summaryrefslogtreecommitdiff
path: root/src/select/select.c
blob: 687be8559a0fb630fa7ca0d68fc3e96debab91db (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
/*
 * This file is part of LibCSS
 * Licensed under the MIT License,
 *                http://www.opensource.org/licenses/mit-license.php
 * Copyright 2009 John-Mark Bell <jmb@netsurf-browser.org>
 */

#include <string.h>

#include <parserutils/utils/hash.h>

#include <libcss/computed.h>
#include <libcss/select.h>

#include "stylesheet.h"
#include "select/hash.h"
#include "select/propset.h"
#include "utils/parserutilserror.h"
#include "utils/utils.h"

/**
 * CSS selection context
 */
struct css_select_ctx {
	uint32_t n_sheets;		/**< Number of sheets */

	const css_stylesheet **sheets;	/**< Array of sheets */

	css_alloc alloc;		/**< Allocation routine */
	void *pw;			/**< Client-specific private data */
};

/**
 * State for each property during selection
 */
typedef struct css_select_state {
	void *node;			/* Node we're selecting for */
	uint64_t pseudo_element;	/* Pseudo element to select for */
	uint64_t pseudo_classes;	/* Currently active pseudo classes */
	uint64_t media;			/* Currently active media types */
	css_computed_style *result;	/* Style to populate */

	css_select_handler *handler;	/* Handler functions */
	void *pw;			/* Client data for handlers */

	uint32_t current_sheet;		/* Identity of current sheet */

/** \todo We need a better way of knowing the number of properties
 * Bytecode opcodes cover 84 properties, then there's a 
 * further 15 generated from the side bits */
/* Stylesheet identity is a monotonically increasing number based at 1 and
 * increasing by 1 for every applicable stylesheet encountered, including 
 * imports. Imported sheets' identities are below that of the sheet that 
 * imported them. */
#define N_PROPS (99)
	struct {
		uint32_t specificity;	/* Specificity of property in result */
		uint32_t sheet;		/* Identity of applicable stylesheet */
		uint32_t set       : 1,	/* Whether property is set in result */
		         origin    : 2,	/* Origin of property in result */
		         important : 1,	/* Importance of property in result */
		         index     : 16;/* Index of corresponding rule */
	} props[N_PROPS];
#undef N_PROPS
} css_select_state;

static css_error select_from_sheet(css_select_ctx *ctx, 
		const css_stylesheet *sheet, css_select_state *state);
static css_error match_selectors_in_sheet(css_select_ctx *ctx, 
		const css_stylesheet *sheet, css_select_state *state);
static css_error match_selector_chain(css_select_ctx *ctx, 
		const css_selector *selector, css_origin origin,
		css_select_state *state, 
		const parserutils_hash_entry *universal);
static css_error match_named_combinator(css_select_ctx *ctx, 
		css_combinator type, const parserutils_hash_entry *name, 
		css_select_state *state, void *node, void **next_node);
static css_error match_universal_combinator(css_select_ctx *ctx, 
		css_combinator type, const css_selector *selector, 
		css_select_state *state, void *node, void **next_node);
static css_error match_details(css_select_ctx *ctx, void *node, 
		const css_selector_detail *detail, css_select_state *state, 
		bool *match);
static css_error match_detail(css_select_ctx *ctx, void *node, 
		const css_selector_detail *detail, css_select_state *state, 
		bool *match);
static css_error cascade_style(css_select_ctx *ctx, css_style *style, 
		uint32_t specificity, css_origin origin, uint32_t rule_index,
		css_select_state *state);

/**
 * Create a selection context
 *
 * \param alloc   Memory (de)allocation function
 * \param pw      Client-specific private data
 * \param result  Pointer to location to receive created context
 * \return CSS_OK on success, appropriate error otherwise.
 */
css_error css_select_ctx_create(css_alloc alloc, void *pw,
		css_select_ctx **result)
{
	css_select_ctx *c;

	if (alloc == NULL || result == NULL)
		return CSS_BADPARM;

	c = alloc(NULL, sizeof(css_select_ctx), pw);
	if (c == NULL)
		return CSS_NOMEM;

	c->n_sheets = 0;
	c->sheets = NULL;

	c->alloc = alloc;
	c->pw = pw;

