Merge pull request #75 from typst/semantics

Frame Role and PDF outline

12 files changed, 87 insertions, 21 deletions

diff --git a/src/library/graphics/hide.rs b/src/library/graphics/hide.rs
index 28afe320..4ba5e023 100644
--- a/src/library/graphics/hide.rs
+++ b/src/library/graphics/hide.rs
@@ -22,7 +22,11 @@ impl Layout for HideNode {
 
         // Clear the frames.
         for frame in &mut frames {
-            *frame = Arc::new(Frame { elements: vec![], ..**frame });
+            *frame = Arc::new({
+                let mut empty = Frame::new(frame.size);
+                empty.baseline = frame.baseline;
+                empty
+            });
         }
 
         Ok(frames)
diff --git a/src/library/graphics/shape.rs b/src/library/graphics/shape.rs
index 9da8d8df..82eb2d9d 100644
--- a/src/library/graphics/shape.rs
+++ b/src/library/graphics/shape.rs
@@ -93,6 +93,10 @@ impl<const S: ShapeKind> Layout for ShapeNode<S> {
             let mut pod = Regions::one(regions.first, regions.base, regions.expand);
             frames = child.layout(ctx, &pod, styles)?;
 
+            for frame in frames.iter_mut() {
+                Arc::make_mut(frame).apply_role(Role::GenericBlock);
+            }
+
             // Relayout with full expansion into square region to make sure
             // the result is really a square or circle.
             if is_quadratic(S) {
diff --git a/src/library/layout/flow.rs b/src/library/layout/flow.rs
index 6193a68f..f779c8b1 100644
--- a/src/library/layout/flow.rs
+++ b/src/library/layout/flow.rs
@@ -182,7 +182,12 @@ impl FlowLayouter {
 
         let frames = node.layout(ctx, &self.regions, styles)?;
         let len = frames.len();
-        for (i, frame) in frames.into_iter().enumerate() {
+        for (i, mut frame) in frames.into_iter().enumerate() {
+            // Set the generic block role.
+            if frame.role().map_or(true, Role::is_weak) {
+                Arc::make_mut(&mut frame).apply_role(Role::GenericBlock);
+            }
+
             // Grow our size, shrink the region and save the frame for later.
             let size = frame.size;
             self.used.y += size.y;
diff --git a/src/library/layout/grid.rs b/src/library/layout/grid.rs
index 4cad9de6..2d6eb259 100644
--- a/src/library/layout/grid.rs
+++ b/src/library/layout/grid.rs
@@ -450,6 +450,7 @@ impl<'a> GridLayouter<'a> {
     /// Layout a row with fixed height and return its frame.
     fn layout_single_row(&mut self, height: Length, y: usize) -> TypResult<Frame> {
         let mut output = Frame::new(Size::new(self.used.x, height));
+
         let mut pos = Point::zero();
 
         for (x, &rcol) in self.rcols.iter().enumerate() {
@@ -464,6 +465,14 @@ impl<'a> GridLayouter<'a> {
 
                 let pod = Regions::one(size, base, Spec::splat(true));
                 let frame = node.layout(self.ctx, &pod, self.styles)?.remove(0);
+                match frame.role() {
+                    Some(Role::ListLabel | Role::ListItemBody) => {
+                        output.apply_role(Role::ListItem)
+                    }
+                    Some(Role::TableCell) => output.apply_role(Role::TableRow),
+                    _ => {}
+                }
+
                 output.push_frame(pos, frame);
             }
 
