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/*-
* Copyright (c) 1992, 1993, 1994
* The Regents of the University of California. All rights reserved.
* Copyright (c) 1992, 1993, 1994, 1995, 1996
* Keith Bostic. All rights reserved.
*
* See the LICENSE file for redistribution information.
*/
#include "config.h"
#ifndef lint
static const char sccsid[] = "@(#)ex_undo.c 10.6 (Berkeley) 3/6/96";
#endif /* not lint */
#include <sys/types.h>
#include <sys/queue.h>
#include <bitstring.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include "../common/common.h"
/*
* ex_undo -- u
* Undo the last change.
*
* PUBLIC: int ex_undo __P((SCR *, EXCMD *));
*/
int
ex_undo(sp, cmdp)
SCR *sp;
EXCMD *cmdp;
{
EXF *ep;
MARK m;
/*
* !!!
* Historic undo always set the previous context mark.
*/
m.lno = sp->lno;
m.cno = sp->cno;
if (mark_set(sp, ABSMARK1, &m, 1))
return (1);
/*
* !!!
* Multiple undo isn't available in ex, as there's no '.' command.
* Whether 'u' is undo or redo is toggled each time, unless there
* was a change since the last undo, in which case it's an undo.
*/
ep = sp->ep;
if (!F_ISSET(ep, F_UNDO)) {
F_SET(ep, F_UNDO);
ep->lundo = FORWARD;
}
switch (ep->lundo) {
case BACKWARD:
if (log_forward(sp, &m))
return (1);
ep->lundo = FORWARD;
break;
case FORWARD:
if (log_backward(sp, &m))
return (1);
ep->lundo = BACKWARD;
break;
case NOTSET:
abort();
}
sp->lno = m.lno;
sp->cno = m.cno;
return (0);
}
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