Implement log

ugit/base.py

@@ -1,6 +1,10 @@
-from pathlib import Path, PurePath
+import itertools
+import operator
 import os
 
+from collections import namedtuple
+from pathlib import Path, PurePath
+
 from . import data
 
 
@@ -93,5 +97,26 @@ def commit(message):
     return oid
 
 
+Commit = namedtuple("Commit", ["tree", "parent", "message"])
+
+
+def get_commit(oid):
+    parent = None
+
+    commit = data.get_object(oid, "commit").decode()
+    lines = iter(commit.splitlines())
+    for line in itertools.takewhile(operator.truth, lines):
+        key, value = line.split(" ", 1)
+        if key == "tree":
+            tree = value
+        elif key == "parent":
+            parent = value
+        else:
+            assert False, f"Unknown field {key}"
+
+    message = "\n".join(lines)
+    return Commit(tree=tree, parent=parent, message=message)
+
+
 def is_ignored(path):
     return ".ugit" in path.split("/")