	*result = c;

	return CSS_OK;
}

/**
 * Destroy a selection context
 *
 * \param ctx  The context to destroy
 * \return CSS_OK on success, appropriate error otherwise
 */
css_error css_select_ctx_destroy(css_select_ctx *ctx)
{
	if (ctx == NULL)
		return CSS_BADPARM;

	if (ctx->sheets != NULL)
		ctx->alloc(ctx->sheets, 0, ctx->pw);

	ctx->alloc(ctx, 0, ctx->pw);

	return CSS_OK;
}

/**
 * Append a stylesheet to a selection context
 *
 * \param ctx    The context to append to
 * \param sheet  The sheet to append
 * \return CSS_OK on success, appropriate error otherwise
 */
css_error css_select_ctx_append_sheet(css_select_ctx *ctx, 
		const css_stylesheet *sheet)
{
	if (ctx == NULL || sheet == NULL)
		return CSS_BADPARM;

	return css_select_ctx_insert_sheet(ctx, sheet, ctx->n_sheets);
}

/**
 * Insert a stylesheet into a selection context
 * 
 * \param ctx    The context to insert into
 * \param sheet  Sheet to insert
 * \param index  Index in context to insert sheet
 * \return CSS_OK on success, appropriate error otherwise
 */
css_error css_select_ctx_insert_sheet(css_select_ctx *ctx,
		const css_stylesheet *sheet, uint32_t index)
{
	const css_stylesheet **temp;

	if (ctx == NULL || sheet == NULL)
		return CSS_BADPARM;

	/* Index must be in the range [0, n_sheets]
	 * The latter being equivalent to append */
	if (index > ctx->n_sheets)
		return CSS_INVALID;

	temp = ctx->alloc(ctx->sheets, 
			(ctx->n_sheets + 1) * sizeof(css_stylesheet *),
			ctx->pw);
	if (temp == NULL)
		return CSS_NOMEM;

	ctx->sheets = temp;

	if (index < ctx->n_sheets) {
		memmove(&ctx->sheets[index + 1], &ctx->sheets[index],
			(ctx->n_sheets - index) * sizeof(css_stylesheet *));
	}

	ctx->sheets[index] = sheet;

	ctx->n_sheets++;

	return CSS_OK;
}

/**
 * Remove a sheet from a selection context
 *
 * \param ctx    The context to remove from
 * \param sheet  Sheet to remove
 * \return CSS_OK on success, appropriate error otherwise
 */
css_error css_select_ctx_remove_sheet(css_select_ctx *ctx,
		const css_stylesheet *sheet)
{
	uint32_t index;

	if (ctx == NULL || sheet == NULL)
		return CSS_BADPARM;

	for (index = 0; index < ctx->n_sheets; index++) {
		if (ctx->sheets[index] == sheet)
			break;
	}

	if (index == ctx->n_sheets)
		return CSS_INVALID;

	memmove(&ctx->sheets[index], &ctx->sheets[index + 1],
			(ctx->n_sheets - index) * sizeof(css_stylesheet *));

	ctx->n_sheets--;

	return CSS_OK;

}

/**
 * Count the number of top-level sheets in a selection context
 *
 * \param ctx    Context to consider
 * \param count  Pointer to location to receive count of sheets
 * \return CSS_OK on success, appropriate error otherwise
 */
css_error css_select_ctx_count_sheets(css_select_ctx *ctx, uint32_t *count)
{
	if (ctx == NULL || count == NULL)
		return CSS_BADPARM;

	*count = ctx->n_sheets;

	return CSS_OK;
}

/**
 * Retrieve a sheet from a selection context
 *
 * \param ctx    Context to look in
 * \param index  Index in context to look
 * \param sheet  Pointer to location to receive sheet
 * \return CSS_OK on success, appropriate error otherwise
 */
css_error css_select_ctx_get_sheet(css_select_ctx *ctx, uint32_t index,
		const css_stylesheet **sheet)
{
	if (ctx == NULL || sheet == NULL)
		return CSS_BADPARM;

	if (index > ctx->n_sheets)
		return CSS_INVALID;

