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  * Similar to wrap_text, but emit only o vline.
105  */
106 int
107 wrap_one(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
108 {
109 	struct vline *vl, *t;
110 
111 	/*
112 	 * be lazy: call wrap_text and then discard the continuations.
113 	 */
114 
115 	if (!wrap_text(buffer, prfx, l, width))
116 		return 0;
117 
118 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
119 		if (vl->flags & L_CONTINUATION) {
120 			TAILQ_REMOVE(&buffer->head, vl, vlines);
121 			free(vl->line);
122 			free(vl);
123 		}
124 	}
125 
126 	return 1;
127 }
128 
129 /*
130  * Build a list of visual line by wrapping the given line, assuming
131  * that when printed will have a leading prefix prfx.
132  */
133 int
134 wrap_text(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
135 {
136 	const char	*separators = " \t-";
137 	const char	*start, *end, *line, *lastsep, *lastchar;
138 	uint32_t	 cp = 0, state = 0;
139 	size_t		 cur, prfxwidth, w;
140 	int		 flags;
141 
142 	if ((line = l->line) == NULL)
143 		return push_line(buffer, l, NULL, 0, 0);
144 
145 	prfxwidth = utf8_swidth(prfx);
146 	cur = prfxwidth;
147 	start = line;
148 	lastsep = NULL;
149 	lastchar = line;
150 	flags = 0;
151 	for (; *line; line++) {
152 		if (utf8_decode(&state, &cp, *line))
153 			continue;
154 		w = utf8_chwidth(cp);
155 		if (cur + w >= width -1) {
156 			end = lastsep == NULL
157 				? utf8_next_cp((char*)lastchar)
158 				: utf8_next_cp((char*)lastsep);
159 			if (!push_line(buffer, l, start, end - start, flags))
160 				return 0;
161 			flags = L_CONTINUATION;
162 			start = end;
163 			cur = prfxwidth + utf8_swidth_between(start, lastchar);
164 		} else if (strchr(separators, *line) != NULL) {
165 			lastsep = line;
166 		}
167 
168 		lastchar = utf8_prev_cp(line, l->line);
169 		cur += w;
170 	}
171 
172 	return push_line(buffer, l, start, line - start, flags);
173 }
174 
175 int
176 hardwrap_text(struct buffer *buffer, struct line *l, size_t width)
177 {
178 	const char	*line, *start, *lastchar;
179 	int		 cont;
180 	uint32_t	 state = 0, cp = 0;
181 	size_t		 cur, w;
182 
183 	if ((line = l->line) == NULL)
184 		return push_line(buffer, l, NULL, 0, 0);
185 
186 	start = line;
187 	lastchar = line;
188 	cont = 0;
189 	cur = 0;
190 	for (; *line; line++) {
191 		if (utf8_decode(&state, &cp, *line))
192 			continue;
193 		w = utf8_chwidth(cp);
194 		if (cur + w >= width) {
195 			if (!push_line(buffer, l, start, lastchar - start, cont))
196 				return 0;
197 			cont = 1;
198 			cur = 0;
199 			start = lastchar;
200 		}
201 
202 		lastchar = utf8_prev_cp(line, l->line);
203 		cur += w;
204 	}
205 
206 	return push_line(buffer, l, start, line - start, cont);
207 }