ref-filter: add info_source to valid_atom

Add the source of object data to prevent parsing of unneeded data.
The goal is to improve performance by avoiding calling expensive
functions when we don't need the information they provide
or when we could get it by using a cheaper function.

It is stored in valid_atoms because it depends on the atoms we are
interested in.

Signed-off-by: Olga Telezhnaia <olyatelezhnaya@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

ref-filter.c

@@ -41,6 +41,7 @@ void setup_ref_filter_porcelain_msg(void)
 
 typedef enum { FIELD_STR, FIELD_ULONG, FIELD_TIME } cmp_type;
 typedef enum { COMPARE_EQUAL, COMPARE_UNEQUAL, COMPARE_NONE } cmp_status;
+typedef enum { SOURCE_NONE = 0, SOURCE_OBJ, SOURCE_OTHER } info_source;
 
 struct align {
 	align_type position;
@@ -73,6 +74,7 @@ struct refname_atom {
 static struct used_atom {
 	const char *name;
 	cmp_type type;
+	info_source source;
 	union {
 		char color[COLOR_MAXLEN];
 		struct align align;
@@ -380,49 +382,50 @@ static int head_atom_parser(const struct ref_format *format, struct used_atom *a
 
 static struct {
 	const char *name;
+	info_source source;
 	cmp_type cmp_type;
 	int (*parser)(const struct ref_format *format, struct used_atom *atom,
 		      const char *arg, struct strbuf *err);
 } valid_atom[] = {
-	{ "refname" , FIELD_STR, refname_atom_parser },
-	{ "objecttype" },
-	{ "objectsize", FIELD_ULONG },
-	{ "objectname", FIELD_STR, objectname_atom_parser },
-	{ "tree" },
-	{ "parent" },
-	{ "numparent", FIELD_ULONG },
-	{ "object" },
-	{ "type" },
-	{ "tag" },
-	{ "author" },
-	{ "authorname" },
-	{ "authoremail" },
-	{ "authordate", FIELD_TIME },
-	{ "committer" },
-	{ "committername" },
-	{ "committeremail" },
-	{ "committerdate", FIELD_TIME },
-	{ "tagger" },
-	{ "taggername" },
-	{ "taggeremail" },
-	{ "taggerdate", FIELD_TIME },
-	{ "creator" },
-	{ "creatordate", FIELD_TIME },
-	{ "subject", FIELD_STR, subject_atom_parser },
-	{ "body", FIELD_STR, body_atom_parser },
-	{ "trailers", FIELD_STR, trailers_atom_parser },
-	{ "contents", FIELD_STR, contents_atom_parser },
-	{ "upstream", FIELD_STR, remote_ref_atom_parser },
-	{ "push", FIELD_STR, remote_ref_atom_parser },
-	{ "symref", FIELD_STR, refname_atom_parser },
-	{ "flag" },
-	{ "HEAD", FIELD_STR, head_atom_parser },
-	{ "color", FIELD_STR, color_atom_parser },
-	{ "align", FIELD_STR, align_atom_parser },
-	{ "end" },
-	{ "if", FIELD_STR, if_atom_parser },
-	{ "then" },
-	{ "else" },
+	{ "refname", SOURCE_NONE, FIELD_STR, refname_atom_parser },
+	{ "objecttype", SOURCE_OTHER },
+	{ "objectsize", SOURCE_OTHER, FIELD_ULONG },
+	{ "objectname", SOURCE_OTHER, FIELD_STR, objectname_atom_parser },
+	{ "tree", SOURCE_OBJ },
+	{ "parent", SOURCE_OBJ },
+	{ "numparent", SOURCE_OBJ, FIELD_ULONG },
+	{ "object", SOURCE_OBJ },
+	{ "type", SOURCE_OBJ },
+	{ "tag", SOURCE_OBJ },
+	{ "author", SOURCE_OBJ },
+	{ "authorname", SOURCE_OBJ },
+	{ "authoremail", SOURCE_OBJ },
+	{ "authordate", SOURCE_OBJ, FIELD_TIME },
+	{ "committer", SOURCE_OBJ },
+	{ "committername", SOURCE_OBJ },
+	{ "committeremail", SOURCE_OBJ },
+	{ "committerdate", SOURCE_OBJ, FIELD_TIME },
+	{ "tagger", SOURCE_OBJ },
+	{ "taggername", SOURCE_OBJ },
+	{ "taggeremail", SOURCE_OBJ },
+	{ "taggerdate", SOURCE_OBJ, FIELD_TIME },
+	{ "creator", SOURCE_OBJ },
+	{ "creatordate", SOURCE_OBJ, FIELD_TIME },
+	{ "subject", SOURCE_OBJ, FIELD_STR, subject_atom_parser },
+	{ "body", SOURCE_OBJ, FIELD_STR, body_atom_parser },
+	{ "trailers", SOURCE_OBJ, FIELD_STR, trailers_atom_parser },
+	{ "contents", SOURCE_OBJ, FIELD_STR, contents_atom_parser },
+	{ "upstream", SOURCE_NONE, FIELD_STR, remote_ref_atom_parser },
+	{ "push", SOURCE_NONE, FIELD_STR, remote_ref_atom_parser },
+	{ "symref", SOURCE_NONE, FIELD_STR, refname_atom_parser },
+	{ "flag", SOURCE_NONE },
+	{ "HEAD", SOURCE_NONE, FIELD_STR, head_atom_parser },
+	{ "color", SOURCE_NONE, FIELD_STR, color_atom_parser },
+	{ "align", SOURCE_NONE, FIELD_STR, align_atom_parser },
+	{ "end", SOURCE_NONE },
+	{ "if", SOURCE_NONE, FIELD_STR, if_atom_parser },
+	{ "then", SOURCE_NONE },
+	{ "else", SOURCE_NONE },
 };
 
 #define REF_FORMATTING_STATE_INIT  { 0, NULL }
@@ -498,6 +501,7 @@ static int parse_ref_filter_atom(const struct ref_format *format,
 	REALLOC_ARRAY(used_atom, used_atom_cnt);
 	used_atom[at].name = xmemdupz(atom, ep - atom);
 	used_atom[at].type = valid_atom[i].cmp_type;
+	used_atom[at].source = valid_atom[i].source;
 	if (arg) {
 		arg = used_atom[at].name + (arg - atom) + 1;
 		if (!*arg) {