[PATCH v2 5/9] ref-filter: add `short` modifier to 'tree' atom

["Hariom Verma via GitGitGadget" <gitgitgadget@gmail.com>]

From: Hariom Verma <hariom18599@gmail.com>

Sometimes while using 'tree' atom, user might want to see abbrev hash
instead of full 40 character hash.

Just like 'objectname', it might be convenient for users to have the
`:short` and `:short=<length>` option for printing 'tree' hash.

Let's introduce `short` option to 'tree' atom.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored-by: Heba Waly <heba.waly@gmail.com>
Signed-off-by: Hariom Verma <hariom18599@gmail.com>
---
 Documentation/git-for-each-ref.txt | 2 ++
 ref-filter.c                       | 9 ++++-----
 t/t6300-for-each-ref.sh            | 6 ++++++
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/Documentation/git-for-each-ref.txt b/Documentation/git-for-each-ref.txt
index e6ce8af612..40ebdfcc41 100644
--- a/Documentation/git-for-each-ref.txt
+++ b/Documentation/git-for-each-ref.txt
@@ -222,6 +222,8 @@ worktreepath::
 In addition to the above, for commit and tag objects, the header
 field names (`tree`, `parent`, `object`, `type`, and `tag`) can
 be used to specify the value in the header field.
+Field `tree` can also be used with modifier `:short` and
+`:short=<length>` just like `objectname`.
 
 For commit and tag objects, the special `creatordate` and `creator`
 fields will correspond to the appropriate date or name-email-date tuple
diff --git a/ref-filter.c b/ref-filter.c
index cc544eadaf..f9d85661eb 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -497,7 +497,7 @@ static struct {
 	{ "objectsize", SOURCE_OTHER, FIELD_ULONG, objectsize_atom_parser },
 	{ "objectname", SOURCE_OTHER, FIELD_STR, oid_atom_parser },
 	{ "deltabase", SOURCE_OTHER, FIELD_STR, deltabase_atom_parser },
-	{ "tree", SOURCE_OBJ },
+	{ "tree", SOURCE_OBJ, FIELD_STR, oid_atom_parser },
 	{ "parent", SOURCE_OBJ },
 	{ "numparent", SOURCE_OBJ, FIELD_ULONG },
 	{ "object", SOURCE_OBJ },
@@ -1005,10 +1005,9 @@ static void grab_commit_values(struct atom_value *val, int deref, struct object
 			continue;
 		if (deref)
 			name++;
-		if (!strcmp(name, "tree")) {
-			v->s = xstrdup(oid_to_hex(get_commit_tree_oid(commit)));
-		}
-		else if (!strcmp(name, "numparent")) {
+		if (grab_oid(name, "tree", get_commit_tree_oid(commit), v, &used_atom[i]))
+			continue;
+		if (!strcmp(name, "numparent")) {
 			v->value = commit_list_count(commit->parents);
 			v->s = xstrfmt("%lu", (unsigned long)v->value);
 		}
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index 64fbc91146..e30bbff6d9 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -116,6 +116,9 @@ test_atom head objectname:short $(git rev-parse --short refs/heads/master)
 test_atom head objectname:short=1 $(git rev-parse --short=1 refs/heads/master)
 test_atom head objectname:short=10 $(git rev-parse --short=10 refs/heads/master)
 test_atom head tree $(git rev-parse refs/heads/master^{tree})
+test_atom head tree:short $(git rev-parse --short refs/heads/master^{tree})
+test_atom head tree:short=1 $(git rev-parse --short=1 refs/heads/master^{tree})
+test_atom head tree:short=10 $(git rev-parse --short=10 refs/heads/master^{tree})
 test_atom head parent ''
 test_atom head numparent 0
 test_atom head object ''
@@ -167,6 +170,9 @@ test_atom tag objectname:short $(git rev-parse --short refs/tags/testtag)
 test_atom head objectname:short=1 $(git rev-parse --short=1 refs/heads/master)
 test_atom head objectname:short=10 $(git rev-parse --short=10 refs/heads/master)
 test_atom tag tree ''
+test_atom tag tree:short ''
+test_atom tag tree:short=1 ''
+test_atom tag tree:short=10 ''
 test_atom tag parent ''
 test_atom tag numparent ''
 test_atom tag object $(git rev-parse refs/tags/testtag^0)
-- 
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