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ladybird/Libraries/LibWeb/CSS/StyleResolver.cpp
Andreas Kling d65bebd8cf LibWeb: Cache parsed inline style of DOM elements 
Instead of invoking the CSS parser every time we compute the style for
an element that has a "style" attribute, we now cache the result of
parsing the inline style whenever the "style" attribute is set.

This is a nice boost to relayout performance since we no longer hit the
CSS parser at all.
2020-12-07 20:00:27 +01:00

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/*
* 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.
*/
#include <AK/QuickSort.h>
#include <LibWeb/CSS/Parser/CSSParser.h>
#include <LibWeb/CSS/SelectorEngine.h>
#include <LibWeb/CSS/StyleResolver.h>
#include <LibWeb/CSS/StyleSheet.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/DOM/Element.h>
#include <LibWeb/Dump.h>
#include <ctype.h>
#include <stdio.h>
namespace Web::CSS {
StyleResolver::StyleResolver(DOM::Document& document)
: m_document(document)
{
}
StyleResolver::~StyleResolver()
{
}
static StyleSheet& default_stylesheet()
{
static StyleSheet* sheet;
if (!sheet) {
extern const char default_stylesheet_source[];
String css = default_stylesheet_source;
sheet = parse_css(CSS::ParsingContext(), css).leak_ref();
}
return *sheet;
}
static StyleSheet& quirks_mode_stylesheet()
{
static StyleSheet* sheet;
if (!sheet) {
extern const char quirks_mode_stylesheet_source[];
String css = quirks_mode_stylesheet_source;
sheet = parse_css(CSS::ParsingContext(), css).leak_ref();
}
return *sheet;
}
template<typename Callback>
void StyleResolver::for_each_stylesheet(Callback callback) const
{
callback(default_stylesheet());
if (document().in_quirks_mode())
callback(quirks_mode_stylesheet());
for (auto& sheet : document().style_sheets().sheets()) {
callback(sheet);
}
}
Vector<MatchingRule> StyleResolver::collect_matching_rules(const DOM::Element& element) const
{
Vector<MatchingRule> matching_rules;
size_t style_sheet_index = 0;
for_each_stylesheet([&](auto& sheet) {
size_t rule_index = 0;
for (auto& rule : sheet.rules()) {
size_t selector_index = 0;
for (auto& selector : rule.selectors()) {
if (SelectorEngine::matches(selector, element)) {
matching_rules.append({ rule, style_sheet_index, rule_index, selector_index });
break;
}
++selector_index;
}
++rule_index;
}
++style_sheet_index;
});
return matching_rules;
}
bool StyleResolver::is_inherited_property(CSS::PropertyID property_id)
{
static HashTable<CSS::PropertyID> inherited_properties;
if (inherited_properties.is_empty()) {
inherited_properties.set(CSS::PropertyID::BorderCollapse);
inherited_properties.set(CSS::PropertyID::BorderSpacing);
inherited_properties.set(CSS::PropertyID::Color);
inherited_properties.set(CSS::PropertyID::FontFamily);
inherited_properties.set(CSS::PropertyID::FontSize);
inherited_properties.set(CSS::PropertyID::FontStyle);
inherited_properties.set(CSS::PropertyID::FontVariant);
inherited_properties.set(CSS::PropertyID::FontWeight);
inherited_properties.set(CSS::PropertyID::LetterSpacing);
inherited_properties.set(CSS::PropertyID::LineHeight);
inherited_properties.set(CSS::PropertyID::ListStyle);
inherited_properties.set(CSS::PropertyID::ListStyleImage);
inherited_properties.set(CSS::PropertyID::ListStylePosition);
inherited_properties.set(CSS::PropertyID::ListStyleType);
inherited_properties.set(CSS::PropertyID::TextAlign);
inherited_properties.set(CSS::PropertyID::TextIndent);
inherited_properties.set(CSS::PropertyID::TextTransform);
inherited_properties.set(CSS::PropertyID::Visibility);
inherited_properties.set(CSS::PropertyID::WhiteSpace);
inherited_properties.set(CSS::PropertyID::WordSpacing);
// FIXME: This property is not supposed to be inherited, but we currently
// rely on inheritance to propagate decorations into line boxes.
