1 files changed, 20 insertions, 0 deletions
diff --git a/src/util/mod.rs b/src/util/mod.rs
index 2f91100f..32ec8dc4 100644
--- a/src/util/mod.rs
+++ b/src/util/mod.rs
@@ -9,10 +9,30 @@ pub use mac_roman::decode_mac_roman;
 
 use std::cell::RefMut;
 use std::cmp::Ordering;
+use std::fmt::{self, Debug, Formatter};
 use std::ops::Range;
 use std::path::{Component, Path, PathBuf};
 use std::sync::Arc;
 
+/// Turn a closure into a struct implementing [`Debug`].
+pub fn debug<F>(f: F) -> impl Debug
+where
+    F: Fn(&mut Formatter) -> fmt::Result,
+{
+    struct Wrapper<F>(F);
+
+    impl<F> Debug for Wrapper<F>
+    where
+        F: Fn(&mut Formatter) -> fmt::Result,
+    {
+        fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+            self.0(f)
+        }
+    }
+
+    Wrapper(f)
+}
+
 /// Additional methods for strings.
 pub trait StrExt {
     /// The number of code units this string would use if it was encoded in