ref-filter: introduce objectname_atom_parser()

Introduce objectname_atom_parser() which will parse the
'%(objectname)' atom and store information into the 'used_atom'
structure based on the modifiers used along with the atom.

Helped-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Karthik Nayak <Karthik.188@gmail.com>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

ref-filter.c

@@ -43,6 +43,7 @@ static struct used_atom {
 			enum { C_BARE, C_BODY, C_BODY_DEP, C_LINES, C_SIG, C_SUB } option;
 			unsigned int nlines;
 		} contents;
+		enum { O_FULL, O_SHORT } objectname;
 	} u;
 } *used_atom;
 static int used_atom_cnt, need_tagged, need_symref;
@@ -102,6 +103,16 @@ static void contents_atom_parser(struct used_atom *atom, const char *arg)
 		die(_("unrecognized %%(contents) argument: %s"), arg);
 }
 
+static void objectname_atom_parser(struct used_atom *atom, const char *arg)
+{
+	if (!arg)
+		atom->u.objectname = O_FULL;
+	else if (!strcmp(arg, "short"))
+		atom->u.objectname = O_SHORT;
+	else
+		die(_("unrecognized %%(objectname) argument: %s"), arg);
+}
+
 static align_type parse_align_position(const char *s)
 {
 	if (!strcmp(s, "right"))
@@ -160,7 +171,7 @@ static struct {
 	{ "refname" },
 	{ "objecttype" },
 	{ "objectsize", FIELD_ULONG },
-	{ "objectname" },
+	{ "objectname", FIELD_STR, objectname_atom_parser },
 	{ "tree" },
 	{ "parent" },
 	{ "numparent", FIELD_ULONG },
@@ -440,15 +451,17 @@ static void *get_obj(const unsigned char *sha1, struct object **obj, unsigned lo
 }
 
 static int grab_objectname(const char *name, const unsigned char *sha1,
-			    struct atom_value *v)
+			   struct atom_value *v, struct used_atom *atom)
 {
-	if (!strcmp(name, "objectname")) {
-		v->s = xstrdup(sha1_to_hex(sha1));
-		return 1;
-	}
-	if (!strcmp(name, "objectname:short")) {
-		v->s = xstrdup(find_unique_abbrev(sha1, DEFAULT_ABBREV));
-		return 1;
+	if (starts_with(name, "objectname")) {
+		if (atom->u.objectname == O_SHORT) {
+			v->s = xstrdup(find_unique_abbrev(sha1, DEFAULT_ABBREV));
+			return 1;
+		} else if (atom->u.objectname == O_FULL) {
+			v->s = xstrdup(sha1_to_hex(sha1));
+			return 1;
+		} else
+			die("BUG: unknown %%(objectname) option");
 	}
 	return 0;
 }
@@ -472,7 +485,7 @@ static void grab_common_values(struct atom_value *val, int deref, struct object
 			v->s = xstrfmt("%lu", sz);
 		}
 		else if (deref)
-			grab_objectname(name, obj->oid.hash, v);
+			grab_objectname(name, obj->oid.hash, v, &used_atom[i]);
 	}
 }
 
@@ -996,7 +1009,7 @@ static void populate_value(struct ref_array_item *ref)
 				v->s = xstrdup(buf + 1);
 			}
 			continue;
-		} else if (!deref && grab_objectname(name, ref->objectname, v)) {
+		} else if (!deref && grab_objectname(name, ref->objectname, v, atom)) {
 			continue;
 		} else if (!strcmp(name, "HEAD")) {
 			const char *head;