inherited_properties.set(CSS::PropertyID::TextDecoration);
}
return inherited_properties.contains(property_id);
}
static Vector<String> split_on_whitespace(const StringView& string)
{
if (string.is_empty())
return {};
Vector<String> v;
size_t substart = 0;
for (size_t i = 0; i < string.length(); ++i) {
char ch = string.characters_without_null_termination()[i];
if (isspace(ch)) {
size_t sublen = i - substart;
if (sublen != 0)
v.append(string.substring_view(substart, sublen));
substart = i + 1;
}
}
size_t taillen = string.length() - substart;
if (taillen != 0)
v.append(string.substring_view(substart, taillen));
return v;
}
enum class Edge {
Top,
Right,
Bottom,
Left,
All,
};
static bool contains(Edge a, Edge b)
{
return a == b || b == Edge::All;
}
static inline void set_property_border_width(StyleProperties& style, const StyleValue& value, Edge edge)
{
ASSERT(value.is_length());
if (contains(Edge::Top, edge))
style.set_property(CSS::PropertyID::BorderTopWidth, value);
if (contains(Edge::Right, edge))
style.set_property(CSS::PropertyID::BorderRightWidth, value);
if (contains(Edge::Bottom, edge))
style.set_property(CSS::PropertyID::BorderBottomWidth, value);
if (contains(Edge::Left, edge))
style.set_property(CSS::PropertyID::BorderLeftWidth, value);
}
static inline void set_property_border_color(StyleProperties& style, const StyleValue& value, Edge edge)
{
ASSERT(value.is_color());
if (contains(Edge::Top, edge))
style.set_property(CSS::PropertyID::BorderTopColor, value);
if (contains(Edge::Right, edge))
style.set_property(CSS::PropertyID::BorderRightColor, value);
if (contains(Edge::Bottom, edge))
style.set_property(CSS::PropertyID::BorderBottomColor, value);
if (contains(Edge::Left, edge))
style.set_property(CSS::PropertyID::BorderLeftColor, value);
}
static inline void set_property_border_style(StyleProperties& style, const StyleValue& value, Edge edge)
{
ASSERT(value.is_string());
if (contains(Edge::Top, edge))
style.set_property(CSS::PropertyID::BorderTopStyle, value);
if (contains(Edge::Right, edge))
style.set_property(CSS::PropertyID::BorderRightStyle, value);
if (contains(Edge::Bottom, edge))
style.set_property(CSS::PropertyID::BorderBottomStyle, value);
if (contains(Edge::Left, edge))
style.set_property(CSS::PropertyID::BorderLeftStyle, value);
}
static void set_property_expanding_shorthands(StyleProperties& style, CSS::PropertyID property_id, const StyleValue& value, DOM::Document& document)
{
CSS::ParsingContext context(document);
if (property_id == CSS::PropertyID::Border) {
set_property_expanding_shorthands(style, CSS::PropertyID::BorderTop, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BorderRight, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BorderBottom, value, document);
set_property_expanding_shorthands(style, CSS::PropertyID::BorderLeft, value, document);
}
if (property_id == CSS::PropertyID::BorderTop
|| property_id == CSS::PropertyID::BorderRight
|| property_id == CSS::PropertyID::BorderBottom
|| property_id == CSS::PropertyID::BorderLeft) {
Edge edge = Edge::All;
switch (property_id) {
case CSS::PropertyID::BorderTop:
edge = Edge::Top;
break;
case CSS::PropertyID::BorderRight:
edge = Edge::Right;
break;
case CSS::PropertyID::BorderBottom:
edge = Edge::Bottom;
break;
case CSS::PropertyID::BorderLeft:
edge = Edge::Left;
break;
default:
break;
}
auto parts = split_on_whitespace(value.to_string());
if (value.is_length()) {
set_property_border_width(style, value, edge);
return;
}
if (value.is_color()) {
set_property_border_color(style, value, edge);
