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[] = "$Id: ex_undo.c,v 10.7 2001/06/25 15:19:21 skimo Exp $ (Berkeley) $Date: 2001/06/25 15:19:21 $";
  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(SCR *sp, EXCMD *cmdp)
  34 {
  35         EXF *ep;
  36         MARK m;
  37
  38         /*
  39          * !!!
  40          * Historic undo always set the previous context mark.
  41          */
  42         m.lno = sp->lno;
  43         m.cno = sp->cno;
  44         if (mark_set(sp, ABSMARK1, &m, 1))
  45                 return (1);
  46
  47         /*
  48          * !!!
  49          * Multiple undo isn't available in ex, as there's no '.' command.
  50          * Whether 'u' is undo or redo is toggled each time, unless there
  51          * was a change since the last undo, in which case it's an undo.
  52          */
  53         ep = sp->ep;
  54         if (!F_ISSET(ep, F_UNDO)) {
  55                 F_SET(ep, F_UNDO);
  56                 ep->lundo = FORWARD;
  57         }
  58         switch (ep->lundo) {
  59         case BACKWARD:
  60                 if (log_forward(sp, &m))
  61                         return (1);
  62                 ep->lundo = FORWARD;
  63                 break;
  64         case FORWARD:
  65                 if (log_backward(sp, &m))
  66                         return (1);
  67                 ep->lundo = BACKWARD;
  68                 break;
  69         case NOTSET:
  70                 abort();
  71         }
  72         sp->lno = m.lno;
  73         sp->cno = m.cno;
  74         return (0);
  75 }