1/* undo.c: This file contains the undo routines for the ed line editor */
2/*-
3 * Copyright (c) 1993 Andrew Moore, Talke Studio.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <sys/cdefs.h>
29#include "ed.h"
30
31
32#define USIZE 100				/* undo stack size */
33static undo_t *ustack = NULL;			/* undo stack */
34static long usize = 0;				/* stack size variable */
35static long u_p = 0;				/* undo stack pointer */
36
37/* push_undo_stack: return pointer to initialized undo node */
38undo_t *
39push_undo_stack(int type, long from, long to)
40{
41	undo_t *t;
42
43#if defined(sun) || defined(NO_REALLOC_NULL)
44	if (ustack == NULL &&
45	    (ustack = (undo_t *) malloc((usize = USIZE) * sizeof(undo_t))) == NULL) {
46		fprintf(stderr, "%s\n", strerror(errno));
47		errmsg = "out of memory";
48		return NULL;
49	}
50#endif
51	t = ustack;
52	if (u_p < usize ||
53	    (t = (undo_t *) realloc(ustack, (usize += USIZE) * sizeof(undo_t))) != NULL) {
54		ustack = t;
55		ustack[u_p].type = type;
56		ustack[u_p].t = get_addressed_line_node(to);
57		ustack[u_p].h = get_addressed_line_node(from);
58		return ustack + u_p++;
59	}
60	/* out of memory - release undo stack */
61	fprintf(stderr, "%s\n", strerror(errno));
62	errmsg = "out of memory";
63	clear_undo_stack();
64	free(ustack);
65	ustack = NULL;
66	usize = 0;
67	return NULL;
68}
69
70
71/* USWAP: swap undo nodes */
72#define USWAP(x,y) { \
73	undo_t utmp; \
74	utmp = x, x = y, y = utmp; \
75}
76
77
78long u_current_addr = -1;	/* if >= 0, undo enabled */
79long u_addr_last = -1;		/* if >= 0, undo enabled */
80
81/* pop_undo_stack: undo last change to the editor buffer */
82int
83pop_undo_stack(void)
84{
85	long n;
86	long o_current_addr = current_addr;
87	long o_addr_last = addr_last;
88
89	if (u_current_addr == -1 || u_addr_last == -1) {
90		errmsg = "nothing to undo";
91		return ERR;
92	} else if (u_p)
93		modified = 1;
94	get_addressed_line_node(0);	/* this get_addressed_line_node last! */
95	SPL1();
96	for (n = u_p; n-- > 0;) {
97		switch(ustack[n].type) {
98		case UADD:
99			REQUE(ustack[n].h->q_back, ustack[n].t->q_forw);
100			break;
101		case UDEL:
102			REQUE(ustack[n].h->q_back, ustack[n].h);
103			REQUE(ustack[n].t, ustack[n].t->q_forw);
104			break;
105		case UMOV:
106		case VMOV:
107			REQUE(ustack[n - 1].h, ustack[n].h->q_forw);
108			REQUE(ustack[n].t->q_back, ustack[n - 1].t);
109			REQUE(ustack[n].h, ustack[n].t);
110			n--;
111			break;
112		default:
113			/*NOTREACHED*/
114			;
115		}
116		ustack[n].type ^= 1;
117	}
118	/* reverse undo stack order */
119	for (n = u_p; n-- > (u_p + 1)/ 2;)
120		USWAP(ustack[n], ustack[u_p - 1 - n]);
121	if (isglobal)
122		clear_active_list();
123	current_addr = u_current_addr, u_current_addr = o_current_addr;
124	addr_last = u_addr_last, u_addr_last = o_addr_last;
125	SPL0();
126	return 0;
127}
128
129
130/* clear_undo_stack: clear the undo stack */
131void
132clear_undo_stack(void)
133{
134	line_t *lp, *ep, *tl;
135
136	while (u_p--)
137		if (ustack[u_p].type == UDEL) {
138			ep = ustack[u_p].t->q_forw;
139			for (lp = ustack[u_p].h; lp != ep; lp = tl) {
140				unmark_line_node(lp);
141				tl = lp->q_forw;
142				free(lp);
143			}
144		}
145	u_p = 0;
146	u_current_addr = current_addr;
147	u_addr_last = addr_last;
148}
149