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/*
* Copyright (C) 1999 Lars Knoll (knoll@kde.org)
* (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
* Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
* Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights
* reserved.
* Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
* Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
* Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
* (http://www.torchmobile.com/)
* Copyright (c) 2011, Code Aurora Forum. All rights reserved.
* Copyright (C) Research In Motion Limited 2011. All rights reserved.
* Copyright (C) 2012 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_SELECTOR_FILTER_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_CSS_SELECTOR_FILTER_H_
#include <memory>
#include "base/macros.h"
#include "third_party/blink/renderer/core/dom/element.h"
#include "third_party/blink/renderer/platform/wtf/bloom_filter.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"
namespace blink {
class CSSSelector;
class CORE_EXPORT SelectorFilter {
DISALLOW_NEW();
public:
class ParentStackFrame {
DISALLOW_NEW();
public:
ParentStackFrame() : element(nullptr) {}
explicit ParentStackFrame(Element& element) : element(&element) {}
void Trace(Visitor*);
Member<Element> element;
Vector<unsigned, 4> identifier_hashes;
};
SelectorFilter() = default;
void PushParent(Element& parent);
void PopParent(Element& parent);
bool ParentStackIsConsistent(const ContainerNode* parent_node) const {
return !parent_stack_.IsEmpty() &&
parent_stack_.back().element == parent_node;
}
template <unsigned maximumIdentifierCount>
inline bool FastRejectSelector(const unsigned* identifier_hashes) const;
static void CollectIdentifierHashes(const CSSSelector&,
unsigned* identifier_hashes,
unsigned maximum_identifier_count);
void Trace(Visitor*);
private:
void PushParentStackFrame(Element& parent);
void PopParentStackFrame();
HeapVector<ParentStackFrame> parent_stack_;
// With 100 unique strings in the filter, 2^12 slot table has false positive
// rate of ~0.2%.
using IdentifierFilter = BloomFilter<12>;
std::unique_ptr<IdentifierFilter> ancestor_identifier_filter_;
DISALLOW_COPY_AND_ASSIGN(SelectorFilter);
};
template <unsigned maximumIdentifierCount>
inline bool SelectorFilter::FastRejectSelector(
const unsigned* identifier_hashes) const {
DCHECK(ancestor_identifier_filter_);
for (unsigned n = 0; n < maximumIdentifierCount && identifier_hashes[n];
++n) {
if (!ancestor_identifier_filter_->MayContain(identifier_hashes[n]))
return true;
}
return false;
}
} // namespace blink
WTF_ALLOW_INIT_WITH_MEM_FUNCTIONS(blink::SelectorFilter::ParentStackFrame)
#endif
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