Tracked memoization

30 files changed, 97 insertions, 60 deletions

diff --git a/src/library/graphics/hide.rs b/src/library/graphics/hide.rs
index 505dd1f6..65684272 100644
--- a/src/library/graphics/hide.rs
+++ b/src/library/graphics/hide.rs
@@ -14,7 +14,7 @@ impl HideNode {
 impl Layout for HideNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
diff --git a/src/library/graphics/image.rs b/src/library/graphics/image.rs
index c0249b3c..7523471d 100644
--- a/src/library/graphics/image.rs
+++ b/src/library/graphics/image.rs
@@ -41,7 +41,7 @@ impl ImageNode {
 impl Layout for ImageNode {
     fn layout(
         &self,
-        _: &dyn World,
+        _: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
diff --git a/src/library/graphics/line.rs b/src/library/graphics/line.rs
index ebfec1b2..192f8350 100644
--- a/src/library/graphics/line.rs
+++ b/src/library/graphics/line.rs
@@ -40,7 +40,7 @@ impl LineNode {
 impl Layout for LineNode {
     fn layout(
         &self,
-        _: &dyn World,
+        _: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
diff --git a/src/library/graphics/shape.rs b/src/library/graphics/shape.rs
index d9162557..eea02568 100644
--- a/src/library/graphics/shape.rs
+++ b/src/library/graphics/shape.rs
@@ -78,7 +78,7 @@ impl<const S: ShapeKind> ShapeNode<S> {
 impl<const S: ShapeKind> Layout for ShapeNode<S> {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
diff --git a/src/library/graphics/transform.rs b/src/library/graphics/transform.rs
index 34d45bd0..b110f343 100644
--- a/src/library/graphics/transform.rs
+++ b/src/library/graphics/transform.rs
@@ -25,7 +25,7 @@ impl MoveNode {
 impl Layout for MoveNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
@@ -86,7 +86,7 @@ impl<const T: TransformKind> TransformNode<T> {
 impl<const T: TransformKind> Layout for TransformNode<T> {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
diff --git a/src/library/layout/align.rs b/src/library/layout/align.rs
index 0c758cf2..705d555b 100644
--- a/src/library/layout/align.rs
+++ b/src/library/layout/align.rs
@@ -28,7 +28,7 @@ impl AlignNode {
 impl Layout for AlignNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
diff --git a/src/library/layout/columns.rs b/src/library/layout/columns.rs
index e0163f63..8ae4394e 100644
--- a/src/library/layout/columns.rs
+++ b/src/library/layout/columns.rs
@@ -28,7 +28,7 @@ impl ColumnsNode {
 impl Layout for ColumnsNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
diff --git a/src/library/layout/flow.rs b/src/library/layout/flow.rs
index 05c10789..7cb52910 100644
--- a/src/library/layout/flow.rs
+++ b/src/library/layout/flow.rs
@@ -25,7 +25,7 @@ pub enum FlowChild {
 impl Layout for FlowNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
@@ -149,7 +149,7 @@ impl FlowLayouter {
     /// Layout a node.
     pub fn layout_node(
         &mut self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         node: &LayoutNode,
         styles: StyleChain,
     ) -> SourceResult<()> {
diff --git a/src/library/layout/grid.rs b/src/library/layout/grid.rs
index cd4fc6b4..2c246df9 100644
--- a/src/library/layout/grid.rs
+++ b/src/library/layout/grid.rs
@@ -33,7 +33,7 @@ impl GridNode {
 impl Layout for GridNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
@@ -93,7 +93,7 @@ castable! {
 /// Performs grid layout.
 pub struct GridLayouter<'a> {
     /// The core context.
-    world: &'a dyn World,
+    world: Tracked<'a, dyn World>,
     /// The grid cells.
     cells: &'a [LayoutNode],
     /// The column tracks including gutter tracks.
@@ -133,7 +133,7 @@ impl<'a> GridLayouter<'a> {
     ///
     /// This prepares grid layout by unifying content and gutter tracks.
     pub fn new(
-        world: &'a dyn World,
+        world: Tracked<'a, dyn World>,
         tracks: Spec<&[TrackSizing]>,
         gutter: Spec<&[TrackSizing]>,
         cells: &'a [LayoutNode],
diff --git a/src/library/layout/pad.rs b/src/library/layout/pad.rs
index 983bfa11..06c3672f 100644
--- a/src/library/layout/pad.rs
+++ b/src/library/layout/pad.rs
@@ -28,7 +28,7 @@ impl PadNode {
 impl Layout for PadNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
diff --git a/src/library/layout/page.rs b/src/library/layout/page.rs
index ba597263..9cbbcca5 100644
--- a/src/library/layout/page.rs
+++ b/src/library/layout/page.rs
@@ -57,7 +57,7 @@ impl PageNode {
     /// Layout the page run into a sequence of frames, one per page.
     pub fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         mut page: usize,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
@@ -180,7 +180,7 @@ impl Marginal {
     /// Resolve the marginal based on the page number.
     pub fn resolve(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         page: usize,
     ) -> SourceResult<Option<Content>> {
         Ok(match self {
diff --git a/src/library/layout/place.rs b/src/library/layout/place.rs
index 862c969e..01da62e5 100644
--- a/src/library/layout/place.rs
+++ b/src/library/layout/place.rs
@@ -21,7 +21,7 @@ impl PlaceNode {
 impl Layout for PlaceNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
diff --git a/src/library/layout/stack.rs b/src/library/layout/stack.rs
index a9fc1621..b9a26642 100644
--- a/src/library/layout/stack.rs
+++ b/src/library/layout/stack.rs
@@ -27,7 +27,7 @@ impl StackNode {
 impl Layout for StackNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
@@ -168,7 +168,7 @@ impl<'a> StackLayouter<'a> {
     /// Layout an arbitrary node.
     pub fn layout_node(
         &mut self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         node: &LayoutNode,
         styles: StyleChain,
     ) -> SourceResult<()> {
diff --git a/src/library/math/mod.rs b/src/library/math/mod.rs
index d71f6976..1f5ea8f3 100644
--- a/src/library/math/mod.rs
+++ b/src/library/math/mod.rs
@@ -48,7 +48,11 @@ impl Show for MathNode {
         }
     }
 
