revision.c: introduce --min-parents and --max-parents options

Introduce --min-parents and --max-parents options which limit the
revisions to those commits which have at least (or at most) that many
commits, where negative arguments for --max-parents= denote infinity
(i.e. no upper limit).

In particular:

  --max-parents=1 is the same as --no-merges;
  --min-parents=2 is the same as --merges;
  --max-parents=0 shows only roots; and
  --min-parents=3 shows only octopus merges

Using --min-parents=n and --max-parents=m with n>m gives you what you ask
for (i.e. nothing) for obvious reasons, just like when you give --merges
(show only merge commits) and --no-merges (show only non-merge commits) at
the same time.

Also, introduce --no-min-parents and --no-max-parents to do the obvious
thing for convenience.

We compute the number of parents only when we limit by that, so there
is no performance impact when there are no limiters.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 21 insertions, 7 deletions

diff --git a/revision.c b/revision.c
index 626f6a2..8540a5d 100644
--- a/revision.c
+++ b/revision.c
@@ -945,6 +945,7 @@ void init_revisions(struct rev_info *revs, const char *prefix)
 	revs->min_age = -1;
 	revs->skip_count = -1;
 	revs->max_count = -1;
+	revs->max_parents = -1;
 
 	revs->commit_format = CMIT_FMT_DEFAULT;
 
@@ -1280,9 +1281,17 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 	} else if (!strcmp(arg, "--remove-empty")) {
 		revs->remove_empty_trees = 1;
 	} else if (!strcmp(arg, "--merges")) {
-		revs->merges_only = 1;
+		revs->min_parents = 2;
 	} else if (!strcmp(arg, "--no-merges")) {
-		revs->no_merges = 1;
+		revs->max_parents = 1;
+	} else if (!prefixcmp(arg, "--min-parents=")) {
+		revs->min_parents = atoi(arg+14);
+	} else if (!prefixcmp(arg, "--no-min-parents")) {
+		revs->min_parents = 0;
+	} else if (!prefixcmp(arg, "--max-parents=")) {
+		revs->max_parents = atoi(arg+14);
+	} else if (!prefixcmp(arg, "--no-max-parents")) {
+		revs->max_parents = -1;
 	} else if (!strcmp(arg, "--boundary")) {
 		revs->boundary = 1;
 	} else if (!strcmp(arg, "--left-right")) {
@@ -1301,7 +1310,7 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 			die("--cherry is incompatible with --left-only");
 		revs->cherry_mark = 1;
 		revs->right_only = 1;
-		revs->no_merges = 1;
+		revs->max_parents = 1;
 		revs->limited = 1;
 	} else if (!strcmp(arg, "--count")) {
 		revs->count = 1;
@@ -2032,10 +2041,15 @@ enum commit_action get_commit_action(struct rev_info *revs, struct commit *commi
 		return commit_ignore;
 	if (revs->min_age != -1 && (commit->date > revs->min_age))
 		return commit_ignore;
-	if (revs->no_merges && commit->parents && commit->parents->next)
-		return commit_ignore;
-	if (revs->merges_only && !(commit->parents && commit->parents->next))
-		return commit_ignore;
+	if (revs->min_parents || (revs->max_parents >= 0)) {
+		int n = 0;
+		struct commit_list *p;
+		for (p = commit->parents; p; p = p->next)
+			n++;
+		if ((n < revs->min_parents) ||
+		    ((revs->max_parents >= 0) && (n > revs->max_parents)))
+			return commit_ignore;
+	}
 	if (!commit_match(commit, revs))
 		return commit_ignore;
 	if (revs->prune && revs->dense) {