Implement math kerning and fix various `math.attach` bugs (#4762)

1 files changed, 21 insertions, 0 deletions

diff --git a/crates/typst-utils/src/lib.rs b/crates/typst-utils/src/lib.rs
index 4d5f8e0c..831b2374 100644
--- a/crates/typst-utils/src/lib.rs
+++ b/crates/typst-utils/src/lib.rs
@@ -83,6 +83,27 @@ impl<T: Clone> ArcExt<T> for Arc<T> {
     }
 }
 
+/// Extra methods for [`Option`].
+pub trait OptionExt<T> {
+    /// Maps an `Option<T>` to `U` by applying a function to a contained value
+    /// (if `Some`) or returns a default (if `None`).
+    fn map_or_default<U: Default, F>(self, f: F) -> U
+    where
+        F: FnOnce(T) -> U;
+}
+
+impl<T> OptionExt<T> for Option<T> {
+    fn map_or_default<U: Default, F>(self, f: F) -> U
+    where
+        F: FnOnce(T) -> U,
+    {
+        match self {
+            Some(x) => f(x),
+            None => U::default(),
+        }
+    }
+}
+
 /// Extra methods for [`[T]`](slice).
 pub trait SliceExt<T> {
     /// Split a slice into consecutive runs with the same key and yield for