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ladybird/Userland/Libraries/LibWeb/Layout/TreeBuilder.cpp
Andreas Kling afe6abfc09 LibWeb: Use an ancestor filter to quickly reject many CSS selectors 
Given a selector like `.foo .bar #baz`, we know that elements with
the class names `foo` and `bar` must be present in the ancestor chain of
the candidate element, or the selector cannot match.

By keeping track of the current ancestor chain during style computation,
and which strings are used in tag names and attribute names, we can do
a quick check before evaluating the selector itself, to see if all the
required ancestors are present.

The way this works:

1. CSS::Selector now has a cache of up to 8 strings that must be present
   in the ancestor chain of a matching element. Note that we actually
   store string *hashes*, not the strings themselves.

2. When Document performs a recursive style update, we now push and pop
   elements to the ancestor chain stack as they are entered and exited.

3. When entering/exiting an ancestor, StyleComputer collects all the
   relevant string hashes from that ancestor element and updates a
   counting bloom filter.

4. Before evaluating a selector, we first check if any of the hashes
   required by the selector are definitely missing from the ancestor
   filter. If so, it cannot be a match, and we reject it immediately.

5. Otherwise, we carry on and evaluate the selector as usual.

I originally tried doing this with a HashMap, but we ended up losing
a huge chunk of the time saved to HashMap instead. As it turns out,
a simple counting bloom filter is way better at handling this.
The cost is a flat 8KB per StyleComputer, and since it's a bloom filter,
false positives are a thing.

This is extremely efficient, and allows us to quickly reject the
majority of selectors on many huge websites.

Some example rejection rates:
- https://amazon.com: 77%
- https://github.com/SerenityOS/serenity: 61%
- https://nytimes.com: 57%
- https://store.steampowered.com: 55%
- https://en.wikipedia.org: 45%
- https://youtube.com: 32%
- https://shopify.com: 25%

This also yields a chunky 37% speedup on StyleBench. :^)
2024-03-22 18:27:32 +01:00

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/*
* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2022-2023, Sam Atkins <atkinssj@serenityos.org>
* Copyright (c) 2022, MacDue <macdue@dueutil.tech>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Error.h>
#include <AK/Optional.h>
#include <AK/TemporaryChange.h>
#include <LibWeb/CSS/StyleComputer.h>
#include <LibWeb/CSS/StyleValues/DisplayStyleValue.h>
#include <LibWeb/CSS/StyleValues/IdentifierStyleValue.h>
#include <LibWeb/CSS/StyleValues/PercentageStyleValue.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/DOM/Element.h>
#include <LibWeb/DOM/ParentNode.h>
#include <LibWeb/DOM/ShadowRoot.h>
#include <LibWeb/Dump.h>
#include <LibWeb/HTML/HTMLButtonElement.h>
#include <LibWeb/HTML/HTMLInputElement.h>
#include <LibWeb/HTML/HTMLLIElement.h>
#include <LibWeb/HTML/HTMLOListElement.h>
#include <LibWeb/HTML/HTMLSlotElement.h>
#include <LibWeb/Layout/ListItemBox.h>
#include <LibWeb/Layout/ListItemMarkerBox.h>
#include <LibWeb/Layout/Node.h>
#include <LibWeb/Layout/SVGMaskBox.h>
#include <LibWeb/Layout/TableGrid.h>
#include <LibWeb/Layout/TableWrapper.h>
#include <LibWeb/Layout/TextNode.h>
#include <LibWeb/Layout/TreeBuilder.h>
#include <LibWeb/Layout/Viewport.h>
#include <LibWeb/SVG/SVGForeignObjectElement.h>
namespace Web::Layout {
TreeBuilder::TreeBuilder() = default;
static bool has_inline_or_in_flow_block_children(Layout::Node const& layout_node)
{
for (auto child = layout_node.first_child(); child; child = child->next_sibling()) {
if (child->is_inline())
return true;
if (!child->is_floating() && !child->is_absolutely_positioned())
return true;
}
return false;
}
static bool has_in_flow_block_children(Layout::Node const& layout_node)
{
if (layout_node.children_are_inline())
return false;
for (auto child = layout_node.first_child(); child; child = child->next_sibling()) {
if (child->is_inline())
continue;
if (!child->is_floating() && !child->is_absolutely_positioned())
return true;
}
return false;
}
// The insertion_parent_for_*() functions maintain the invariant that the in-flow children of
// block-level boxes must be either all block-level or all inline-level.
