move per-region state to Current

crates/typst-layout/src/grid/layouter.rs

@@ -43,6 +43,36 @@ pub struct GridLayouter<'a> {
     /// Rowspans not yet laid out because not all of their spanned rows were
     /// laid out yet.
     pub(super) rowspans: Vec<Rowspan>,
+    /// Grid layout state for the current region.
+    pub(super) current: Current,
+    /// Frames for finished regions.
+    pub(super) finished: Vec<Frame>,
+    /// The amount and height of header rows on each finished region.
+    pub(super) finished_header_rows: Vec<FinishedHeaderRowInfo>,
+    /// Whether this is an RTL grid.
+    pub(super) is_rtl: bool,
+    /// Currently repeating headers, one per level.
+    /// Sorted by increasing levels.
+    ///
+    /// Note that some levels may be absent, in particular level 0, which does
+    /// not exist (so the first level is >= 1).
+    pub(super) repeating_headers: Vec<&'a Header>,
+    /// Headers, repeating or not, awaiting their first successful layout.
+    /// Sorted by increasing levels.
+    pub(super) pending_headers: &'a [Repeatable<Header>],
+    pub(super) upcoming_headers: &'a [Repeatable<Header>],
+    /// If this is `Some`, this will receive the currently laid out row's
+    /// height if it is auto or relative. This is used for header height
+    /// calculation.
+    /// TODO: consider refactoring this into something nicer.
+    pub(super) current_row_height: Option<Abs>,
+    /// The span of the grid element.
+    pub(super) span: Span,
+}
+
+/// Grid layout state for the current region. This should be reset or updated
+/// on each region break.
+pub struct Current {
     /// The initial size of the current region before we started subtracting.
     pub(super) initial: Size,
     /// The amount of repeated header rows at the start of the current region.
@@ -68,32 +98,6 @@ pub struct GridLayouter<'a> {
     ///
     /// A value of zero indicates no headers were placed.
     pub(super) current_last_repeated_header_end: usize,
-    /// Frames for finished regions.
-    pub(super) finished: Vec<Frame>,
-    /// The amount and height of header rows on each finished region.
-    pub(super) finished_header_rows: Vec<FinishedHeaderRowInfo>,
-    /// Whether this is an RTL grid.
-    pub(super) is_rtl: bool,
-    /// Currently repeating headers, one per level.
-    /// Sorted by increasing levels.
-    ///
-    /// Note that some levels may be absent, in particular level 0, which does
-    /// not exist (so the first level is >= 1).
-    pub(super) repeating_headers: Vec<&'a Header>,
-    /// Headers, repeating or not, awaiting their first successful layout.
-    /// Sorted by increasing levels.
-    pub(super) pending_headers: &'a [Repeatable<Header>],
-    pub(super) upcoming_headers: &'a [Repeatable<Header>],
-    /// The height for each repeating header that was placed in this region.
-    /// Note that this includes headers not at the top of the region (pending
-    /// headers), and excludes headers removed by virtue of a new, conflicting
-    /// header being found.
-    pub(super) repeating_header_heights: Vec<Abs>,
-    /// If this is `Some`, this will receive the currently laid out row's
-    /// height if it is auto or relative. This is used for header height
-    /// calculation.
-    /// TODO: consider refactoring this into something nicer.
-    pub(super) current_row_height: Option<Abs>,
     /// Stores the length of `lrows` before a sequence of trailing rows
     /// equipped with orphan prevention were laid out. In this case, if no more
     /// rows are laid out after those rows before the region ends, the rows
@@ -116,11 +120,14 @@ pub struct GridLayouter<'a> {
     /// In particular, non-repeating headers only occupy the initial region,
     /// but disappear on new regions, so they can be ignored.
     pub(super) repeating_header_height: Abs,
+    /// The height for each repeating header that was placed in this region.
+    /// Note that this includes headers not at the top of the region (pending
+    /// headers), and excludes headers removed by virtue of a new, conflicting
+    /// header being found.
+    pub(super) repeating_header_heights: Vec<Abs>,
     /// The simulated footer height for this region.
     /// The simulation occurs before any rows are laid out for a region.
     pub(super) footer_height: Abs,
-    /// The span of the grid element.
-    pub(super) span: Span,
 }
 
