xref: /freebsd/bin/ed/undo.c (revision 315ee00f)
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 */
33 static undo_t *ustack = NULL;			/* undo stack */
34 static long usize = 0;				/* stack size variable */
35 static long u_p = 0;				/* undo stack pointer */
36 
37 /* push_undo_stack: return pointer to initialized undo node */
38 undo_t *
39 push_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 
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
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 		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 */
131 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