summaryrefslogtreecommitdiffstats
path: root/servo/components/style/invalidation/stylesheets.rs
blob: d845897aa44ee3226bec640ea5add0bd9e42cb5b (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
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

//! A collection of invalidations due to changes in which stylesheets affect a
//! document.

#![deny(unsafe_code)]

use crate::context::QuirksMode;
use crate::dom::{TDocument, TElement, TNode};
use crate::invalidation::element::element_wrapper::{ElementSnapshot, ElementWrapper};
use crate::invalidation::element::restyle_hints::RestyleHint;
use crate::media_queries::Device;
use crate::selector_map::{MaybeCaseInsensitiveHashMap, PrecomputedHashMap};
use crate::selector_parser::{SelectorImpl, Snapshot, SnapshotMap};
use crate::shared_lock::SharedRwLockReadGuard;
use crate::stylesheets::{CssRule, StylesheetInDocument};
use crate::stylesheets::{EffectiveRules, EffectiveRulesIterator};
use crate::values::AtomIdent;
use crate::LocalName as SelectorLocalName;
use crate::{Atom, ShrinkIfNeeded};
use selectors::parser::{Component, LocalName, Selector};

/// The kind of change that happened for a given rule.
#[repr(u32)]
#[derive(Clone, Copy, Debug, Eq, Hash, MallocSizeOf, PartialEq)]
pub enum RuleChangeKind {
    /// The rule was inserted.
    Insertion,
    /// The rule was removed.
    Removal,
    /// Some change in the rule which we don't know about, and could have made
    /// the rule change in any way.
    Generic,
    /// A change in the declarations of a style rule.
    StyleRuleDeclarations,
}

/// A style sheet invalidation represents a kind of element or subtree that may
/// need to be restyled. Whether it represents a whole subtree or just a single
/// element is determined by the given InvalidationKind in
/// StylesheetInvalidationSet's maps.
#[derive(Debug, Eq, Hash, MallocSizeOf, PartialEq)]
enum Invalidation {
    /// An element with a given id.
    ID(AtomIdent),
    /// An element with a given class name.
    Class(AtomIdent),
    /// An element with a given local name.
    LocalName {
        name: SelectorLocalName,
        lower_name: SelectorLocalName,
    },
}

impl Invalidation {
    fn is_id(&self) -> bool {
        matches!(*self, Invalidation::ID(..))
    }

    fn is_id_or_class(&self) -> bool {
        matches!(*self, Invalidation::ID(..) | Invalidation::Class(..))
    }
}

/// Whether we should invalidate just the element, or the whole subtree within
/// it.
#[derive(Clone, Copy, Debug, Eq, MallocSizeOf, Ord, PartialEq, PartialOrd)]
enum InvalidationKind {
    None = 0,
    Element,
    Scope,
}

impl std::ops::BitOrAssign for InvalidationKind {
    #[inline]
    fn bitor_assign(&mut self, other: Self) {
        *self = std::cmp::max(*self, other);
    }
}

impl InvalidationKind {
    #[inline]
    fn is_scope(self) -> bool {
        matches!(self, Self::Scope)
    }

    #[inline]
    fn add(&mut self, other: Option<&InvalidationKind>) {
        if let Some(other) = other {
            *self |= *other;
        }
    }
}

/// A set of invalidations due to stylesheet additions.
///
/// TODO(emilio): We might be able to do the same analysis for media query
/// changes too (or even selector changes?).
#[derive(Debug, Default, MallocSizeOf)]
pub struct StylesheetInvalidationSet {
    classes: MaybeCaseInsensitiveHashMap<Atom, InvalidationKind>,
    ids: MaybeCaseInsensitiveHashMap<Atom, InvalidationKind>,
    local_names: PrecomputedHashMap<SelectorLocalName, InvalidationKind>,
    fully_invalid: bool,
}

impl StylesheetInvalidationSet {
    /// Create an empty `StylesheetInvalidationSet`.
    pub fn new() -> Self {
        Default::default()
    }

