contrib/nvi2/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 $";
  14 #endif /* not lint */
  15
  16 #include <sys/types.h>
  17 #include <sys/queue.h>
  18 #include <sys/time.h>
  19
  20 #include <bitstring.h>
  21 #include <limits.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24
  25 #include "../common/common.h"
  26
  27 /*
  28  * ex_undo -- u
  29  *      Undo the last change.
  30  *
  31  * PUBLIC: int ex_undo(SCR *, EXCMD *);
  32  */
  33 int
  34 ex_undo(SCR *sp, EXCMD *cmdp)
  35 {
  36         EXF *ep;
  37         MARK m;
  38
  39         /*
  40          * !!!
  41          * Historic undo always set the previous context mark.
  42          */
  43         m.lno = sp->lno;
  44         m.cno = sp->cno;
  45         if (mark_set(sp, ABSMARK1, &m, 1))
  46                 return (1);
  47
  48         /*
  49          * !!!
  50          * Multiple undo isn't available in ex, as there's no '.' command.
  51          * Whether 'u' is undo or redo is toggled each time, unless there
  52          * was a change since the last undo, in which case it's an undo.
  53          */
  54         ep = sp->ep;
  55         if (!F_ISSET(ep, F_UNDO)) {
  56                 F_SET(ep, F_UNDO);
  57                 ep->lundo = FORWARD;
  58         }
  59         switch (ep->lundo) {
  60         case BACKWARD:
  61                 if (log_forward(sp, &m))
  62                         return (1);
  63                 ep->lundo = FORWARD;
  64                 break;
  65         case FORWARD:
  66                 if (log_backward(sp, &m))
  67                         return (1);
  68                 ep->lundo = BACKWARD;
  69                 break;
  70         case NOTSET:
  71                 abort();
  72         }
  73         sp->lno = m.lno;
  74         sp->cno = m.cno;
  75         return (0);
  76 }