Write-tree for listing files

how_to/Change_08.md

@@ -0,0 +1,26 @@
+- write-tree: List files
+
+The next command is `write-tree`. This command will take the current working
+directory and store it to the object database. If `hash-object` was for storing
+an individual file, then `write-tree` is for storing a whole directory.
+
+Like `hash-object`, `write-tree` is going to give us an OID after it's done and
+we'll be able to use the OID in order to retrieve the directory at a later time.
+
+In Git's lingo a "tree" means a directory.
+
+We'll get into the details in later changes, in this change we'll only prepare
+the code around the feature:
+
+  + Create a `write-tree` CLI command
+
+  + Create a `write_tree()` function in base module. Why in base module and not
+  in data module? Because `write_tree()` is not going to write to disk directly
+  but use the object database provided by data to store the directory. Hence it
+  belongs to the higher-level base module.
+
+  + Add code to `write_tree()` to print a directory recursively. For now nothing
+  is written anywhere, but we just coded the boilerplate to recursively scan a
+  directory.
+
+We continue in the next change.

ugit/base.py

@@ -1 +1,14 @@
+from pathlib import Path
+
 from . import data
+
+
+def write_tree(directory="."):
+    with Path.iterdir(directory) as it:
+        for entry in it:
+            full = f"{directory}/{entry.name}"
+            if entry.is_file(follow_symlinks=False):
+                # TODO write the file to object store
+                print(full)
+            elif entry.is_dir(follow_symlinks=False):
+                write_tree(full)

ugit/cli.py

@@ -25,6 +25,9 @@ def parse_args():
     cat_file_parser.set_defaults(func=cat_file)
     cat_file_parser.add_argument("object")
 
+    write_tree_parser = commands.add_parser("write-tree")
+    write_tree_parser.set_defaults(func=write_tree)
+
     hash_object_parser = commands.add_parser("hash-object")
     hash_object_parser.set_defaults(func=hash_object)
     hash_object_parser.add_argument("file")
@@ -45,3 +48,7 @@ def hash_object(args):
 def cat_file(args):
     sys.stdout.flush()
     sys.stdout.buffer.write(data.get_object(args.object), expected=None)
+
+
+def write_tree(args):
+    base.write_tree()