    /// Mark the DOM tree styles' as fully invalid.
    pub fn invalidate_fully(&mut self) {
        debug!("StylesheetInvalidationSet::invalidate_fully");
        self.clear();
        self.fully_invalid = true;
    }

    fn shrink_if_needed(&mut self) {
        if self.fully_invalid {
            return;
        }
        self.classes.shrink_if_needed();
        self.ids.shrink_if_needed();
        self.local_names.shrink_if_needed();
    }

    /// Analyze the given stylesheet, and collect invalidations from their
    /// rules, in order to avoid doing a full restyle when we style the document
    /// next time.
    pub fn collect_invalidations_for<S>(
        &mut self,
        device: &Device,
        stylesheet: &S,
        guard: &SharedRwLockReadGuard,
    ) where
        S: StylesheetInDocument,
    {
        debug!("StylesheetInvalidationSet::collect_invalidations_for");
        if self.fully_invalid {
            debug!(" > Fully invalid already");
            return;
        }

        if !stylesheet.enabled() || !stylesheet.is_effective_for_device(device, guard) {
            debug!(" > Stylesheet was not effective");
            return; // Nothing to do here.
        }

        let quirks_mode = device.quirks_mode();
        for rule in stylesheet.effective_rules(device, guard) {
            self.collect_invalidations_for_rule(
                rule,
                guard,
                device,
                quirks_mode,
                /* is_generic_change = */ false,
            );
            if self.fully_invalid {
                break;
            }
        }

        self.shrink_if_needed();

        debug!(" > resulting class invalidations: {:?}", self.classes);
        debug!(" > resulting id invalidations: {:?}", self.ids);
        debug!(
            " > resulting local name invalidations: {:?}",
            self.local_names
        );
        debug!(" > fully_invalid: {}", self.fully_invalid);
    }

    /// Clears the invalidation set, invalidating elements as needed if
    /// `document_element` is provided.
    ///
    /// Returns true if any invalidations ocurred.
    pub fn flush<E>(&mut self, document_element: Option<E>, snapshots: Option<&SnapshotMap>) -> bool
    where
        E: TElement,
    {
        debug!(
            "Stylist::flush({:?}, snapshots: {})",
            document_element,
            snapshots.is_some()
        );
        let have_invalidations = match document_element {
            Some(e) => self.process_invalidations(e, snapshots),
            None => false,
        };
        self.clear();
        have_invalidations
    }

    /// Returns whether there's no invalidation to process.
    pub fn is_empty(&self) -> bool {
        !self.fully_invalid &&
            self.classes.is_empty() &&
            self.ids.is_empty() &&
            self.local_names.is_empty()
    }

    fn invalidation_kind_for<E>(
        &self,
        element: E,
        snapshot: Option<&Snapshot>,
        quirks_mode: QuirksMode,
    ) -> InvalidationKind
    where
        E: TElement,
    {
        debug_assert!(!self.fully_invalid);

        let mut kind = InvalidationKind::None;

        if !self.classes.is_empty() {
            element.each_class(|c| {
                kind.add(self.classes.get(c, quirks_mode));
            });

            if kind.is_scope() {
                return kind;
            }

            if let Some(snapshot) = snapshot {
                snapshot.each_class(|c| {
                    kind.add(self.classes.get(c, quirks_mode));
                });

                if kind.is_scope() {
                    return kind;
                }
            }
        }

        if !self.ids.is_empty() {
            if let Some(ref id) = element.id() {
                kind.add(self.ids.get(id, quirks_mode));
                if kind.is_scope() {
                    return kind;
                }
            }

            if let Some(ref old_id) = snapshot.and_then(|s| s.id_attr()) {
                kind.add(self.ids.get(old_id, quirks_mode));
                if kind.is_scope() {
                    return kind;
                }
            }
        }

        if !self.local_names.is_empty() {
            kind.add(self.local_names.get(element.local_name()));
        }

        kind
    }

    /// Clears the invalidation set without processing.
    pub fn clear(&mut self) {
        self.classes.clear();
        self.ids.clear();
        self.local_names.clear();
        self.fully_invalid = false;
        debug_assert!(self.is_empty());
    }

    fn process_invalidations<E>(&self, element: E, snapshots: Option<&SnapshotMap>) -> bool
    where
        E: TElement,
    {
        debug!("Stylist::process_invalidations({:?}, {:?})", element, self);

