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__FBSDID("$FreeBSD$");
30
31#include "ed.h"
32
33
34#define USIZE 100				/* undo stack size */
35static undo_t *ustack = NULL;			/* undo stack */
36static long usize = 0;				/* stack size variable */
37static long u_p = 0;				/* undo stack pointer */
38
39/* push_undo_stack: return pointer to initialized undo node */
40undo_t *
41push_undo_stack(int type, long from, long to)
42{
43	undo_t *t;
44
45#if defined(sun) || defined(NO_REALLOC_NULL)
46	if (ustack == NULL &&
47	    (ustack = (undo_t *) malloc((usize = USIZE) * sizeof(undo_t))) == NULL) {
48		fprintf(stderr, "%s\n", strerror(errno));
49		errmsg = "out of memory";
50		return NULL;
51	}
52#endif
53	t = ustack;
54	if (u_p < usize ||
55	    (t = (undo_t *) realloc(ustack, (usize += USIZE) * sizeof(undo_t))) != NULL) {
56		ustack = t;
57		ustack[u_p].type = type;
58		ustack[u_p].t = get_addressed_line_node(to);
59		ustack[u_p].h = get_addressed_line_node(from);
60		return ustack + u_p++;
61	}
62	/* out of memory - release undo stack */
63	fprintf(stderr, "%s\n", strerror(errno));
64	errmsg = "out of memory";
65	clear_undo_stack();
66	free(ustack);
67	ustack = NULL;
68	usize = 0;
69	return NULL;
70}
71
72
73/* USWAP: swap undo nodes */
74#define USWAP(x,y) { \
75	undo_t utmp; \
76	utmp = x, x = y, y = utmp; \
77}
78
79
80long u_current_addr = -1;	/* if >= 0, undo enabled */
81long u_addr_last = -1;		/* if >= 0, undo enabled */
82
83/* pop_undo_stack: undo last change to the editor buffer */
84int
85pop_undo_stack(void)
86{
87	long n;
88	long o_current_addr = current_addr;
89	long o_addr_last = addr_last;
90
91	if (u_current_addr == -1 || u_addr_last == -1) {
92		errmsg = "nothing to undo";
93		return ERR;
94	} else if (u_p)
95		modified = 1;
96	get_addressed_line_node(0);	/* this get_addressed_line_node last! */
97	SPL1();
98	for (n = u_p; n-- > 0;) {
99		switch(ustack[n].type) {
100		case UADD:
101			REQUE(ustack[n].h->q_back, ustack[n].t->q_forw);
102			break;
103		case UDEL:
104			REQUE(ustack[n].h->q_back, ustack[n].h);
105			REQUE(ustack[n].t, ustack[n].t->q_forw);
106			break;
107		case UMOV:
108		case VMOV:
109			REQUE(ustack[n - 1].h, ustack[n].h->q_forw);
110			REQUE(ustack[n].t->q_back, ustack[n - 1].t);
111			REQUE(ustack[n].h, ustack[n].t);
112			n--;
113			break;
114		default:
115			/*NOTREACHED*/
116			;
117		}
118		ustack[n].type ^= 1;
119	}
120	/* reverse undo stack order */
121	for (n = u_p; n-- > (u_p + 1)/ 2;)
122		USWAP(ustack[n], ustack[u_p - 1 - n]);
123	if (isglobal)
124		clear_active_list();
125	current_addr = u_current_addr, u_current_addr = o_current_addr;
126	addr_last = u_addr_last, u_addr_last = o_addr_last;
127	SPL0();
128	return 0;
129}
130
131
132/* clear_undo_stack: clear the undo stack */
133void
134clear_undo_stack(void)
135{
136	line_t *lp, *ep, *tl;
137
138	while (u_p--)
139		if (ustack[u_p].type == UDEL) {
140			ep = ustack[u_p].t->q_forw;
141			for (lp = ustack[u_p].h; lp != ep; lp = tl) {
142				unmark_line_node(lp);
143				tl = lp->q_forw;
144				free(lp);
145			}
146		}
147	u_p = 0;
148	u_current_addr = current_addr;
149	u_addr_last = addr_last;
150}
151