static Layout::Node& insertion_parent_for_inline_node(Layout::NodeWithStyle& layout_parent)
{
auto last_child_creating_anonymous_wrapper_if_needed = [](auto& layout_parent) -> Layout::Node& {
if (!layout_parent.last_child()
|| !layout_parent.last_child()->is_anonymous()
|| !layout_parent.last_child()->children_are_inline()
|| layout_parent.last_child()->is_generated()) {
layout_parent.append_child(layout_parent.create_anonymous_wrapper());
}
return *layout_parent.last_child();
};
if (layout_parent.display().is_inline_outside() && layout_parent.display().is_flow_inside())
return layout_parent;
if (layout_parent.display().is_flex_inside() || layout_parent.display().is_grid_inside())
return last_child_creating_anonymous_wrapper_if_needed(layout_parent);
if (!has_in_flow_block_children(layout_parent) || layout_parent.children_are_inline())
return layout_parent;
// Parent has block-level children, insert into an anonymous wrapper block (and create it first if needed)
return last_child_creating_anonymous_wrapper_if_needed(layout_parent);
}
static Layout::Node& insertion_parent_for_block_node(Layout::NodeWithStyle& layout_parent, Layout::Node& layout_node)
{
if (!has_inline_or_in_flow_block_children(layout_parent)) {
// Parent block has no children, insert this block into parent.
return layout_parent;
}
bool is_out_of_flow = layout_node.is_absolutely_positioned() || layout_node.is_floating();
if (is_out_of_flow
&& !layout_parent.display().is_flex_inside()
&& !layout_parent.display().is_grid_inside()
&& layout_parent.last_child()->is_anonymous()
&& layout_parent.last_child()->children_are_inline()) {
// Block is out-of-flow & previous sibling was wrapped in an anonymous block.
// Join the previous sibling inside the anonymous block.
return *layout_parent.last_child();
}
if (!layout_parent.children_are_inline()) {
// Parent block has block-level children, insert this block into parent.
return layout_parent;
}
if (is_out_of_flow) {
// Block is out-of-flow, it can have inline siblings if necessary.
return layout_parent;
}
// Parent block has inline-level children (our siblings).
// First move these siblings into an anonymous wrapper block.
Vector<JS::Handle<Layout::Node>> children;
{
JS::GCPtr<Layout::Node> next;
for (JS::GCPtr<Layout::Node> child = layout_parent.first_child(); child; child = next) {
next = child->next_sibling();
// NOTE: We let out-of-flow children stay in the parent, to preserve tree structure.
if (child->is_floating() || child->is_absolutely_positioned())
continue;
layout_parent.remove_child(*child);
children.append(*child);
}
}
layout_parent.append_child(layout_parent.create_anonymous_wrapper());
layout_parent.set_children_are_inline(false);
for (auto& child : children) {
layout_parent.last_child()->append_child(*child);
}
layout_parent.last_child()->set_children_are_inline(true);
// Then it's safe to insert this block into parent.
return layout_parent;
}
void TreeBuilder::insert_node_into_inline_or_block_ancestor(Layout::Node& node, CSS::Display display, AppendOrPrepend mode)
{
if (node.display().is_contents())
return;
if (display.is_inline_outside()) {
// Inlines can be inserted into the nearest ancestor without "display: contents".
auto& nearest_ancestor_without_display_contents = [&]() -> Layout::NodeWithStyle& {
for (auto& ancestor : m_ancestor_stack.in_reverse()) {
if (!ancestor->display().is_contents())
return ancestor;
}
VERIFY_NOT_REACHED();
}();
auto& insertion_point = insertion_parent_for_inline_node(nearest_ancestor_without_display_contents);
if (mode == AppendOrPrepend::Prepend)
insertion_point.prepend_child(node);
else
insertion_point.append_child(node);
insertion_point.set_children_are_inline(true);
} else {
// Non-inlines can't be inserted into an inline parent, so find the nearest non-inline ancestor.
