feat: add FullName(Ref)::category_and_shortname() (#364)

It's a combination of `shorten()` and `category()` for convenience.

git-ref/src/fullname.rs

@@ -117,6 +117,12 @@ impl FullName {
     pub fn category(&self) -> Option<crate::Category> {
         self.to_ref().category()
     }
+
+    /// Classify this name, or return `None` if it's unclassified. If `Some`,
+    /// the shortened name is returned as well.
+    pub fn category_and_short_name(&self) -> Option<(crate::Category, &BStr)> {
+        self.to_ref().category_and_short_name()
+    }
 }
 
 impl<'a> FullNameRef<'a> {

git-ref/src/name.rs

@@ -49,16 +49,27 @@ impl<'a> FullNameRef<'a> {
 
     /// Classify this name, or return `None` if it's unclassified.
     pub fn category(&self) -> Option<Category> {
-        for kind in &[
-            Category::Tag,
-            Category::LocalBranch,
-            Category::RemoteBranch,
-            Category::Note,
-        ] {
-            if self.0.starts_with(kind.prefix()) {
-                return (*kind).into();
+        self.category_and_short_name().map(|(cat, _)| cat)
+    }
+
+    /// Classify this name, or return `None` if it's unclassified. If `Some`,
+    /// the shortened name is returned as well.
+    pub fn category_and_short_name(&self) -> Option<(Category, &'a BStr)> {
+        for category in &[Category::Tag, Category::LocalBranch, Category::RemoteBranch] {
+            if let Some(shortened) = self.0.strip_prefix(category.prefix().as_ref()) {
+                return Some((*category, shortened.as_bstr()));
             }
         }
+
+        if self.0.starts_with(Category::Note.prefix()) {
+            return Some((
+                Category::Note,
+                self.0
+                    .strip_prefix(b"refs/")
+                    .expect("we checked for refs/notes above")
+                    .as_bstr(),
+            ));
+        }
         None
     }
 }

git-ref/tests/fullname/mod.rs

@@ -19,6 +19,10 @@ fn shorten_and_category() {
         assert_eq!(name.to_ref().shorten(), expected);
         assert_eq!(name.shorten(), expected);
         assert_eq!(name.category(), category);
+        assert_eq!(
+            name.category_and_short_name(),
+            category.map(|cat| (cat, expected.into()))
+        );
         assert_eq!(name.to_ref().category(), category);
     }