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render_html.c (16141B)
1 /*
2 * MD4C: Markdown parser for C
3 * (http://github.com/mity/md4c)
4 *
5 * Copyright (c) 2016-2017 Martin Mitas
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
22 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
23 * IN THE SOFTWARE.
24 */
25
26 #include <stdio.h>
27 #include <string.h>
28
29 #include "render_html.h"
30 #include "entity.h"
31
32
33 #ifdef _MSC_VER
34 /* MSVC does not understand "inline" when building as pure C (not C++).
35 * However it understands "__inline" */
36 #ifndef __cplusplus
37 #define inline __inline
38 #endif
39 #endif
40
41 #ifdef _WIN32
42 #define snprintf _snprintf
43 #endif
44
45
46
47 typedef struct MD_RENDER_HTML_tag MD_RENDER_HTML;
48 struct MD_RENDER_HTML_tag {
49 void (*process_output)(const MD_CHAR*, MD_SIZE, void*);
50 void* userdata;
51 unsigned flags;
52 int image_nesting_level;
53 };
54
55
56 /*****************************************
57 *** HTML rendering helper functions ***
58 *****************************************/
59
60 #define ISDIGIT(ch) ('0' <= (ch) && (ch) <= '9')
61 #define ISLOWER(ch) ('a' <= (ch) && (ch) <= 'z')
62 #define ISUPPER(ch) ('A' <= (ch) && (ch) <= 'Z')
63 #define ISALNUM(ch) (ISLOWER(ch) || ISUPPER(ch) || ISDIGIT(ch))
64
65
66 static inline void
67 render_text(MD_RENDER_HTML* r, const MD_CHAR* text, MD_SIZE size)
68 {
69 r->process_output(text, size, r->userdata);
70 }
71
72 #define RENDER_LITERAL(r, literal) render_text((r), (literal), strlen(literal))
73
74
75 static void
76 render_html_escaped(MD_RENDER_HTML* r, const MD_CHAR* data, MD_SIZE size)
77 {
78 MD_OFFSET beg = 0;
79 MD_OFFSET off = 0;
80
81 /* Some characters need to be escaped in normal HTML text. */
82 #define HTML_NEED_ESCAPE(ch) \
83 ((ch) == '&' || (ch) == '<' || (ch) == '>' || (ch) == '"')
84
85 while(1) {
86 while(off < size && !HTML_NEED_ESCAPE(data[off]))
87 off++;
88 if(off > beg)
89 render_text(r, data + beg, off - beg);
90
91 if(off < size) {
92 switch(data[off]) {
93 case '&': RENDER_LITERAL(r, "&"); break;
94 case '<': RENDER_LITERAL(r, "<"); break;
95 case '>': RENDER_LITERAL(r, ">"); break;
96 case '"': RENDER_LITERAL(r, """); break;
97 }
98 off++;
99 } else {
100 break;
101 }
102 beg = off;
103 }
104 }
105
106 static void
107 render_url_escaped(MD_RENDER_HTML* r, const MD_CHAR* data, MD_SIZE size)
108 {
109 static const MD_CHAR hex_chars[] = "0123456789ABCDEF";
110 MD_OFFSET beg = 0;
111 MD_OFFSET off = 0;
112
113 #define URL_NEED_ESCAPE(ch) \
114 (!ISALNUM(ch) && strchr("-_.+!*'(),%#@?=;:/,+$", ch) == NULL)
115
116 while(1) {
117 while(off < size && !URL_NEED_ESCAPE(data[off]))
118 off++;
119 if(off > beg)
120 render_text(r, data + beg, off - beg);
121
122 if(off < size) {
123 char hex[3];
124
125 switch(data[off]) {
126 case '&': RENDER_LITERAL(r, "&"); break;
127 case '\'': RENDER_LITERAL(r, "'"); break;