auto& nearest_non_inline_ancestor = [&]() -> Layout::NodeWithStyle& {
for (auto& ancestor : m_ancestor_stack.in_reverse()) {
if (ancestor->display().is_contents())
continue;
if (!ancestor->display().is_inline_outside())
return ancestor;
if (!ancestor->display().is_flow_inside())
return ancestor;
if (ancestor->dom_node() && is<SVG::SVGForeignObjectElement>(*ancestor->dom_node()))
return ancestor;
}
VERIFY_NOT_REACHED();
}();
auto& insertion_point = insertion_parent_for_block_node(nearest_non_inline_ancestor, node);
if (mode == AppendOrPrepend::Prepend)
insertion_point.prepend_child(node);
else
insertion_point.append_child(node);
// After inserting an in-flow block-level box into a parent, mark the parent as having non-inline children.
if (!node.is_floating() && !node.is_absolutely_positioned())
insertion_point.set_children_are_inline(false);
}
}
void TreeBuilder::create_pseudo_element_if_needed(DOM::Element& element, CSS::Selector::PseudoElement::Type pseudo_element, AppendOrPrepend mode)
{
auto& document = element.document();
auto& style_computer = document.style_computer();
auto pseudo_element_style = style_computer.compute_pseudo_element_style_if_needed(element, pseudo_element);
if (!pseudo_element_style)
return;
auto initial_quote_nesting_level = m_quote_nesting_level;
auto [pseudo_element_content, final_quote_nesting_level] = pseudo_element_style->content(initial_quote_nesting_level);
m_quote_nesting_level = final_quote_nesting_level;
auto pseudo_element_display = pseudo_element_style->display();
// ::before and ::after only exist if they have content. `content: normal` computes to `none` for them.
// We also don't create them if they are `display: none`.
if (pseudo_element_display.is_none()
|| pseudo_element_content.type == CSS::ContentData::Type::Normal
|| pseudo_element_content.type == CSS::ContentData::Type::None)
return;
auto pseudo_element_node = DOM::Element::create_layout_node_for_display_type(document, pseudo_element_display, *pseudo_element_style, nullptr);
if (!pseudo_element_node)
return;
auto generated_for = Node::GeneratedFor::NotGenerated;
if (pseudo_element == CSS::Selector::PseudoElement::Type::Before) {
generated_for = Node::GeneratedFor::PseudoBefore;
} else if (pseudo_element == CSS::Selector::PseudoElement::Type::After) {
generated_for = Node::GeneratedFor::PseudoAfter;
} else {
VERIFY_NOT_REACHED();
}
pseudo_element_node->set_generated_for(generated_for, element);
pseudo_element_node->set_initial_quote_nesting_level(initial_quote_nesting_level);
// FIXME: Handle images, and multiple values
if (pseudo_element_content.type == CSS::ContentData::Type::String) {
auto text = document.heap().allocate<DOM::Text>(document.realm(), document, pseudo_element_content.data);
auto text_node = document.heap().allocate_without_realm<Layout::TextNode>(document, *text);
text_node->set_generated_for(generated_for, element);
push_parent(verify_cast<NodeWithStyle>(*pseudo_element_node));
insert_node_into_inline_or_block_ancestor(*text_node, text_node->display(), AppendOrPrepend::Append);
pop_parent();
} else {
TODO();
}
element.set_pseudo_element_node({}, pseudo_element, pseudo_element_node);
insert_node_into_inline_or_block_ancestor(*pseudo_element_node, pseudo_element_display, mode);
}
static bool is_ignorable_whitespace(Layout::Node const& node)
{
if (node.is_text_node() && static_cast<TextNode const&>(node).text_for_rendering().bytes_as_string_view().is_whitespace())
return true;
if (node.is_anonymous() && node.is_block_container() && static_cast<BlockContainer const&>(node).children_are_inline()) {
bool contains_only_white_space = true;
node.for_each_in_inclusive_subtree_of_type<TextNode>([&contains_only_white_space](auto& text_node) {
if (!text_node.text_for_rendering().bytes_as_string_view().is_whitespace()) {
contains_only_white_space = false;
return IterationDecision::Break;
}
return IterationDecision::Continue;
});
if (contains_only_white_space)
return true;
}
return false;
}
i32 TreeBuilder::calculate_list_item_index(DOM::Node& dom_node)
{
if (is<HTML::HTMLLIElement>(dom_node)) {
auto& li = static_cast<HTML::HTMLLIElement&>(dom_node);
if (li.value() != 0)
return li.value();
}
if (dom_node.previous_sibling() != nullptr) {
DOM::Node* current = dom_node.previous_sibling();
while (current != nullptr) {
if (is<HTML::HTMLLIElement>(*current))
return calculate_list_item_index(*current) + 1;
current = current->previous_sibling();
}
}
if (is<HTML::HTMLOListElement>(*dom_node.parent())) {
auto& ol = static_cast<HTML::HTMLOListElement&>(*dom_node.parent());
return ol.start();
}
return 1;
}
void TreeBuilder::create_layout_tree(DOM::Node& dom_node, TreeBuilder::Context& context)
{
if (dom_node.is_element())
dom_node.document().style_computer().push_ancestor(static_cast<DOM::Element const&>(dom_node));
ScopeGuard pop_ancestor_guard = [&] {
if (dom_node.is_element())
dom_node.document().style_computer().pop_ancestor(static_cast<DOM::Element const&>(dom_node));
};
JS::GCPtr<Layout::Node> layout_node;
Optional<TemporaryChange<bool>> has_svg_root_change;
ScopeGuard remove_stale_layout_node_guard = [&] {
// If we didn't create a layout node for this DOM node,
// go through the DOM tree and remove any old layout & paint nodes since they are now all stale.
