[RFC PATCH 10/13] walken: add unfiltered object walk from HEAD

[Emily Shaffer <emilyshaffer@google.com>]

Provide a demonstration of a revision walk which traverses all types of
object, not just commits. This type of revision walk is used for
operations such as creating packfiles and performing fetches or clones,
so it's useful to teach new developers how it works. For starters, only
demonstrate the unfiltered version, as this will make the tutorial
easier to follow.

This commit is part of a tutorial on revision walking.

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
---
 builtin/walken.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 77 insertions(+), 2 deletions(-)

diff --git a/builtin/walken.c b/builtin/walken.c
index 86c8d29c48..408af6c841 100644
--- a/builtin/walken.c
+++ b/builtin/walken.c
@@ -12,6 +12,7 @@
 #include "parse-options.h"
 #include "pretty.h"
 #include "line-log.h"
+#include "list-objects.h"
 #include "grep.h"
 
 static const char * const walken_usage[] = {
@@ -19,6 +20,11 @@ static const char * const walken_usage[] = {
 	NULL,
 };
 
+static int commit_count;
+static int tag_count;
+static int blob_count;
+static int tree_count;
+
 /*
  * Within init_walken_defaults() we can call into other useful defaults to set
  * in the global scope or on the_repository. It's okay to borrow from other
@@ -93,6 +99,70 @@ static int git_walken_config(const char *var, const char *value, void *cb)
 	return git_default_config(var, value, cb);
 }
 
+static void walken_show_commit(struct commit *cmt, void *buf)
+{
+	commit_count++;
+}
+
+static void walken_show_object(struct object *obj, const char *str, void *buf)
+{
+	switch (obj->type) {
+	case OBJ_TREE:
+		tree_count++;
+		break;
+	case OBJ_BLOB:
+		blob_count++;
+		break;
+	case OBJ_TAG:
+		tag_count++;
+		break;
+	case OBJ_COMMIT:
+		printf(_("Unexpectedly encountered a commit in "
+			 "walken_show_object!\n"));
+		commit_count++;
+		break;
+	default:
+		printf(_("Unexpected object type %s!\n"),
+		       type_name(obj->type));
+		break;
+	}
+}
+
+/*
+ * walken_object_walk() is invoked by cmd_walken() after initialization. It does
+ * a walk of all object types.
+ */
+static int walken_object_walk(struct rev_info *rev)
+{
+	struct list_objects_filter_options filter_options = {};
+	struct oidset omitted;
+	oidset_init(&omitted, 0);
+
+	printf("walken_object_walk beginning...\n");
+
+	rev->tree_objects = 1;
+	rev->blob_objects = 1;
+	rev->tag_objects = 1;
+	rev->tree_blobs_in_commit_order = 1;
+	rev->exclude_promisor_objects = 1;
+
+	if (prepare_revision_walk(rev))
+		die(_("revision walk setup failed"));
+
+	commit_count = 0;
+	tag_count = 0;
+	blob_count = 0;
+	tree_count = 0;
+
+	traverse_commit_list(rev, walken_show_commit, walken_show_object, NULL);
+
+	printf(_("Object walk completed. Found %d commits, %d blobs, %d tags, "
+	       "and %d trees.\n"), commit_count, blob_count, tag_count,
+	       tree_count);
+
+	return 0;
+}
+
 /*
  * walken_commit_walk() is invoked by cmd_walken() after initialization. It
  * does the commit walk only.
@@ -151,9 +221,14 @@ int cmd_walken(int argc, const char **argv, const char *prefix)
 
 	/* Before we do the walk, we need to set a starting point. It's not
 	 * coming from opt. */
-	final_rev_info_setup(argc, argv, prefix, &rev);
 
-	walken_commit_walk(&rev);
+	if (1) {
+		add_head_to_pending(&rev);
+		walken_object_walk(&rev);
+	} else {
+		final_rev_info_setup(argc, argv, prefix, &rev);
+		walken_commit_walk(&rev);
+	}
 
 	printf(_("cmd_walken incoming...\n"));
 	return 0;
-- 
2.22.0.rc1.311.g5d7573a151-goog