ref-filter: add function to print single ref_array_item

ref-filter functions are useful for printing git object information
using a format specifier. However, some other modules may not want to use
this functionality on a ref-array but only print a single item.

Expose a pretty_print_ref function to create, pretty print and free
individual ref-items.

Signed-off-by: Lukas Puehringer <luk.puehringer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: lukpueh

ref-filter.c

@@ -1329,7 +1329,7 @@ static struct ref_array_item *new_ref_array_item(const char *refname,
 	return ref;
 }
 
-static int filter_ref_kind(struct ref_filter *filter, const char *refname)
+static int ref_kind_from_refname(const char *refname)
 {
 	unsigned int i;
 
@@ -1342,11 +1342,7 @@ static int filter_ref_kind(struct ref_filter *filter, const char *refname)
 		{ "refs/tags/", FILTER_REFS_TAGS}
 	};
 
-	if (filter->kind == FILTER_REFS_BRANCHES ||
-	    filter->kind == FILTER_REFS_REMOTES ||
-	    filter->kind == FILTER_REFS_TAGS)
-		return filter->kind;
-	else if (!strcmp(refname, "HEAD"))
+	if (!strcmp(refname, "HEAD"))
 		return FILTER_REFS_DETACHED_HEAD;
 
 	for (i = 0; i < ARRAY_SIZE(ref_kind); i++) {
@@ -1357,6 +1353,15 @@ static int filter_ref_kind(struct ref_filter *filter, const char *refname)
 	return FILTER_REFS_OTHERS;
 }
 
+static int filter_ref_kind(struct ref_filter *filter, const char *refname)
+{
+	if (filter->kind == FILTER_REFS_BRANCHES ||
+	    filter->kind == FILTER_REFS_REMOTES ||
+	    filter->kind == FILTER_REFS_TAGS)
+		return filter->kind;
+	return ref_kind_from_refname(refname);
+}
+
 /*
  * A call-back given to for_each_ref().  Filter refs and keep them for
  * later object processing.
@@ -1637,6 +1642,16 @@ void show_ref_array_item(struct ref_array_item *info, const char *format, int qu
 	putchar('\n');
 }
 
+void pretty_print_ref(const char *name, const unsigned char *sha1,
+		const char *format)
+{
+	struct ref_array_item *ref_item;
+	ref_item = new_ref_array_item(name, sha1, 0);
+	ref_item->kind = ref_kind_from_refname(name);
+	show_ref_array_item(ref_item, format, 0);
+	free_array_item(ref_item);
+}
+
 /*  If no sorting option is given, use refname to sort as default */
 struct ref_sorting *ref_default_sorting(void)
 {

ref-filter.h

@@ -107,4 +107,11 @@ struct ref_sorting *ref_default_sorting(void);
 /*  Function to parse --merged and --no-merged options */
 int parse_opt_merge_filter(const struct option *opt, const char *arg, int unset);
 
+/*
+ * Print a single ref, outside of any ref-filter. Note that the
+ * name must be a fully qualified refname.
+ */
+void pretty_print_ref(const char *name, const unsigned char *sha1,
+		const char *format);
+
 #endif /*  REF_FILTER_H  */