Merge 5aa9b90a7b3e7f5ed964bf6727e445bdfc5211cd into 9b09146a6b5e936966ed7ee73bce9dd2df3810ae

crates/typst-library/src/foundations/content.rs

@@ -412,7 +412,7 @@ impl Content {
     /// Queries the content tree for all elements that match the given selector.
     ///
     /// Elements produced in `show` rules will not be included in the results.
-    pub fn query(&self, selector: Selector) -> Vec<Content> {
+    pub fn query(&self, selector: &Selector) -> Vec<Content> {
         let mut results = Vec::new();
         self.traverse(&mut |element| -> ControlFlow<()> {
             if selector.matches(&element, None) {

crates/typst-library/src/foundations/selector.rs

@@ -93,6 +93,8 @@ pub enum Selector {
     Before { selector: Arc<Self>, end: Arc<Self>, inclusive: bool },
     /// Matches all matches of `selector` after `start`.
     After { selector: Arc<Self>, start: Arc<Self>, inclusive: bool },
+    /// Matches all children of `ancestor` matching `selector`
+    Within { selector: Arc<Self>, ancestor: Arc<Self> },
 }
 
 impl Selector {
@@ -139,7 +141,10 @@ impl Selector {
             }
             Self::Location(location) => target.location() == Some(*location),
             // Not supported here.
-            Self::Regex(_) | Self::Before { .. } | Self::After { .. } => false,
+            Self::Regex(_)
+            | Self::Before { .. }
+            | Self::After { .. }
+            | Self::Within { .. } => false,
         }
     }
 }
@@ -221,6 +226,15 @@ impl Selector {
             inclusive,
         }
     }
+
+    /// Returns a modified selector that only matches `self` if it is contained in an `ancestor`.
+    #[func]
+    pub fn within(self, ancestor: LocatableSelector) -> Selector {
+        Self::Within {
+            selector: Arc::new(self),
+            ancestor: Arc::new(ancestor.0),
+        }
+    }
 }
 
 impl From<Location> for Selector {
@@ -266,6 +280,9 @@ impl Repr for Selector {
                     inclusive_arg
                 )
             }
+            Self::Within { selector, ancestor } => {
+                eco_format!("{}.within({})", selector.repr(), ancestor.repr())
+            }
         }
     }
 }
@@ -352,7 +369,8 @@ impl FromValue for LocatableSelector {
                     }
                 }
                 Selector::Before { selector, end: split, .. }
-                | Selector::After { selector, start: split, .. } => {
+                | Selector::After { selector, start: split, .. }
+                | Selector::Within { selector, ancestor: split } => {
                     for selector in [selector, split] {
                         validate(selector)?;
                     }
@@ -431,7 +449,8 @@ impl FromValue for ShowableSelector {
                 | Selector::Location(_)
                 | Selector::Can(_)
                 | Selector::Before { .. }
-                | Selector::After { .. } => {
+                | Selector::After { .. }
+                | Selector::Within { .. } => {
                     bail!("this selector cannot be used with show")
                 }
             }

crates/typst-library/src/introspection/introspector.rs

@@ -185,6 +185,11 @@ impl Introspector {
                 }
                 list
             }
+            Selector::Within { selector, ancestor } => self
+                .query(ancestor)
+                .iter()
+                .flat_map(|children| children.query(selector))
+                .collect(),
             // Not supported here.
             Selector::Can(_) | Selector::Regex(_) => EcoVec::new(),
         };

tests/suite/introspection/query.typ

@@ -250,3 +250,27 @@
   t("b")
   block(height: 1fr, metadata("b"))
 }
+
+--- query-within ---
+
+#let test-selector(selector, ref) = context {
+  test(query(selector).map(e => e.body), ref)
+}
+
+= A #strong[a] #label("strong")
+
+#strong[b] #label("strong")
+
+== B
+
+== C #strong[c] #label("strong")
+>
+#test-selector(
+  selector(<strong>).within(heading),
+  ([a], [c]),
+)
+
+#test-selector(
+  selector(<strong>).within(heading.where(level: 2)),
+  ([c], ),
+)