        {
            let mut data = match element.mutate_data() {
                Some(data) => data,
                None => return false,
            };

            if self.fully_invalid {
                debug!("process_invalidations: fully_invalid({:?})", element);
                data.hint.insert(RestyleHint::restyle_subtree());
                return true;
            }
        }

        if self.is_empty() {
            debug!("process_invalidations: empty invalidation set");
            return false;
        }

        let quirks_mode = element.as_node().owner_doc().quirks_mode();
        self.process_invalidations_in_subtree(element, snapshots, quirks_mode)
    }

    /// Process style invalidations in a given subtree. This traverses the
    /// subtree looking for elements that match the invalidations in our hash
    /// map members.
    ///
    /// Returns whether it invalidated at least one element's style.
    #[allow(unsafe_code)]
    fn process_invalidations_in_subtree<E>(
        &self,
        element: E,
        snapshots: Option<&SnapshotMap>,
        quirks_mode: QuirksMode,
    ) -> bool
    where
        E: TElement,
    {
        debug!("process_invalidations_in_subtree({:?})", element);
        let mut data = match element.mutate_data() {
            Some(data) => data,
            None => return false,
        };

        if !data.has_styles() {
            return false;
        }

        if data.hint.contains_subtree() {
            debug!(
                "process_invalidations_in_subtree: {:?} was already invalid",
                element
            );
            return false;
        }

        let element_wrapper = snapshots.map(|s| ElementWrapper::new(element, s));
        let snapshot = element_wrapper.as_ref().and_then(|e| e.snapshot());

        match self.invalidation_kind_for(element, snapshot, quirks_mode) {
            InvalidationKind::None => {},
            InvalidationKind::Element => {
                debug!(
                    "process_invalidations_in_subtree: {:?} matched self",
                    element
                );
                data.hint.insert(RestyleHint::RESTYLE_SELF);
            },
            InvalidationKind::Scope => {
                debug!(
                    "process_invalidations_in_subtree: {:?} matched subtree",
                    element
                );
                data.hint.insert(RestyleHint::restyle_subtree());
                return true;
            },
        }

        let mut any_children_invalid = false;

        for child in element.traversal_children() {
            let child = match child.as_element() {
                Some(e) => e,
                None => continue,
            };

            any_children_invalid |=
                self.process_invalidations_in_subtree(child, snapshots, quirks_mode);
        }

        if any_children_invalid {
            debug!(
                "Children of {:?} changed, setting dirty descendants",
                element
            );
            unsafe { element.set_dirty_descendants() }
        }

        data.hint.contains(RestyleHint::RESTYLE_SELF) || any_children_invalid
    }

    /// TODO(emilio): Reuse the bucket stuff from selectormap? That handles
    /// :is() / :where() etc.
    fn scan_component(
        component: &Component<SelectorImpl>,
        invalidation: &mut Option<Invalidation>,
    ) {
        match *component {
            Component::LocalName(LocalName {
                ref name,
                ref lower_name,
            }) => {
                if invalidation.is_none() {
                    *invalidation = Some(Invalidation::LocalName {
                        name: name.clone(),
                        lower_name: lower_name.clone(),
                    });
                }
            },
            Component::Class(ref class) => {
                if invalidation.as_ref().map_or(true, |s| !s.is_id_or_class()) {
                    *invalidation = Some(Invalidation::Class(class.clone()));
                }
            },
            Component::ID(ref id) => {
                if invalidation.as_ref().map_or(true, |s| !s.is_id()) {
                    *invalidation = Some(Invalidation::ID(id.clone()));
                }
            },
            _ => {
                // Ignore everything else, at least for now.
            },
        }
    }

