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/*
* Copyright (C) 1999 Lars Knoll (knoll@kde.org)
* Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc.
* All rights reserved.
* Copyright (C) 2013 Google Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_CSS_RESOLVER_MATCHED_PROPERTIES_CACHE_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_CSS_RESOLVER_MATCHED_PROPERTIES_CACHE_H_
#include "base/macros.h"
#include "third_party/blink/renderer/core/css/css_property_value_set.h"
#include "third_party/blink/renderer/core/css/resolver/match_result.h"
#include "third_party/blink/renderer/platform/heap/handle.h"
#include "third_party/blink/renderer/platform/wtf/forward.h"
#include "third_party/blink/renderer/platform/wtf/hash_map.h"
#include "third_party/blink/renderer/platform/wtf/noncopyable.h"
namespace blink {
class ComputedStyle;
class StyleResolverState;
class CachedMatchedProperties final
: public GarbageCollectedFinalized<CachedMatchedProperties> {
public:
HeapVector<MatchedProperties> matched_properties;
scoped_refptr<ComputedStyle> computed_style;
scoped_refptr<ComputedStyle> parent_computed_style;
void Set(const ComputedStyle&,
const ComputedStyle& parent_style,
const MatchedPropertiesVector&);
void Clear();
void Trace(blink::Visitor* visitor) { visitor->Trace(matched_properties); }
};
// Specialize the HashTraits for CachedMatchedProperties to check for dead
// entries in the MatchedPropertiesCache.
struct CachedMatchedPropertiesHashTraits
: HashTraits<Member<CachedMatchedProperties>> {
static const WTF::WeakHandlingFlag kWeakHandlingFlag = WTF::kWeakHandling;
static bool IsAlive(Member<CachedMatchedProperties>& cached_properties) {
// Semantics see |CachedMatchedPropertiesHashTraits::TraceInCollection|.
if (cached_properties) {
for (const auto& matched_properties :
cached_properties->matched_properties) {
if (!ThreadHeap::IsHeapObjectAlive(matched_properties.properties)) {
return false;
}
}
}
return true;
}
template <typename VisitorDispatcher>
static bool TraceInCollection(
VisitorDispatcher visitor,
Member<CachedMatchedProperties>& cached_properties,
WTF::WeakHandlingFlag weakness) {
// Only honor the cache's weakness semantics if the collection is traced
// with |kWeakPointersActWeak|. Otherwise just trace the cachedProperties
// strongly, i.e., call trace on it.
if (cached_properties && weakness == WTF::kWeakHandling) {
// A given cache entry is only kept alive if none of the MatchedProperties
// in the CachedMatchedProperties value contain a dead "properties" field.
// If there is a dead field the entire cache entry is removed.
for (const auto& matched_properties :
cached_properties->matched_properties) {
if (!ThreadHeap::IsHeapObjectAlive(matched_properties.properties)) {
// For now report the cache entry as dead. This might not
// be the final result if in a subsequent call for this entry,
// the "properties" field has been marked via another path.
return true;
}
}
}
// At this point none of the entries in the matchedProperties vector
// had a dead "properties" field so trace CachedMatchedProperties strongly.
visitor->Trace(cached_properties);
return false;
}
};
class MatchedPropertiesCache {
DISALLOW_NEW();
public:
MatchedPropertiesCache();
~MatchedPropertiesCache() { DCHECK(cache_.IsEmpty()); }
const CachedMatchedProperties* Find(unsigned hash,
const StyleResolverState&,
const MatchedPropertiesVector&);
void Add(const ComputedStyle&,
const ComputedStyle& parent_style,
unsigned hash,
const MatchedPropertiesVector&);
void Clear();
void ClearViewportDependent();
static bool IsCacheable(const StyleResolverState&);
static bool IsStyleCacheable(const ComputedStyle&);
void Trace(blink::Visitor*);
private:
using Cache = HeapHashMap<unsigned,
Member<CachedMatchedProperties>,
DefaultHash<unsigned>::Hash,
HashTraits<unsigned>,
CachedMatchedPropertiesHashTraits>;
Cache cache_;
DISALLOW_COPY_AND_ASSIGN(MatchedPropertiesCache);
};
} // namespace blink
#endif
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