-    fn realize(&self, _: &dyn World, styles: StyleChain) -> SourceResult<Content> {
+    fn realize(
+        &self,
+        _: Tracked<dyn World>,
+        styles: StyleChain,
+    ) -> SourceResult<Content> {
         let node = self::rex::RexNode {
             tex: self.formula.clone(),
             display: self.display,
@@ -64,7 +68,7 @@ impl Show for MathNode {
 
     fn finalize(
         &self,
-        _: &dyn World,
+        _: Tracked<dyn World>,
         styles: StyleChain,
         mut realized: Content,
     ) -> SourceResult<Content> {
diff --git a/src/library/math/rex.rs b/src/library/math/rex.rs
index 76ba5177..96e8e438 100644
--- a/src/library/math/rex.rs
+++ b/src/library/math/rex.rs
@@ -22,7 +22,7 @@ pub struct RexNode {
 impl Layout for RexNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         _: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
diff --git a/src/library/prelude.rs b/src/library/prelude.rs
index 48eebaf6..44d1af7f 100644
--- a/src/library/prelude.rs
+++ b/src/library/prelude.rs
@@ -6,6 +6,7 @@ pub use std::io;
 pub use std::num::NonZeroUsize;
 pub use std::sync::Arc;
 
+pub use comemo::Tracked;
 pub use typst_macros::node;
 
 pub use crate::diag::{with_alternative, At, SourceError, SourceResult, StrResult};
diff --git a/src/library/structure/doc.rs b/src/library/structure/doc.rs
index ba848b64..c3af3f1c 100644
--- a/src/library/structure/doc.rs
+++ b/src/library/structure/doc.rs
@@ -9,7 +9,7 @@ impl DocNode {
     /// Layout the document into a sequence of frames, one per page.
     pub fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
         let mut frames = vec![];
diff --git a/src/library/structure/heading.rs b/src/library/structure/heading.rs
index 855c0503..01738496 100644
--- a/src/library/structure/heading.rs
+++ b/src/library/structure/heading.rs
@@ -82,13 +82,13 @@ impl Show for HeadingNode {
         }
     }
 