    /// Collect invalidations for a given selector.
    ///
    /// We look at the outermost local name, class, or ID selector to the left
    /// of an ancestor combinator, in order to restyle only a given subtree.
    ///
    /// If the selector has no ancestor combinator, then we do the same for
    /// the only sequence it has, but record it as an element invalidation
    /// instead of a subtree invalidation.
    ///
    /// We prefer IDs to classs, and classes to local names, on the basis
    /// that the former should be more specific than the latter. We also
    /// prefer to generate subtree invalidations for the outermost part
    /// of the selector, to reduce the amount of traversal we need to do
    /// when flushing invalidations.
    fn collect_invalidations(
        &mut self,
        selector: &Selector<SelectorImpl>,
        quirks_mode: QuirksMode,
    ) {
        debug!(
            "StylesheetInvalidationSet::collect_invalidations({:?})",
            selector
        );

        let mut element_invalidation: Option<Invalidation> = None;
        let mut subtree_invalidation: Option<Invalidation> = None;

        let mut scan_for_element_invalidation = true;
        let mut scan_for_subtree_invalidation = false;

        let mut iter = selector.iter();

        loop {
            for component in &mut iter {
                if scan_for_element_invalidation {
                    Self::scan_component(component, &mut element_invalidation);
                } else if scan_for_subtree_invalidation {
                    Self::scan_component(component, &mut subtree_invalidation);
                }
            }
            match iter.next_sequence() {
                None => break,
                Some(combinator) => {
                    scan_for_subtree_invalidation = combinator.is_ancestor();
                },
            }
            scan_for_element_invalidation = false;
        }

        if let Some(s) = subtree_invalidation {
            debug!(" > Found subtree invalidation: {:?}", s);
            if self.insert_invalidation(s, InvalidationKind::Scope, quirks_mode) {
                return;
            }
        }

        if let Some(s) = element_invalidation {
            debug!(" > Found element invalidation: {:?}", s);
            if self.insert_invalidation(s, InvalidationKind::Element, quirks_mode) {
                return;
            }
        }

        // The selector was of a form that we can't handle. Any element could
        // match it, so let's just bail out.
        debug!(" > Can't handle selector or OOMd, marking fully invalid");
        self.invalidate_fully()
    }

    fn insert_invalidation(
        &mut self,
        invalidation: Invalidation,
        kind: InvalidationKind,
        quirks_mode: QuirksMode,
    ) -> bool {
        match invalidation {
            Invalidation::Class(c) => {
                let entry = match self.classes.try_entry(c.0, quirks_mode) {
                    Ok(e) => e,
                    Err(..) => return false,
                };
                *entry.or_insert(InvalidationKind::None) |= kind;
            },
            Invalidation::ID(i) => {
                let entry = match self.ids.try_entry(i.0, quirks_mode) {
                    Ok(e) => e,
                    Err(..) => return false,
                };
                *entry.or_insert(InvalidationKind::None) |= kind;
            },
            Invalidation::LocalName { name, lower_name } => {
                let insert_lower = name != lower_name;
                if self.local_names.try_reserve(1).is_err() {
                    return false;
                }
                let entry = self.local_names.entry(name);
                *entry.or_insert(InvalidationKind::None) |= kind;
                if insert_lower {
                    if self.local_names.try_reserve(1).is_err() {
                        return false;
                    }
                    let entry = self.local_names.entry(lower_name);
                    *entry.or_insert(InvalidationKind::None) |= kind;
                }
            },
        }

        true
    }

    /// Collects invalidations for a given CSS rule, if not fully invalid
    /// already.
    ///
    /// TODO(emilio): we can't check whether the rule is inside a non-effective
    /// subtree, we potentially could do that.
    pub fn rule_changed<S>(
        &mut self,
        stylesheet: &S,
        rule: &CssRule,
        guard: &SharedRwLockReadGuard,
        device: &Device,
        quirks_mode: QuirksMode,
        change_kind: RuleChangeKind,
    ) where
        S: StylesheetInDocument,
    {
        debug!("StylesheetInvalidationSet::rule_changed");
        if self.fully_invalid {
            return;
        }

        if !stylesheet.enabled() || !stylesheet.is_effective_for_device(device, guard) {
            debug!(" > Stylesheet was not effective");
            return; // Nothing to do here.
        }

