WIP [no ci] tag table headers

crates/typst-library/src/model/table.rs

@@ -2,6 +2,7 @@ use std::num::{NonZeroU32, NonZeroUsize};
 use std::sync::Arc;
 
 use ecow::EcoString;
+use typst_macros::Cast;
 use typst_utils::NonZeroExt;
 
 use crate::diag::{bail, HintedStrResult, HintedString, SourceResult};
@@ -361,15 +362,40 @@ fn show_cellgrid_html(grid: CellGrid, styles: StyleChain) -> Content {
 
 impl Show for Packed<TableElem> {
     fn show(&self, engine: &mut Engine, styles: StyleChain) -> SourceResult<Content> {
-        Ok(if TargetElem::target_in(styles).is_html() {
+        let elem = if TargetElem::target_in(styles).is_html() {
             // TODO: This is a hack, it is not clear whether the locator is actually used by HTML.
             // How can we find out whether locator is actually used?
             let locator = Locator::root();
             show_cellgrid_html(table_to_cellgrid(self, engine, locator, styles)?, styles)
         } else {
-            BlockElem::multi_layouter(self.clone(), engine.routines.layout_table).pack()
+            let children = self
+                .children
+                .iter()
+                .map(|c| match c.clone() {
+                    TableChild::Header(header) => {
+                        let mut header = header.unpack();
+                        header.children = header
+                            .children
+                            .into_iter()
+                            .map(|item| match item {
+                                TableItem::Cell(cell) => {
+                                    let mut cell = cell.unpack();
+                                    cell.push_header_scope(Smart::Custom(TableHeaderScope::Column));
+                                    TableItem::Cell(Packed::new(cell))
                                 }
-        .spanned(self.span()))
+                                item => item,
+                            })
+                            .collect();
+                        TableChild::Header(Packed::new(header))
+                    }
+                    child => child,
+                })
+                .collect();
+            let mut table = self.clone().unpack();
+            table.children = children;
+            BlockElem::multi_layouter(Packed::new(table), engine.routines.layout_table).pack()
+        };
+        Ok(elem.spanned(self.span()))
     }
 }
 
@@ -810,6 +836,9 @@ pub struct TableCell {
     #[fold]
     pub stroke: Sides<Option<Option<Arc<Stroke>>>>,
 
+    // TODO: feature gate
+    pub header_scope: Smart<TableHeaderScope>,
+
     /// Whether rows spanned by this cell can be placed in different pages.
     /// When equal to `{auto}`, a cell spanning only fixed-size rows is
     /// unbreakable, while a cell spanning at least one `{auto}`-sized row is
@@ -847,3 +876,10 @@ impl From<Content> for TableCell {
         value.unpack::<Self>().unwrap_or_else(Self::new)
     }
 }
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Cast)]
+pub enum TableHeaderScope {
+    Both,
+    Column,
+    Row,
+}

crates/typst-pdf/src/tags.rs

@@ -5,14 +5,14 @@ use krilla::page::Page;
 use krilla::surface::Surface;
 use krilla::tagging::{
     ArtifactType, ContentTag, Identifier, Node, SpanTag, TableCellSpan, TableDataCell,
-    TableHeaderCell, TableHeaderScope, Tag, TagBuilder, TagGroup, TagKind, TagTree,
+    TableHeaderCell, Tag, TagBuilder, TagGroup, TagKind, TagTree,
 };
-use typst_library::foundations::{Content, LinkMarker, Packed, StyleChain};
+use typst_library::foundations::{Content, LinkMarker, Packed, StyleChain, Smart};
 use typst_library::introspection::Location;
 use typst_library::layout::RepeatElem;
 use typst_library::model::{
     Destination, FigureCaption, FigureElem, HeadingElem, Outlinable, OutlineBody,
-    OutlineEntry, TableCell, TableElem,
+    OutlineEntry, TableCell, TableElem, TableHeaderScope,
 };
 use typst_library::pdf::{ArtifactElem, ArtifactKind, PdfTagElem, PdfTagKind};
 use typst_library::visualize::ImageElem;
@@ -141,10 +141,14 @@ impl TableCtx {
 
         // TODO: possibly set internal field on TableCell when resolving
         // the cell grid.
-        let is_header = false;
+        let header_scope = cell.header_scope(StyleChain::default());
         let span = TableCellSpan { rows: rowspan as i32, cols: colspan as i32 };
-        let tag = if is_header {
-            let scope = TableHeaderScope::Column; // TODO
+        let tag = if let Smart::Custom(scope) = header_scope {
+            let scope = match scope {
+                TableHeaderScope::Both => krilla::tagging::TableHeaderScope::Both,
+                TableHeaderScope::Column => krilla::tagging::TableHeaderScope::Column,
+                TableHeaderScope::Row => krilla::tagging::TableHeaderScope::Row,
+            };
             TagKind::TH(TableHeaderCell::new(scope).with_span(span))
         } else {
             TagKind::TD(TableDataCell::new().with_span(span))
@@ -167,14 +171,37 @@ impl TableCtx {
     fn build_table(self, mut nodes: Vec<TagNode>) -> Vec<TagNode> {
         // Table layouting ensures that there are no overlapping cells, and that
         // any gaps left by the user are filled with empty cells.
+        let mut row_chunk = Vec::new();
+        let mut is_header_chunk = false;
         for row in self.rows.into_iter() {
-            let mut row_nodes = Vec::new();
-            for (_, tag, nodes) in row.into_iter().flatten() {
-                row_nodes.push(TagNode::Group(tag, nodes));
+            let mut is_header_row = true;
+            let row_nodes = row
+                .into_iter()
+                .flatten()
+                .map(|(cell, tag, nodes)| {
+                    is_header_row &= cell.header_scope(StyleChain::default()).is_custom();
+                    TagNode::Group(tag, nodes)
+                })
+                .collect();
+
+            let row = TagNode::Group(TagKind::TR.into(), row_nodes);
+            if row_chunk.is_empty() {
+                is_header_chunk = is_header_row;
+                row_chunk.push(row);
+            } else if is_header_chunk == is_header_row {
+                row_chunk.push(row);
+            } else {
+                let tag = if is_header_chunk { TagKind::THead } else { TagKind::TBody };
+                nodes.push(TagNode::Group(tag.into(), std::mem::take(&mut row_chunk)));
+
+                is_header_chunk = is_header_row;
+                row_chunk.push(row);
+            }
         }
 
-            // TODO: generate `THead`, `TBody`, and `TFoot`
-            nodes.push(TagNode::Group(TagKind::TR.into(), row_nodes));
+        if !row_chunk.is_empty() {
+            let tag = if is_header_chunk { TagKind::THead } else { TagKind::TBody };
+            nodes.push(TagNode::Group(tag.into(), row_chunk));
         }
 
         nodes