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Anonymous table box construction fixups (CSS 2.2 §17.2.1) #783

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Anonymous table box construction fixups (CSS 2.2 §17.2.1) #783

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eb70c39
Implement anonymous table box construction fixups (CSS 2.2 §17.2.1)
nicoburns Aug 24, 2026
640f18d
Fix WPT regressions: ignore captions in table grid, treat replaced el…
nicoburns Aug 24, 2026
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103 changes: 87 additions & 16 deletions packages/blitz-dom/src/layout/construct.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,6 @@ const DUMMY_NAME: QualName = qual_name!("div", html);
/// The kind of anonymous box to generate, determining which precomputed
/// pseudo-element supplies its style (and hence its `display`).
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[allow(dead_code, reason = "table variants are used by upcoming table fixups")]
pub(crate) enum AnonKind {
Block,
Table,
Expand Down Expand Up @@ -136,6 +135,10 @@ pub(crate) enum ConstructionTaskResultData {
pub(crate) struct LayoutChildren {
pub(crate) children: ThinVec<NodeId>,
pub(crate) anonymous_block_id: Option<NodeId>,
/// The currently-open anonymous table wrapping a run of table-internal
/// children occurring outside a table (missing-parent fixup, CSS 2.2
/// §17.2.1). Closed by any non-table-internal sibling.
pub(crate) anonymous_table_id: Option<NodeId>,
/// All anonymous blocks created while collecting these layout children.
///
/// These are recorded on the container node so they can be deallocated the
Expand Down Expand Up @@ -182,6 +185,7 @@ impl LayoutChildren {
}

self.anonymous_block_id = None;
self.anonymous_table_id = None;
}

fn push_wrapped(
Expand All @@ -190,6 +194,15 @@ impl LayoutChildren {
child_id: NodeId,
doc: &mut BaseDocument,
) {
// A wrapped (text/inline) child terminates any open run of
// table-internal children, except that whitespace between
// table-internal boxes is discarded (CSS 2.2 §17.2.1).
if self.anonymous_table_id.is_some() {
if doc.nodes[child_id].is_whitespace_node() {
return;
}
self.anonymous_table_id = None;
}
if self.anonymous_block_id.is_none() {
self.create_anonymous_block(container_node_id, doc);
}
Expand All @@ -198,6 +211,27 @@ impl LayoutChildren {
.push(child_id);
}

/// Append a table-internal child (row, row group, cell, ...) occurring
/// outside a table to the currently-open anonymous table, opening one
/// first if needed. Consecutive runs share a single anonymous table.
fn push_wrapped_in_table(
&mut self,
container_node_id: NodeId,
child_id: NodeId,
doc: &mut BaseDocument,
) {
if self.anonymous_table_id.is_none() {
self.maybe_push_anon_block(doc);
let node_id = create_anonymous_node(doc, container_node_id, AnonKind::Table);
self.children.push(node_id);
self.anonymous_blocks.push(node_id);
self.anonymous_table_id = Some(node_id);
}
doc.nodes[self.anonymous_table_id.unwrap()]
.children
.push(child_id);
}

fn create_anonymous_block(&mut self, container_node_id: NodeId, doc: &mut BaseDocument) {
let node_id = create_anonymous_node(doc, container_node_id, AnonKind::Block);
self.children.push(node_id);
Expand Down Expand Up @@ -242,6 +276,14 @@ fn text_item_needs_wrap(child_node_kind: NodeKind, _display_outside: DisplayOuts
child_node_kind == NodeKind::Text
}

/// Whether a node is a replaced element. Table display values on replaced
/// elements are treated as ordinary content (CSS 2.2 §17.2.1 applies to
/// non-replaced elements only).
fn node_is_replaced(node: &Node) -> bool {
node.element_data()
.is_some_and(|el| is_replaced_element(&el.name.local))
}

/// Push a single hoisted child, recursing through display:contents nodes and
/// wrapping text/inline children per the ancestor container's `WrapContext`.
fn push_hoisted_child(
Expand All @@ -256,6 +298,12 @@ fn push_hoisted_child(
collect_layout_children_with_wrap(doc, child_id, out, wrap);
return;
}
if child_display.outside() == DisplayOutside::InternalTable && !node_is_replaced(child) {
if let Some(wrap_ctx) = wrap {
out.push_wrapped_in_table(wrap_ctx.container_node_id, child_id, doc);
return;
}
}
if let Some(wrap_ctx) = wrap {
let child_node_kind = child.data.kind();
let display_outside = if child.is_or_contains_block() {
Expand Down Expand Up @@ -327,6 +375,10 @@ struct FlowClassification {
all_inline: bool,
all_out_of_flow: bool,
has_contents: bool,
/// The container has table-internal children (rows, row groups, cells,
/// ...) which, occurring outside a table, must be wrapped in an
/// anonymous table box.
has_stray_table_internal: bool,
}

