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Date:: Wed Jul 14 14:05:35 2021 UTC
Message:: refactor struct vline the new `meta.data' field will be useful for holding completions data.
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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 /*
18  * A streaming gemtext parser.
19  *
20  * TODO:
21  *  - handle NULs
22  *  - UTF8
23  */
24 
25 #include "defaults.h"
26 #include "parser.h"
27 #include "telescope.h"
28 
29 #include <ctype.h>
30 #include <string.h>
31 #include <stdlib.h>
32 
33 static int	gemtext_parse(struct parser*, const char*, size_t);
34 static int	gemtext_foreach_line(struct parser*, const char*, size_t);
35 static int	gemtext_free(struct parser*);
36 
37 static int	parse_text(struct parser*, enum line_type, const char*, size_t);
38 static int	parse_link(struct parser*, enum line_type, const char*, size_t);
39 static int	parse_title(struct parser*, enum line_type, const char*, size_t);
40 static int	parse_item(struct parser*, enum line_type, const char*, size_t);
41 static int	parse_quote(struct parser*, enum line_type, const char*, size_t);
42 static int	parse_pre_start(struct parser*, enum line_type, const char*, size_t);
43 static int	parse_pre_cnt(struct parser*, enum line_type, const char*, size_t);
44 static int	parse_pre_end(struct parser*, enum line_type, const char*, size_t);
45 static void	search_title(struct parser*, enum line_type);
46 
47 typedef int (parselinefn)(struct parser*, enum line_type, const char*, size_t);
48 
49 static parselinefn *parsers[] = {
50 	[LINE_TEXT]		= parse_text,
51 	[LINE_LINK]		= parse_link,
52 	[LINE_TITLE_1]		= parse_title,
53 	[LINE_TITLE_2]		= parse_title,
54 	[LINE_TITLE_3]		= parse_title,
55 	[LINE_ITEM]		= parse_item,
56 	[LINE_QUOTE]		= parse_quote,
57 	[LINE_PRE_START]	= parse_pre_start,
58 	[LINE_PRE_CONTENT]	= parse_pre_cnt,
59 	[LINE_PRE_END]		= parse_pre_end,
60 };
61 
62 void
63 gemtext_initparser(struct parser *p)
64 {
65 	memset(p, 0, sizeof(*p));
66 
67 	p->name = "text/gemini";
68 	p->parse = &gemtext_parse;
69 	p->free  = &gemtext_free;
70 }
71 
72 static inline int
73 emit_line(struct parser *p, enum line_type type, char *line, char *alt)
74 {
75 	struct line *l;
76 
77 	if ((l = calloc(1, sizeof(*l))) == NULL)
78 		return 0;
79 
80 	l->type = type;
81 	l->line = line;
82 	l->meta.alt = alt;
83 
84 	switch (l->type) {
85 	case LINE_PRE_START:
86 	case LINE_PRE_END:
87 		if (hide_pre_context)
88 			l->flags = L_HIDDEN;
89 		break;
90 	case LINE_PRE_CONTENT:
91 		if (hide_pre_blocks)
92 			l->flags = L_HIDDEN;
93 		break;
94 	default:
95 		l->flags = 0;
96 		break;
97 	}
98 
99 	if (TAILQ_EMPTY(&p->head))
100 		TAILQ_INSERT_HEAD(&p->head, l, lines);
101 	else
102 		TAILQ_INSERT_TAIL(&p->head, l, lines);
103 
104 	return 1;
105 }
106 
107 static int
108 parse_text(struct parser *p, enum line_type t, const char *buf, size_t len)
109 {
110 	char *l;
111 
112 	if ((l = calloc(1, len+1)) == NULL)
113 		return 0;
114 	memcpy(l, buf, len);
115 	return emit_line(p, t, l, NULL);
116 }
117 
118 static int
119 parse_link(struct parser *p, enum line_type t, const char *buf, size_t len)
120 {
121 	char *l, *u;