if (!layout_node) {
dom_node.for_each_in_inclusive_subtree([&](auto& node) {
node.detach_layout_node({});
node.set_paintable(nullptr);
if (is<DOM::Element>(node))
static_cast<DOM::Element&>(node).clear_pseudo_element_nodes({});
return IterationDecision::Continue;
});
}
};
if (dom_node.is_svg_container()) {
has_svg_root_change.emplace(context.has_svg_root, true);
} else if (dom_node.requires_svg_container() && !context.has_svg_root) {
return;
}
auto& document = dom_node.document();
auto& style_computer = document.style_computer();
RefPtr<CSS::StyleProperties> style;
CSS::Display display;
if (is<DOM::Element>(dom_node)) {
auto& element = static_cast<DOM::Element&>(dom_node);
element.clear_pseudo_element_nodes({});
VERIFY(!element.needs_style_update());
style = element.computed_css_values();
display = style->display();
if (display.is_none())
return;
layout_node = element.create_layout_node(*style);
} else if (is<DOM::Document>(dom_node)) {
style = style_computer.create_document_style();
display = style->display();
layout_node = document.heap().allocate_without_realm<Layout::Viewport>(static_cast<DOM::Document&>(dom_node), *style);
} else if (is<DOM::Text>(dom_node)) {
layout_node = document.heap().allocate_without_realm<Layout::TextNode>(document, static_cast<DOM::Text&>(dom_node));
display = CSS::Display(CSS::DisplayOutside::Inline, CSS::DisplayInside::Flow);
}
if (context.layout_svg_mask && is<SVG::SVGMaskElement>(dom_node)) {
layout_node = document.heap().allocate_without_realm<Layout::SVGMaskBox>(document, static_cast<SVG::SVGMaskElement&>(dom_node), *style);
// We're here if our parent is a use of an SVG mask, but we don't want to lay out any <mask> elements that could be a child of this mask.
context.layout_svg_mask = false;
}
if (!layout_node)
return;
if (!dom_node.parent_or_shadow_host()) {
m_layout_root = layout_node;
} else if (layout_node->is_svg_box()) {
m_ancestor_stack.last()->append_child(*layout_node);
} else {
insert_node_into_inline_or_block_ancestor(*layout_node, display, AppendOrPrepend::Append);
}
auto* shadow_root = is<DOM::Element>(dom_node) ? verify_cast<DOM::Element>(dom_node).shadow_root_internal() : nullptr;
// Add node for the ::before pseudo-element.
