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