1 /* undo.c: This file contains the undo routines for the ed line editor */
3 * Copyright (c) 1993 Andrew Moore, Talke Studio.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
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.
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
30 static char * const rcsid = "@(#)undo.c,v 1.1 1994/02/01 00:34:44 alm Exp";
32 static char * const rcsid =
40 #define USIZE 100 /* undo stack size */
41 undo_t *ustack = NULL; /* undo stack */
42 long usize = 0; /* stack size variable */
43 long u_p = 0; /* undo stack pointer */
45 /* push_undo_stack: return pointer to initialized undo node */
47 push_undo_stack(type, from, to)
54 #if defined(sun) || defined(NO_REALLOC_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");
64 (t = (undo_t *) realloc(ustack, (usize += USIZE) * sizeof(undo_t))) != NULL) {
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++;
71 /* out of memory - release undo stack */
72 fprintf(stderr, "%s\n", strerror(errno));
73 sprintf(errmsg, "out of memory");
82 /* USWAP: swap undo nodes */
83 #define USWAP(x,y) { \
85 utmp = x, x = y, y = utmp; \
89 long u_current_addr = -1; /* if >= 0, undo enabled */
90 long u_addr_last = -1; /* if >= 0, undo enabled */
92 /* pop_undo_stack: undo last change to the editor buffer */
97 long o_current_addr = current_addr;
98 long o_addr_last = addr_last;
100 if (u_current_addr == -1 || u_addr_last == -1) {
101 sprintf(errmsg, "nothing to undo");
105 get_addressed_line_node(0); /* this get_addressed_line_node last! */
107 for (n = u_p; n-- > 0;) {
108 switch(ustack[n].type) {
110 REQUE(ustack[n].h->q_back, ustack[n].t->q_forw);
113 REQUE(ustack[n].h->q_back, ustack[n].h);
114 REQUE(ustack[n].t, ustack[n].t->q_forw);
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);
129 /* reverse undo stack order */
130 for (n = u_p; n-- > (u_p + 1)/ 2;)
131 USWAP(ustack[n], ustack[u_p - 1 - n]);
134 current_addr = u_current_addr, u_current_addr = o_current_addr;
135 addr_last = u_addr_last, u_addr_last = o_addr_last;
141 /* clear_undo_stack: clear the undo stack */
145 line_t *lp, *ep, *tl;
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);
157 u_current_addr = current_addr;
158 u_addr_last = addr_last;