122 	const char *url_start;
123 
124 	if (len <= 2)
125 		return emit_line(p, t, NULL, NULL);
126 	buf += 2;
127 	len -= 2;
128 
129 	while (len > 0 && isspace(buf[0])) {
130 		buf++;
131 		len--;
132 	}
133 
134 	if (len == 0)
135 		return emit_line(p, t, NULL, NULL);
136 
137 	url_start = buf;
138 	while (len > 0 && !isspace(buf[0])) {
139 		buf++;
140 		len--;
141 	}
142 
143 	if ((u = calloc(1, buf - url_start + 1)) == NULL)
144 		return 0;
145 	memcpy(u, url_start, buf - url_start);
146 
147 	if (len == 0)
148 		goto nolabel;
149 
150 	while (len > 0 && isspace(buf[0])) {
151 		buf++;
152 		len--;
153 	}
154 
155 	if (len == 0)
156 		goto nolabel;
157 
158 	if ((l = calloc(1, len + 1)) == NULL)
159 		return 0;
160 
161 	memcpy(l, buf, len);
162 	return emit_line(p, t, l, u);
163 
164 nolabel:
165 	if ((l = strdup(u)) == NULL)
166 		return 0;
167 	return emit_line(p, t, l, u);
168 }
169 
170 static int
171 parse_title(struct parser *p, enum line_type t, const char *buf, size_t len)
172 {
173 	char *l;
174 
175 	switch (t) {
176 	case LINE_TITLE_1:
177 		if (len <= 1)
178 			return emit_line(p, t, NULL, NULL);
179 		buf++;
180 		len--;
181 		break;
182 	case LINE_TITLE_2:
183 		if (len <= 2)
184 			return emit_line(p, t, NULL, NULL);
185 		buf += 2;
186 		len -= 2;
187 		break;
188 	case LINE_TITLE_3:
189 		if (len <= 3)
190 			return emit_line(p, t, NULL, NULL);
191 		buf += 3;
192 		len -= 3;
193 		break;
194 	default:
195 		/* unreachable */
196 		abort();
197 	}
198 
199 	while (len > 0 && isspace(buf[0])) {
200 		buf++;
201 		len--;
202 	}
203 
204 	if (len == 0)
205 		return emit_line(p, t, NULL, NULL);
206 
207 	if (t == LINE_TITLE_1 && *p->title == '\0')
208 		strncpy(p->title, buf, MIN(sizeof(p->title)-1, len));
209 
210 	if ((l = calloc(1, len+1)) == NULL)
211 		return 0;
212 	memcpy(l, buf, len);
213 	return emit_line(p, t, l, NULL);
214 }
215 
216 static int
217 parse_item(struct parser *p, enum line_type t, const char *buf, size_t len)
218 {
219 	char *l;
220 
221 	if (len == 1)
222 		return emit_line(p, t, NULL, NULL);
223 
224 	buf++;
225 	len--;
226 
227 	while (len > 0 && isspace(buf[0])) {
228 		buf++;
229 		len--;
230 	}
231 
232 	if (len == 0)
233 		return emit_line(p, t, NULL, NULL);
234 
235 	if ((l = calloc(1, len+1)) == NULL)
236 		return 0;
237 	memcpy(l, buf, len);
238 	return emit_line(p, t, l, NULL);
239 }
240 
241 static int
242 parse_quote(struct parser *p, enum line_type t, const char *buf, size_t len)
243 {
244 	char *l;
245 
246 	if (len == 1)
247 		return emit_line(p, t, NULL, NULL);
248 
249 	buf++;
250 	len--;
251 
252 	while (len > 0 && isspace(buf[0])) {
253 		buf++;
254 		len--;
255 	}
256 
257 	if (len == 0)
258 		return emit_line(p, t, NULL, NULL);
259 
260 	if ((l = calloc(1, len+1)) == NULL)
261 		return 0;
262 	memcpy(l, buf, len);
263 	return emit_line(p, t, l, NULL);
264 }
265 
266 static int
267 parse_pre_start(struct parser *p, enum line_type t, const char *buf, size_t len)
268 {
269 	char *l;
270 
271 	if (len <= 3)
272 		return emit_line(p, t, NULL, NULL);
273 
274 	buf += 3;
275 	len -= 3;
276 
277 	while (len > 0 && isspace(buf[0])) {
278 		buf++;
279 		len--;
280 	}
281 
282 	if (len == 0)
