tag: add --points-at list option

tgrennan · gitster · commit ae7706b9ac98 · 2012-02-08T19:59:41.000-08:00
This filters the list for tags of the given object.
Example,

   john$ git tag v1.0-john v1.0
   john$ git tag -l --points-at v1.0
   v1.0-john
   v1.0

Signed-off-by: Tom Grennan &lt;tmgrennan@gmail.com&gt;
Reviewed-by: Jeff King &lt;peff@peff.net&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/Documentation/git-tag.txt b/Documentation/git-tag.txt
@@ -12,7 +12,8 @@ SYNOPSIS
 'git tag' [-a | -s | -u <key-id>] [-f] [-m <msg> | -F <file>]
 	<tagname> [<commit> | <object>]
 'git tag' -d <tagname>...
-'git tag' [-n[<num>]] -l [--contains <commit>] [<pattern>...]
+'git tag' [-n[<num>]] -l [--contains <commit>] [--points-at <object>]
+	[<pattern>...]
 'git tag' -v <tagname>...
 
 DESCRIPTION
@@ -86,6 +87,9 @@ OPTIONS
 --contains <commit>::
 	Only list tags which contain the specified commit.
 
+--points-at <object>::
+	Only list tags of the given object.
+
 -m <msg>::
 --message=<msg>::
 	Use the given tag message (instead of prompting).
diff --git a/builtin/tag.c b/builtin/tag.c
@@ -15,11 +15,13 @@
 #include "diff.h"
 #include "revision.h"
 #include "gpg-interface.h"
+#include "sha1-array.h"
 
 static const char * const git_tag_usage[] = {
 	"git tag [-a|-s|-u <key-id>] [-f] [-m <msg>|-F <file>] <tagname> [<head>]",
 	"git tag -d <tagname>...",
-	"git tag -l [-n[<num>]] [<pattern>...]",
+	"git tag -l [-n[<num>]] [--contains <commit>] [--points-at <object>] "
+		"\n\t\t[<pattern>...]",
 	"git tag -v <tagname>...",
 	NULL
 };
@@ -30,6 +32,8 @@ struct tag_filter {
 	struct commit_list *with_commit;
 };
 
+static struct sha1_array points_at;
+
 static int match_pattern(const char **patterns, const char *ref)
 {
 	/* no pattern means match everything */
@@ -41,6 +45,24 @@ static int match_pattern(const char **patterns, const char *ref)
 	return 0;
 }
 
+static const unsigned char *match_points_at(const char *refname,
+					    const unsigned char *sha1)
+{
+	const unsigned char *tagged_sha1 = NULL;
+	struct object *obj;
+
+	if (sha1_array_lookup(&points_at, sha1) >= 0)
+		return sha1;
+	obj = parse_object(sha1);
+	if (!obj)
+		die(_("malformed object at '%s'"), refname);
+	if (obj->type == OBJ_TAG)
+		tagged_sha1 = ((struct tag *)obj)->tagged->sha1;
+	if (tagged_sha1 && sha1_array_lookup(&points_at, tagged_sha1) >= 0)
+		return tagged_sha1;
+	return NULL;
+}
+
 static int in_commit_list(const struct commit_list *want, struct commit *c)
 {
 	for (; want; want = want->next)
@@ -105,6 +127,9 @@ static int show_reference(const char *refname, const unsigned char *sha1,
 				return 0;
 		}
 
+		if (points_at.nr && !match_points_at(refname, sha1))
+			return 0;
+
 		if (!filter->lines) {
 			printf("%s\n", refname);
 			return 0;
@@ -375,6 +400,23 @@ static int strbuf_check_tag_ref(struct strbuf *sb, const char *name)
 	return check_refname_format(sb->buf, 0);
 }
 
+int parse_opt_points_at(const struct option *opt __attribute__ ((unused)),
+			const char *arg, int unset)
+{
+	unsigned char sha1[20];
+
+	if (unset) {
+		sha1_array_clear(&points_at);
+		return 0;
+	}
+	if (!arg)
+		return error(_("switch 'points-at' requires an object"));
+	if (get_sha1(arg, sha1))
+		return error(_("malformed object name '%s'"), arg);
+	sha1_array_append(&points_at, sha1);
+	return 0;
+}
+
 int cmd_tag(int argc, const char **argv, const char *prefix)
 {
 	struct strbuf buf = STRBUF_INIT;
@@ -417,6 +459,10 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 			PARSE_OPT_LASTARG_DEFAULT,
 			parse_opt_with_commit, (intptr_t)"HEAD",
 		},
+		{
+			OPTION_CALLBACK, 0, "points-at", NULL, "object",
+			"print only tags of the object", 0, parse_opt_points_at
+		},
 		OPT_END()
 	};
 
@@ -448,6 +494,8 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 		die(_("-n option is only allowed with -l."));
 	if (with_commit)
 		die(_("--contains option is only allowed with -l."));
+	if (points_at.nr)
+		die(_("--points-at option is only allowed with -l."));
 	if (delete)
 		return for_each_tag_name(argv, delete_tag);
 	if (verify)
diff --git a/t/t7004-tag.sh b/t/t7004-tag.sh
@@ -1269,4 +1269,43 @@ test_expect_success 'mixing incompatibles modes and options is forbidden' '
 	test_must_fail git tag -v -s
 '
 
+# check points-at
+
+test_expect_success '--points-at cannot be used in non-list mode' '
+	test_must_fail git tag --points-at=v4.0 foo
+'
+
+test_expect_success '--points-at finds lightweight tags' '
+	echo v4.0 >expect &&
+	git tag --points-at v4.0 >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--points-at finds annotated tags of commits' '
+	git tag -m "v4.0, annotated" annotated-v4.0 v4.0 &&
+	echo annotated-v4.0 >expect &&
+	git tag -l --points-at v4.0 "annotated*" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--points-at finds annotated tags of tags' '
+	git tag -m "describing the v4.0 tag object" \
+		annotated-again-v4.0 annotated-v4.0 &&
+	cat >expect <<-\EOF &&
+	annotated-again-v4.0
+	annotated-v4.0
+	EOF
+	git tag --points-at=annotated-v4.0 >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'multiple --points-at are OR-ed together' '
+	cat >expect <<-\EOF &&
+	v2.0
+	v3.0
+	EOF
+	git tag --points-at=v2.0 --points-at=v3.0 >actual &&
+	test_cmp expect actual
+'
+
 test_done
