simplify looking up entries by path (#470)

Author: Byron

git-repository/src/object/tree/mod.rs

@@ -60,6 +60,24 @@ impl<'repo> Tree<'repo> {
         }
         Ok(None)
     }
+
+    /// Like [`lookup_path()`][Self::lookup_path()], but takes a `Path` directly via `relative_path`, a path relative to this tree.
+    ///
+    /// # Note
+    ///
+    /// If any path component contains illformed UTF-8 and thus can't be converted to bytes on platforms which can't do so natively,
+    /// the returned component will be empty which makes the lookup fail.
+    pub fn lookup_path_by_path(
+        self,
+        relative_path: impl AsRef<std::path::Path>,
+    ) -> Result<Option<git_object::tree::Entry>, find::existing::Error> {
+        self.lookup_path(
+            relative_path
+                .as_ref()
+                .components()
+                .map(|c| git_path::os_str_into_bstr(c.as_os_str()).unwrap_or("".into()).as_ref()),
+        )
+    }
 }
 
 ///

git-repository/src/revision/spec/parse/delegate/navigate.rs

@@ -124,17 +124,13 @@ impl<'repo> delegate::Navigate for Delegate<'repo> {
                         return Ok(tree_id);
                     }
                     let tree = repo.find_object(tree_id)?.into_tree();
-                    let entry = tree
-                        .lookup_path(git_path::from_bstr(path).components().map(|c| {
-                            git_path::os_str_into_bstr(c.as_os_str())
-                                .expect("no illformed UTF-8")
-                                .as_ref()
-                        }))?
-                        .ok_or_else(|| Error::PathNotFound {
-                            path: path.into(),
-                            object: obj.attach(repo).shorten_or_id(),
-                            tree: tree_id.attach(repo).shorten_or_id(),
-                        })?;
+                    let entry =
+                        tree.lookup_path_by_path(git_path::from_bstr(path))?
+                            .ok_or_else(|| Error::PathNotFound {
+                                path: path.into(),
+                                object: obj.attach(repo).shorten_or_id(),
+                                tree: tree_id.attach(repo).shorten_or_id(),
+                            })?;
                     Ok(entry.oid)
                 };
                 for obj in objs.iter() {