feat: FullName(Ref)::strip_prefix() (#364)

Get a short-hand for any reference name.

Author: Byron

git-ref/src/fullname.rs

@@ -105,6 +105,13 @@ impl FullName {
         }
         self
     }
+
+    /// Strip well-known prefixes from the name and return it.
+    ///
+    /// If there is no such prefix, the original name is returned.
+    pub fn strip_prefix(&self) -> &BStr {
+        self.to_ref().strip_prefix()
+    }
 }
 
 impl<'a> FullNameRef<'a> {

git-ref/src/name.rs

@@ -21,6 +21,19 @@ impl<'a> FullNameRef<'a> {
     pub fn as_bstr(&self) -> &'a BStr {
         self.0
     }
+
+    /// Strip well-known prefixes from the name and return it.
+    ///
+    /// If there is no such prefix, the original name is returned.
+    pub fn strip_prefix(&self) -> &'a BStr {
+        let n = self.as_bstr();
+        n.strip_prefix(b"refs/tags/")
+            .or_else(|| n.strip_prefix(b"refs/heads/"))
+            .or_else(|| n.strip_prefix(b"refs/remotes/"))
+            .or_else(|| n.strip_prefix(b"refs/"))
+            .map(|n| n.as_bstr())
+            .unwrap_or(n)
+    }
 }
 
 impl<'a> PartialNameRef<'a> {

git-ref/tests/fullname/mod.rs

@@ -5,6 +5,28 @@ fn file_name() {
     let name: git_ref::FullName = "refs/heads/main".try_into().unwrap();
     assert_eq!(name.to_ref().file_name(), "main");
 }
+#[test]
+fn strip_prefix() {
+    for (input, expected) in vec![
+        ("refs/tags/tag-name", "tag-name"),
+        ("refs/heads/main", "main"),
+        ("refs/remotes/origin/main", "origin/main"),
+        ("refs/notes/note-name", "notes/note-name"),
+    ] {
+        let name: git_ref::FullName = input.try_into().unwrap();
+        assert_eq!(name.to_ref().strip_prefix(), expected);
+        assert_eq!(name.strip_prefix(), expected);
+    }
+
+    let special = "HEAD";
+    let name: git_ref::FullName = special.try_into().unwrap();
+    assert_eq!(
+        name.strip_prefix(),
+        special,
+        "the whole name is returned if there is no prefix"
+    );
+    assert_eq!(name.strip_prefix(), name.to_ref().strip_prefix());
+}
 
 #[test]
 fn prefix_with_namespace_and_stripping() {