128 default:
129 hex[0] = '%';
130 hex[1] = hex_chars[((unsigned)data[off] >> 4) & 0xf];
131 hex[2] = hex_chars[((unsigned)data[off] >> 0) & 0xf];
132 render_text(r, hex, 3);
133 break;
134 }
135 off++;
136 } else {
137 break;
138 }
139
140 beg = off;
141 }
142 }
143
144 static unsigned
145 hex_val(char ch)
146 {
147 if('0' <= ch && ch <= '9')
148 return ch - '0';
149 if('A' <= ch && ch <= 'Z')
150 return ch - 'A' + 10;
151 else
152 return ch - 'a' + 10;
153 }
154
155 static void
156 render_utf8_codepoint(MD_RENDER_HTML* r, unsigned codepoint,
157 void (*fn_append)(MD_RENDER_HTML*, const MD_CHAR*, MD_SIZE))
158 {
159 static const MD_CHAR utf8_replacement_char[] = { 0xef, 0xbf, 0xbd };
160
161 unsigned char utf8[4];
162 size_t n;
163
164 if(codepoint <= 0x7f) {
165 n = 1;
166 utf8[0] = codepoint;
167 } else if(codepoint <= 0x7ff) {
168 n = 2;
169 utf8[0] = 0xc0 | ((codepoint >> 6) & 0x1f);
170 utf8[1] = 0x80 + ((codepoint >> 0) & 0x3f);
171 } else if(codepoint <= 0xffff) {
172 n = 3;
173 utf8[0] = 0xe0 | ((codepoint >> 12) & 0xf);
174 utf8[1] = 0x80 + ((codepoint >> 6) & 0x3f);
175 utf8[2] = 0x80 + ((codepoint >> 0) & 0x3f);
176 } else {
177 n = 4;
178 utf8[0] = 0xf0 | ((codepoint >> 18) & 0x7);
179 utf8[1] = 0x80 + ((codepoint >> 12) & 0x3f);
180 utf8[2] = 0x80 + ((codepoint >> 6) & 0x3f);
181 utf8[3] = 0x80 + ((codepoint >> 0) & 0x3f);
182 }
183
184 if(0 < codepoint && codepoint <= 0x10ffff)
185 fn_append(r, (char*)utf8, n);
186 else
187 fn_append(r, utf8_replacement_char, 3);
188 }
189
190 /* Translate entity to its UTF-8 equivalent, or output the verbatim one
191 * if such entity is unknown (or if the translation is disabled). */
192 static void
193 render_entity(MD_RENDER_HTML* r, const MD_CHAR* text, MD_SIZE size,
194 void (*fn_append)(MD_RENDER_HTML*, const MD_CHAR*, MD_SIZE))
195 {
196 if(r->flags & MD_RENDER_FLAG_VERBATIM_ENTITIES) {
197 fn_append(r, text, size);
198 return;
199 }
200
201 /* We assume UTF-8 output is what is desired. */
202 if(size > 3 && text[1] == '#') {
203 unsigned codepoint = 0;
204
205 if(text[2] == 'x' || text[2] == 'X') {
206 /* Hexadecimal entity (e.g. "�")). */
207 MD_SIZE i;
208 for(i = 3; i < size-1; i++)
209 codepoint = 16 * codepoint + hex_val(text[i]);
210 } else {
211 /* Decimal entity (e.g. "&1234;") */
212 MD_SIZE i;
213 for(i = 2; i < size-1; i++)
214 codepoint = 10 * codepoint + (text[i] - '0');
215 }
216
217 render_utf8_codepoint(r, codepoint, fn_append);
218 return;
219 } else {
220 /* Named entity (e.g. " "). */
221 const struct entity* ent;
222
223 ent = entity_lookup(text, size);
224 if(ent != NULL) {
225 render_utf8_codepoint(r, ent->codepoints[0], fn_append);
226 if(ent->codepoints[1])
227 render_utf8_codepoint(r, ent->codepoints[1], fn_append);
228 return;
229 }
230 }
231
232 fn_append(r, text, size);
233 }
234
235 static void