	*sheet = ctx->sheets[index];

	return CSS_OK;
}

/**
 * Select a style for the given node
 *
 * \param ctx             Selection context to use
 * \param node            Node to select style for
 * \param pseudo_element  Pseudo element to select for, instead
 * \param pseudo_classes  Currently active pseudo classes
 * \param media           Currently active media types
 * \param result          Pointer to style to populate
 * \param handler         Dispatch table of handler functions
 * \param pw              Client-specific private data for handler functions
 * \return CSS_OK on success, appropriate error otherwise.
 *
 * In computing the style, no reference is made to the parent node's
 * style. Therefore, the resultant computed style is not ready for
 * immediate use, as some properties may be marked as inherited.
 * Use css_computed_style_compose() to obtain a fully computed style.
 *
 * This two-step approach to style computation is designed to allow
 * the client to store the partially computed style and efficiently
 * update the fully computed style for a node when layout changes.
 */
css_error css_select_style(css_select_ctx *ctx, void *node,
		uint64_t pseudo_element, uint64_t pseudo_classes,
		uint64_t media,	css_computed_style *result,
		css_select_handler *handler, void *pw)
{
	uint32_t i;
	css_error error;
	css_select_state state;

	if (ctx == NULL || node == NULL || result == NULL)
		return CSS_BADPARM;

	/* Set up the selection state */
	memset(&state, 0, sizeof(css_select_state));
	state.node = node;
	state.pseudo_element = pseudo_element;
	state.pseudo_classes = pseudo_classes;
	state.media = media;
	state.result = result;
	state.handler = handler;
	state.pw = pw;

	/* Iterate through the top-level stylesheets, selecting styles
	 * from those which apply to our current media requirements */
	for (i = 0; i < ctx->n_sheets; i++) {
		if ((ctx->sheets[i]->media & media) != 0) {
			error = select_from_sheet(ctx, ctx->sheets[i], &state);
			if (error != CSS_OK)
				return error;
		}
	}

	/* Finally, fix up any remaining unset properties.
	 * Those properties which are inherited, need to be set as inherit.
	 * Those which are not inherited need to be set to their default value.
	 */
	/** \todo fixup unset properties */

	return CSS_OK;
}

/******************************************************************************
 * Selection engine internals below here                                      *
 ******************************************************************************/
css_error select_from_sheet(css_select_ctx *ctx, const css_stylesheet *sheet, 
		css_select_state *state)
{
	const css_stylesheet *s = sheet;
	const css_rule *rule = s->rule_list;

	do {
		/* Find first non-charset rule, if we're at the list head */
		if (rule == s->rule_list) {
			for (; rule != NULL; rule = rule->next) {
				if (rule->type != CSS_RULE_CHARSET)
					break;
			}
		}

		if (rule != NULL && rule->type == CSS_RULE_IMPORT) {
			/* Current rule is an import */
			const css_rule_import *import = 
					(const css_rule_import *) rule;

			if (import->sheet != NULL &&
					(import->sheet->media & 
					state->media) != 0) {
				/* It's applicable, so process it */
				s = import->sheet;
				rule = s->rule_list;
			} else {
				/* Not applicable; skip over it */
				rule = rule->next;
			}
		} else {
			/* Gone past import rules in this sheet */
			css_error error;

			/* Process this sheet */
			state->current_sheet++;

			error = match_selectors_in_sheet(ctx, s, state);
			if (error != CSS_OK)
				return error;

			/* Find next sheet to process */
			if (s->ownerRule != NULL) {
				s = s->ownerRule->parent;
				rule = s->ownerRule->next;
			} else {
				s = NULL;
			}
		}
	} while (s != NULL);

	return CSS_OK;
}

css_error match_selectors_in_sheet(css_select_ctx *ctx, 
		const css_stylesheet *sheet, css_select_state *state)
{
	const parserutils_hash_entry *universal;
	const parserutils_hash_entry *element;
	const css_selector **selectors;
	const uint8_t *name;
	size_t len;
	parserutils_error perror;
	css_error error;

