contrib/nvi/ex/ex_undo.c

   1 /*-
   2  * Copyright (c) 1992, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Copyright (c) 1992, 1993, 1994, 1995, 1996
   5  *      Keith Bostic.  All rights reserved.
   6  *
   7  * See the LICENSE file for redistribution information.
   8  */
   9
  10 #include "config.h"
  11
  12 #ifndef lint
  13 static const char sccsid[] = "@(#)ex_undo.c     10.6 (Berkeley) 3/6/96";
  14 #endif /* not lint */
  15
  16 #include <sys/types.h>
  17 #include <sys/queue.h>
  18
  19 #include <bitstring.h>
  20 #include <limits.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23
  24 #include "../common/common.h"
  25
  26 /*
  27  * ex_undo -- u
  28  *      Undo the last change.
  29  *
  30  * PUBLIC: int ex_undo __P((SCR *, EXCMD *));
  31  */
  32 int
  33 ex_undo(sp, cmdp)
  34         SCR *sp;
  35         EXCMD *cmdp;
  36 {
  37         EXF *ep;
  38         MARK m;
  39
  40         /*
  41          * !!!
  42          * Historic undo always set the previous context mark.
  43          */
  44         m.lno = sp->lno;
  45         m.cno = sp->cno;
  46         if (mark_set(sp, ABSMARK1, &m, 1))
  47                 return (1);
  48
  49         /*
  50          * !!!
  51          * Multiple undo isn't available in ex, as there's no '.' command.
  52          * Whether 'u' is undo or redo is toggled each time, unless there
  53          * was a change since the last undo, in which case it's an undo.
  54          */
  55         ep = sp->ep;
  56         if (!F_ISSET(ep, F_UNDO)) {
  57                 F_SET(ep, F_UNDO);
  58                 ep->lundo = FORWARD;
  59         }
  60         switch (ep->lundo) {
  61         case BACKWARD:
  62                 if (log_forward(sp, &m))
  63                         return (1);
  64                 ep->lundo = FORWARD;
  65                 break;
  66         case FORWARD:
  67                 if (log_backward(sp, &m))
  68                         return (1);
  69                 ep->lundo = BACKWARD;
  70                 break;
  71         case NOTSET:
  72                 abort();
  73         }
  74         sp->lno = m.lno;
  75         sp->cno = m.cno;
  76         return (0);
  77 }