return;
}
if (value.is_string()) {
auto parts = split_on_whitespace(value.to_string());
if (parts.size() == 1) {
if (auto value = parse_line_style(context, parts[0])) {
set_property_border_style(style, value.release_nonnull(), edge);
set_property_border_color(style, ColorStyleValue::create(Gfx::Color::Black), edge);
set_property_border_width(style, LengthStyleValue::create(Length(3, Length::Type::Px)), edge);
return;
}
}
RefPtr<LengthStyleValue> line_width_value;
RefPtr<ColorStyleValue> color_value;
RefPtr<StringStyleValue> line_style_value;
for (auto& part : parts) {
if (auto value = parse_line_width(context, part)) {
if (line_width_value)
return;
line_width_value = move(value);
continue;
}
if (auto value = parse_color(context, part)) {
if (color_value)
return;
color_value = move(value);
continue;
}
if (auto value = parse_line_style(context, part)) {
if (line_style_value)
return;
line_style_value = move(value);
continue;
}
}
if (line_width_value)
set_property_border_width(style, line_width_value.release_nonnull(), edge);
if (color_value)
set_property_border_color(style, color_value.release_nonnull(), edge);
if (line_style_value)
set_property_border_style(style, line_style_value.release_nonnull(), edge);
return;
}
return;
}
if (property_id == CSS::PropertyID::BorderStyle) {
auto parts = split_on_whitespace(value.to_string());
if (value.is_string() && parts.size() == 3) {
auto top = parse_css_value(context, parts[0]);
auto right = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
auto left = parse_css_value(context, parts[1]);
if (top && right && bottom && left) {
style.set_property(CSS::PropertyID::BorderTopStyle, *top);
style.set_property(CSS::PropertyID::BorderRightStyle, *right);
style.set_property(CSS::PropertyID::BorderBottomStyle, *bottom);
style.set_property(CSS::PropertyID::BorderLeftStyle, *left);
}
} else {
style.set_property(CSS::PropertyID::BorderTopStyle, value);
style.set_property(CSS::PropertyID::BorderRightStyle, value);
style.set_property(CSS::PropertyID::BorderBottomStyle, value);
style.set_property(CSS::PropertyID::BorderLeftStyle, value);
}
return;
}
if (property_id == CSS::PropertyID::BorderWidth) {
auto parts = split_on_whitespace(value.to_string());
if (value.is_string() && parts.size() == 2) {
auto vertical_border_width = parse_css_value(context, parts[0]);
auto horizontal_border_width = parse_css_value(context, parts[1]);
if (vertical_border_width && horizontal_border_width) {
style.set_property(CSS::PropertyID::BorderTopWidth, *vertical_border_width);
style.set_property(CSS::PropertyID::BorderRightWidth, *horizontal_border_width);
style.set_property(CSS::PropertyID::BorderBottomWidth, *vertical_border_width);
style.set_property(CSS::PropertyID::BorderLeftWidth, *horizontal_border_width);
}
} else {
style.set_property(CSS::PropertyID::BorderTopWidth, value);
style.set_property(CSS::PropertyID::BorderRightWidth, value);
style.set_property(CSS::PropertyID::BorderBottomWidth, value);
style.set_property(CSS::PropertyID::BorderLeftWidth, value);
}
return;
}
if (property_id == CSS::PropertyID::BorderColor) {
auto parts = split_on_whitespace(value.to_string());
if (value.is_string() && parts.size() == 4) {
auto top = parse_css_value(context, parts[0]);
auto right = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
auto left = parse_css_value(context, parts[3]);
if (top && right && bottom && left) {
style.set_property(CSS::PropertyID::BorderTopColor, *top);
style.set_property(CSS::PropertyID::BorderRightColor, *right);
style.set_property(CSS::PropertyID::BorderBottomColor, *bottom);
