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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 MatchedPropertiesCache_h
#define MatchedPropertiesCache_h
#include "core/css/StylePropertySet.h"
#include "core/css/resolver/MatchResult.h"
#include "platform/heap/Handle.h"
#include "wtf/Forward.h"
#include "wtf/HashMap.h"
#include "wtf/Noncopyable.h"
namespace blink {
class ComputedStyle;
class StyleResolverState;
class CachedMatchedProperties final
: public GarbageCollectedFinalized<CachedMatchedProperties> {
public:
HeapVector<MatchedProperties> matchedProperties;
RefPtr<ComputedStyle> computedStyle;
RefPtr<ComputedStyle> parentComputedStyle;
void set(const ComputedStyle&,
const ComputedStyle& parentStyle,
const MatchedPropertiesVector&);
void clear();
DEFINE_INLINE_TRACE() { visitor->trace(matchedProperties); }
};
// Specialize the HashTraits for CachedMatchedProperties to check for dead
// entries in the MatchedPropertiesCache.
struct CachedMatchedPropertiesHashTraits
: HashTraits<Member<CachedMatchedProperties>> {
static const WTF::WeakHandlingFlag weakHandlingFlag =
WTF::WeakHandlingInCollections;
template <typename VisitorDispatcher>
static bool traceInCollection(
VisitorDispatcher visitor,
Member<CachedMatchedProperties>& cachedProperties,
WTF::ShouldWeakPointersBeMarkedStrongly strongify) {
// Only honor the cache's weakness semantics if the collection is traced
// with WeakPointersActWeak. Otherwise just trace the cachedProperties
// strongly, ie. call trace on it.
if (cachedProperties && strongify == WTF::WeakPointersActWeak) {
// 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& matchedProperties :
cachedProperties->matchedProperties) {
if (!ThreadHeap::isHeapObjectAlive(matchedProperties.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.
// FIXME: traceInCollection is also called from WeakProcessing to check if
// the entry is dead. Avoid calling trace in that case by only calling
// trace when cachedProperties is not yet marked.
if (!ThreadHeap::isHeapObjectAlive(cachedProperties))
visitor->trace(cachedProperties);
return false;
}
};
class MatchedPropertiesCache {
DISALLOW_NEW();
WTF_MAKE_NONCOPYABLE(MatchedPropertiesCache);
public:
MatchedPropertiesCache();
~MatchedPropertiesCache() { ASSERT(m_cache.isEmpty()); }
const CachedMatchedProperties* find(unsigned hash,
const StyleResolverState&,
const MatchedPropertiesVector&);
void add(const ComputedStyle&,
const ComputedStyle& parentStyle,
unsigned hash,
const MatchedPropertiesVector&);
void clear();
void clearViewportDependent();
static bool isCacheable(const StyleResolverState&);
DECLARE_TRACE();
private:
using Cache = HeapHashMap<unsigned,
Member<CachedMatchedProperties>,
DefaultHash<unsigned>::Hash,
HashTraits<unsigned>,
CachedMatchedPropertiesHashTraits>;
Cache m_cache;
};
} // namespace blink
#endif
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