move top hline state to row group data

crates/typst-library/src/layout/grid/resolve.rs

@@ -671,14 +671,14 @@ impl<'a> CellGrid<'a> {
         let mut rows = vec![];
 
         // Number of content columns: Always at least one.
-        let columns = tracks.x.len().max(1);
+        let num_cols = tracks.x.len().max(1);
 
         // Number of content rows: At least as many as given, but also at least
         // as many as needed to place each item.
-        let r = {
+        let num_rows = {
             let len = entries.len();
             let given = tracks.y.len();
-            let needed = len / columns + (len % columns).clamp(0, 1);
+            let needed = len / num_cols + (len % num_cols).clamp(0, 1);
             given.max(needed)
         };
 
@@ -690,7 +690,7 @@ impl<'a> CellGrid<'a> {
         };
 
         // Collect content and gutter columns.
-        for x in 0..columns {
+        for x in 0..num_cols {
             cols.push(get_or(tracks.x, x, auto));
             if has_gutter {
                 cols.push(get_or(gutter.x, x, zero));
@@ -698,7 +698,7 @@ impl<'a> CellGrid<'a> {
         }
 
         // Collect content and gutter rows.
-        for y in 0..r {
+        for y in 0..num_rows {
             rows.push(get_or(tracks.y, y, auto));
             if has_gutter {
                 rows.push(get_or(gutter.y, y, zero));
@@ -936,6 +936,27 @@ struct RowGroupData {
     range: Option<Range<usize>>,
     span: Span,
     kind: RowGroupKind,
+
+    /// Start of the range of indices of hlines at the top of the row group.
+    /// This is always the first index after the last hline before we started
+    /// building the row group - any upcoming hlines would appear at least at
+    /// this index.
+    ///
+    /// These hlines were auto-positioned and appeared before any auto-pos
+    /// cells, so they will appear at the first possible row (above the
+    /// first row spanned by the row group).
+    top_hlines_start: usize,
+
+    /// End of the range of indices of hlines at the top of the row group.
+    ///
+    /// This starts as `None`, meaning that, if we stop the loop before we find
+    /// any auto-pos cells, all auto-pos hlines after the last hline (after the
+    /// index `top_hlines_start`) should be moved to the top of the row group.
+    ///
+    /// It becomes `Some(index of last hline at the top)` when an auto-pos cell
+    /// is found, as auto-pos hlines after any auto-pos cells appear below
+    /// them, not at the top of the row group.
+    top_hlines_end: Option<usize>,
 }
 
 impl<'x> CellGridResolver<'_, '_, 'x> {
@@ -1107,8 +1128,13 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
                     bail!(span, "cannot have more than one header");
                 }
 
-                row_group_data =
+                row_group_data = Some(RowGroupData {
-                    Some(RowGroupData { range: None, span, kind: RowGroupKind::Header });
+                    range: None,
+                    span,
+                    kind: RowGroupKind::Header,
+                    top_hlines_start: pending_hlines.len(),
+                    top_hlines_end: None,
+                });
 
                 *repeat_header = repeat;
 
@@ -1133,8 +1159,13 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
                     bail!(span, "cannot have more than one footer");
                 }
 
-                row_group_data =
+                row_group_data = Some(RowGroupData {
-                    Some(RowGroupData { range: None, span, kind: RowGroupKind::Footer });
+                    range: None,
+                    span,
+                    kind: RowGroupKind::Footer,
+                    top_hlines_start: pending_hlines.len(),
+                    top_hlines_end: None,
+                });
 
                 *repeat_footer = repeat;
 
@@ -1301,8 +1332,9 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
 
             // Cell's header or footer must expand to include the cell's
             // occupied positions, if possible.
-            if let Some(RowGroupData { range: group_range, kind, .. }) =
+            if let Some(RowGroupData {
-                &mut row_group_data
+                range: group_range, kind, top_hlines_end, ..
+            }) = &mut row_group_data
             {
                 *group_range = Some(
                     expand_row_group(
@@ -1316,6 +1348,14 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
                     )
                     .at(cell_span)?,
                 );
+
+                if top_hlines_end.is_none()
+                    && local_auto_index > first_available_row * columns
+                {
+                    // Auto index was moved, so upcoming auto-pos hlines should
+                    // no longer appear at the top.
+                    *top_hlines_end = Some(pending_hlines.len());
+                }
             }
 
             // Let's resolve the cell so it can determine its own fields
@@ -1428,6 +1468,19 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
                 }
             };
 
+            let top_hlines_end = row_group.top_hlines_end.unwrap_or(pending_hlines.len());
+            for (_, top_hline, has_auto_y) in pending_hlines
+                .get_mut(row_group.top_hlines_start..top_hlines_end)
+                .unwrap_or(&mut [])
+            {
+                if *has_auto_y {
+                    // Move this hline to the top of the child, as it was
+                    // placed before the first automatically positioned cell
+                    // and had an automatic index.
+                    top_hline.index = group_range.start;
+                }
+            }
+
             match row_group.kind {
                 RowGroupKind::Header => {
                     if group_range.start != 0 {

tests/suite/layout/grid/footers.typ

@@ -437,6 +437,38 @@
   )
 )
 
+--- grid-footer-top-hlines-with-only-row-pos-cell ---
+// Top hlines should attach to the top of the footer.
+#set page(margin: 2pt)
+#set text(6pt)
+#table(
+  columns: 3,
+  inset: 2.5pt,
+  table.footer(
+    table.hline(stroke: red),
+    table.vline(stroke: blue),
+    table.cell(x: 2, y: 2)[a],
+    table.hline(stroke: 3pt),
+    table.vline(stroke: 3pt),
+  )
+)
+
+--- grid-footer-top-hlines-with-row-and-auto-pos-cell ---
+#set page(margin: 2pt)
+#set text(6pt)
+#table(
+  columns: 3,
+  inset: 2.5pt,
+  table.footer(
+    table.hline(stroke: red),
+    table.vline(stroke: blue),
+    table.cell(x: 2, y: 2)[a],
+    [b],
+    table.hline(stroke: 3pt),
+    table.vline(stroke: 3pt),
+  )
+)
+
 --- grid-footer-below-rowspans ---
 // Footer should go below the rowspans.
 #set page(margin: 2pt)