@@ -505,6 +514,13 @@ impl<'a> GridLayouter<'a> {
                 // Push the layouted frames into the individual output frames.
                 let frames = node.layout(self.ctx, &pod, self.styles)?;
                 for (output, frame) in outputs.iter_mut().zip(frames) {
+                    match frame.role() {
+                        Some(Role::ListLabel | Role::ListItemBody) => {
+                            output.apply_role(Role::ListItem)
+                        }
+                        Some(Role::TableCell) => output.apply_role(Role::TableRow),
+                        _ => {}
+                    }
                     output.push_frame(pos, frame);
                 }
             }
diff --git a/src/library/layout/page.rs b/src/library/layout/page.rs
index 8435e510..115a1923 100644
--- a/src/library/layout/page.rs
+++ b/src/library/layout/page.rs
@@ -110,16 +110,28 @@ impl PageNode {
             let pad = padding.resolve(styles).relative_to(size);
             let pw = size.x - pad.left - pad.right;
             let py = size.y - pad.bottom;
-            for (marginal, pos, area) in [
-                (header, Point::with_x(pad.left), Size::new(pw, pad.top)),
-                (footer, Point::new(pad.left, py), Size::new(pw, pad.bottom)),
-                (foreground, Point::zero(), size),
-                (background, Point::zero(), size),
+            for (role, marginal, pos, area) in [
+                (
+                    Role::Header,
+                    header,
+                    Point::with_x(pad.left),
+                    Size::new(pw, pad.top),
+                ),
+                (
+                    Role::Footer,
+                    footer,
+                    Point::new(pad.left, py),
+                    Size::new(pw, pad.bottom),
+                ),
+                (Role::Foreground, foreground, Point::zero(), size),
+                (Role::Background, background, Point::zero(), size),
             ] {
                 if let Some(content) = marginal.resolve(ctx, page)? {
                     let pod = Regions::one(area, area, Spec::splat(true));
-                    let sub = content.layout(ctx, &pod, styles)?.remove(0);
-                    if std::ptr::eq(marginal, background) {
+                    let mut sub = content.layout(ctx, &pod, styles)?.remove(0);
+                    Arc::make_mut(&mut sub).apply_role(role);
+
+                    if role == Role::Background {
                         Arc::make_mut(frame).prepend_frame(pos, sub);
                     } else {
                         Arc::make_mut(frame).push_frame(pos, sub);
diff --git a/src/library/layout/stack.rs b/src/library/layout/stack.rs
index 828ff8e3..9c2cbccd 100644
--- a/src/library/layout/stack.rs
+++ b/src/library/layout/stack.rs
@@ -194,7 +194,12 @@ impl<'a> StackLayouter<'a> {
 
         let frames = node.layout(ctx, &self.regions, styles)?;
         let len = frames.len();
-        for (i, frame) in frames.into_iter().enumerate() {
+        for (i, mut frame) in frames.into_iter().enumerate() {
+            // Set the generic block role.
+            if frame.role().map_or(true, Role::is_weak) {
+                Arc::make_mut(&mut frame).apply_role(Role::GenericBlock);
+            }
+
             // Grow our size, shrink the region and save the frame for later.
             let size = frame.size.to_gen(self.axis);
             self.used.main += size.main;
diff --git a/src/library/math/rex.rs b/src/library/math/rex.rs
index 0268fb9c..f839a9e8 100644
--- a/src/library/math/rex.rs
+++ b/src/library/math/rex.rs
@@ -66,6 +66,7 @@ impl Layout for RexNode {
         let mut backend = FrameBackend {
             frame: {
                 let mut frame = Frame::new(size);
+                frame.apply_role(Role::Formula);
                 frame.baseline = Some(baseline);
                 frame
             },
diff --git a/src/library/structure/heading.rs b/src/library/structure/heading.rs
index a0973b90..af2b3626 100644
--- a/src/library/structure/heading.rs
+++ b/src/library/structure/heading.rs
@@ -65,7 +65,8 @@ impl HeadingNode {
 
 impl Show for HeadingNode {
     fn unguard(&self, sel: Selector) -> ShowNode {
-        Self { body: self.body.unguard(sel), ..*self }.pack()
+        let body = self.body.unguard(sel).role(Role::Heading(self.level.get()));
+        Self { body, ..*self }.pack()
     }
 
     fn encode(&self, _: StyleChain) -> Dict {
@@ -114,7 +115,7 @@ impl Show for HeadingNode {
             realized = realized.underlined();
         }
 