 #[derive(Debug, Default)]
@@ -188,21 +195,23 @@ impl<'a> GridLayouter<'a> {
             lrows: vec![],
             unbreakable_rows_left: 0,
             rowspans: vec![],
-            initial: regions.size,
-            current_repeating_header_rows: 0,
-            current_last_repeated_header_end: 0,
             finished: vec![],
             finished_header_rows: vec![],
             is_rtl: TextElem::dir_in(styles) == Dir::RTL,
             repeating_headers: vec![],
             upcoming_headers: &grid.headers,
-            repeating_header_heights: vec![],
             pending_headers: Default::default(),
-            lrows_orphan_snapshot: None,
             current_row_height: None,
+            current: Current {
+                initial: regions.size,
+                current_repeating_header_rows: 0,
+                current_last_repeated_header_end: 0,
+                lrows_orphan_snapshot: None,
                 header_height: Abs::zero(),
                 repeating_header_height: Abs::zero(),
+                repeating_header_heights: vec![],
                 footer_height: Abs::zero(),
+            },
             span,
         }
     }
@@ -215,7 +224,7 @@ impl<'a> GridLayouter<'a> {
             // Ensure rows in the first region will be aware of the possible
             // presence of the footer.
             self.prepare_footer(footer, engine, 0)?;
-            self.regions.size.y -= self.footer_height;
+            self.regions.size.y -= self.current.footer_height;
         }
 
         let mut y = 0;
@@ -344,7 +353,7 @@ impl<'a> GridLayouter<'a> {
                     self.layout_relative_row(engine, disambiguator, v, y)?
                 }
                 Sizing::Fr(v) => {
-                    self.lrows_orphan_snapshot = None;
+                    self.current.lrows_orphan_snapshot = None;
                     self.lrows.push(Row::Fr(v, y, disambiguator))
                 }
             }
@@ -1094,7 +1103,7 @@ impl<'a> GridLayouter<'a> {
             target.set_max(
                 region.y
                     - if i > 0 {
-                        self.repeating_header_height + self.footer_height
+                        self.current.repeating_header_height + self.current.footer_height
                     } else {
                         Abs::zero()
                     },
@@ -1325,7 +1334,7 @@ impl<'a> GridLayouter<'a> {
             && !self.regions.size.y.fits(height)
             && may_progress_with_offset(
                 self.regions,
-                self.header_height + self.footer_height,
+                self.current.header_height + self.current.footer_height,
             )
         {
             self.finish_region(engine, false)?;
@@ -1459,7 +1468,7 @@ impl<'a> GridLayouter<'a> {
     fn push_row(&mut self, frame: Frame, y: usize, is_last: bool) {
         // There is now a row after the rows equipped with orphan prevention,
         // so no need to remove them anymore.
-        self.lrows_orphan_snapshot = None;
+        self.current.lrows_orphan_snapshot = None;
         self.regions.size.y -= frame.height();
         self.lrows.push(Row::Frame(frame, y, is_last));
     }
@@ -1470,11 +1479,11 @@ impl<'a> GridLayouter<'a> {
         engine: &mut Engine,
         last: bool,
     ) -> SourceResult<()> {
-        if let Some(orphan_snapshot) = self.lrows_orphan_snapshot.take() {
+        if let Some(orphan_snapshot) = self.current.lrows_orphan_snapshot.take() {
             if !last {
                 self.lrows.truncate(orphan_snapshot);
-                self.current_repeating_header_rows =
+                self.current.current_repeating_header_rows =
-                    self.current_repeating_header_rows.min(orphan_snapshot);
+                    self.current.current_repeating_header_rows.min(orphan_snapshot);
             }
         }
 
