Read tree and move HEAD in checkout

ugit/base.py

@@ -97,6 +97,12 @@ def commit(message):
     return oid
 
 
+def checkout(oid):
+    commit = get_commit(oid)
+    read_tree(commit.tree)
+    data.set_HEAD(oid)
+
+
 Commit = namedtuple("Commit", ["tree", "parent", "message"])
 
 

ugit/cli.py

@@ -45,6 +45,10 @@ def parse_args():
     log_parser.set_defaults(func=log)
     log_parser.add_argument("oid", nargs="?")
 
+    checkout_parser = commands.add_parser("checkout")
+    checkout_parser.set_defaults(func=checkout)
+    checkout_parser.add_argument("oid")
+
     return parser.parse_args()
 
 
@@ -85,3 +89,7 @@ def log(args):
         print("")
 
         oid = commit.parent
+
+
+def checkout(args):
+    base.checkout(args.oid)