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 "defaults.h"
21 #include "telescope.h"
22 #include "utf8.h"
23 
24 /*
25  * Text wrapping
26  * =============
27  *
28  * There's a simple text wrapping algorithm.
29  *
30  * 1. if it's a line in a pre-formatted block:
31  *    a. hard wrap.
32  *    b. repeat
33  * 2. otherwise advance the line char by char.
34  * 3. when ending the space, split the line at the last occurrence of
35  *    a "word separator" (i.e. " \t-") or at point if none.
36  * 4. repeat
37  *
38  */
39 
40 void
41 erase_buffer(struct buffer *buffer)
42 {
43 	empty_vlist(buffer);
44 	empty_linelist(buffer);
45 }
46 
47 void
48 empty_linelist(struct buffer *buffer)
49 {
50 	struct line *l, *lt;
51 
52 	TAILQ_FOREACH_SAFE(l, &buffer->page.head, lines, lt) {
53 		TAILQ_REMOVE(&buffer->page.head, l, lines);
54 		free(l->line);
55 		free(l->alt);
56 		free(l);
57 	}
58 }
59 
60 void
61 empty_vlist(struct buffer *buffer)
62 {
63 	struct vline *vl, *t;
64 
65 	buffer->top_line = NULL;
66 	buffer->line_off = 0;
67 	buffer->current_line = NULL;
68 	buffer->line_max = 0;
69 
70 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
71 		TAILQ_REMOVE(&buffer->head, vl, vlines);
72 		free(vl->line);
73 		free(vl);
74 	}
75 }
76 
77 static int
78 push_line(struct buffer *buffer, struct line *l, const char *buf, size_t len, int flags)
79 {
80 	struct vline *vl;
81 
82 	if (!(l->flags & L_HIDDEN))
83 		buffer->line_max++;
84 
85 	if ((vl = calloc(1, sizeof(*vl))) == NULL)
86 		return 0;
87 
88 	if (len != 0 && (vl->line = calloc(1, len+1)) == NULL) {
89 		free(vl);
90 		return 0;
91 	}
92 
93 	vl->parent = l;
94 	if (len != 0)
95 		memcpy(vl->line, buf, len);
96 	vl->flags = flags;
97 
98 	if (TAILQ_EMPTY(&buffer->head))
99 		TAILQ_INSERT_HEAD(&buffer->head, vl, vlines);
100 	else
101 		TAILQ_INSERT_TAIL(&buffer->head, vl, vlines);
102 	return 1;
103 }
104 
105 /*
106  * Similar to wrap_text, but emit only o vline.
107  */
108 int
109 wrap_one(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
110 {
111 	struct vline *vl, *t;
112 
113 	/*
114 	 * be lazy: call wrap_text and then discard the continuations.
115 	 */
116 
117 	if (!wrap_text(buffer, prfx, l, width))
118 		return 0;
119 
120 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
121 		if (vl->flags & L_CONTINUATION) {
122 			TAILQ_REMOVE(&buffer->head, vl, vlines);
123 			free(vl->line);
124 			free(vl);
125 			buffer->line_max--;
126 		}
127 	}
128 
129 	return 1;
130 }
131 
132 /*
133  * Build a list of visual line by wrapping the given line, assuming
134  * that when printed will have a leading prefix prfx.
135  */
136 int
137 wrap_text(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
138 {
139 	const char	*separators = " \t-";
140 	const char	*start, *end, *line, *lastsep, *lastchar;
141 	uint32_t	 cp = 0, state = 0;
142 	size_t		 cur, prfxwidth, w;
143 	int		 flags;
144 
145 	if ((line = l->line) == NULL)
146 		return push_line(buffer, l, NULL, 0, 0);
147 
148 	prfxwidth = utf8_swidth(prfx);
149 	cur = prfxwidth;
150 	start = line;
151 	lastsep = NULL;
152 	lastchar = line;
153 	flags = 0;
154 	for (; *line; line++) {
155 		if (utf8_decode(&state, &cp, *line))
156 			continue;
157 		w = utf8_chwidth(cp);
158 		if (cur + w >= width -1) {
159 			end = lastsep == NULL
160 				? utf8_next_cp((char*)lastchar)
161 				: utf8_next_cp((char*)lastsep);
162 			if (!push_line(buffer, l, start, end - start, flags))
163 				return 0;
164 			flags = L_CONTINUATION;
165 			start = end;
166 			cur = prfxwidth + utf8_swidth_between(start, lastchar);
167 		} else if (strchr(separators, *line) != NULL) {
168 			lastsep = line;
169 		}
170 
171 		lastchar = utf8_prev_cp(line, l->line);
172 		cur += w;
173 	}
174 
175 	return push_line(buffer, l, start, line - start, flags);
176 }
177 
178 int
179 hardwrap_text(struct buffer *buffer, struct line *l, size_t width)
180 {
181 	const char	*line, *start, *lastchar;
182 	int		 cont;
183 	uint32_t	 state = 0, cp = 0;
184 	size_t		 cur, w;
185 
186 	if ((line = l->line) == NULL)
187 		return push_line(buffer, l, NULL, 0, 0);
188 
189 	start = line;
190 	lastchar = line;
191 	cont = 0;
192 	cur = 0;
193 	for (; *line; line++) {
194 		if (utf8_decode(&state, &cp, *line))
195 			continue;
196 		w = utf8_chwidth(cp);
197 		if (cur + w >= width) {
198 			if (!push_line(buffer, l, start, lastchar - start, cont))
199 				return 0;
200 			cont = L_CONTINUATION;
201 			if (dont_wrap_pre)
202                                 return 1;
203 			cur = 0;
204 			start = lastchar;
205 		}
206 
207 		lastchar = utf8_prev_cp(line, l->line);
208 		cur += w;
209 	}
210 
211 	return push_line(buffer, l, start, line - start, cont);
212 }