@@ -1485,11 +1494,12 @@ impl<'a> GridLayouter<'a> {
         {
             // Remove the last row in the region if it is a gutter row.
             self.lrows.pop().unwrap();
-            self.current_repeating_header_rows =
+            self.current.current_repeating_header_rows =
-                self.current_repeating_header_rows.min(self.lrows.len());
+                self.current.current_repeating_header_rows.min(self.lrows.len());
         }
 
         let footer_would_be_widow = if let Some(last_header_row) = self
+            .current
             .current_repeating_header_rows
             .checked_sub(1)
             .and_then(|last_header_index| self.lrows.get(last_header_index))
@@ -1502,21 +1512,21 @@ impl<'a> GridLayouter<'a> {
                     .as_ref()
                     .and_then(Repeatable::as_repeated)
                     .is_none_or(|footer| footer.start != last_header_end)
-                && self.lrows.len() == self.current_repeating_header_rows
+                && self.lrows.len() == self.current.current_repeating_header_rows
                 && may_progress_with_offset(
                     self.regions,
                     // Since we're trying to find a region where to place all
                     // repeating + pending headers, it makes sense to use
                     // 'header_height' and include even non-repeating pending
                     // headers for this check.
-                    self.header_height + self.footer_height,
+                    self.current.header_height + self.current.footer_height,
                 )
             {
                 // Header and footer would be alone in this region, but there are more
                 // rows beyond the header and the footer. Push an empty region.
                 self.lrows.clear();
-                self.current_last_repeated_header_end = 0;
+                self.current.current_last_repeated_header_end = 0;
-                self.current_repeating_header_rows = 0;
+                self.current.current_repeating_header_rows = 0;
                 true
             } else {
                 false
@@ -1533,7 +1543,7 @@ impl<'a> GridLayouter<'a> {
                     // This header height isn't doing much as we just confirmed
                     // that there are no headers in this region, but let's keep
                     // it here for correctness. It will add zero anyway.
-                    self.header_height + self.footer_height,
+                    self.current.header_height + self.current.footer_height,
                 )
                 && footer.start != 0
         } else {
@@ -1564,9 +1574,9 @@ impl<'a> GridLayouter<'a> {
 
         // Determine the size of the grid in this region, expanding fully if
         // there are fr rows.
-        let mut size = Size::new(self.width, used).min(self.initial);
+        let mut size = Size::new(self.width, used).min(self.current.initial);
-        if fr.get() > 0.0 && self.initial.y.is_finite() {
+        if fr.get() > 0.0 && self.current.initial.y.is_finite() {
-            size.y = self.initial.y;
+            size.y = self.current.initial.y;
         }
 
         // The frame for the region.
@@ -1588,7 +1598,7 @@ impl<'a> GridLayouter<'a> {
             };
 
             let height = frame.height();
-            if i < self.current_repeating_header_rows {
+            if i < self.current.current_repeating_header_rows {
                 header_row_height += height;
             }
 
@@ -1688,18 +1698,18 @@ impl<'a> GridLayouter<'a> {
             output,
             rrows,
             FinishedHeaderRowInfo {
-                repeated: self.current_repeating_header_rows,
+                repeated: self.current.current_repeating_header_rows,
-                last_repeated_header_end: self.current_last_repeated_header_end,
+                last_repeated_header_end: self.current.current_last_repeated_header_end,
                 height: header_row_height,
             },
         );
 
         if !last {
-            self.current_repeating_header_rows = 0;
+            self.current.current_repeating_header_rows = 0;
-            self.current_last_repeated_header_end = 0;
+            self.current.current_last_repeated_header_end = 0;
-            self.header_height = Abs::zero();
+            self.current.header_height = Abs::zero();
-            self.repeating_header_height = Abs::zero();
+            self.current.repeating_header_height = Abs::zero();
-            self.repeating_header_heights.clear();
+            self.current.repeating_header_heights.clear();
 
