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 
55 		if (l->type != LINE_COMPL &&
56 		    l->type != LINE_COMPL_CURRENT)
57 			free(l->meta.alt);
58 
59 		free(l);
60 	}
61 }
62 
63 void
64 empty_vlist(struct buffer *buffer)
65 {
66 	struct vline *vl, *t;
67 
68 	buffer->top_line = NULL;
69 	buffer->line_off = 0;
70 	buffer->current_line = NULL;
71 	buffer->line_max = 0;
72 
73 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
74 		TAILQ_REMOVE(&buffer->head, vl, vlines);
75 		free(vl->line);
76 		free(vl);
77 	}
78 }
79 
80 static int
81 push_line(struct buffer *buffer, const struct line *l, const char *buf, size_t len, int flags)
82 {
83 	struct vline *vl;
84 
85 	buffer->line_max++;
86 
87 	if ((vl = calloc(1, sizeof(*vl))) == NULL)
88 		return 0;
89 
90 	if (len != 0 && (vl->line = calloc(1, len+1)) == NULL) {
91 		free(vl);
92 		return 0;
93 	}
94 
95 	vl->parent = l;
96 	if (len != 0)
97 		memcpy(vl->line, buf, len);
98 	vl->flags = flags;
99 
100 	if (TAILQ_EMPTY(&buffer->head))
101 		TAILQ_INSERT_HEAD(&buffer->head, vl, vlines);
102 	else
103 		TAILQ_INSERT_TAIL(&buffer->head, vl, vlines);
104 	return 1;
105 }
106 
107 /*
108  * Similar to wrap_text, but emit only o vline.
109  */
110 int
111 wrap_one(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
112 {
113 	struct vline *vl, *t;
114 
115 	/*
116 	 * be lazy: call wrap_text and then discard the continuations.
117 	 */
118 
119 	if (!wrap_text(buffer, prfx, l, width))
120 		return 0;
121 
122 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
123 		if (vl->flags & L_CONTINUATION) {
124 			TAILQ_REMOVE(&buffer->head, vl, vlines);
125 			free(vl->line);
126 			free(vl);
127 		}
128 	}
129 
130 	return 1;
131 }
132 
133 /*
134  * Build a list of visual line by wrapping the given line, assuming
135  * that when printed will have a leading prefix prfx.
136  */
137 int
138 wrap_text(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
139 {
140 	const char	*separators = " \t-";
141 	const char	*start, *end, *line, *lastsep, *lastchar;
142 	uint32_t	 cp = 0, state = 0;
143 	size_t		 cur, prfxwidth, w;
144 	int		 flags;
145 
146 	if ((line = l->line) == NULL)
147 		return push_line(buffer, l, NULL, 0, 0);
148 
149 	prfxwidth = utf8_swidth(prfx);
150 	cur = prfxwidth;
151 	start = line;
152 	lastsep = NULL;
153 	lastchar = line;
154 	flags = 0;
155 	for (; *line; line++) {
156 		if (utf8_decode(&state, &cp, *line))
157 			continue;
158 		w = utf8_chwidth(cp);
159 		if (cur + w >= width -1) {
160 			end = lastsep == NULL
161 				? utf8_next_cp((char*)lastchar)
162 				: utf8_next_cp((char*)lastsep);
163 			if (!push_line(buffer, l, start, end - start, flags))
164 				return 0;
165 			flags = L_CONTINUATION;
166 			start = end;
167 			cur = prfxwidth + utf8_swidth_between(start, lastchar);
168 		} else if (strchr(separators, *line) != NULL) {
169 			lastsep = line;
170 		}
171 
172 		lastchar = utf8_prev_cp(line, l->line);
173 		cur += w;
174 	}
175 
176 	return push_line(buffer, l, start, line - start, flags);
177 }
178 
179 int
180 hardwrap_text(struct buffer *buffer, struct line *l, size_t width)
181 {
182 	const char	*line, *start, *lastchar;
183 	int		 cont;
184 	uint32_t	 state = 0, cp = 0;
185 	size_t		 cur, w;
186 
187 	if ((line = l->line) == NULL)
188 		return push_line(buffer, l, NULL, 0, 0);
189 
190 	start = line;
191 	lastchar = line;
192 	cont = 0;
193 	cur = 0;
194 	for (; *line; line++) {
195 		if (utf8_decode(&state, &cp, *line))
196 			continue;
197 		w = utf8_chwidth(cp);
198 		if (cur + w >= width) {
199 			if (!push_line(buffer, l, start, lastchar - start, cont))
200 				return 0;
201 			cont = 1;
202 			cur = 0;
203 			start = lastchar;
204 		}
205 
206 		lastchar = utf8_prev_cp(line, l->line);
207 		cur += w;
208 	}
209 
210 	return push_line(buffer, l, start, line - start, cont);
211 }