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 
56 		if (l->type != LINE_COMPL &&
57 		    l->type != LINE_COMPL_CURRENT)
58 			free(l->meta.alt);
59 
60 		free(l);
61 	}
62 }
63 
64 void
65 empty_vlist(struct buffer *buffer)
66 {
67 	struct vline *vl, *t;
68 
69 	buffer->top_line = NULL;
70 	buffer->line_off = 0;
71 	buffer->current_line = NULL;
72 	buffer->line_max = 0;
73 
74 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
75 		TAILQ_REMOVE(&buffer->head, vl, vlines);
76 		free(vl->line);
77 		free(vl);
78 	}
79 }
80 
81 static int
82 push_line(struct buffer *buffer, struct line *l, const char *buf, size_t len, int flags)
83 {
84 	struct vline *vl;
85 
86 	if (!(l->flags & L_HIDDEN))
87 		buffer->line_max++;
88 
89 	if ((vl = calloc(1, sizeof(*vl))) == NULL)
90 		return 0;
91 
92 	if (len != 0 && (vl->line = calloc(1, len+1)) == NULL) {
93 		free(vl);
94 		return 0;
95 	}
96 
97 	vl->parent = l;
98 	if (len != 0)
99 		memcpy(vl->line, buf, len);
100 	vl->flags = flags;
101 
102 	if (TAILQ_EMPTY(&buffer->head))
103 		TAILQ_INSERT_HEAD(&buffer->head, vl, vlines);
104 	else
105 		TAILQ_INSERT_TAIL(&buffer->head, vl, vlines);
106 	return 1;
107 }
108 
109 /*
110  * Similar to wrap_text, but emit only o vline.
111  */
112 int
113 wrap_one(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
114 {
115 	struct vline *vl, *t;
116 
117 	/*
118 	 * be lazy: call wrap_text and then discard the continuations.
119 	 */
120 
121 	if (!wrap_text(buffer, prfx, l, width))
122 		return 0;
123 
124 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
125 		if (vl->flags & L_CONTINUATION) {
126 			TAILQ_REMOVE(&buffer->head, vl, vlines);
127 			free(vl->line);
128 			free(vl);
129 			buffer->line_max--;
130 		}
131 	}
132 
133 	return 1;
134 }
135 
136 /*
137  * Build a list of visual line by wrapping the given line, assuming
138  * that when printed will have a leading prefix prfx.
139  */
140 int
141 wrap_text(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
142 {
143 	const char	*separators = " \t-";
144 	const char	*start, *end, *line, *lastsep, *lastchar;
145 	uint32_t	 cp = 0, state = 0;
146 	size_t		 cur, prfxwidth, w;
147 	int		 flags;
148 
149 	if ((line = l->line) == NULL)
150 		return push_line(buffer, l, NULL, 0, 0);
151 
152 	prfxwidth = utf8_swidth(prfx);
153 	cur = prfxwidth;
154 	start = line;
155 	lastsep = NULL;
156 	lastchar = line;
157 	flags = 0;
158 	for (; *line; line++) {
159 		if (utf8_decode(&state, &cp, *line))
160 			continue;
161 		w = utf8_chwidth(cp);
162 		if (cur + w >= width -1) {
163 			end = lastsep == NULL
164 				? utf8_next_cp((char*)lastchar)
165 				: utf8_next_cp((char*)lastsep);
166 			if (!push_line(buffer, l, start, end - start, flags))
167 				return 0;
168 			flags = L_CONTINUATION;
169 			start = end;
170 			cur = prfxwidth + utf8_swidth_between(start, lastchar);
171 		} else if (strchr(separators, *line) != NULL) {
172 			lastsep = line;
173 		}
174 
175 		lastchar = utf8_prev_cp(line, l->line);
176 		cur += w;
177 	}
178 
179 	return push_line(buffer, l, start, line - start, flags);
180 }
181 
182 int
183 hardwrap_text(struct buffer *buffer, struct line *l, size_t width)
184 {
185 	const char	*line, *start, *lastchar;
186 	int		 cont;
187 	uint32_t	 state = 0, cp = 0;
188 	size_t		 cur, w;
189 
190 	if ((line = l->line) == NULL)
191 		return push_line(buffer, l, NULL, 0, 0);
192 
193 	start = line;
194 	lastchar = line;
195 	cont = 0;
196 	cur = 0;
197 	for (; *line; line++) {
198 		if (utf8_decode(&state, &cp, *line))
199 			continue;
200 		w = utf8_chwidth(cp);
201 		if (cur + w >= width) {
202 			if (!push_line(buffer, l, start, lastchar - start, cont))
203 				return 0;
204 			cont = L_CONTINUATION;
205 			if (dont_wrap_pre)
206                                 return 1;
207 			cur = 0;
208 			start = lastchar;
209 		}
210 
211 		lastchar = utf8_prev_cp(line, l->line);
212 		cur += w;
213 	}
214 
215 	return push_line(buffer, l, start, line - start, cont);
216 }