             let disambiguator = self.finished.len();
             if let Some(Repeatable::Repeated(footer)) = &self.grid.footer {
@@ -1710,7 +1720,7 @@ impl<'a> GridLayouter<'a> {
             // Note that header layout will only subtract this again if it has
             // to skip regions to fit headers, so there is no risk of
             // subtracting this twice.
-            self.regions.size.y -= self.footer_height;
+            self.regions.size.y -= self.current.footer_height;
 
             if !self.repeating_headers.is_empty() || !self.pending_headers.is_empty() {
                 // Add headers to the new region.
@@ -1732,14 +1742,14 @@ impl<'a> GridLayouter<'a> {
         self.finished.push(output);
         self.rrows.push(resolved_rows);
         self.regions.next();
-        self.initial = self.regions.size;
+        self.current.initial = self.regions.size;
 
         if !self.grid.headers.is_empty() {
             self.finished_header_rows.push(header_row_info);
         }
 
         // Ensure orphan prevention is handled before resolving rows.
-        debug_assert!(self.lrows_orphan_snapshot.is_none());
+        debug_assert!(self.current.lrows_orphan_snapshot.is_none());
     }
 }
 

crates/typst-layout/src/grid/repeated.rs

@@ -142,15 +142,16 @@ impl<'a> GridLayouter<'a> {
 
         // Ensure upcoming rows won't see that these headers will occupy any
         // space in future regions anymore.
-        for removed_height in self.repeating_header_heights.drain(first_conflicting_pos..)
+        for removed_height in
+            self.current.repeating_header_heights.drain(first_conflicting_pos..)
         {
-            self.repeating_header_height -= removed_height;
+            self.current.repeating_header_height -= removed_height;
         }
 
         // Non-repeating headers stop at the pending stage for orphan
         // prevention only. Flushing pending headers, so those will no longer
         // appear in a future region.
-        self.header_height = self.repeating_header_height;
+        self.current.header_height = self.current.repeating_header_height;
 
         // Let's try to place them at least once.
         // This might be a waste as we could generate an orphan and thus have
@@ -223,7 +224,7 @@ impl<'a> GridLayouter<'a> {
                 // available size for consistency with the first region, so we
                 // need to consider the footer when evaluating if skipping yet
                 // another region would make a difference.
-                self.footer_height,
+                self.current.footer_height,
             )
         {
             // Advance regions without any output until we can place the
@@ -238,7 +239,7 @@ impl<'a> GridLayouter<'a> {
             // if 'full' changes? (Assuming height doesn't change for now...)
             skipped_region = true;
 
-            self.regions.size.y -= self.footer_height;
+            self.regions.size.y -= self.current.footer_height;
         }
 
         if let Some(Repeatable::Repeated(footer)) = &self.grid.footer {
@@ -246,11 +247,11 @@ impl<'a> GridLayouter<'a> {
                 // Simulate the footer again; the region's 'full' might have
                 // changed.
                 // TODO: maybe this should go in the loop, a bit hacky as is...
-                self.regions.size.y += self.footer_height;
+                self.regions.size.y += self.current.footer_height;
-                self.footer_height = self
+                self.current.footer_height = self
                     .simulate_footer(footer, &self.regions, engine, disambiguator)?
                     .height;
-                self.regions.size.y -= self.footer_height;
+                self.regions.size.y -= self.current.footer_height;
             }
         }
 
@@ -265,22 +266,22 @@ impl<'a> GridLayouter<'a> {
         // within 'layout_row'.
         self.unbreakable_rows_left += repeating_header_rows + pending_header_rows;
 
-        self.current_last_repeated_header_end =
+        self.current.current_last_repeated_header_end =
             self.repeating_headers.last().map(|h| h.end).unwrap_or_default();
 
         // Reset the header height for this region.
         // It will be re-calculated when laying out each header row.
-        self.header_height = Abs::zero();
+        self.current.header_height = Abs::zero();
-        self.repeating_header_height = Abs::zero();
+        self.current.repeating_header_height = Abs::zero();
-        self.repeating_header_heights.clear();
+        self.current.repeating_header_heights.clear();
 