style.set_property(CSS::PropertyID::BorderLeftColor, *left);
}
} else {
style.set_property(CSS::PropertyID::BorderTopColor, value);
style.set_property(CSS::PropertyID::BorderRightColor, value);
style.set_property(CSS::PropertyID::BorderBottomColor, value);
style.set_property(CSS::PropertyID::BorderLeftColor, value);
}
return;
}
if (property_id == CSS::PropertyID::Background) {
if (value.to_string() == "none") {
style.set_property(CSS::PropertyID::BackgroundColor, ColorStyleValue::create(Color::Transparent));
return;
}
auto parts = split_on_whitespace(value.to_string());
NonnullRefPtrVector<StyleValue> values;
for (auto& part : parts) {
auto value = parse_css_value(context, part);
if (!value)
return;
values.append(value.release_nonnull());
}
// HACK: Disallow more than one color value in a 'background' shorthand
size_t color_value_count = 0;
for (auto& value : values)
color_value_count += value.is_color();
if (values[0].is_color() && color_value_count == 1)
style.set_property(CSS::PropertyID::BackgroundColor, values[0]);
for (auto& value : values) {
if (!value.is_string())
continue;
auto string = value.to_string();
set_property_expanding_shorthands(style, CSS::PropertyID::BackgroundImage, value, document);
}
return;
}
if (property_id == CSS::PropertyID::BackgroundImage) {
if (!value.is_string())
return;
auto string = value.to_string();
if (!string.starts_with("url("))
return;
if (!string.ends_with(')'))
return;
auto url = string.substring_view(4, string.length() - 5);
if (url.length() >= 2 && url.starts_with('"') && url.ends_with('"'))
url = url.substring_view(1, url.length() - 2);
else if (url.length() >= 2 && url.starts_with('\'') && url.ends_with('\''))
url = url.substring_view(1, url.length() - 2);
auto background_image_value = ImageStyleValue::create(document.complete_url(url), document);
style.set_property(CSS::PropertyID::BackgroundImage, move(background_image_value));
return;
}
if (property_id == CSS::PropertyID::Margin) {
if (value.is_length()) {
style.set_property(CSS::PropertyID::MarginTop, value);
style.set_property(CSS::PropertyID::MarginRight, value);
style.set_property(CSS::PropertyID::MarginBottom, value);
style.set_property(CSS::PropertyID::MarginLeft, value);
return;
}
if (value.is_string()) {
auto parts = split_on_whitespace(value.to_string());
if (value.is_string() && parts.size() == 2) {
auto vertical = parse_css_value(context, parts[0]);
auto horizontal = parse_css_value(context, parts[1]);
if (vertical && horizontal) {
style.set_property(CSS::PropertyID::MarginTop, *vertical);
style.set_property(CSS::PropertyID::MarginBottom, *vertical);
style.set_property(CSS::PropertyID::MarginLeft, *horizontal);
style.set_property(CSS::PropertyID::MarginRight, *horizontal);
}
return;
}
if (value.is_string() && parts.size() == 3) {
auto top = parse_css_value(context, parts[0]);
auto horizontal = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
if (top && horizontal && bottom) {
style.set_property(CSS::PropertyID::MarginTop, *top);
style.set_property(CSS::PropertyID::MarginBottom, *bottom);
style.set_property(CSS::PropertyID::MarginLeft, *horizontal);
style.set_property(CSS::PropertyID::MarginRight, *horizontal);
}
return;
}
if (value.is_string() && parts.size() == 4) {
auto top = parse_css_value(context, parts[0]);
auto right = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
auto left = parse_css_value(context, parts[3]);
if (top && right && bottom && left) {
style.set_property(CSS::PropertyID::MarginTop, *top);
