ref-filter: implement %(if), %(then), and %(else) atoms

Implement %(if), %(then) and %(else) atoms. Used as
%(if)...%(then)...%(end) or %(if)...%(then)...%(else)...%(end). If the
format string between %(if) and %(then) expands to an empty string, or
to only whitespaces, then the whole %(if)...%(end) expands to the string
following %(then). Otherwise, it expands to the string following
%(else), if any. Nesting of this construct is possible.

This is in preparation for porting over `git branch -l` to use
ref-filter APIs for printing.

Add documentation and tests regarding the same.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/t/t6302-for-each-ref-filter.sh b/t/t6302-for-each-ref-filter.sh
index d0ab09f4bd..fed30133d4 100755
--- a/t/t6302-for-each-ref-filter.sh
+++ b/t/t6302-for-each-ref-filter.sh
@@ -327,4 +327,80 @@ test_expect_success 'reverse version sort' '
 	test_cmp expect actual
 '
 
+test_expect_success 'improper usage of %(if), %(then), %(else) and %(end) atoms' '
+	test_must_fail git for-each-ref --format="%(if)" &&
+	test_must_fail git for-each-ref --format="%(then) %(end)" &&
+	test_must_fail git for-each-ref --format="%(else) %(end)" &&
+	test_must_fail git for-each-ref --format="%(if) %(else) %(end)" &&
+	test_must_fail git for-each-ref --format="%(if) %(then) %(then) %(end)" &&
+	test_must_fail git for-each-ref --format="%(then) %(else) %(end)" &&
+	test_must_fail git for-each-ref --format="%(if) %(else) %(end)" &&
+	test_must_fail git for-each-ref --format="%(if) %(then) %(else)" &&
+	test_must_fail git for-each-ref --format="%(if) %(else) %(then) %(end)" &&
+	test_must_fail git for-each-ref --format="%(if) %(then) %(else) %(else) %(end)" &&
+	test_must_fail git for-each-ref --format="%(if) %(end)"
+'
+
+test_expect_success 'check %(if)...%(then)...%(end) atoms' '
+	git for-each-ref --format="%(refname)%(if)%(authorname)%(then) Author: %(authorname)%(end)" >actual &&
+	cat >expect <<-\EOF &&
+	refs/heads/master Author: A U Thor
+	refs/heads/side Author: A U Thor
+	refs/odd/spot Author: A U Thor
+	refs/tags/annotated-tag
+	refs/tags/doubly-annotated-tag
+	refs/tags/doubly-signed-tag
+	refs/tags/foo1.10 Author: A U Thor
+	refs/tags/foo1.3 Author: A U Thor
+	refs/tags/foo1.6 Author: A U Thor
+	refs/tags/four Author: A U Thor
+	refs/tags/one Author: A U Thor
+	refs/tags/signed-tag
+	refs/tags/three Author: A U Thor
+	refs/tags/two Author: A U Thor
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success 'check %(if)...%(then)...%(else)...%(end) atoms' '
+	git for-each-ref --format="%(if)%(authorname)%(then)%(authorname)%(else)No author%(end): %(refname)" >actual &&
+	cat >expect <<-\EOF &&
+	A U Thor: refs/heads/master
+	A U Thor: refs/heads/side
+	A U Thor: refs/odd/spot
+	No author: refs/tags/annotated-tag
+	No author: refs/tags/doubly-annotated-tag
+	No author: refs/tags/doubly-signed-tag
+	A U Thor: refs/tags/foo1.10
+	A U Thor: refs/tags/foo1.3
+	A U Thor: refs/tags/foo1.6
+	A U Thor: refs/tags/four
+	A U Thor: refs/tags/one
+	No author: refs/tags/signed-tag
+	A U Thor: refs/tags/three
+	A U Thor: refs/tags/two
+	EOF
+	test_cmp expect actual
+'
+test_expect_success 'ignore spaces in %(if) atom usage' '
+	git for-each-ref --format="%(refname:short): %(if)%(HEAD)%(then)Head ref%(else)Not Head ref%(end)" >actual &&
+	cat >expect <<-\EOF &&
+	master: Head ref
+	side: Not Head ref
+	odd/spot: Not Head ref
+	annotated-tag: Not Head ref
+	doubly-annotated-tag: Not Head ref
+	doubly-signed-tag: Not Head ref
+	foo1.10: Not Head ref
+	foo1.3: Not Head ref
+	foo1.6: Not Head ref
+	four: Not Head ref
+	one: Not Head ref
+	signed-tag: Not Head ref
+	three: Not Head ref
+	two: Not Head ref
+	EOF
+	test_cmp expect actual
+'
+
 test_done