ref-filter: introduce struct used_atom

Introduce the 'used_atom' structure to replace the existing
implementation of 'used_atom' (which is a list of atoms). This helps
us parse atoms beforehand and store required details into the
'used_atom' for future usage.

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>

Author: KarthikNayak

ref-filter.c

@@ -26,8 +26,10 @@ typedef enum { FIELD_STR, FIELD_ULONG, FIELD_TIME } cmp_type;
  * indexed with the "atom number", which is an index into this
  * array.
  */
-static const char **used_atom;
-static cmp_type *used_atom_type;
+static struct used_atom {
+	const char *name;
+	cmp_type type;
+} *used_atom;
 static int used_atom_cnt, need_tagged, need_symref;
 static int need_color_reset_at_eol;
 
@@ -122,8 +124,8 @@ int parse_ref_filter_atom(const char *atom, const char *ep)
 
 	/* Do we have the atom already used elsewhere? */
 	for (i = 0; i < used_atom_cnt; i++) {
-		int len = strlen(used_atom[i]);
-		if (len == ep - atom && !memcmp(used_atom[i], atom, len))
+		int len = strlen(used_atom[i].name);
+		if (len == ep - atom && !memcmp(used_atom[i].name, atom, len))
 			return i;
 	}
 
@@ -150,12 +152,11 @@ int parse_ref_filter_atom(const char *atom, const char *ep)
 	at = used_atom_cnt;
 	used_atom_cnt++;
 	REALLOC_ARRAY(used_atom, used_atom_cnt);
-	REALLOC_ARRAY(used_atom_type, used_atom_cnt);
-	used_atom[at] = xmemdupz(atom, ep - atom);
-	used_atom_type[at] = valid_atom[i].cmp_type;
+	used_atom[at].name = xmemdupz(atom, ep - atom);
+	used_atom[at].type = valid_atom[i].cmp_type;
 	if (*atom == '*')
 		need_tagged = 1;
-	if (!strcmp(used_atom[at], "symref"))
+	if (!strcmp(used_atom[at].name, "symref"))
 		need_symref = 1;
 	return at;
 }
@@ -315,7 +316,7 @@ int verify_ref_format(const char *format)
 		at = parse_ref_filter_atom(sp + 2, ep);
 		cp = ep + 1;
 
-		if (skip_prefix(used_atom[at], "color:", &color))
+		if (skip_prefix(used_atom[at].name, "color:", &color))
 			need_color_reset_at_eol = !!strcmp(color, "reset");
 	}
 	return 0;
@@ -359,7 +360,7 @@ static void grab_common_values(struct atom_value *val, int deref, struct object
 	int i;
 
 	for (i = 0; i < used_atom_cnt; i++) {
-		const char *name = used_atom[i];
+		const char *name = used_atom[i].name;
 		struct atom_value *v = &val[i];
 		if (!!deref != (*name == '*'))
 			continue;
@@ -383,7 +384,7 @@ static void grab_tag_values(struct atom_value *val, int deref, struct object *ob
 	struct tag *tag = (struct tag *) obj;
 
 	for (i = 0; i < used_atom_cnt; i++) {
-		const char *name = used_atom[i];
+		const char *name = used_atom[i].name;
 		struct atom_value *v = &val[i];
 		if (!!deref != (*name == '*'))
 			continue;
@@ -405,7 +406,7 @@ static void grab_commit_values(struct atom_value *val, int deref, struct object
 	struct commit *commit = (struct commit *) obj;
 
 	for (i = 0; i < used_atom_cnt; i++) {
-		const char *name = used_atom[i];
+		const char *name = used_atom[i].name;
 		struct atom_value *v = &val[i];
 		if (!!deref != (*name == '*'))
 			continue;
@@ -535,7 +536,7 @@ static void grab_person(const char *who, struct atom_value *val, int deref, stru
 	const char *wholine = NULL;
 
 	for (i = 0; i < used_atom_cnt; i++) {
-		const char *name = used_atom[i];
+		const char *name = used_atom[i].name;
 		struct atom_value *v = &val[i];
 		if (!!deref != (*name == '*'))
 			continue;
@@ -573,7 +574,7 @@ static void grab_person(const char *who, struct atom_value *val, int deref, stru
 	if (!wholine)
 		return;
 	for (i = 0; i < used_atom_cnt; i++) {
-		const char *name = used_atom[i];
+		const char *name = used_atom[i].name;
 		struct atom_value *v = &val[i];
 		if (!!deref != (*name == '*'))
 			continue;
@@ -663,7 +664,7 @@ static void grab_sub_body_contents(struct atom_value *val, int deref, struct obj
 	unsigned long sublen = 0, bodylen = 0, nonsiglen = 0, siglen = 0;
 
 	for (i = 0; i < used_atom_cnt; i++) {
-		const char *name = used_atom[i];
+		const char *name = used_atom[i].name;
 		struct atom_value *v = &val[i];
 		const char *valp = NULL;
 		if (!!deref != (*name == '*'))
@@ -809,7 +810,7 @@ static void populate_value(struct ref_array_item *ref)
 
 	/* Fill in specials first */
 	for (i = 0; i < used_atom_cnt; i++) {
-		const char *name = used_atom[i];
+		const char *name = used_atom[i].name;
 		struct atom_value *v = &ref->value[i];
 		int deref = 0;
 		const char *refname;
@@ -1464,7 +1465,7 @@ static int cmp_ref_sorting(struct ref_sorting *s, struct ref_array_item *a, stru
 {
 	struct atom_value *va, *vb;
 	int cmp;
-	cmp_type cmp_type = used_atom_type[s->atom];
+	cmp_type cmp_type = used_atom[s->atom].type;
 
 	get_ref_atom_value(a, s->atom, &va);
 	get_ref_atom_value(b, s->atom, &vb);