style.set_property(CSS::PropertyID::MarginBottom, *bottom);
style.set_property(CSS::PropertyID::MarginLeft, *left);
style.set_property(CSS::PropertyID::MarginRight, *right);
}
return;
}
dbg() << "Unsure what to do with CSS margin value '" << value.to_string() << "'";
return;
}
return;
}
if (property_id == CSS::PropertyID::Padding) {
if (value.is_length()) {
style.set_property(CSS::PropertyID::PaddingTop, value);
style.set_property(CSS::PropertyID::PaddingRight, value);
style.set_property(CSS::PropertyID::PaddingBottom, value);
style.set_property(CSS::PropertyID::PaddingLeft, value);
return;
}
if (value.is_string()) {
auto parts = split_on_whitespace(value.to_string());
if (value.is_string() && parts.size() == 2) {
auto vertical = parse_css_value(context, parts[0]);
auto horizontal = parse_css_value(context, parts[1]);
if (vertical && horizontal) {
style.set_property(CSS::PropertyID::PaddingTop, *vertical);
style.set_property(CSS::PropertyID::PaddingBottom, *vertical);
style.set_property(CSS::PropertyID::PaddingLeft, *horizontal);
style.set_property(CSS::PropertyID::PaddingRight, *horizontal);
}
return;
}
if (value.is_string() && parts.size() == 3) {
auto top = parse_css_value(context, parts[0]);
auto horizontal = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
if (top && bottom && horizontal) {
style.set_property(CSS::PropertyID::PaddingTop, *top);
style.set_property(CSS::PropertyID::PaddingBottom, *bottom);
style.set_property(CSS::PropertyID::PaddingLeft, *horizontal);
style.set_property(CSS::PropertyID::PaddingRight, *horizontal);
}
return;
}
if (value.is_string() && parts.size() == 4) {
auto top = parse_css_value(context, parts[0]);
auto right = parse_css_value(context, parts[1]);
auto bottom = parse_css_value(context, parts[2]);
auto left = parse_css_value(context, parts[3]);
if (top && bottom && left && right) {
style.set_property(CSS::PropertyID::PaddingTop, *top);
style.set_property(CSS::PropertyID::PaddingBottom, *bottom);
style.set_property(CSS::PropertyID::PaddingLeft, *left);
style.set_property(CSS::PropertyID::PaddingRight, *right);
}
return;
}
dbg() << "Unsure what to do with CSS padding value '" << value.to_string() << "'";
return;
}
return;
}
if (property_id == CSS::PropertyID::ListStyle) {
auto parts = split_on_whitespace(value.to_string());
if (!parts.is_empty()) {
auto value = parse_css_value(context, parts[0]);
if (!value)
return;
style.set_property(CSS::PropertyID::ListStyleType, value.release_nonnull());
}
return;
}
style.set_property(property_id, value);
}
NonnullRefPtr<StyleProperties> StyleResolver::resolve_style(const DOM::Element& element, const StyleProperties* parent_style) const
{
auto style = StyleProperties::create();
if (parent_style) {
parent_style->for_each_property([&](auto property_id, auto& value) {
if (is_inherited_property(property_id))
set_property_expanding_shorthands(style, property_id, value, m_document);
});
}
element.apply_presentational_hints(*style);
auto matching_rules = collect_matching_rules(element);
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_specificity < b_specificity;
});
for (auto& match : matching_rules) {
for (auto& property : match.rule->declaration().properties()) {
set_property_expanding_shorthands(style, property.property_id, property.value, m_document);
}
}
if (auto* inline_style = element.inline_style()) {
for (auto& property : inline_style->properties()) {
set_property_expanding_shorthands(style, property.property_id, property.value, m_document);
}
}
return style;
}
}
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