        // If the change is generic, we don't have the old rule information to know e.g., the old
        // media condition, or the old selector text, so we might need to invalidate more
        // aggressively. That only applies to the changed rules, for other rules we can just
        // collect invalidations as normal.
        let is_generic_change = change_kind == RuleChangeKind::Generic;
        self.collect_invalidations_for_rule(rule, guard, device, quirks_mode, is_generic_change);
        if self.fully_invalid {
            return;
        }

        if !is_generic_change && !EffectiveRules::is_effective(guard, device, quirks_mode, rule) {
            return;
        }

        let rules = EffectiveRulesIterator::effective_children(device, quirks_mode, guard, rule);
        for rule in rules {
            self.collect_invalidations_for_rule(
                rule,
                guard,
                device,
                quirks_mode,
                /* is_generic_change = */ false,
            );
            if self.fully_invalid {
                break;
            }
        }
    }

    /// Collects invalidations for a given CSS rule.
    fn collect_invalidations_for_rule(
        &mut self,
        rule: &CssRule,
        guard: &SharedRwLockReadGuard,
        device: &Device,
        quirks_mode: QuirksMode,
        is_generic_change: bool,
    ) {
        use crate::stylesheets::CssRule::*;
        debug!("StylesheetInvalidationSet::collect_invalidations_for_rule");
        debug_assert!(!self.fully_invalid, "Not worth being here!");

        match *rule {
            Style(ref lock) => {
                if is_generic_change {
                    // TODO(emilio): We need to do this for selector / keyframe
                    // name / font-face changes, because we don't have the old
                    // selector / name.  If we distinguish those changes
                    // specially, then we can at least use this invalidation for
                    // style declaration changes.
                    return self.invalidate_fully();
                }

                let style_rule = lock.read_with(guard);
                for selector in style_rule.selectors.slice() {
                    self.collect_invalidations(selector, quirks_mode);
                    if self.fully_invalid {
                        return;
                    }
                }
            },
            Namespace(..) => {
                // It's not clear what handling changes for this correctly would
                // look like.
            },
            LayerStatement(..) => {
                // Layer statement insertions might alter styling order, so we need to always
                // invalidate fully.
                return self.invalidate_fully();
            },
            Document(..) | Import(..) | Media(..) | Supports(..) | Container(..) |
            LayerBlock(..) => {
                // Do nothing, relevant nested rules are visited as part of rule iteration.
            },
            FontFace(..) => {
                // Do nothing, @font-face doesn't affect computed style information on it's own.
                // We'll restyle when the font face loads, if needed.
            },
            Page(..) | Margin(..) => {
                // Do nothing, we don't support OM mutations on print documents, and page rules
                // can't affect anything else.
            },
            Keyframes(ref lock) => {
                if is_generic_change {
                    return self.invalidate_fully();
                }
                let keyframes_rule = lock.read_with(guard);
                if device.animation_name_may_be_referenced(&keyframes_rule.name) {
                    debug!(
                        " > Found @keyframes rule potentially referenced \
                         from the page, marking the whole tree invalid."
                    );
                    self.invalidate_fully();
                } else {
                    // Do nothing, this animation can't affect the style of existing elements.
                }
            },
            CounterStyle(..) | Property(..) | FontFeatureValues(..) | FontPaletteValues(..) => {
                debug!(" > Found unsupported rule, marking the whole subtree invalid.");
                self.invalidate_fully();
            },
        }
    }
}