if (is<DOM::Element>(dom_node) && layout_node->can_have_children()) {
auto& element = static_cast<DOM::Element&>(dom_node);
push_parent(verify_cast<NodeWithStyle>(*layout_node));
create_pseudo_element_if_needed(element, CSS::Selector::PseudoElement::Type::Before, AppendOrPrepend::Prepend);
pop_parent();
}
if ((dom_node.has_children() || shadow_root) && layout_node->can_have_children()) {
push_parent(verify_cast<NodeWithStyle>(*layout_node));
if (shadow_root) {
for (auto* node = shadow_root->first_child(); node; node = node->next_sibling()) {
create_layout_tree(*node, context);
}
} else {
// This is the same as verify_cast<DOM::ParentNode>(dom_node).for_each_child
for (auto* node = verify_cast<DOM::ParentNode>(dom_node).first_child(); node; node = node->next_sibling())
create_layout_tree(*node, context);
}
pop_parent();
}
if (is<ListItemBox>(*layout_node)) {
auto& element = static_cast<DOM::Element&>(dom_node);
auto marker_style = style_computer.compute_style(element, CSS::Selector::PseudoElement::Type::Marker);
auto list_item_marker = document.heap().allocate_without_realm<ListItemMarkerBox>(document, layout_node->computed_values().list_style_type(), layout_node->computed_values().list_style_position(), calculate_list_item_index(dom_node), *marker_style);
static_cast<ListItemBox&>(*layout_node).set_marker(list_item_marker);
element.set_pseudo_element_node({}, CSS::Selector::PseudoElement::Type::Marker, list_item_marker);
layout_node->append_child(*list_item_marker);
}
if (is<HTML::HTMLSlotElement>(dom_node)) {
auto slottables = static_cast<HTML::HTMLSlotElement&>(dom_node).assigned_nodes_internal();
push_parent(verify_cast<NodeWithStyle>(*layout_node));
for (auto const& slottable : slottables)
slottable.visit([&](auto& node) { create_layout_tree(node, context); });
pop_parent();
}
if (is<SVG::SVGGraphicsElement>(dom_node)) {
auto& graphics_element = static_cast<SVG::SVGGraphicsElement&>(dom_node);
// Create the layout tree for the SVG mask as a child of the masked element. Note: This will create
// a new subtree for each use of the mask (so there's not a 1-to-1 mapping from DOM node to mask
// layout node). Each use of a mask may be laid out differently so this duplication is necessary.
if (auto mask = graphics_element.mask()) {
TemporaryChange<bool> layout_mask(context.layout_svg_mask, true);
push_parent(verify_cast<NodeWithStyle>(*layout_node));
create_layout_tree(const_cast<SVG::SVGMaskElement&>(*mask), context);
pop_parent();
}
}
// https://html.spec.whatwg.org/multipage/rendering.html#button-layout
// If the computed value of 'inline-size' is 'auto', then the used value is the fit-content inline size.
if (dom_node.is_html_button_element() && dom_node.layout_node()->computed_values().width().is_auto()) {
auto& computed_values = verify_cast<NodeWithStyle>(*dom_node.layout_node()).mutable_computed_values();
computed_values.set_width(CSS::Size::make_fit_content());
}
// https://html.spec.whatwg.org/multipage/rendering.html#button-layout
// If the element is an input element, or if it is a button element and its computed value for
// 'display' is not 'inline-grid', 'grid', 'inline-flex', or 'flex', then the element's box has
// a child anonymous button content box with the following behaviors:
if (dom_node.is_html_button_element() && !display.is_grid_inside() && !display.is_flex_inside()) {
auto& parent = *dom_node.layout_node();
// If the box does not overflow in the vertical axis, then it is centered vertically.
// FIXME: Only apply alignment when box overflows
auto flex_computed_values = parent.computed_values().clone_inherited_values();
auto& mutable_flex_computed_values = static_cast<CSS::MutableComputedValues&>(*flex_computed_values);
mutable_flex_computed_values.set_display(CSS::Display { CSS::DisplayOutside::Block, CSS::DisplayInside::Flex });
mutable_flex_computed_values.set_justify_content(CSS::JustifyContent::Center);
mutable_flex_computed_values.set_flex_direction(CSS::FlexDirection::Column);
mutable_flex_computed_values.set_height(CSS::Size::make_percentage(CSS::Percentage(100)));
mutable_flex_computed_values.set_min_height(parent.computed_values().min_height());
auto flex_wrapper = parent.heap().template allocate_without_realm<BlockContainer>(parent.document(), nullptr, move(flex_computed_values));
auto content_box_computed_values = parent.computed_values().clone_inherited_values();
auto content_box_wrapper = parent.heap().template allocate_without_realm<BlockContainer>(parent.document(), nullptr, move(content_box_computed_values));
content_box_wrapper->set_children_are_inline(parent.children_are_inline());
Vector<JS::Handle<Node>> sequence;
for (auto child = parent.first_child(); child; child = child->next_sibling()) {
if (child->is_generated_for_before_pseudo_element())
continue;
sequence.append(*child);
}
for (auto& node : sequence) {
parent.remove_child(*node);
content_box_wrapper->append_child(*node);
}
flex_wrapper->append_child(*content_box_wrapper);
parent.append_child(*flex_wrapper);
parent.set_children_are_inline(false);
}
// Add nodes for the ::after pseudo-element.