-    fn realize(&self, _: &dyn World, _: StyleChain) -> SourceResult<Content> {
+    fn realize(&self, _: Tracked<dyn World>, _: StyleChain) -> SourceResult<Content> {
         Ok(Content::block(self.body.clone()))
     }
 
     fn finalize(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         styles: StyleChain,
         mut realized: Content,
     ) -> SourceResult<Content> {
@@ -149,7 +149,11 @@ pub enum Leveled<T> {
 
 impl<T: Cast + Clone> Leveled<T> {
     /// Resolve the value based on the level.
-    pub fn resolve(&self, world: &dyn World, level: NonZeroUsize) -> SourceResult<T> {
+    pub fn resolve(
+        &self,
+        world: Tracked<dyn World>,
+        level: NonZeroUsize,
+    ) -> SourceResult<T> {
         Ok(match self {
             Self::Value(value) => value.clone(),
             Self::Mapping(mapping) => mapping(level),
diff --git a/src/library/structure/list.rs b/src/library/structure/list.rs
index f63374f3..9da14733 100644
--- a/src/library/structure/list.rs
+++ b/src/library/structure/list.rs
@@ -100,7 +100,11 @@ impl<const L: ListKind> Show for ListNode<L> {
         }
     }
 
-    fn realize(&self, world: &dyn World, styles: StyleChain) -> SourceResult<Content> {
+    fn realize(
+        &self,
+        world: Tracked<dyn World>,
+        styles: StyleChain,
+    ) -> SourceResult<Content> {
         let mut cells = vec![];
         let mut number = self.start;
 
@@ -145,7 +149,7 @@ impl<const L: ListKind> Show for ListNode<L> {
 
     fn finalize(
         &self,
-        _: &dyn World,
+        _: Tracked<dyn World>,
         styles: StyleChain,
         realized: Content,
     ) -> SourceResult<Content> {
@@ -208,7 +212,7 @@ impl Label {
     /// Resolve the value based on the level.
     pub fn resolve(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         kind: ListKind,
         number: usize,
     ) -> SourceResult<Content> {
diff --git a/src/library/structure/reference.rs b/src/library/structure/reference.rs
index 5d1dab38..0a9f4f9c 100644
--- a/src/library/structure/reference.rs
+++ b/src/library/structure/reference.rs
@@ -22,7 +22,7 @@ impl Show for RefNode {
         }
     }
 
-    fn realize(&self, _: &dyn World, _: StyleChain) -> SourceResult<Content> {
+    fn realize(&self, _: Tracked<dyn World>, _: StyleChain) -> SourceResult<Content> {
         Ok(Content::Text(format_eco!("@{}", self.0)))
     }
 }
diff --git a/src/library/structure/table.rs b/src/library/structure/table.rs
index f1ca7e03..9f89cd2b 100644
--- a/src/library/structure/table.rs
+++ b/src/library/structure/table.rs
@@ -72,7 +72,11 @@ impl Show for TableNode {
         }
     }
 
-    fn realize(&self, world: &dyn World, styles: StyleChain) -> SourceResult<Content> {
+    fn realize(
+        &self,
+        world: Tracked<dyn World>,
+        styles: StyleChain,
+    ) -> SourceResult<Content> {
         let fill = styles.get(Self::FILL);
         let stroke = styles.get(Self::STROKE).map(RawStroke::unwrap_or_default);
         let padding = styles.get(Self::PADDING);
@@ -110,7 +114,7 @@ impl Show for TableNode {
 
     fn finalize(
         &self,
-        _: &dyn World,
+        _: Tracked<dyn World>,
         styles: StyleChain,
         realized: Content,
     ) -> SourceResult<Content> {
@@ -129,7 +133,12 @@ pub enum Celled<T> {
 
