;-------------------------------------------------------------
;+
; NAME:
;       STRESS
; PURPOSE:
;       String edit by sub-string. Precede, Follow, Delete, Replace.
; CATEGORY:
; CALLING SEQUENCE:
;       new = stress(old,cmd,n,oldss,newss,ned)
; INPUTS:
;       old = string to edit.                               in
;       cmd = edit command:                                 in
;         'P' = precede.
;         'F' = follow.
;         'D' = delete.
;         'R' = replace.
;       n = occurrence number to process (0 = all).         in
;       oldss = reference substring.                        in
;       oldss may have any of the following forms:
;         1. s    a single substring.
;         2. s...    start at substring s, end at end of string.
;         3. ...e    from start of string to substring e.
;         4. s...e   from subs s to subs e.
;         5. ...     entire string.
;       newss = substring to add. Not needed for 'D'        in
; KEYWORD PARAMETERS:
; OUTPUTS:
;       ned = number of occurrences actually changed.       out
;       new = resulting string after editing.               out
; COMMON BLOCKS:
; NOTES:
; MODIFICATION HISTORY:
;       Written by R. Sterner, 6 Jan, 1985.
;       RES --- 23 May, 1988 fixed a bug in SSTYP = 2.
;       Converted to SUN 13 Aug, 1989 --- R. Sterner. (FOR loop change).
;       Johns Hopkins University Applied Physics Laboratory.
;
; Copyright (C) 1985, Johns Hopkins University/Applied Physics Laboratory
; This software may be used, copied, or redistributed as long as it is not
; sold and this copyright notice is reproduced on each copy made.  This
; routine is provided as is without any express or implied warranties
; whatsoever.  Other limitations apply as described in the file disclaimer.txt.
;-
;-------------------------------------------------------------

        FUNCTION STRESS,STRNG,CMDX,N,OLD,NEW,NED, help = h

        if (n_params(0) lt 3) or keyword_set(h) then begin
          print,' String edit by sub-string. Precede, Follow, Delete, Replace.'
          print,' new = stress(old,cmd,n,oldss,newss,ned)
          print,'   old = string to edit.                               in'
          print,'   cmd = edit command:                                 in'
          print,"     'P' = precede.
          print,"     'F' = follow.
          print,"     'D' = delete.
          print,"     'R' = replace.
          print,'   n = occurrence number to process (0 = all).         in'
          print,'   oldss = reference substring.                        in'
          print,'   oldss may have any of the following forms:
          print,'     1. s        a single substring.
          print,'     2. s...    start at substring s, end at end of string.
          print,'     3. ...e    from start of string to substring e.
          print,'     4. s...e   from subs s to subs e.
          print,'     5. ...     entire string.
          print,"   newss = substring to add. Not needed for 'D'        in"
          print,'   ned = number of occurrences actually changed.       out'
          print,'   new = resulting string after editing.               out'
          return, -1
        endif

        CMD = STRUPCASE(CMDX)
        PDOT = STRPOS(OLD,'...')
        SSL = STRLEN(OLD)
        SSTYP = 0
        POS1 = -1
        POS2 = -1
        RSTR = STRNG
        IF (PDOT EQ -1) THEN SSTYP = 1
;       IF ((PDOT>0) EQ SSL-3) THEN SSTYP = 2
        IF (PDOT GT 0) AND (PDOT EQ SSL-3) THEN SSTYP = 2
        IF (PDOT EQ 0) AND (SSL GT 3) THEN SSTYP = 3
        IF (PDOT GT 0) AND (PDOT LT SSL-3) THEN SSTYP = 4
        IF (PDOT EQ 0) AND (SSL EQ 3) THEN SSTYP = 5
        NED = 0         ; number of occurrences actually changed.


        CASE SSTYP OF
1:        BEGIN
            S = OLD
            E = ''
          END
2:        BEGIN
            S = STRSUB(OLD,0,SSL-4)
            E = ''
          END
3:        BEGIN
            S = ''
            E = STRSUB(OLD,3,SSL-1)
          END
4:        BEGIN
            S = STRSUB(OLD,0,PDOT-1)
            E = STRSUB(OLD,PDOT+3,SSL-1)
          END
5:        BEGIN
            S = ''
            E = ''
          END
ELSE:     PRINT, 'ERROR IN SSTYP'
        ENDCASE


;---------------  Find substring # N start  ---------------
        POS = -1
        nfor = n>1
LOOP:
        FOR I = 1, nfor DO BEGIN
          POS = POS + 1
          CASE SSTYP OF
    1:      POS = STRPOS(RSTR,S,POS)
    2:      POS = STRPOS(RSTR,S,POS)
    4:      POS = STRPOS(RSTR,S,POS)
    3:      POS = STRPOS(RSTR,E,POS)
    5:      POS = 0
          ENDCASE
          IF POS LT 0 THEN GOTO, DONE
        ENDFOR

;----------  Find substring # N END  ----------------
        CASE SSTYP OF
1:        BEGIN
            POS1 = POS
            POS2 = POS + STRLEN(S) - 1
          END
2:        BEGIN
            POS1 = POS
            POS2 = STRLEN(RSTR) - 1
          END
3:        BEGIN
            POS1 = 0
            POS2 = POS + STRLEN(E) - 1
          END
4:        BEGIN
            POS1 = POS
            POS2 = STRPOS(RSTR,E,POS+1)
            IF (POS2 LT 0) THEN GOTO, DONE
            POS2 = POS2 + STRLEN(E) - 1
          END
5:        BEGIN
            POS1 = 0
            POS2 = STRLEN(RSTR) - 1
          END
        ENDCASE

;------------  edit string  --------------
        CASE CMD OF
'P':      BEGIN
            RSTR = STREP_L(RSTR,CMD,POS1,NEW)
            POS = POS + STRLEN(NEW)
          END
'F':      BEGIN
            RSTR = STREP_L(RSTR,CMD,POS2,NEW)
            POS = POS + STRLEN(NEW)
          END
'R':      BEGIN
            RSTR = STREP_L(RSTR,'D',POS1,POS2-POS1+1)
            IF (POS1 GT 0) THEN $
              RSTR = STREP_L(RSTR,'F',POS1-1,NEW)
            IF (POS1 EQ 0) THEN $
              RSTR = STREP_L(RSTR,'P',0,NEW)
            POS = POS + STRLEN(NEW) - 1
          END
'D':      BEGIN
            RSTR = STREP_L(RSTR,CMD,POS1,POS2-POS1+1)
            POS = POS - 1
          END
ELSE:     BEGIN
            PRINT, 'Error in cmd'
            RETURN,RSTR
          END
ENDCASE

        NED = NED + 1
        IF SSTYP EQ 5 THEN RETURN,RSTR
        IF N EQ 0 THEN GOTO, LOOP

DONE:
        RETURN, RSTR
        END