impl Default for FlowClassification {
Expand All @@ -336,6 +388,7 @@ impl Default for FlowClassification {
all_inline: true,
all_out_of_flow: true,
has_contents: false,
has_stray_table_internal: false,
}
}
}
Expand Down Expand Up @@ -421,9 +474,17 @@ fn classify_flow_children(
classification.all_out_of_flow = false;
match display.outside() {
DisplayOutside::None => {}
DisplayOutside::Block
| DisplayOutside::TableCaption
| DisplayOutside::InternalTable => classification.all_inline = false,
DisplayOutside::InternalTable => {
classification.all_inline = false;
// Table display values on replaced elements are treated
// as ordinary content, not table-internal boxes.
if !node_is_replaced(child) {
classification.has_stray_table_internal = true;
}
}
DisplayOutside::Block | DisplayOutside::TableCaption => {
classification.all_inline = false
}
DisplayOutside::Inline => {
classification.all_block = false;

Expand Down Expand Up @@ -568,7 +629,7 @@ fn collect_layout_children_with_wrap(
// ::before/::after pseudos must be checked too: a pseudo with
// display:contents hoists its text content into the container.
let container = &doc.nodes[container_node_id];
let has_text_node_or_contents = container
let needs_complex = container
.children
.iter()
.copied()
Expand All @@ -578,10 +639,12 @@ fn collect_layout_children_with_wrap(
.any(|child| {
let display = child.display_style().unwrap_or(Display::inline());
let node_kind = child.data.kind();
display.inside() == DisplayInside::Contents || node_kind == NodeKind::Text
display.inside() == DisplayInside::Contents
|| display.outside() == DisplayOutside::InternalTable
|| node_kind == NodeKind::Text
});

if !has_text_node_or_contents {
if !needs_complex {
return push_non_whitespace_children_and_pseudos(
&mut out.children,
&doc.nodes[container_node_id],
Expand All @@ -598,7 +661,9 @@ fn collect_layout_children_with_wrap(
}

DisplayInside::Table => {
let (table_context, tlayout_children) = build_table_context(doc, container_node_id);
let (table_context, tlayout_children, anonymous_nodes) =
build_table_context(doc, container_node_id);
out.anonymous_blocks.extend(anonymous_nodes);
#[allow(clippy::arc_with_non_send_sync)]
let data = SpecialElementData::TableRoot(Arc::new(table_context));
doc.nodes[container_node_id]
Expand All @@ -618,13 +683,9 @@ fn collect_layout_children_with_wrap(
}
}

// Flow, FlowRoot and TableCell, plus internal table displays (row,
// row group, column, ...) occurring outside of a table. Blitz does
// not yet generate anonymous table wrapper boxes for the latter, so
// they are laid out as flow containers, which crucially ensures
// their text children get wrapped rather than being pushed as bare
// layout children (text nodes carry no style and cannot be laid out
// as block/flex/grid items).
// Flow, FlowRoot and TableCell. Table-internal children (rows, row
// groups, cells, ...) occurring outside a table are wrapped in an
// anonymous table box by the classification below.
_ => {
let mut classification = FlowClassification::default();
classify_flow_children(doc, container_node_id, &mut classification);
Expand Down Expand Up @@ -663,7 +724,10 @@ fn collect_layout_children_with_wrap(

// If the children are either all inline or all block then simply return the regular children
// as the layout children
if classification.all_block & !classification.has_contents {
if classification.all_block
& !classification.has_contents
& !classification.has_stray_table_internal
{
return push_non_whitespace_children_and_pseudos(
&mut out.children,
&doc.nodes[container_node_id],
Expand Down Expand Up @@ -866,6 +930,13 @@ fn collect_complex_layout_children(
});
collect_layout_children_with_wrap(doc, child_id, out, wrap)
}
// Table-internal children occurring outside a table get wrapped in
// an anonymous table box (missing-parent fixup)
else if child_display.outside() == DisplayOutside::InternalTable
&& !node_is_replaced(&doc.nodes[child_id])
{
out.push_wrapped_in_table(container_node_id, child_id, doc);
}
// Push nodes that need wrapping into the current "anonymous block container".
// If there is not an open one then we create one.
else if needs_wrap(child_node_kind, display_outside) {
Expand Down
9 changes: 9 additions & 0 deletions packages/blitz-dom/src/layout/damage.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -214,6 +214,15 @@ pub(crate) fn compute_layout_damage(old: &ComputedValues, new: &ComputedValues)
return true;
}

// Table properties (border-spacing, border-collapse, ...) are baked
// into the TableContext at construction time, so changing them
// requires reconstructing the table's box tree.
if old.get_inherited_table() != new.get_inherited_table()
|| old.get_table() != new.get_table()
{
return true;
}

if new_box.display.outside() == DisplayOutside::Block
&& new_box.display.inside() == DisplayInside::Flow
{
Expand Down
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