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/* undo.c: This file contains the undo routines for the ed line editor */
/* ed line editor.
Copyright (C) 1993, 1994 Andrew Moore, Talke Studio
All Rights Reserved
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef lint
static char *rcsid = "@(#)$Id: undo.c,v 1.7 1994/11/13 04:25:44 alm Exp $";
#endif /* not lint */
#include "ed.h"
#define USIZE 100 /* undo stack size */
undo_t *ustack = NULL; /* undo stack */
long usize = 0; /* stack size variable */
long u_p = 0; /* undo stack pointer */
/* push_undo_stack: return pointer to intialized undo node */
undo_t *
push_undo_stack (type, from, to)
int type;
long from;
long to;
{
undo_t *t;
if ((t = ustack) == NULL &&
(t = ustack = (undo_t *) malloc ((usize = USIZE) * sizeof (undo_t))) == NULL)
{
fprintf (stderr, "%s\n", strerror (errno));
sprintf (errmsg, "Out of memory");
return NULL;
}
else if (u_p >= usize &&
(t = (undo_t *) realloc (ustack, (usize += USIZE) * sizeof (undo_t))) == NULL)
{
/* out of memory - release undo stack */
fprintf (stderr, "%s\n", strerror (errno));
sprintf (errmsg, "Out of memory");
clear_undo_stack ();
free (ustack);
ustack = NULL;
usize = 0;
return NULL;
}
ustack = t;
ustack[u_p].type = type;
ustack[u_p].t = get_addressed_line_node (to);
ustack[u_p].h = get_addressed_line_node (from);
return ustack + u_p++;
}
/* USWAP: swap undo nodes */
#define USWAP(x, y) \
do \
{ \
undo_t utmp; \
utmp = (x), (x) = (y), (y) = utmp; \
} \
while (0)
long u_current_addr = -1; /* if >= 0, undo enabled */
long u_addr_last = -1; /* if >= 0, undo enabled */
/* pop_undo_stack: undo last change to the editor buffer */
int
pop_undo_stack ()
{
long n;
long o_current_addr = current_addr;
long o_addr_last = addr_last;
if (u_current_addr == -1 || u_addr_last == -1)
{
sprintf (errmsg, "Nothing to undo");
return ERR;
}
else if (u_p)
modified = 1;
get_addressed_line_node (0); /* this get_addressed_line_node last! */
SPL1 ();
for (n = u_p; n-- > 0;)
{
switch (ustack[n].type)
{
case UADD:
REQUE (ustack[n].h->q_back, ustack[n].t->q_forw);
break;
case UDEL:
REQUE (ustack[n].h->q_back, ustack[n].h);
REQUE (ustack[n].t, ustack[n].t->q_forw);
break;
case UMOV:
case VMOV:
REQUE (ustack[n - 1].h, ustack[n].h->q_forw);
REQUE (ustack[n].t->q_back, ustack[n - 1].t);
REQUE (ustack[n].h, ustack[n].t);
n--;
break;
default:
/*NOTREACHED */
;
}
ustack[n].type ^= 1;
}
/* reverse undo stack order */
for (n = u_p; n-- > (u_p + 1) / 2;)
USWAP (ustack[n], ustack[u_p - 1 - n]);
if (isglobal)
clear_active_list ();
current_addr = u_current_addr, u_current_addr = o_current_addr;
addr_last = u_addr_last, u_addr_last = o_addr_last;
SPL0 ();
return 0;
}
/* clear_undo_stack: clear the undo stack */
void
clear_undo_stack ()
{
line_t *lp, *ep, *tl;
while (u_p--)
if (ustack[u_p].type == UDEL)
{
ep = ustack[u_p].t->q_forw;
for (lp = ustack[u_p].h; lp != ep; lp = tl)
{
unmark_line_node (lp);
tl = lp->q_forw;
free (lp);
}
}
u_p = 0;
u_current_addr = current_addr;
u_addr_last = addr_last;
}
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