1 /*
2 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
3 * (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
4 * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
5 * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
6 * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
7 * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
8 * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
9 * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
10 * Copyright (C) Research In Motion Limited 2011. All rights reserved.
11 * Copyright (C) 2012 Google Inc. All rights reserved.
12 *
13 * This library is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU Library General Public
15 * License as published by the Free Software Foundation; either
16 * version 2 of the License, or (at your option) any later version.
17 *
18 * This library is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 * Library General Public License for more details.
22 *
23 * You should have received a copy of the GNU Library General Public License
24 * along with this library; see the file COPYING.LIB. If not, write to
25 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
26 * Boston, MA 02110-1301, USA.
27 */
28
29 #ifndef SelectorFilter_h
30 #define SelectorFilter_h
31
32 #include "core/dom/Element.h"
33 #include "wtf/BloomFilter.h"
34 #include "wtf/Vector.h"
35
36 namespace WebCore {
37
38 class CSSSelector;
39
40 class SelectorFilter {
41 public:
42 void pushParentStackFrame(Element& parent);
43 void popParentStackFrame();
44
45 void setupParentStack(Element& parent);
46 void pushParent(Element& parent);
popParent()47 void popParent() { popParentStackFrame(); }
parentStackIsEmpty()48 bool parentStackIsEmpty() const { return m_parentStack.isEmpty(); }
parentStackIsConsistent(const ContainerNode * parentNode)49 bool parentStackIsConsistent(const ContainerNode* parentNode) const { return !m_parentStack.isEmpty() && m_parentStack.last().element == parentNode; }
50
51 template <unsigned maximumIdentifierCount>
52 inline bool fastRejectSelector(const unsigned* identifierHashes) const;
53 static void collectIdentifierHashes(const CSSSelector*, unsigned* identifierHashes, unsigned maximumIdentifierCount);
54
55 private:
56 struct ParentStackFrame {
ParentStackFrameParentStackFrame57 ParentStackFrame() : element(0) { }
ParentStackFrameParentStackFrame58 ParentStackFrame(Element& element) : element(&element) { }
59 Element* element;
60 Vector<unsigned, 4> identifierHashes;
61 };
62 Vector<ParentStackFrame> m_parentStack;
63
64 // With 100 unique strings in the filter, 2^12 slot table has false positive rate of ~0.2%.
65 static const unsigned bloomFilterKeyBits = 12;
66 OwnPtr<BloomFilter<bloomFilterKeyBits> > m_ancestorIdentifierFilter;
67 };
68
69 template <unsigned maximumIdentifierCount>
fastRejectSelector(const unsigned * identifierHashes)70 inline bool SelectorFilter::fastRejectSelector(const unsigned* identifierHashes) const
71 {
72 ASSERT(m_ancestorIdentifierFilter);
73 for (unsigned n = 0; n < maximumIdentifierCount && identifierHashes[n]; ++n) {
74 if (!m_ancestorIdentifierFilter->mayContain(identifierHashes[n]))
75 return true;
76 }
77 return false;
78 }
79
80 }
81
82 #endif
83