if (is<DOM::Element>(dom_node) && layout_node->can_have_children()) {
auto& element = static_cast<DOM::Element&>(dom_node);
push_parent(verify_cast<NodeWithStyle>(*layout_node));
create_pseudo_element_if_needed(element, CSS::Selector::PseudoElement::Type::After, AppendOrPrepend::Append);
pop_parent();
}
}
JS::GCPtr<Layout::Node> TreeBuilder::build(DOM::Node& dom_node)
{
VERIFY(dom_node.is_document());
dom_node.document().style_computer().reset_ancestor_filter();
Context context;
m_quote_nesting_level = 0;
create_layout_tree(dom_node, context);
if (auto* root = dom_node.document().layout_node())
fixup_tables(*root);
return move(m_layout_root);
}
template<CSS::DisplayInternal internal, typename Callback>
void TreeBuilder::for_each_in_tree_with_internal_display(NodeWithStyle& root, Callback callback)
{
root.for_each_in_inclusive_subtree_of_type<Box>([&](auto& box) {
auto const display = box.display();
if (display.is_internal() && display.internal() == internal)
callback(box);
return IterationDecision::Continue;
});
}
template<CSS::DisplayInside inside, typename Callback>
void TreeBuilder::for_each_in_tree_with_inside_display(NodeWithStyle& root, Callback callback)
{
root.for_each_in_inclusive_subtree_of_type<Box>([&](auto& box) {
auto const display = box.display();
if (display.is_outside_and_inside() && display.inside() == inside)
callback(box);
return IterationDecision::Continue;
});
}
void TreeBuilder::fixup_tables(NodeWithStyle& root)
{
remove_irrelevant_boxes(root);
generate_missing_child_wrappers(root);
auto table_root_boxes = generate_missing_parents(root);
missing_cells_fixup(table_root_boxes);
}
void TreeBuilder::remove_irrelevant_boxes(NodeWithStyle& root)
{
// The following boxes are discarded as if they were display:none:
Vector<JS::Handle<Node>> to_remove;
// Children of a table-column.
for_each_in_tree_with_internal_display<CSS::DisplayInternal::TableColumn>(root, [&](Box& table_column) {
table_column.for_each_child([&](auto& child) {
to_remove.append(child);
});
});
// Children of a table-column-group which are not a table-column.
for_each_in_tree_with_internal_display<CSS::DisplayInternal::TableColumnGroup>(root, [&](Box& table_column_group) {
table_column_group.for_each_child([&](auto& child) {
if (!child.display().is_table_column())
to_remove.append(child);
});
});
// FIXME:
// Anonymous inline boxes which contain only white space and are between two immediate siblings each of which is a table-non-root box.
// Anonymous inline boxes which meet all of the following criteria:
// - they contain only white space
// - they are the first and/or last child of a tabular container
// - whose immediate sibling, if any, is a table-non-root box
for (auto& box : to_remove)
box->parent()->remove_child(*box);
}
static bool is_table_track(CSS::Display display)
{
return display.is_table_row() || display.is_table_column();
}
static bool is_table_track_group(CSS::Display display)
{
// Unless explicitly mentioned otherwise, mentions of table-row-groups in this spec also encompass the specialized
// table-header-groups and table-footer-groups.