	/* Get node's name */
	error = state->handler->node_name(state->pw, state->node, &name, &len);
	if (error != CSS_OK)
		return error;

	/* Intern it */
	perror = parserutils_hash_insert(sheet->dictionary,
			name, len, &element);
	if (perror != PARSERUTILS_OK)
		return css_error_from_parserutils_error(perror);

	/* Intern universal selector string */
	perror = parserutils_hash_insert(sheet->dictionary, 
			(const uint8_t *) "*", 1, &universal);
	if (perror != PARSERUTILS_OK)
		return css_error_from_parserutils_error(perror);

	/* Find hash chain that applies to current node */
	error = css_selector_hash_find(sheet->selectors, element, &selectors);
	if (error != CSS_OK)
		return error;

	/* Process any matching selectors */
	while (*selectors != NULL) {
		error = match_selector_chain(ctx, *selectors, 
				sheet->origin, state, universal);
		if (error != CSS_OK)
			return error;

		error = css_selector_hash_iterate(sheet->selectors, selectors,
				&selectors);
		if (error != CSS_OK)
			return error;
	}

	/* Find hash chain for universal selector */
	error = css_selector_hash_find(sheet->selectors, universal, &selectors);
	if (error != CSS_OK)
		return error;

	/* Process any matching selectors */
	while (*selectors != NULL) {
		error = match_selector_chain(ctx, *selectors, 
				sheet->origin, state, universal);
		if (error != CSS_OK)
			return error;

		error = css_selector_hash_iterate(sheet->selectors, selectors,
				&selectors);
		if (error != CSS_OK)
			return error;
	}

	return CSS_OK;
}

css_error match_selector_chain(css_select_ctx *ctx, 
		const css_selector *selector, css_origin origin, 
		css_select_state *state, 
		const parserutils_hash_entry *universal)
{
	const css_selector *s = selector;
	void *node = state->node;
	css_error error;

	do {
		void *next_node = NULL;
		const css_selector_detail *detail = &s->data;
		bool match = false;

		/* First, consider any named combinator on this selector */
		if (s->data.comb != CSS_COMBINATOR_NONE &&
				s->combinator->data.name != universal) {
			error = match_named_combinator(ctx, s->data.comb, 
					s->combinator->data.name, state, node, 
					&next_node);
			if (error != CSS_OK)
				return error;

			/* No match for combinator, so reject selector chain */
			if (next_node == NULL)
				return CSS_OK;
		}

		/* Now match details on this selector */
		error = match_details(ctx, node, detail, state, &match);
		if (error != CSS_OK)
			return error;

		/* Details don't match, so reject selector chain */
		if (match == false)
			return CSS_OK;

		/* If we had a universal combinator, then consider that */
		if (s->data.comb != CSS_COMBINATOR_NONE &&
				s->combinator->data.name == universal) {
			error = match_universal_combinator(ctx, s->data.comb, 
					s->combinator, state, node, &next_node);
			if (error != CSS_OK)
				return error;

			/* No match for combinator, so reject selector chain */
			if (next_node == NULL)
				return CSS_OK;
		}

		/* Details matched, so progress to combining selector */
		s = s->combinator;
		node = next_node;
	} while (s != NULL);

	/* If we got here, then the entire selector chain matched, so cascade */
	return cascade_style(ctx,
			((css_rule_selector *) selector->rule)->style, 
			selector->specificity, origin, selector->rule->index,
			state);
}

css_error match_named_combinator(css_select_ctx *ctx, css_combinator type,
		const parserutils_hash_entry *name, css_select_state *state,
		void *node, void **next_node)
{
	css_error error;

