1 /*
2  * Copyright (c) 2021 Omar Polo <op@omarpolo.com>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include "telescope.h"
18 
19 #include <stdlib.h>
20 #include <string.h>
21 
22 /*
23  * Text wrapping
24  * =============
25  *
26  * There's a simple text wrapping algorithm.
27  *
28  * 1. if it's a line in a pre-formatted block:
29  *    a. hard wrap.
30  *    b. repeat
31  * 2. otherwise advance the line char by char.
32  * 3. when ending the space, split the line at the last occurrence of
33  *    a "word separator" (i.e. " \t-") or at point if none.
34  * 4. repeat
35  *
36  */
37 
38 static int
39 push_line(struct window *window, const struct line *l, const char *buf, size_t len, int cont)
40 {
41 	struct vline *vl;
42 
43 	window->line_max++;
44 
45 	if ((vl = calloc(1, sizeof(*vl))) == NULL)
46 		return 0;
47 
48 	if (len != 0 && (vl->line = calloc(1, len+1)) == NULL) {
49 		free(vl);
50 		return 0;
51 	}
52 
53 	vl->parent = l;
54 	if (len != 0)
55 		memcpy(vl->line, buf, len);
56 	vl->flags = cont;
57 
58 	if (TAILQ_EMPTY(&window->head))
59 		TAILQ_INSERT_HEAD(&window->head, vl, vlines);
60 	else
61 		TAILQ_INSERT_TAIL(&window->head, vl, vlines);
62 	return 1;
63 }
64 
65 /*
66  * Build a list of visual line by wrapping the given line, assuming
67  * that when printed will have a leading prefix prfx.
68  */
69 int
70 wrap_text(struct window *window, const char *prfx, struct line *l, size_t width)
71 {
72 	const char	*separators = " \t-";
73 	const char	*start, *end, *line, *lastsep, *lastchar;
74 	uint32_t	 cp = 0, state = 0;
75 	size_t		 cur, prfxwidth, w;
76 	int		 cont;
77 
78 	if ((line = l->line) == NULL)
79 		return push_line(window, l, NULL, 0, 0);
80 
81 	prfxwidth = utf8_swidth(prfx);
82 	cur = prfxwidth;
83 	start = line;
84 	lastsep = NULL;
85 	lastchar = line;
86 	cont = 0;
87 	for (; *line; line++) {
88 		if (utf8_decode(&state, &cp, *line))
89 			continue;
90 		w = utf8_chwidth(cp);
91 		if (cur + w >= width -1) {
92 			end = lastsep == NULL
93 				? utf8_next_cp((char*)lastchar)
94 				: utf8_next_cp((char*)lastsep);
95 			if (!push_line(window, l, start, end - start, cont))
96 				return 0;
97 			cont = 1;
98 			start = end;
99 			cur = prfxwidth + utf8_swidth_between(start, lastchar);
100 		} else {
101 			if (strchr(separators, *line) != NULL)
102 				lastsep = line;
103 		}
104 
105 		lastchar = utf8_prev_cp(line, l->line);
106 		cur += w;
107 	}
108 
109 	return push_line(window, l, start, line - start, cont);
110 }
111 
112 int
113 hardwrap_text(struct window *window, struct line *l, size_t width)
114 {
115 	const char	*line, *start, *lastchar;
116 	int		 cont;
117 	uint32_t	 state = 0, cp = 0;
118 	size_t		 cur, w;
119 
120 	if ((line = l->line) == NULL)
121 		return push_line(window, l, NULL, 0, 0);
122 
123 	start = line;
124 	lastchar = line;
125 	cont = 0;
126 	cur = 0;
127 	for (; *line; line++) {
128 		if (utf8_decode(&state, &cp, *line))
129 			continue;
130 		w = utf8_chwidth(cp);
131 		if (cur + w >= width) {
132 			if (!push_line(window, l, start, lastchar - start, cont))
133 				return 0;
134 			cont = 1;
135 			cur = 0;
136 			start = lastchar;
137 		}
138 
139 		lastchar = utf8_prev_cp(line, l->line);
140 		cur += w;
141 	}
142 
143 	return push_line(window, l, start, line - start, cont);
144 }