 impl<T: Cast + Clone> Celled<T> {
     /// Resolve the value based on the cell position.
-    pub fn resolve(&self, world: &dyn World, x: usize, y: usize) -> SourceResult<T> {
+    pub fn resolve(
+        &self,
+        world: Tracked<dyn World>,
+        x: usize,
+        y: usize,
+    ) -> SourceResult<T> {
         Ok(match self {
             Self::Value(value) => value.clone(),
             Self::Func(func, span) => {
diff --git a/src/library/text/deco.rs b/src/library/text/deco.rs
index 3d030d45..1242488b 100644
--- a/src/library/text/deco.rs
+++ b/src/library/text/deco.rs
@@ -48,7 +48,11 @@ impl<const L: DecoLine> Show for DecoNode<L> {
         dict! { "body" => Value::Content(self.0.clone()) }
     }
 
-    fn realize(&self, _: &dyn World, styles: StyleChain) -> SourceResult<Content> {
+    fn realize(
+        &self,
+        _: Tracked<dyn World>,
+        styles: StyleChain,
+    ) -> SourceResult<Content> {
         Ok(self.0.clone().styled(TextNode::DECO, Decoration {
             line: L,
             stroke: styles.get(Self::STROKE).unwrap_or_default(),
diff --git a/src/library/text/link.rs b/src/library/text/link.rs
index f89bbd67..c06fea55 100644
--- a/src/library/text/link.rs
+++ b/src/library/text/link.rs
@@ -64,7 +64,7 @@ impl Show for LinkNode {
         }
     }
 
-    fn realize(&self, _: &dyn World, _: StyleChain) -> SourceResult<Content> {
+    fn realize(&self, _: Tracked<dyn World>, _: StyleChain) -> SourceResult<Content> {
         Ok(self.body.clone().unwrap_or_else(|| match &self.dest {
             Destination::Url(url) => {
                 let mut text = url.as_str();
@@ -80,7 +80,7 @@ impl Show for LinkNode {
 
     fn finalize(
         &self,
-        _: &dyn World,
+        _: Tracked<dyn World>,
         styles: StyleChain,
         mut realized: Content,
     ) -> SourceResult<Content> {
diff --git a/src/library/text/mod.rs b/src/library/text/mod.rs
index 55b866cb..934f5e15 100644
--- a/src/library/text/mod.rs
+++ b/src/library/text/mod.rs
@@ -507,7 +507,7 @@ impl Show for StrongNode {
         dict! { "body" => Value::Content(self.0.clone()) }
     }
 
-    fn realize(&self, _: &dyn World, _: StyleChain) -> SourceResult<Content> {
+    fn realize(&self, _: Tracked<dyn World>, _: StyleChain) -> SourceResult<Content> {
         Ok(self.0.clone().styled(TextNode::BOLD, Toggle))
     }
 }
@@ -532,7 +532,7 @@ impl Show for EmphNode {
         dict! { "body" => Value::Content(self.0.clone()) }
     }
 
