(a$, "GOSUB") <> 0 OR INSTR(a$, "ON") <> 0 AND INSTR(a$, "GOTO") <> 0 THEN
       FOR i = n TO LEN(a$)
           IF VAL(MID$(a$, i, 1)) = 0 AND MID$(a$, i, 1) <> "0" AND MID$(a$, i, 1) <> "," AND MID$(a$, i, 1) <> " " THEN EXIT FOR
           IF MID$(a$, i, 2) = ", " THEN n = i + 1: EXIT FOR
       NEXT
       IF n <> i + 1 THEN EXIT DO
   ELSE
       EXIT DO
   END IF
LOOP
RETURN
'[resnxt]
'RESUME NEXT

sub tryKill fileName$
   on error goto [err]
   kill fileName$
   exit sub
[err]
   print "ERR: failed to kill a file ";fileName$
end sub