Add graph-objects command

libwyag.py

@@ -38,6 +38,7 @@ def main(argv=sys.argv[1:]):
         case "show-ref"      : cmd_show_ref(args)
         case "status"        : cmd_status(args)
         case "tag"           : cmd_tag(args)
+        case "graph-objects" : cmd_graph_objects(args)
         case _               : print("Bad command.")
 
 class GitRepository (object):
@@ -1542,3 +1543,78 @@ def cmd_commit(args):
     else: # Otherwise, we update HEAD itself.
         with open(repo_file(repo, "HEAD"), "w") as fd:
             fd.write(commit + "\n")
+
+argsp = argsubparsers.add_parser("graph-objects", help="Show git objects in a dot graph")
+
+argsp.add_argument("object",
+                   nargs="?",
+                   metavar="object",
+                   help="The object the graph will start from")
+
+def graph_objects_tree(repo, sha, seen):
+    if sha in seen:
+        return
+    seen.append(sha)
+
+    yield f"t_{sha} [label=\"tree {sha[0:7]}\"]"
+    # TODO: inefficient
+    obj = object_read(repo, sha)
+
+    for item in obj.items:
+        if len(item.mode) == 5:
+            type = item.mode[0:1]
+        else:
+            type = item.mode[0:2]
+
+        match type:
+            case b'04': type = "tree"
+            case b'10': type = "blob"
+            case b'12': type = "blob" # a symlink
+            case b'16': type = "commit" # a submodule
+            case b'sc': type = "subcommit"
+            case _: raise Exception(f"Weird tree leaf mode {item.mode}")
+
+        if type == "tree":
+            yield f"t_{sha} -> t_{item.sha}"
+            yield from graph_objects_tree(repo, item.sha, seen)
+        if type == "commit" or type == "subcommit":
+            yield f"t_{sha} -> c_{item.sha}"
+            yield from graph_objects(repo, item.sha, seen)
+        if type == "blob":
+            yield f"b_{item.sha} [label=\"{item.sha[0:7]} {item.path}\"]"
+            yield f"t_{sha} -> b_{item.sha}"
+
+
+def graph_objects(repo, sha, seen):
+    if sha in seen:
+        return
+    seen.append(sha)
+
+    obj = object_read(repo, sha)
+
+    match obj.fmt:
+        case b"commit": #
+            message = obj.kvlm[None]
+            yield f"c_{sha} [label=\"{sha[0:7]}: {message.decode('utf8')}\"]"
+            tree_sha = obj.kvlm[b"tree"].decode("ascii")
+            yield f"c_{sha} -> t_{tree_sha}"
+            yield from graph_objects_tree(repo, tree_sha, seen)
+        case b"tree":
+            yield from graph_objects_tree(repo, sha, seen)
+
+def cmd_graph_objects(args):
+    repo = repo_find()
+
+    if args.object == None:
+        obj_name = "HEAD"
+    else:
+        obj_name = args.object
+
+    obj_sha = object_find(repo, obj_name)
+    graph = "digraph objectgraph{\n"
+    graph += "  node[shape=rect]\n"
+    for str in graph_objects(repo, obj_sha, list()):
+        graph += "  " + str + "\n"
+    graph += "}"
+
+    print(graph)