         // Use indices to avoid double borrow. We don't mutate headers in
         // 'layout_row' so this is fine.
         let mut i = 0;
         while let Some(&header) = self.repeating_headers.get(i) {
             let header_height = self.layout_header_rows(header, engine, disambiguator)?;
-            self.header_height += header_height;
+            self.current.header_height += header_height;
-            self.repeating_header_height += header_height;
+            self.current.repeating_header_height += header_height;
 
             // We assume that this vector will be sorted according
             // to increasing levels like 'repeating_headers' and
@@ -300,26 +301,26 @@ impl<'a> GridLayouter<'a> {
             // headers which have now stopped repeating. They are always at
             // the end and new pending headers respect the existing sort,
             // so the vector will remain sorted.
-            self.repeating_header_heights.push(header_height);
+            self.current.repeating_header_heights.push(header_height);
 
             i += 1;
         }
 
-        self.current_repeating_header_rows = self.lrows.len();
+        self.current.current_repeating_header_rows = self.lrows.len();
 
         if !self.pending_headers.is_empty() {
             // Restore snapshot: if pending headers placed again turn out to be
             // orphans, remove their rows again.
-            self.lrows_orphan_snapshot = Some(self.lrows.len());
+            self.current.lrows_orphan_snapshot = Some(self.lrows.len());
         }
 
         for header in self.pending_headers {
             let header_height =
                 self.layout_header_rows(header.unwrap(), engine, disambiguator)?;
-            self.header_height += header_height;
+            self.current.header_height += header_height;
             if matches!(header, Repeatable::Repeated(_)) {
-                self.repeating_header_height += header_height;
+                self.current.repeating_header_height += header_height;
-                self.repeating_header_heights.push(header_height);
+                self.current.repeating_header_heights.push(header_height);
             }
         }
 
@@ -359,7 +360,7 @@ impl<'a> GridLayouter<'a> {
                 // 'header_height == repeating_header_height' here
                 // (there won't be any pending headers at this point, other
                 // than the ones we are about to place).
-                self.header_height + self.footer_height,
+                self.current.header_height + self.current.footer_height,
             )
         {
             // Note that, after the first region skip, the new headers will go
@@ -382,10 +383,10 @@ impl<'a> GridLayouter<'a> {
             // region, so multi-page rows and cells can effectively ignore
             // this header.
             if !short_lived {
-                self.header_height += header_height;
+                self.current.header_height += header_height;
                 if matches!(header, Repeatable::Repeated(_)) {
-                    self.repeating_header_height += header_height;
+                    self.current.repeating_header_height += header_height;
-                    self.repeating_header_heights.push(header_height);
+                    self.current.repeating_header_heights.push(header_height);
                 }
             }
         }
@@ -393,7 +394,7 @@ impl<'a> GridLayouter<'a> {
         // Remove new headers at the end of the region if upcoming child doesn't fit.
         // TODO: Short lived if footer comes afterwards
         if !short_lived {
-            self.lrows_orphan_snapshot = Some(initial_row_count);
+            self.current.lrows_orphan_snapshot = Some(initial_row_count);
         }
 
         Ok(())
@@ -466,7 +467,7 @@ impl<'a> GridLayouter<'a> {
         // That is unnecessary at the moment as 'prepare_footers' is only
         // called at the start of the region, but what about when we can have
         // footers in the middle of the region? Let's think about this then.
-        self.footer_height = if skipped_region {
+        self.current.footer_height = if skipped_region {
             // Simulate the footer again; the region's 'full' might have
             // changed.
             self.simulate_footer(footer, &self.regions, engine, disambiguator)?
@@ -489,7 +490,7 @@ impl<'a> GridLayouter<'a> {
         // Ensure footer rows have their own height available.
         // Won't change much as we're creating an unbreakable row group
         // anyway, so this is mostly for correctness.
-        self.regions.size.y += self.footer_height;
+        self.regions.size.y += self.current.footer_height;
 
