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 erase_buffer(struct buffer *buffer)
40 {
41 	empty_vlist(buffer);
42 	empty_linelist(buffer);
43 }
44 
45 void
46 empty_linelist(struct buffer *buffer)
47 {
48 	struct line *l, *lt;
49 
50 	TAILQ_FOREACH_SAFE(l, &buffer->page.head, lines, lt) {
51 		TAILQ_REMOVE(&buffer->page.head, l, lines);
52 		free(l->line);
53 		free(l->alt);
54 		free(l);
55 	}
56 }
57 
58 void
59 empty_vlist(struct buffer *buffer)
60 {
61 	struct vline *vl, *t;
62 
63 	buffer->top_line = NULL;
64 	buffer->line_off = 0;
65 	buffer->current_line = NULL;
66 	buffer->line_max = 0;
67 
68 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
69 		TAILQ_REMOVE(&buffer->head, vl, vlines);
70 		free(vl->line);
71 		free(vl);
72 	}
73 }
74 
75 static int
76 push_line(struct buffer *buffer, const struct line *l, const char *buf, size_t len, int flags)
77 {
78 	struct vline *vl;
79 
80 	buffer->line_max++;
81 
82 	if ((vl = calloc(1, sizeof(*vl))) == NULL)
83 		return 0;
84 
85 	if (len != 0 && (vl->line = calloc(1, len+1)) == NULL) {
86 		free(vl);
87 		return 0;
88 	}
89 
90 	vl->parent = l;
91 	if (len != 0)
92 		memcpy(vl->line, buf, len);
93 	vl->flags = flags;
94 
95 	if (TAILQ_EMPTY(&buffer->head))
96 		TAILQ_INSERT_HEAD(&buffer->head, vl, vlines);
97 	else
98 		TAILQ_INSERT_TAIL(&buffer->head, vl, vlines);
99 	return 1;
100 }
101 
102 /*
103  * Build a list of visual line by wrapping the given line, assuming
104  * that when printed will have a leading prefix prfx.
105  */
106 int
107 wrap_text(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
108 {
109 	const char	*separators = " \t-";
110 	const char	*start, *end, *line, *lastsep, *lastchar;
111 	uint32_t	 cp = 0, state = 0;
112 	size_t		 cur, prfxwidth, w;
113 	int		 flags;
114 
115 	if ((line = l->line) == NULL)
116 		return push_line(buffer, l, NULL, 0, 0);
117 
118 	prfxwidth = utf8_swidth(prfx);
119 	cur = prfxwidth;
120 	start = line;
121 	lastsep = NULL;
122 	lastchar = line;
123 	flags = 0;
124 	for (; *line; line++) {
125 		if (utf8_decode(&state, &cp, *line))
126 			continue;
127 		w = utf8_chwidth(cp);
128 		if (cur + w >= width -1) {
129 			end = lastsep == NULL
130 				? utf8_next_cp((char*)lastchar)
131 				: utf8_next_cp((char*)lastsep);
132 			if (!push_line(buffer, l, start, end - start, flags))
133 				return 0;
134 			flags = L_CONTINUATION;
135 			start = end;
136 			cur = prfxwidth + utf8_swidth_between(start, lastchar);
137 		} else if (strchr(separators, *line) != NULL) {
138 			lastsep = line;
139 		}
140 
141 		lastchar = utf8_prev_cp(line, l->line);
142 		cur += w;
143 	}
144 
145 	return push_line(buffer, l, start, line - start, flags);
146 }
147 
148 int
149 hardwrap_text(struct buffer *buffer, struct line *l, size_t width)
150 {
151 	const char	*line, *start, *lastchar;
152 	int		 cont;
153 	uint32_t	 state = 0, cp = 0;
154 	size_t		 cur, w;
155 
156 	if ((line = l->line) == NULL)
157 		return push_line(buffer, l, NULL, 0, 0);
158 
159 	start = line;
160 	lastchar = line;
161 	cont = 0;
162 	cur = 0;
163 	for (; *line; line++) {
164 		if (utf8_decode(&state, &cp, *line))
165 			continue;
166 		w = utf8_chwidth(cp);
167 		if (cur + w >= width) {
168 			if (!push_line(buffer, l, start, lastchar - start, cont))
169 				return 0;
170 			cont = 1;
171 			cur = 0;
172 			start = lastchar;
173 		}
174 
175 		lastchar = utf8_prev_cp(line, l->line);
176 		cur += w;
177 	}
178 
179 	return push_line(buffer, l, start, line - start, cont);
180 }