-    fn realize(&self, _: &dyn World, _: StyleChain) -> SourceResult<Content> {
+    fn realize(&self, _: Tracked<dyn World>, _: StyleChain) -> SourceResult<Content> {
         Ok(self.0.clone().styled(TextNode::ITALIC, Toggle))
     }
 }
diff --git a/src/library/text/par.rs b/src/library/text/par.rs
index 00a1e034..6910c23a 100644
--- a/src/library/text/par.rs
+++ b/src/library/text/par.rs
@@ -64,7 +64,7 @@ impl ParNode {
 impl Layout for ParNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
@@ -496,7 +496,7 @@ fn collect<'a>(
 /// Prepare paragraph layout by shaping the whole paragraph and layouting all
 /// contained inline-level nodes.
 fn prepare<'a>(
-    world: &dyn World,
+    world: Tracked<dyn World>,
     par: &'a ParNode,
     text: &'a str,
     segments: Vec<(Segment<'a>, StyleChain<'a>)>,
@@ -561,7 +561,7 @@ fn prepare<'a>(
 /// items for them.
 fn shape_range<'a>(
     items: &mut Vec<Item<'a>>,
-    world: &dyn World,
+    world: Tracked<dyn World>,
     bidi: &BidiInfo<'a>,
     range: Range,
     styles: StyleChain<'a>,
@@ -627,7 +627,7 @@ fn shared_get<'a, K: Key<'a>>(
 /// Find suitable linebreaks.
 fn linebreak<'a>(
     p: &'a Preparation<'a>,
-    world: &dyn World,
+    world: Tracked<dyn World>,
     width: Length,
 ) -> Vec<Line<'a>> {
     match p.styles.get(ParNode::LINEBREAKS) {
@@ -641,7 +641,7 @@ fn linebreak<'a>(
 /// very unbalanced line, but is fast and simple.
 fn linebreak_simple<'a>(
     p: &'a Preparation<'a>,
-    world: &dyn World,
+    world: Tracked<dyn World>,
     width: Length,
 ) -> Vec<Line<'a>> {
     let mut lines = vec![];
@@ -701,7 +701,7 @@ fn linebreak_simple<'a>(
 /// text.
 fn linebreak_optimized<'a>(
     p: &'a Preparation<'a>,
-    world: &dyn World,
+    world: Tracked<dyn World>,
     width: Length,
 ) -> Vec<Line<'a>> {
     /// The cost of a line or paragraph layout.
@@ -914,7 +914,7 @@ impl Breakpoints<'_> {
 /// Create a line which spans the given range.
 fn line<'a>(
     p: &'a Preparation,
-    world: &dyn World,
+    world: Tracked<dyn World>,
     mut range: Range,
     mandatory: bool,
     hyphen: bool,
@@ -1022,7 +1022,7 @@ fn line<'a>(
 /// Combine layouted lines into one frame per region.
 fn stack(
     p: &Preparation,
-    world: &dyn World,
+    world: Tracked<dyn World>,
     lines: &[Line],
     regions: &Regions,
 ) -> SourceResult<Vec<Frame>> {
@@ -1072,7 +1072,7 @@ fn stack(
 /// Commit to a line and build its frame.
 fn commit(
     p: &Preparation,
-    world: &dyn World,
+    world: Tracked<dyn World>,
     line: &Line,
     regions: &Regions,
     width: Length,
diff --git a/src/library/text/raw.rs b/src/library/text/raw.rs
index 5bce2a90..e7c73a91 100644
--- a/src/library/text/raw.rs
+++ b/src/library/text/raw.rs
@@ -59,7 +59,11 @@ impl Show for RawNode {
         }
     }
 
-    fn realize(&self, _: &dyn World, styles: StyleChain) -> SourceResult<Content> {
+    fn realize(
+        &self,
+        _: Tracked<dyn World>,
+        styles: StyleChain,
+    ) -> SourceResult<Content> {
         let lang = styles.get(Self::LANG).as_ref().map(|s| s.to_lowercase());
         let foreground = THEME
             .settings
@@ -111,7 +115,7 @@ impl Show for RawNode {
 
     fn finalize(
         &self,
-        _: &dyn World,
+        _: Tracked<dyn World>,
         styles: StyleChain,
         mut realized: Content,
     ) -> SourceResult<Content> {
diff --git a/src/library/text/repeat.rs b/src/library/text/repeat.rs
index 78a21069..e3bae3fc 100644
--- a/src/library/text/repeat.rs
+++ b/src/library/text/repeat.rs
@@ -14,7 +14,7 @@ impl RepeatNode {
 impl Layout for RepeatNode {
     fn layout(
         &self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
     ) -> SourceResult<Vec<Frame>> {
diff --git a/src/library/text/shaping.rs b/src/library/text/shaping.rs
index c1d0341b..16989acf 100644
--- a/src/library/text/shaping.rs
+++ b/src/library/text/shaping.rs
@@ -80,7 +80,7 @@ impl<'a> ShapedText<'a> {
     ///
     /// The `justification` defines how much extra advance width each
     /// [justifiable glyph](ShapedGlyph::is_justifiable) will get.
-    pub fn build(&self, world: &dyn World, justification: Length) -> Frame {
+    pub fn build(&self, world: Tracked<dyn World>, justification: Length) -> Frame {
         let (top, bottom) = self.measure(world);
         let size = Size::new(self.width, top + bottom);
 
