1 /*        $NetBSD: undo.c,v 1.8 2021/11/02 08:04:20 nia Exp $         */
2 
3 /* undo.c: This file contains the undo routines for the ed line editor */
4 /*-
5  * Copyright (c) 1993 Andrew Moore, Talke Studio.
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 #ifndef lint
32 #if 0
33 static char *rcsid = "@(#)undo.c,v 1.1 1994/02/01 00:34:44 alm Exp";
34 #else
35 __RCSID("$NetBSD: undo.c,v 1.8 2021/11/02 08:04:20 nia Exp $");
36 #endif
37 #endif /* not lint */
38 
39 #include "ed.h"
40 
41 
42 #define USIZE 100                                 /* undo stack size */
43 undo_t *ustack = NULL;                                      /* undo stack */
44 long usize = 0;                                             /* stack size variable */
45 long u_p = 0;                                               /* undo stack pointer */
46 
47 /* push_undo_stack: return pointer to initialized undo node */
48 undo_t *
push_undo_stack(int type,long from,long to)49 push_undo_stack(int type, long from, long to)
50 {
51           int err;
52 
53           if (u_p < usize ||
54               (err = reallocarr(&ustack, usize += USIZE, sizeof(undo_t))) == 0) {
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(err));
62           seterrmsg("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 
78 long u_current_addr = -1;     /* if >= 0, undo enabled */
79 long u_addr_last = -1;                  /* if >= 0, undo enabled */
80 
81 /* pop_undo_stack: undo last change to the editor buffer */
82 int
pop_undo_stack(void)83 pop_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                     seterrmsg("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 */
131 void
clear_undo_stack(void)132 clear_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