-        realized = realized.styled_with_map(map);
+        realized = realized.styled_with_map(map).role(Role::Heading(self.level.get()));
         realized = realized.spaced(
             resolve!(Self::ABOVE).resolve(styles),
             resolve!(Self::BELOW).resolve(styles),
diff --git a/src/library/structure/list.rs b/src/library/structure/list.rs
index 84603eb3..015ef520 100644
--- a/src/library/structure/list.rs
+++ b/src/library/structure/list.rs
@@ -78,7 +78,7 @@ impl<const L: ListKind> Show for ListNode<L> {
     fn unguard(&self, sel: Selector) -> ShowNode {
         Self {
             items: self.items.map(|item| ListItem {
-                body: Box::new(item.body.unguard(sel)),
+                body: Box::new(item.body.unguard(sel).role(Role::ListItemBody)),
                 ..*item
             }),
             ..*self
@@ -108,9 +108,15 @@ impl<const L: ListKind> Show for ListNode<L> {
 
         for (item, map) in self.items.iter() {
             number = item.number.unwrap_or(number);
+
             cells.push(LayoutNode::default());
-            cells
-                .push(label.resolve(ctx, L, number)?.styled_with_map(map.clone()).pack());
+            cells.push(
+                label
+                    .resolve(ctx, L, number)?
+                    .styled_with_map(map.clone())
+                    .role(Role::ListLabel)
+                    .pack(),
+            );
             cells.push(LayoutNode::default());
             cells.push((*item.body).clone().styled_with_map(map.clone()).pack());
             number += 1;
@@ -155,7 +161,9 @@ impl<const L: ListKind> Show for ListNode<L> {
             }
         }
 
-        Ok(realized.spaced(above, below))
+        Ok(realized
+            .role(Role::List { ordered: L == ORDERED })
+            .spaced(above, below))
     }
 }
 
diff --git a/src/library/structure/table.rs b/src/library/structure/table.rs
index cd70db30..0f74fc96 100644
--- a/src/library/structure/table.rs
+++ b/src/library/structure/table.rs
@@ -52,7 +52,11 @@ impl Show for TableNode {
         Self {
             tracks: self.tracks.clone(),
             gutter: self.gutter.clone(),
-            cells: self.cells.iter().map(|cell| cell.unguard(sel)).collect(),
+            cells: self
+                .cells
+                .iter()
+                .map(|cell| cell.unguard(sel).role(Role::TableCell))
+                .collect(),
         }
         .pack()
     }
@@ -100,7 +104,8 @@ impl Show for TableNode {
             tracks: self.tracks.clone(),
             gutter: self.gutter.clone(),
             cells,
-        }))
+        })
+        .role(Role::Table))
     }
 
     fn finalize(
diff --git a/src/library/text/par.rs b/src/library/text/par.rs
index 695d8066..41246b00 100644
--- a/src/library/text/par.rs
+++ b/src/library/text/par.rs
@@ -551,11 +551,14 @@ fn prepare<'a>(
                 } else {
                     let size = Size::new(regions.first.x, regions.base.y);
                     let pod = Regions::one(size, regions.base, Spec::splat(false));
+
                     let mut frame = node.layout(ctx, &pod, styles)?.remove(0);
                     let shift = styles.get(TextNode::BASELINE);
 
-                    if !shift.is_zero() {
-                        Arc::make_mut(&mut frame).translate(Point::with_y(shift));
+                    if !shift.is_zero() || frame.role().map_or(true, Role::is_weak) {
+                        let frame = Arc::make_mut(&mut frame);
+                        frame.translate(Point::with_y(shift));
+                        frame.apply_role(Role::GenericInline);
                     }
 
                     items.push(Item::Frame(frame));
@@ -1063,6 +1066,7 @@ fn stack(
     let mut finished = vec![];
     let mut first = true;
     let mut output = Frame::new(Size::with_x(width));
+    output.apply_role(Role::Paragraph);
 
     // Stack the lines into one frame per region.
     for line in lines {
@@ -1072,6 +1076,7 @@ fn stack(
         while !regions.first.y.fits(height) && !regions.in_last() {
             finished.push(Arc::new(output));
             output = Frame::new(Size::with_x(width));
+            output.apply_role(Role::Paragraph);
             regions.next();
             first = true;
         }
diff --git a/src/library/text/raw.rs b/src/library/text/raw.rs
index a24d2170..31db811a 100644
--- a/src/library/text/raw.rs
+++ b/src/library/text/raw.rs
@@ -123,7 +123,7 @@ impl Show for RawNode {
             realized = realized.spaced(styles.get(Self::ABOVE), styles.get(Self::BELOW));
         }
 
-        Ok(realized.styled_with_map(map))
+        Ok(realized.styled_with_map(map).role(Role::Code))
     }
 }