@@ -144,7 +144,7 @@ impl<'a> ShapedText<'a> {
     }
 
     /// Measure the top and bottom extent of this text.
-    fn measure(&self, world: &dyn World) -> (Length, Length) {
+    fn measure(&self, world: Tracked<dyn World>) -> (Length, Length) {
         let mut top = Length::zero();
         let mut bottom = Length::zero();
 
@@ -199,7 +199,7 @@ impl<'a> ShapedText<'a> {
     /// shaping process if possible.
     pub fn reshape(
         &'a self,
-        world: &dyn World,
+        world: Tracked<dyn World>,
         text_range: Range<usize>,
     ) -> ShapedText<'a> {
         if let Some(glyphs) = self.slice_safe_to_break(text_range.clone()) {
@@ -218,7 +218,7 @@ impl<'a> ShapedText<'a> {
     }
 
     /// Push a hyphen to end of the text.
-    pub fn push_hyphen(&mut self, world: &dyn World) {
+    pub fn push_hyphen(&mut self, world: Tracked<dyn World>) {
         families(self.styles).find_map(|family| {
             let font = world
                 .book()
@@ -306,7 +306,7 @@ impl Debug for ShapedText<'_> {
 
 /// Holds shaping results and metadata common to all shaped segments.
 struct ShapingContext<'a> {
-    world: &'a dyn World,
+    world: Tracked<'a, dyn World>,
     glyphs: Vec<ShapedGlyph>,
     used: Vec<Font>,
     styles: StyleChain<'a>,
@@ -319,7 +319,7 @@ struct ShapingContext<'a> {
 
 /// Shape text into [`ShapedText`].
 pub fn shape<'a>(
-    world: &dyn World,
+    world: Tracked<dyn World>,
     text: &'a str,
     styles: StyleChain<'a>,
     dir: Dir,
diff --git a/src/library/text/shift.rs b/src/library/text/shift.rs
index b359c5ed..6a5415e8 100644
--- a/src/library/text/shift.rs
+++ b/src/library/text/shift.rs
@@ -42,7 +42,11 @@ impl<const S: ScriptKind> Show for ShiftNode<S> {
         dict! { "body" => Value::Content(self.0.clone()) }
     }
 
-    fn realize(&self, world: &dyn World, styles: StyleChain) -> SourceResult<Content> {
+    fn realize(
+        &self,
+        world: Tracked<dyn World>,
+        styles: StyleChain,
+    ) -> SourceResult<Content> {
         let mut transformed = None;
         if styles.get(Self::TYPOGRAPHIC) {
             if let Some(text) = search_text(&self.0, S) {
@@ -91,7 +95,7 @@ fn search_text(content: &Content, mode: ScriptKind) -> Option<EcoString> {
 
 /// Checks whether the first retrievable family contains all code points of the
 /// given string.
-fn is_shapable(world: &dyn World, text: &str, styles: StyleChain) -> bool {
+fn is_shapable(world: Tracked<dyn World>, text: &str, styles: StyleChain) -> bool {
     for family in styles.get(TextNode::FAMILY).iter() {
         if let Some(font) = world
             .book()
diff --git a/src/library/utility/mod.rs b/src/library/utility/mod.rs
index 3fc413f7..d9b19d64 100644
--- a/src/library/utility/mod.rs
+++ b/src/library/utility/mod.rs
@@ -10,7 +10,9 @@ pub use data::*;
 pub use math::*;
 pub use string::*;
 
-use crate::eval::{Eval, Scopes, Vm};
+use comemo::Track;
+
+use crate::eval::{Eval, Route, Scopes, Vm};
 use crate::library::prelude::*;
 use crate::source::Source;
 
@@ -39,7 +41,8 @@ pub fn eval(vm: &mut Vm, args: &mut Args) -> SourceResult<Value> {
     // Evaluate the source.
     let std = &vm.world.config().std;
     let scopes = Scopes::new(Some(std));
-    let mut sub = Vm::new(vm.world, vec![], scopes);
+    let route = Route::default();
+    let mut sub = Vm::new(vm.world, route.track(), None, scopes);
     let result = ast.eval(&mut sub);
 
     // Handle control flow.