	UNUSED(ctx);

	switch (type) {
	case CSS_COMBINATOR_ANCESTOR:
		error = state->handler->named_ancestor_node(state->pw, node, 
				name->data, name->len, next_node);
		if (error != CSS_OK)
			return error;
		break;
	case CSS_COMBINATOR_PARENT:
		error = state->handler->named_parent_node(state->pw, node, 
				name->data, name->len, next_node);
		if (error != CSS_OK)
			return error;
		break;
	case CSS_COMBINATOR_SIBLING:
		error = state->handler->named_sibling_node(state->pw, node, 
				name->data, name->len, next_node);
		if (error != CSS_OK)
			return error;
		break;
	case CSS_COMBINATOR_NONE:
		break;
	}

	return CSS_OK;
}

css_error match_universal_combinator(css_select_ctx *ctx, css_combinator type,
		const css_selector *selector, css_select_state *state,
		void *node, void **next_node)
{
	const css_selector_detail *detail = &selector->data;
	void *n = node;
	css_error error;

	do {
		bool match = false;

		/* Find candidate node */
		switch (type) {
		case CSS_COMBINATOR_ANCESTOR:
		case CSS_COMBINATOR_PARENT:
			error = state->handler->parent_node(state->pw, n, &n);
			if (error != CSS_OK)
				return error;
			break;
		case CSS_COMBINATOR_SIBLING:
			error = state->handler->sibling_node(state->pw, n, &n);
			if (error != CSS_OK)
				return error;
			break;
		case CSS_COMBINATOR_NONE:
			break;
		}

		/* Match its details */
		error = match_details(ctx, n, detail, state, &match);
		if (error != CSS_OK)
			return error;

		/* If we found a match, use it */
		if (match == true)
			break;

		/* Wanted the parent, but it didn't match, so stop looking */
		if (type == CSS_COMBINATOR_PARENT)
			n = NULL;
	} while (n != NULL);

	*next_node = n;

	return CSS_OK;
}

css_error match_details(css_select_ctx *ctx, void *node, 
		const css_selector_detail *detail, css_select_state *state, 
		bool *match)
{
	css_error error;

	while (detail->next != 0) {
		/* Don't bother with the first detail, as it's the 
		 * element selector */
		detail++;

		error = match_detail(ctx, node, detail, state, match);
		if (error != CSS_OK)
			return error;

		/* Detail doesn't match, so reject selector chain */
		if (*match == false)
			return CSS_OK;
	}

	return CSS_OK;
}


css_error match_detail(css_select_ctx *ctx, void *node, 
		const css_selector_detail *detail, css_select_state *state, 
		bool *match)
{
	css_error error = CSS_OK;

	UNUSED(ctx);

	switch (detail->type) {
	case CSS_SELECTOR_CLASS:
		error = state->handler->node_has_class(state->pw, node,
				detail->name->data, detail->name->len,
				match);
		break;
	case CSS_SELECTOR_ID:
		error = state->handler->node_has_id(state->pw, node,
				detail->name->data, detail->name->len,
				match);
		break;
	case CSS_SELECTOR_PSEUDO:
		/** \todo pseudo classes/elements */
		break;
	case CSS_SELECTOR_ATTRIBUTE:
		error = state->handler->node_has_attribute(state->pw, node,
				detail->name->data, detail->name->len,
				match);
		break;
	case CSS_SELECTOR_ATTRIBUTE_EQUAL:
		error = state->handler->node_has_attribute_equal(state->pw, 
				node, detail->name->data, detail->name->len,
				detail->value->data, detail->value->len,
				match);
		break;
	case CSS_SELECTOR_ATTRIBUTE_DASHMATCH:
		error = state->handler->node_has_attribute_dashmatch(state->pw,
				node, detail->name->data, detail->name->len,
				detail->value->data, detail->value->len,
				match);
		break;
	case CSS_SELECTOR_ATTRIBUTE_INCLUDES:
		error = state->handler->node_has_attribute_includes(state->pw, 
				node, detail->name->data, detail->name->len,
				detail->value->data, detail->value->len,
				match);
		break;
	}

	return error;
}

css_error cascade_style(css_select_ctx *ctx, css_style *style, 
		uint32_t specificity, css_origin origin, uint32_t rule_index,
		css_select_state *state)
{
	UNUSED(ctx);
	UNUSED(style);
	UNUSED(specificity);
	UNUSED(origin);
	UNUSED(rule_index);
	UNUSED(state);

	return CSS_OK;
}