         let footer_len = self.grid.rows.len() - footer.start;
         self.unbreakable_rows_left += footer_len;

crates/typst-layout/src/grid/rowspans.rs

@@ -263,7 +263,7 @@ impl GridLayouter<'_> {
                     // due to orphan/widow prevention, which explains the usage of
                     // 'header_height' (include non-repeating but pending headers) rather
                     // than 'repeating_header_height'.
-                    self.header_height + self.footer_height,
+                    self.current.header_height + self.current.footer_height,
                 )
             {
                 self.finish_region(engine, false)?;
@@ -422,7 +422,9 @@ impl GridLayouter<'_> {
                 let mapped_regions = self.regions.map(&mut custom_backlog, |size| {
                     Size::new(
                         size.x,
-                        size.y - self.repeating_header_height - self.footer_height,
+                        size.y
+                            - self.current.repeating_header_height
+                            - self.current.footer_height,
                     )
                 });
 
@@ -535,7 +537,7 @@ impl GridLayouter<'_> {
                         // and unbreakable rows in general, so there is no risk
                         // of accessing an incomplete list of rows.
                         let initial_header_height = self.lrows
-                            [..self.current_repeating_header_rows]
+                            [..self.current.current_repeating_header_rows]
                             .iter()
                             .map(|row| match row {
                                 Row::Frame(frame, _, _) => frame.height(),
@@ -543,7 +545,9 @@ impl GridLayouter<'_> {
                             })
                             .sum();
 
-                        self.initial.y - initial_header_height - self.footer_height
+                        self.current.initial.y
+                            - initial_header_height
+                            - self.current.footer_height
                     } else {
                         // When measuring unbreakable auto rows, infinite
                         // height is available for content to expand.
@@ -559,7 +563,8 @@ impl GridLayouter<'_> {
                     // Assume only repeating headers will survive starting at
                     // the next region.
                     let backlog = self.regions.backlog.iter().map(|&size| {
-                        size - self.repeating_header_height - self.footer_height
+                        size - self.current.repeating_header_height
+                            - self.current.footer_height
                     });
 
                     heights_up_to_current_region.chain(backlog).collect::<Vec<_>>()
@@ -574,10 +579,10 @@ impl GridLayouter<'_> {
                 height = *rowspan_height;
                 backlog = None;
                 full = rowspan_full;
-                last = self
+                last = self.regions.last.map(|size| {
-                    .regions
+                    size - self.current.repeating_header_height
-                    .last
+                        - self.current.footer_height
-                    .map(|size| size - self.repeating_header_height - self.footer_height);
+                });
             } else {
                 // The rowspan started in the current region, as its vector
                 // of heights in regions is currently empty.
@@ -782,7 +787,8 @@ impl GridLayouter<'_> {
             // Subtract the repeating header and footer height, since that's
             // the height we used when subtracting from the region backlog's
             // heights while measuring cells.
-            simulated_regions.size.y -= self.repeating_header_height + self.footer_height;
+            simulated_regions.size.y -=
+                self.current.repeating_header_height + self.current.footer_height;
         }
 
         if let Some(original_last_resolved_size) = last_resolved_size {
@@ -921,8 +927,8 @@ impl GridLayouter<'_> {
                 // rowspan, since headers and footers are unbreakable, so
                 // assuming the repeating header height and footer height
                 // won't change is safe.
-                self.repeating_header_height,
+                self.current.repeating_header_height,
-                self.footer_height,
+                self.current.footer_height,
             );
 
             let total_spanned_height = rowspan_simulator.simulate_rowspan_layout(
@@ -1006,7 +1012,7 @@ impl GridLayouter<'_> {
                 extra_amount_to_grow -= simulated_regions.size.y.max(Abs::zero());
                 simulated_regions.next();
                 simulated_regions.size.y -=
-                    self.repeating_header_height + self.footer_height;
+                    self.current.repeating_header_height + self.current.footer_height;
                 disambiguator += 1;
             }
             simulated_regions.size.y -= extra_amount_to_grow;