236 render_attribute(MD_RENDER_HTML* r, const MD_ATTRIBUTE* attr,
237 void (*fn_append)(MD_RENDER_HTML*, const MD_CHAR*, MD_SIZE))
238 {
239 int i;
240
241 for(i = 0; attr->substr_offsets[i] < attr->size; i++) {
242 MD_TEXTTYPE type = attr->substr_types[i];
243 MD_OFFSET off = attr->substr_offsets[i];
244 MD_SIZE size = attr->substr_offsets[i+1] - off;
245 const MD_CHAR* text = attr->text + off;
246
247 switch(type) {
248 case MD_TEXT_NULLCHAR: render_utf8_codepoint(r, 0x0000, render_text); break;
249 case MD_TEXT_ENTITY: render_entity(r, text, size, fn_append); break;
250 default: fn_append(r, text, size); break;
251 }
252 }
253 }
254
255
256 static void
257 render_open_ol_block(MD_RENDER_HTML* r, const MD_BLOCK_OL_DETAIL* det)
258 {
259 char buf[64];
260
261 if(det->start == 1) {
262 RENDER_LITERAL(r, "<ol>\n");
263 return;
264 }
265
266 snprintf(buf, sizeof(buf), "<ol start=\"%u\">\n", det->start);
267 RENDER_LITERAL(r, buf);
268 }
269
270 static void
271 render_open_code_block(MD_RENDER_HTML* r, const MD_BLOCK_CODE_DETAIL* det)
272 {
273 RENDER_LITERAL(r, "<pre><code");
274
275 /* If known, output the HTML 5 attribute class="language-LANGNAME". */
276 if(det->lang.text != NULL) {
277 RENDER_LITERAL(r, " class=\"language-");
278 render_attribute(r, &det->lang, render_html_escaped);
279 RENDER_LITERAL(r, "\"");
280 }
281
282 RENDER_LITERAL(r, ">");
283 }
284
285 static void
286 render_open_td_block(MD_RENDER_HTML* r, const MD_CHAR* cell_type, const MD_BLOCK_TD_DETAIL* det)
287 {
288 RENDER_LITERAL(r, "<");
289 RENDER_LITERAL(r, cell_type);
290
291 switch(det->align) {
292 case MD_ALIGN_LEFT: RENDER_LITERAL(r, " align=\"left\">"); break;
293 case MD_ALIGN_CENTER: RENDER_LITERAL(r, " align=\"center\">"); break;
294 case MD_ALIGN_RIGHT: RENDER_LITERAL(r, " align=\"right\">"); break;
295 default: RENDER_LITERAL(r, ">"); break;
296 }
297 }
298
299 static void
300 render_open_a_span(MD_RENDER_HTML* r, const MD_SPAN_A_DETAIL* det)
301 {
302 RENDER_LITERAL(r, "<a href=\"");
303 render_attribute(r, &det->href, render_url_escaped);
304
305 if(det->title.text != NULL) {
306 RENDER_LITERAL(r, "\" title=\"");
307 render_attribute(r, &det->title, render_html_escaped);
308 }
309
310 RENDER_LITERAL(r, "\">");
311 }
312
313 static void
314 render_open_img_span(MD_RENDER_HTML* r, const MD_SPAN_IMG_DETAIL* det)
315 {
316 RENDER_LITERAL(r, "<img src=\"");
317 render_attribute(r, &det->src, render_url_escaped);
318
319 RENDER_LITERAL(r, "\" alt=\"");
320
321 r->image_nesting_level++;
322 }
323
324 static void
325 render_close_img_span(MD_RENDER_HTML* r, const MD_SPAN_IMG_DETAIL* det)
326 {
327 if(det->title.text != NULL) {
328 RENDER_LITERAL(r, "\" title=\"");
329 render_attribute(r, &det->title, render_html_escaped);
330 }
331
332 RENDER_LITERAL(r, "\">");
333
334 r->image_nesting_level--;
335 }
336
337
338 /**************************************
