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 void
39 empty_linelist(struct buffer *buffer)
40 {
41 	struct line *l, *lt;
42 
43 	TAILQ_FOREACH_SAFE(l, &buffer->page.head, lines, lt) {
44 		TAILQ_REMOVE(&buffer->page.head, l, lines);
45 		free(l->line);
46 		free(l->alt);
47 		free(l);
48 	}
49 }
50 
51 void
52 empty_vlist(struct buffer *buffer)
53 {
54 	struct vline *vl, *t;
55 
56 	buffer->current_line = NULL;
57 	buffer->line_max = 0;
58 
59 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
60 		TAILQ_REMOVE(&buffer->head, vl, vlines);
61 		free(vl->line);
62 		free(vl);
63 	}
64 }
65 
66 static int
67 push_line(struct buffer *buffer, const struct line *l, const char *buf, size_t len, int cont)
68 {
69 	struct vline *vl;
70 
71 	buffer->line_max++;
72 
73 	if ((vl = calloc(1, sizeof(*vl))) == NULL)
74 		return 0;
75 
76 	if (len != 0 && (vl->line = calloc(1, len+1)) == NULL) {
77 		free(vl);
78 		return 0;
79 	}
80 
81 	vl->parent = l;
82 	if (len != 0)
83 		memcpy(vl->line, buf, len);
84 	vl->flags = cont;
85 
86 	if (TAILQ_EMPTY(&buffer->head))
87 		TAILQ_INSERT_HEAD(&buffer->head, vl, vlines);
88 	else
89 		TAILQ_INSERT_TAIL(&buffer->head, vl, vlines);
90 	return 1;
91 }
92 
93 /*
94  * Build a list of visual line by wrapping the given line, assuming
95  * that when printed will have a leading prefix prfx.
96  */
97 int
98 wrap_text(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
99 {
100 	const char	*separators = " \t-";
101 	const char	*start, *end, *line, *lastsep, *lastchar;
102 	uint32_t	 cp = 0, state = 0;
103 	size_t		 cur, prfxwidth, w;
104 	int		 cont;
105 
106 	if ((line = l->line) == NULL)
107 		return push_line(buffer, l, NULL, 0, 0);
108 
109 	prfxwidth = utf8_swidth(prfx);
110 	cur = prfxwidth;
111 	start = line;
112 	lastsep = NULL;
113 	lastchar = line;
114 	cont = 0;
115 	for (; *line; line++) {
116 		if (utf8_decode(&state, &cp, *line))
117 			continue;
118 		w = utf8_chwidth(cp);
119 		if (cur + w >= width -1) {
120 			end = lastsep == NULL
121 				? utf8_next_cp((char*)lastchar)
122 				: utf8_next_cp((char*)lastsep);
123 			if (!push_line(buffer, l, start, end - start, cont))
124 				return 0;
125 			cont = 1;
126 			start = end;
127 			cur = prfxwidth + utf8_swidth_between(start, lastchar);
128 		} else {
129 			if (strchr(separators, *line) != NULL)
130 				lastsep = line;
131 		}
132 
133 		lastchar = utf8_prev_cp(line, l->line);
134 		cur += w;
135 	}
136 
137 	return push_line(buffer, l, start, line - start, cont);
138 }
139 
140 int
141 hardwrap_text(struct buffer *buffer, struct line *l, size_t width)
142 {
143 	const char	*line, *start, *lastchar;
144 	int		 cont;
145 	uint32_t	 state = 0, cp = 0;
146 	size_t		 cur, w;
147 
148 	if ((line = l->line) == NULL)
149 		return push_line(buffer, l, NULL, 0, 0);
150 
151 	start = line;
152 	lastchar = line;
153 	cont = 0;
154 	cur = 0;
155 	for (; *line; line++) {
156 		if (utf8_decode(&state, &cp, *line))
157 			continue;
158 		w = utf8_chwidth(cp);
159 		if (cur + w >= width) {
160 			if (!push_line(buffer, l, start, lastchar - start, cont))
161 				return 0;
162 			cont = 1;
163 			cur = 0;
164 			start = lastchar;
165 		}
166 
167 		lastchar = utf8_prev_cp(line, l->line);
168 		cur += w;
169 	}
170 
171 	return push_line(buffer, l, start, line - start, cont);
172 }