return display.is_table_row_group()
|| display.is_table_header_group()
|| display.is_table_footer_group()
|| display.is_table_column_group();
}
static bool is_proper_table_child(Node const& node)
{
auto const display = node.display();
return is_table_track_group(display) || is_table_track(display) || display.is_table_caption();
}
static bool is_not_proper_table_child(Node const& node)
{
if (!node.has_style())
return true;
return !is_proper_table_child(node);
}
static bool is_table_row(Node const& node)
{
return node.display().is_table_row();
}
static bool is_not_table_row(Node const& node)
{
if (!node.has_style())
return true;
return !is_table_row(node);
}
static bool is_table_cell(Node const& node)
{
return node.display().is_table_cell();
}
static bool is_not_table_cell(Node const& node)
{
if (!node.has_style())
return true;
return !is_table_cell(node);
}
template<typename Matcher, typename Callback>
static void for_each_sequence_of_consecutive_children_matching(NodeWithStyle& parent, Matcher matcher, Callback callback)
{
Vector<JS::Handle<Node>> sequence;
auto sequence_is_all_ignorable_whitespace = [&]() -> bool {
for (auto& node : sequence) {
if (!is_ignorable_whitespace(*node))
return false;
}
return true;
};
for (auto child = parent.first_child(); child; child = child->next_sibling()) {
if (matcher(*child) || (!sequence.is_empty() && is_ignorable_whitespace(*child))) {
sequence.append(*child);
} else {
if (!sequence.is_empty()) {
if (!sequence_is_all_ignorable_whitespace())
callback(sequence, child);
sequence.clear();
}
}
}
if (!sequence.is_empty() && !sequence_is_all_ignorable_whitespace())
callback(sequence, nullptr);
}
template<typename WrapperBoxType>
static void wrap_in_anonymous(Vector<JS::Handle<Node>>& sequence, Node* nearest_sibling, CSS::Display display)
{
VERIFY(!sequence.is_empty());
auto& parent = *sequence.first()->parent();
auto computed_values = parent.computed_values().clone_inherited_values();
static_cast<CSS::MutableComputedValues&>(*computed_values).set_display(display);
auto wrapper = parent.heap().template allocate_without_realm<WrapperBoxType>(parent.document(), nullptr, move(computed_values));
for (auto& child : sequence) {
parent.remove_child(*child);
wrapper->append_child(*child);
}
wrapper->set_children_are_inline(parent.children_are_inline());
if (nearest_sibling)
parent.insert_before(*wrapper, *nearest_sibling);
else
parent.append_child(*wrapper);
}
void TreeBuilder::generate_missing_child_wrappers(NodeWithStyle& root)
{
// An anonymous table-row box must be generated around each sequence of consecutive children of a table-root box which are not proper table child boxes.
for_each_in_tree_with_inside_display<CSS::DisplayInside::Table>(root, [&](auto& parent) {
for_each_sequence_of_consecutive_children_matching(parent, is_not_proper_table_child, [&](auto sequence, auto nearest_sibling) {
wrap_in_anonymous<Box>(sequence, nearest_sibling, CSS::Display { CSS::DisplayInternal::TableRow });
});
});
// An anonymous table-row box must be generated around each sequence of consecutive children of a table-row-group box which are not table-row boxes.
for_each_in_tree_with_internal_display<CSS::DisplayInternal::TableRowGroup>(root, [&](auto& parent) {
for_each_sequence_of_consecutive_children_matching(parent, is_not_table_row, [&](auto& sequence, auto nearest_sibling) {
wrap_in_anonymous<Box>(sequence, nearest_sibling, CSS::Display { CSS::DisplayInternal::TableRow });
});
});
// Unless explicitly mentioned otherwise, mentions of table-row-groups in this spec also encompass the specialized
// table-header-groups and table-footer-groups.
for_each_in_tree_with_internal_display<CSS::DisplayInternal::TableHeaderGroup>(root, [&](auto& parent) {
for_each_sequence_of_consecutive_children_matching(parent, is_not_table_row, [&](auto& sequence, auto nearest_sibling) {
wrap_in_anonymous<Box>(sequence, nearest_sibling, CSS::Display { CSS::DisplayInternal::TableRow });
});
});
for_each_in_tree_with_internal_display<CSS::DisplayInternal::TableFooterGroup>(root, [&](auto& parent) {
for_each_sequence_of_consecutive_children_matching(parent, is_not_table_row, [&](auto& sequence, auto nearest_sibling) {
wrap_in_anonymous<Box>(sequence, nearest_sibling, CSS::Display { CSS::DisplayInternal::TableRow });
});
});
// An anonymous table-cell box must be generated around each sequence of consecutive children of a table-row box which are not table-cell boxes. !Testcase
for_each_in_tree_with_internal_display<CSS::DisplayInternal::TableRow>(root, [&](auto& parent) {
for_each_sequence_of_consecutive_children_matching(parent, is_not_table_cell, [&](auto& sequence, auto nearest_sibling) {
wrap_in_anonymous<BlockContainer>(sequence, nearest_sibling, CSS::Display { CSS::DisplayInternal::TableCell });
});
});
}
Vector<JS::Handle<Box>> TreeBuilder::generate_missing_parents(NodeWithStyle& root)
{
Vector<JS::Handle<Box>> table_roots_to_wrap;
root.for_each_in_inclusive_subtree_of_type<Box>([&](auto& parent) {
// An anonymous table-row box must be generated around each sequence of consecutive table-cell boxes whose parent is not a table-row.