339 *** HTML renderer implementation ***
340 **************************************/
341
342 static int
343 enter_block_callback(MD_BLOCKTYPE type, void* detail, void* userdata)
344 {
345 static const MD_CHAR* head[6] = { "<h1>", "<h2>", "<h3>", "<h4>", "<h5>", "<h6>" };
346 MD_RENDER_HTML* r = (MD_RENDER_HTML*) userdata;
347
348 switch(type) {
349 case MD_BLOCK_DOC: /* noop */ break;
350 case MD_BLOCK_QUOTE: RENDER_LITERAL(r, "<blockquote>\n"); break;
351 case MD_BLOCK_UL: RENDER_LITERAL(r, "<ul>\n"); break;
352 case MD_BLOCK_OL: render_open_ol_block(r, (const MD_BLOCK_OL_DETAIL*)detail); break;
353 case MD_BLOCK_LI: RENDER_LITERAL(r, "<li>"); break;
354 case MD_BLOCK_HR: RENDER_LITERAL(r, "<hr>\n"); break;
355 case MD_BLOCK_H: RENDER_LITERAL(r, head[((MD_BLOCK_H_DETAIL*)detail)->level - 1]); break;
356 case MD_BLOCK_CODE: render_open_code_block(r, (const MD_BLOCK_CODE_DETAIL*) detail); break;
357 case MD_BLOCK_HTML: /* noop */ break;
358 case MD_BLOCK_P: RENDER_LITERAL(r, "<p>"); break;
359 case MD_BLOCK_TABLE: RENDER_LITERAL(r, "<table>\n"); break;
360 case MD_BLOCK_THEAD: RENDER_LITERAL(r, "<thead>\n"); break;
361 case MD_BLOCK_TBODY: RENDER_LITERAL(r, "<tbody>\n"); break;
362 case MD_BLOCK_TR: RENDER_LITERAL(r, "<tr>\n"); break;
363 case MD_BLOCK_TH: render_open_td_block(r, "th", (MD_BLOCK_TD_DETAIL*)detail); break;
364 case MD_BLOCK_TD: render_open_td_block(r, "td", (MD_BLOCK_TD_DETAIL*)detail); break;
365 }
366
367 return 0;
368 }
369
370 static int
371 leave_block_callback(MD_BLOCKTYPE type, void* detail, void* userdata)
372 {
373 static const MD_CHAR* head[6] = { "</h1>\n", "</h2>\n", "</h3>\n", "</h4>\n", "</h5>\n", "</h6>\n" };
374 MD_RENDER_HTML* r = (MD_RENDER_HTML*) userdata;
375
376 switch(type) {
377 case MD_BLOCK_DOC: /*noop*/ break;
378 case MD_BLOCK_QUOTE: RENDER_LITERAL(r, "</blockquote>\n"); break;
379 case MD_BLOCK_UL: RENDER_LITERAL(r, "</ul>\n"); break;
380 case MD_BLOCK_OL: RENDER_LITERAL(r, "</ol>\n"); break;
381 case MD_BLOCK_LI: RENDER_LITERAL(r, "</li>\n"); break;
382 case MD_BLOCK_HR: /*noop*/ break;
383 case MD_BLOCK_H: RENDER_LITERAL(r, head[((MD_BLOCK_H_DETAIL*)detail)->level - 1]); break;
384 case MD_BLOCK_CODE: RENDER_LITERAL(r, "</code></pre>\n"); break;
385 case MD_BLOCK_HTML: /* noop */ break;
386 case MD_BLOCK_P: RENDER_LITERAL(r, "</p>\n"); break;
387 case MD_BLOCK_TABLE: RENDER_LITERAL(r, "</table>\n"); break;
388 case MD_BLOCK_THEAD: RENDER_LITERAL(r, "</thead>\n"); break;
389 case MD_BLOCK_TBODY: RENDER_LITERAL(r, "</tbody>\n"); break;
390 case MD_BLOCK_TR: RENDER_LITERAL(r, "</tr>\n"); break;
391 case MD_BLOCK_TH: RENDER_LITERAL(r, "</th>\n"); break;
392 case MD_BLOCK_TD: RENDER_LITERAL(r, "</td>\n"); break;
393 }
394
395 return 0;
396 }
397
398 static int
399 enter_span_callback(MD_SPANTYPE type, void* detail, void* userdata)
400 {
401 MD_RENDER_HTML* r = (MD_RENDER_HTML*) userdata;
402
