Clean up list styling (#4324)

crates/typst/src/foundations/content.rs

@@ -385,6 +385,19 @@ impl Content {
         }
     }
 
+    /// Style this content with a full style map in-place.
+    pub fn style_in_place(&mut self, styles: Styles) {
+        if styles.is_empty() {
+            return;
+        }
+
+        if let Some(style_elem) = self.to_packed_mut::<StyledElem>() {
+            style_elem.styles.apply(styles);
+        } else {
+            *self = StyledElem::new(std::mem::take(self), styles).into();
+        }
+    }
+
     /// Queries the content tree for all elements that match the given selector.
     ///
     /// Elements produced in `show` rules will not be included in the results.

crates/typst/src/model/enum.rs

@@ -7,7 +7,7 @@ use crate::diag::{bail, SourceResult};
 use crate::engine::Engine;
 use crate::foundations::{
     cast, elem, scope, Array, Content, Context, NativeElement, Packed, Show, Smart,
-    StyleChain,
+    StyleChain, Styles,
 };
 use crate::layout::{
     Alignment, Axes, BlockElem, Cell, CellGrid, Em, Fragment, GridLayouter, HAlignment,
@@ -316,6 +316,14 @@ pub struct EnumItem {
     pub body: Content,
 }
 
+impl Packed<EnumItem> {
+    /// Apply styles to this enum item.
+    pub fn styled(mut self, styles: Styles) -> Self {
+        self.body.style_in_place(styles);
+        self
+    }
+}
+
 cast! {
     EnumItem,
     array: Array => {

crates/typst/src/model/list.rs

@@ -4,7 +4,7 @@ use crate::diag::{bail, SourceResult};
 use crate::engine::Engine;
 use crate::foundations::{
     cast, elem, scope, Array, Content, Context, Depth, Func, NativeElement, Packed, Show,
-    Smart, StyleChain, Value,
+    Smart, StyleChain, Styles, Value,
 };
 use crate::layout::{
     Axes, BlockElem, Cell, CellGrid, Em, Fragment, GridLayouter, HAlignment, Length,
@@ -206,6 +206,14 @@ pub struct ListItem {
     pub body: Content,
 }
 
+impl Packed<ListItem> {
+    /// Apply styles to this list item.
+    pub fn styled(mut self, styles: Styles) -> Self {
+        self.body.style_in_place(styles);
+        self
+    }
+}
+
 cast! {
     ListItem,
     v: Content => v.unpack::<Self>().unwrap_or_else(Self::new)

crates/typst/src/model/terms.rs

@@ -2,6 +2,7 @@ use crate::diag::{bail, SourceResult};
 use crate::engine::Engine;
 use crate::foundations::{
     cast, elem, scope, Array, Content, NativeElement, Packed, Show, Smart, StyleChain,
+    Styles,
 };
 use crate::layout::{
     BlockElem, Dir, Em, HElem, Length, Sides, Spacing, StackChild, StackElem, VElem,
@@ -168,6 +169,15 @@ pub struct TermItem {
     pub description: Content,
 }
 
+impl Packed<TermItem> {
+    /// Apply styles to this term item.
+    pub fn styled(mut self, styles: Styles) -> Self {
+        self.term.style_in_place(styles.clone());
+        self.description.style_in_place(styles);
+        self
+    }
+}
+
 cast! {
     TermItem,
     array: Array => {

crates/typst/src/realize/mod.rs

@@ -508,50 +508,26 @@ impl<'a> ListBuilder<'a> {
         let mut items = items.into_iter().peekable();
         let (first, _) = items.peek().unwrap();
         let output = if first.is::<ListItem>() {
-            ListElem::new(
+            let children = items
-                items
                 .map(|(item, local)| {
-                        let mut item = item.to_packed::<ListItem>().unwrap().clone();
+                    item.into_packed::<ListItem>().unwrap().styled(local)
-                        let body = item.body().clone().styled_with_map(local);
-                        item.push_body(body);
-                        item
                 })
-                    .collect(),
+                .collect();
-            )
+            ListElem::new(children).with_tight(self.tight).pack().spanned(span)
-            .with_tight(self.tight)
-            .pack()
-            .spanned(span)
         } else if first.is::<EnumItem>() {
-            EnumElem::new(
+            let children = items
-                items
                 .map(|(item, local)| {
-                        let mut item = item.to_packed::<EnumItem>().unwrap().clone();
+                    item.into_packed::<EnumItem>().unwrap().styled(local)
-                        let body = item.body().clone().styled_with_map(local);
-                        item.push_body(body);
-                        item
                 })
-                    .collect(),
+                .collect();
-            )
+            EnumElem::new(children).with_tight(self.tight).pack().spanned(span)
-            .with_tight(self.tight)
-            .pack()
-            .spanned(span)
         } else if first.is::<TermItem>() {
-            TermsElem::new(
+            let children = items
-                items
                 .map(|(item, local)| {
-                        let mut item = item.to_packed::<TermItem>().unwrap().clone();
+                    item.into_packed::<TermItem>().unwrap().styled(local)
-                        let term = item.term().clone().styled_with_map(local.clone());
-                        let description =
-                            item.description().clone().styled_with_map(local);
-                        item.push_term(term);
-                        item.push_description(description);
-                        item
                 })
-                    .collect(),
+                .collect();
-            )
+            TermsElem::new(children).with_tight(self.tight).pack().spanned(span)
-            .with_tight(self.tight)
-            .pack()
-            .spanned(span)
         } else {
             unreachable!()
         };