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 <stdlib.h>
18 #include <string.h>
19 
20 #include "telescope.h"
21 #include "utf8.h"
22 
23 /*
24  * Text wrapping
25  * =============
26  *
27  * There's a simple text wrapping algorithm.
28  *
29  * 1. if it's a line in a pre-formatted block:
30  *    a. hard wrap.
31  *    b. repeat
32  * 2. otherwise advance the line char by char.
33  * 3. when ending the space, split the line at the last occurrence of
34  *    a "word separator" (i.e. " \t-") or at point if none.
35  * 4. repeat
36  *
37  */
38 
39 void
40 erase_buffer(struct buffer *buffer)
41 {
42 	empty_vlist(buffer);
43 	empty_linelist(buffer);
44 }
45 
46 void
47 empty_linelist(struct buffer *buffer)
48 {
49 	struct line *l, *lt;
50 
51 	TAILQ_FOREACH_SAFE(l, &buffer->page.head, lines, lt) {
52 		TAILQ_REMOVE(&buffer->page.head, l, lines);
53 		free(l->line);
54 		free(l->alt);
55 		free(l);
56 	}
57 }
58 
59 void
60 empty_vlist(struct buffer *buffer)
61 {
62 	struct vline *vl, *t;
63 
64 	buffer->top_line = NULL;
65 	buffer->line_off = 0;
66 	buffer->current_line = NULL;
67 	buffer->line_max = 0;
68 
69 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
70 		TAILQ_REMOVE(&buffer->head, vl, vlines);
71 		free(vl->line);
72 		free(vl);
73 	}
74 }
75 
76 static int
77 push_line(struct buffer *buffer, const struct line *l, const char *buf, size_t len, int flags)
78 {
79 	struct vline *vl;
80 
81 	buffer->line_max++;
82 
83 	if ((vl = calloc(1, sizeof(*vl))) == NULL)
84 		return 0;
85 
86 	if (len != 0 && (vl->line = calloc(1, len+1)) == NULL) {
87 		free(vl);
88 		return 0;
89 	}
90 
91 	vl->parent = l;
92 	if (len != 0)
93 		memcpy(vl->line, buf, len);
94 	vl->flags = flags;
95 
96 	if (TAILQ_EMPTY(&buffer->head))
97 		TAILQ_INSERT_HEAD(&buffer->head, vl, vlines);
98 	else
99 		TAILQ_INSERT_TAIL(&buffer->head, vl, vlines);
100 	return 1;
101 }
102 
103 /*
104  * Build a list of visual line by wrapping the given line, assuming
105  * that when printed will have a leading prefix prfx.
106  */
107 int
108 wrap_text(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
109 {
110 	const char	*separators = " \t-";
111 	const char	*start, *end, *line, *lastsep, *lastchar;
112 	uint32_t	 cp = 0, state = 0;
113 	size_t		 cur, prfxwidth, w;
114 	int		 flags;
115 
116 	if ((line = l->line) == NULL)
117 		return push_line(buffer, l, NULL, 0, 0);
118 
119 	prfxwidth = utf8_swidth(prfx);
120 	cur = prfxwidth;
121 	start = line;
122 	lastsep = NULL;
123 	lastchar = line;
124 	flags = 0;
125 	for (; *line; line++) {
126 		if (utf8_decode(&state, &cp, *line))
127 			continue;
128 		w = utf8_chwidth(cp);
129 		if (cur + w >= width -1) {
130 			end = lastsep == NULL
131 				? utf8_next_cp((char*)lastchar)
132 				: utf8_next_cp((char*)lastsep);
133 			if (!push_line(buffer, l, start, end - start, flags))
134 				return 0;
135 			flags = L_CONTINUATION;
136 			start = end;
137 			cur = prfxwidth + utf8_swidth_between(start, lastchar);
138 		} else if (strchr(separators, *line) != NULL) {
139 			lastsep = line;
140 		}
141 
142 		lastchar = utf8_prev_cp(line, l->line);
143 		cur += w;
144 	}
145 
146 	return push_line(buffer, l, start, line - start, flags);
147 }
148 
149 int
150 hardwrap_text(struct buffer *buffer, struct line *l, size_t width)
151 {
152 	const char	*line, *start, *lastchar;
153 	int		 cont;
154 	uint32_t	 state = 0, cp = 0;
155 	size_t		 cur, w;
156 
157 	if ((line = l->line) == NULL)
158 		return push_line(buffer, l, NULL, 0, 0);
159 
160 	start = line;
161 	lastchar = line;
162 	cont = 0;
163 	cur = 0;
164 	for (; *line; line++) {
165 		if (utf8_decode(&state, &cp, *line))
166 			continue;
167 		w = utf8_chwidth(cp);
168 		if (cur + w >= width) {
169 			if (!push_line(buffer, l, start, lastchar - start, cont))
170 				return 0;
171 			cont = 1;
172 			cur = 0;
173 			start = lastchar;
174 		}
175 
176 		lastchar = utf8_prev_cp(line, l->line);
177 		cur += w;
178 	}
179 
180 	return push_line(buffer, l, start, line - start, cont);
181 }