403 if(r->image_nesting_level > 0) {
404 /* We are inside an image, i.e. rendering the ALT attribute of
405 * <IMG> tag. */
406 return 0;
407 }
408
409 switch(type) {
410 case MD_SPAN_EM: RENDER_LITERAL(r, "<em>"); break;
411 case MD_SPAN_STRONG: RENDER_LITERAL(r, "<strong>"); break;
412 case MD_SPAN_A: render_open_a_span(r, (MD_SPAN_A_DETAIL*) detail); break;
413 case MD_SPAN_IMG: render_open_img_span(r, (MD_SPAN_IMG_DETAIL*) detail); break;
414 case MD_SPAN_CODE: RENDER_LITERAL(r, "<code>"); break;
415 case MD_SPAN_DEL: RENDER_LITERAL(r, "<del>"); break;
416 }
417
418 return 0;
419 }
420
421 static int
422 leave_span_callback(MD_SPANTYPE type, void* detail, void* userdata)
423 {
424 MD_RENDER_HTML* r = (MD_RENDER_HTML*) userdata;
425
426 if(r->image_nesting_level > 0) {
427 /* We are inside an image, i.e. rendering the ALT attribute of
428 * <IMG> tag. */
429 if(r->image_nesting_level == 1 && type == MD_SPAN_IMG)
430 render_close_img_span(r, (MD_SPAN_IMG_DETAIL*) detail);
431 return 0;
432 }
433
434 switch(type) {
435 case MD_SPAN_EM: RENDER_LITERAL(r, "</em>"); break;
436 case MD_SPAN_STRONG: RENDER_LITERAL(r, "</strong>"); break;
437 case MD_SPAN_A: RENDER_LITERAL(r, "</a>"); break;
438 case MD_SPAN_IMG: /*noop, handled above*/ break;
439 case MD_SPAN_CODE: RENDER_LITERAL(r, "</code>"); break;
440 case MD_SPAN_DEL: RENDER_LITERAL(r, "</del>"); break;
441 }
442
443 return 0;
444 }
445
446 static int
447 text_callback(MD_TEXTTYPE type, const MD_CHAR* text, MD_SIZE size, void* userdata)
448 {
449 MD_RENDER_HTML* r = (MD_RENDER_HTML*) userdata;
450
451 switch(type) {
452 case MD_TEXT_NULLCHAR: render_utf8_codepoint(r, 0x0000, render_text); break;
453 case MD_TEXT_BR: RENDER_LITERAL(r, (r->image_nesting_level == 0 ? "<br>\n" : " ")); break;
454 case MD_TEXT_SOFTBR: RENDER_LITERAL(r, (r->image_nesting_level == 0 ? "\n" : " ")); break;
455 case MD_TEXT_HTML: render_text(r, text, size); break;
456 case MD_TEXT_ENTITY: render_entity(r, text, size, render_html_escaped); break;
457 default: render_html_escaped(r, text, size); break;
458 }
459
460 return 0;
461 }
462
463 static void
464 debug_log_callback(const char* msg, void* userdata)
465 {
466 MD_RENDER_HTML* r = (MD_RENDER_HTML*) userdata;
467 if(r->flags & MD_RENDER_FLAG_DEBUG)
468 fprintf(stderr, "MD4C: %s\n", msg);
469 }
470
471 int
472 md_render_html(const MD_CHAR* input, MD_SIZE input_size,
473 void (*process_output)(const MD_CHAR*, MD_SIZE, void*),
474 void* userdata, unsigned parser_flags, unsigned renderer_flags)
475 {
476 MD_RENDER_HTML render = { process_output, userdata, renderer_flags, 0 };
477
478 MD_RENDERER renderer = {
479 enter_block_callback,
480 leave_block_callback,
481 enter_span_callback,
482 leave_span_callback,
483 text_callback,
484 debug_log_callback,
485 parser_flags
486 };
487
488 return md_parse(input, input_size, &renderer, (void*) &render);
489 }
490