Tentative built-in "git show"

This uses the "--no-walk" flag that I never actually implemented (but I'm
sure I mentioned it) to make "git show" be essentially the same thing as
"git whatchanged --no-walk".

It just refuses to add more interesting parents to the revision walking
history, so you don't actually get any history, you just get the commit
you asked for.

I was going to add "--no-walk" as a real argument flag to git-rev-list
too, but I'm not sure anybody actually needs it. Although it might be
useful for porcelain, so I left the door open.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git.c

@@ -363,6 +363,20 @@ static int cmd_whatchanged(int ac, const char **av, char **ep)
 	return cmd_log_wc(ac, av, ep, &wcopt);
 }
 
+static int cmd_show(int ac, const char **av, char **ep)
+{
+	struct whatchanged_opt wcopt;
+
+	memset(&wcopt, 0, sizeof(wcopt));
+	wcopt.do_diff = 1;
+	init_log_tree_opt(&wcopt.logopt);
+	wcopt.logopt.ignore_merges = 0;
+	wcopt.logopt.combine_merges = 1;
+	wcopt.logopt.dense_combined_merges = 1;
+	wcopt.logopt.diffopt.recursive = 1;
+	return cmd_log_wc(ac, av, ep, &wcopt);
+}
+
 static void handle_internal_command(int argc, const char **argv, char **envp)
 {
 	const char *cmd = argv[0];
@@ -373,6 +387,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
 		{ "version", cmd_version },
 		{ "help", cmd_help },
 		{ "log", cmd_log },
+		{ "show", cmd_show },
 		{ "whatchanged", cmd_whatchanged },
 	};
 	int i;

log-tree.c

@@ -182,6 +182,8 @@ int parse_whatchanged_opt(int ac, const char **av, struct whatchanged_opt *wcopt
 	int left = 1;
 
 	ac = setup_revisions(ac, av, rev, "HEAD");
+	if (!strcmp(av[0], "show"))
+		rev->no_walk = 1;
 	while (1 < ac) {
 		const char *arg = av[1];
 		if (!strncmp(arg, "--pretty", 8)) {

revision.c

@@ -375,6 +375,9 @@ static void add_parents_to_list(struct rev_info *revs, struct commit *commit, st
 	if (revs->prune_fn)
 		revs->prune_fn(revs, commit);
 
+	if (revs->no_walk)
+		return;
+
 	parent = commit->parents;
 	while (parent) {
 		struct commit *p = parent->item;
@@ -714,6 +717,8 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 
 void prepare_revision_walk(struct rev_info *revs)
 {
+	if (revs->no_walk)
+		return;
 	sort_by_date(&revs->commits);
 	if (revs->limited)
 		limit_list(revs);

revision.h

@@ -26,6 +26,7 @@ struct rev_info {
 	/* Traversal flags */
 	unsigned int	dense:1,
 			no_merges:1,
+			no_walk:1,
 			remove_empty_trees:1,
 			lifo:1,
 			topo_order:1,