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LibWeb: Compress specificity into a 32-bit unsigned int

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Instead of storing the three-part specificy for every selector,
just mash them together into a 32-bit value instead.
This saves both space and time, and matches the behavior of other
browser engines.
This commit is contained in:
Andreas Kling 2020-06-25 16:43:49 +02:00
parent 8be74ea65c
commit 49dd4b7e8a
4 changed files with 6 additions and 68 deletions
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4
Libraries/LibWeb/CSS/Selector.cpp
View file

@ -37,7 +37,7 @@ Selector::~Selector()
{
}
Specificity Selector::specificity() const
u32 Selector::specificity() const
{
unsigned ids = 0;
unsigned tag_names = 0;
@ -61,7 +61,7 @@ Specificity Selector::specificity() const
}
}
return { ids, classes, tag_names };
return ids * 0x10000 + classes * 0x100 + tag_names;
}
}

2
Libraries/LibWeb/CSS/Selector.h
View file

@ -91,7 +91,7 @@ public:
const Vector<ComplexSelector>& complex_selectors() const { return m_complex_selectors; }
Specificity specificity() const;
u32 specificity() const;
private:
Vector<ComplexSelector> m_complex_selectors;

64
Libraries/LibWeb/CSS/Specificity.h
View file

@ -1,64 +0,0 @@
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
namespace Web {
class Specificity {
public:
Specificity(unsigned ids, unsigned classes, unsigned tag_names)
: m_ids(ids)
, m_classes(classes)
, m_tag_names(tag_names)
{
}
unsigned ids() const { return m_ids; }
unsigned classes() const { return m_classes; }
unsigned tag_names() const { return m_tag_names; }
bool operator<(const Specificity& other) const
{
return m_ids < other.m_ids
|| m_classes < other.m_classes
|| m_tag_names < other.m_tag_names;
}
bool operator==(const Specificity& other) const
{
return m_ids == other.m_ids
|| m_classes == other.m_classes
|| m_tag_names == other.m_tag_names;
}
private:
unsigned m_ids { 0 };
unsigned m_classes { 0 };
unsigned m_tag_names { 0 };
};
}

4
Libraries/LibWeb/CSS/StyleResolver.cpp
View file

@ -497,12 +497,14 @@ NonnullRefPtr<StyleProperties> StyleResolver::resolve_style(const Element& eleme
quick_sort(matching_rules, [&](MatchingRule& a, MatchingRule& b) {
auto& a_selector = a.rule->selectors()[a.selector_index];
auto& b_selector = b.rule->selectors()[b.selector_index];
auto a_specificity = a_selector.specificity();
auto b_specificity = b_selector.specificity();
if (a_selector.specificity() == b_selector.specificity()) {
if (a.style_sheet_index == b.style_sheet_index)
return a.rule_index < b.rule_index;
return a.style_sheet_index < b.style_sheet_index;
}
return a_selector.specificity() < b_selector.specificity();
return a_specificity < b_specificity;
});
for (auto& match : matching_rules) {