undo.c revision 46684 
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#ifndef lint
29#if 0
30static char * const rcsid = "@(#)undo.c,v 1.1 1994/02/01 00:34:44 alm Exp";
31#else
32static char * const rcsid =
33	"$Id: undo.c,v 1.7 1997/08/07 21:33:47 steve Exp $";
34#endif
35#endif /* not lint */
36
37#include "ed.h"
38
39
40#define USIZE 100				/* undo stack size */
41undo_t *ustack = NULL;				/* undo stack */
42long usize = 0;					/* stack size variable */
43long u_p = 0;					/* undo stack pointer */
44
45/* push_undo_stack: return pointer to initialized undo node */
46undo_t *
47push_undo_stack(type, from, to)
48	int type;
49	long from;
50	long to;
51{
52	undo_t *t;
53
54#if defined(sun) || defined(NO_REALLOC_NULL)
55	if (ustack == NULL &&
56	    (ustack = (undo_t *) malloc((usize = USIZE) * sizeof(undo_t))) == NULL) {
57		fprintf(stderr, "%s\n", strerror(errno));
58		sprintf(errmsg, "out of memory");
59		return NULL;
60	}
61#endif
62	t = ustack;
63	if (u_p < usize ||
64	    (t = (undo_t *) realloc(ustack, (usize += USIZE) * sizeof(undo_t))) != NULL) {
65		ustack = t;
66		ustack[u_p].type = type;
67		ustack[u_p].t = get_addressed_line_node(to);
68		ustack[u_p].h = get_addressed_line_node(from);
69		return ustack + u_p++;
70	}
71	/* out of memory - release undo stack */
72	fprintf(stderr, "%s\n", strerror(errno));
73	sprintf(errmsg, "out of memory");
74	clear_undo_stack();
75	free(ustack);
76	ustack = NULL;
77	usize = 0;
78	return NULL;
79}
80
81
82/* USWAP: swap undo nodes */
83#define USWAP(x,y) { \
84	undo_t utmp; \
85	utmp = x, x = y, y = utmp; \
86}
87
88
89long u_current_addr = -1;	/* if >= 0, undo enabled */
90long u_addr_last = -1;		/* if >= 0, undo enabled */
91
92/* pop_undo_stack: undo last change to the editor buffer */
93int
94pop_undo_stack()
95{
96	long n;
97	long o_current_addr = current_addr;
98	long o_addr_last = addr_last;
99
100	if (u_current_addr == -1 || u_addr_last == -1) {
101		sprintf(errmsg, "nothing to undo");
102		return ERR;
103	} else if (u_p)
104		modified = 1;
105	get_addressed_line_node(0);	/* this get_addressed_line_node last! */
106	SPL1();
107	for (n = u_p; n-- > 0;) {
108		switch(ustack[n].type) {
109		case UADD:
110			REQUE(ustack[n].h->q_back, ustack[n].t->q_forw);
111			break;
112		case UDEL:
113			REQUE(ustack[n].h->q_back, ustack[n].h);
114			REQUE(ustack[n].t, ustack[n].t->q_forw);
115			break;
116		case UMOV:
117		case VMOV:
118			REQUE(ustack[n - 1].h, ustack[n].h->q_forw);
119			REQUE(ustack[n].t->q_back, ustack[n - 1].t);
120			REQUE(ustack[n].h, ustack[n].t);
121			n--;
122			break;
123		default:
124			/*NOTREACHED*/
125			;
126		}
127		ustack[n].type ^= 1;
128	}
129	/* reverse undo stack order */
130	for (n = u_p; n-- > (u_p + 1)/ 2;)
131		USWAP(ustack[n], ustack[u_p - 1 - n]);
132	if (isglobal)
133		clear_active_list();
134	current_addr = u_current_addr, u_current_addr = o_current_addr;
135	addr_last = u_addr_last, u_addr_last = o_addr_last;
136	SPL0();
137	return 0;
138}
139
140
141/* clear_undo_stack: clear the undo stack */
142void
143clear_undo_stack()
144{
145	line_t *lp, *ep, *tl;
146
147	while (u_p--)
148		if (ustack[u_p].type == UDEL) {
149			ep = ustack[u_p].t->q_forw;
150			for (lp = ustack[u_p].h; lp != ep; lp = tl) {
151				unmark_line_node(lp);
152				tl = lp->q_forw;
153				free(lp);
154			}
155		}
156	u_p = 0;
157	u_current_addr = current_addr;
158	u_addr_last = addr_last;
159}
160