if (is_not_table_row(parent)) {
for_each_sequence_of_consecutive_children_matching(parent, is_table_cell, [&](auto& sequence, auto nearest_sibling) {
wrap_in_anonymous<Box>(sequence, nearest_sibling, CSS::Display { CSS::DisplayInternal::TableRow });
});
}
// A table-row is misparented if its parent is neither a table-row-group nor a table-root box.
if (!parent.display().is_table_inside() && !is_proper_table_child(parent)) {
for_each_sequence_of_consecutive_children_matching(parent, is_table_row, [&](auto& sequence, auto nearest_sibling) {
wrap_in_anonymous<Box>(sequence, nearest_sibling, CSS::Display::from_short(parent.display().is_inline_outside() ? CSS::Display::Short::InlineTable : CSS::Display::Short::Table));
});
}
// A table-row-group, table-column-group, or table-caption box is misparented if its parent is not a table-root box.
if (!parent.display().is_table_inside() && !is_proper_table_child(parent)) {
for_each_sequence_of_consecutive_children_matching(parent, is_proper_table_child, [&](auto& sequence, auto nearest_sibling) {
wrap_in_anonymous<Box>(sequence, nearest_sibling, CSS::Display::from_short(parent.display().is_inline_outside() ? CSS::Display::Short::InlineTable : CSS::Display::Short::Table));
});
}
// An anonymous table-wrapper box must be generated around each table-root.
if (parent.display().is_table_inside()) {
table_roots_to_wrap.append(parent);
}
return IterationDecision::Continue;
});
for (auto& table_box : table_roots_to_wrap) {
auto* nearest_sibling = table_box->next_sibling();
auto& parent = *table_box->parent();
auto wrapper_computed_values = table_box->computed_values().clone_inherited_values();
table_box->transfer_table_box_computed_values_to_wrapper_computed_values(*wrapper_computed_values);
auto wrapper = parent.heap().allocate_without_realm<TableWrapper>(parent.document(), nullptr, move(wrapper_computed_values));
parent.remove_child(*table_box);
wrapper->append_child(*table_box);
if (nearest_sibling)
parent.insert_before(*wrapper, *nearest_sibling);
else
parent.append_child(*wrapper);
}
return table_roots_to_wrap;
}
template<typename Matcher, typename Callback>
static void for_each_child_box_matching(Box& parent, Matcher matcher, Callback callback)
{
parent.for_each_child_of_type<Box>([&](Box& child_box) {
if (matcher(child_box))
callback(child_box);
});
}
static void fixup_row(Box& row_box, TableGrid const& table_grid, size_t row_index)
{
for (size_t column_index = 0; column_index < table_grid.column_count(); ++column_index) {
if (table_grid.occupancy_grid().contains({ column_index, row_index }))
continue;
auto computed_values = row_box.computed_values().clone_inherited_values();
auto& mutable_computed_values = static_cast<CSS::MutableComputedValues&>(*computed_values);
mutable_computed_values.set_display(Web::CSS::Display { CSS::DisplayInternal::TableCell });
// Ensure that the cell (with zero content height) will have the same height as the row by setting vertical-align to middle.
mutable_computed_values.set_vertical_align(CSS::VerticalAlign::Middle);
auto cell_box = row_box.heap().template allocate_without_realm<BlockContainer>(row_box.document(), nullptr, move(computed_values));
row_box.append_child(cell_box);
}
}
void TreeBuilder::missing_cells_fixup(Vector<JS::Handle<Box>> const& table_root_boxes)
{
// Implements https://www.w3.org/TR/css-tables-3/#missing-cells-fixup.
for (auto& table_box : table_root_boxes) {
auto table_grid = TableGrid::calculate_row_column_grid(*table_box);
size_t row_index = 0;
for_each_child_box_matching(*table_box, TableGrid::is_table_row_group, [&](auto& row_group_box) {
for_each_child_box_matching(row_group_box, is_table_row, [&](auto& row_box) {
fixup_row(row_box, table_grid, row_index);
++row_index;
return IterationDecision::Continue;
});
});
for_each_child_box_matching(*table_box, is_table_row, [&](auto& row_box) {
fixup_row(row_box, table_grid, row_index);
++row_index;
return IterationDecision::Continue;
});
}
}
}
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