283 		return emit_line(p, t, NULL, NULL);
284 
285 	if ((l = calloc(1, len+1)) == NULL)
286 		return 0;
287 
288 	memcpy(l, buf, len);
289 	return emit_line(p, t, l, NULL);
290 }
291 
292 static int
293 parse_pre_cnt(struct parser *p, enum line_type t, const char *buf, size_t len)
294 {
295 	char *l;
296 
297 	if (len == 0)
298 		return emit_line(p, t, NULL, NULL);
299 
300 	if ((l = calloc(1, len+1)) == NULL)
301 		return 0;
302 	memcpy(l, buf, len);
303 	return emit_line(p, t, l, NULL);
304 }
305 
306 static int
307 parse_pre_end(struct parser *p, enum line_type t, const char *buf, size_t len)
308 {
309 	return emit_line(p, t, NULL, NULL);
310 }
311 
312 static inline enum line_type
313 detect_line_type(const char *buf, size_t len, int in_pre)
314 {
315 	if (in_pre) {
316 		if (len >= 3 &&
317 		    buf[0] == '`' && buf[1] == '`' && buf[2] == '`')
318 			return LINE_PRE_END;
319 		else
320 			return LINE_PRE_CONTENT;
321 	}
322 
323 	if (len == 0)
324 		return LINE_TEXT;
325 
326 	switch (*buf) {
327 	case '*': return LINE_ITEM;
328 	case '>': return LINE_QUOTE;
329 	case '=':
330 		if (len >= 1 && buf[1] == '>')
331 			return LINE_LINK;
332 		break;
333 	case '#':
334 		if (len == 1)
335 			return LINE_TEXT;
336 		if (buf[1] != '#')
337 			return LINE_TITLE_1;
338 		if (len == 2)
339 			return LINE_TEXT;
340 		if (buf[2] != '#')
341 			return LINE_TITLE_2;
342 		if (len == 3)
343 			return LINE_TEXT;
344 		return LINE_TITLE_3;
345 	case '`':
346 		if (len < 3)
347 			return LINE_TEXT;
348 		if (buf[0] == '`' && buf[1] == '`' && buf[2] == '`')
349 			return LINE_PRE_START;
350 		break;
351 	}
352 
353 	return LINE_TEXT;
354 }
355 
356 static int
357 gemtext_parse(struct parser *p, const char *buf, size_t size)
358 {
359 	return parser_foreach_line(p, buf, size, gemtext_foreach_line);
360 }
361 
362 static int
363 gemtext_foreach_line(struct parser *p, const char *line, size_t linelen)
364 {
365 	enum line_type t;
366 
367 	t = detect_line_type(line, linelen, p->flags & PARSER_IN_PRE);
368 	if (t == LINE_PRE_START)
369 		p->flags ^= PARSER_IN_PRE;
370 	if (t == LINE_PRE_END)
371 		p->flags ^= PARSER_IN_PRE;
372 	return parsers[t](p, t, line, linelen);
373 }
374 
375 static int
376 gemtext_free(struct parser *p)
377 {
378 	enum line_type	t;
379 
380 	/* flush the buffer */
381 	if (p->len != 0) {
382 		t = detect_line_type(p->buf, p->len, p->flags & PARSER_IN_PRE);
383 		if (!parsers[t](p, t, p->buf, p->len))
384 			return 0;
385 		if ((p->flags & PARSER_IN_PRE) &&
386 		    !emit_line(p, LINE_PRE_END, NULL, NULL))
387 			return 0;
388 	}
389 
390 	free(p->buf);
391 
392 	/*
393 	 * use the first level 2 or 3 header as page title if none
394 	 * found yet.
395 	 */
396 	if (*p->title == '\0')
397 		search_title(p, LINE_TITLE_2);
398 	if (*p->title == '\0')
399 		search_title(p, LINE_TITLE_3);
400 
401 	return 1;
402 }
403 
404 static void
405 search_title(struct parser *p, enum line_type level)
406 {
407 	struct line *l;
408 
409 	TAILQ_FOREACH(l, &p->head, lines) {
410 		if (l->type == level) {
411 			if (l->line == NULL)
412 				continue;
413 			strlcpy(p->title, l->line, sizeof(p->title));
414 			break;
415 		}
416 	}
417 }