for-each-ref: introduce filter_refs()

Introduce filter_refs() which will act as an API for filtering
a set of refs. Based on the type of refs the user has requested,
we iterate through those refs and apply filters as per the
given ref_filter structure and finally store the filtered refs
in the ref_array structure.

Currently this will wrap around ref_filter_handler(). Hence,
ref_filter_handler is made file scope static.

As users of this API will no longer send a ref_filter_cbdata
structure directly, we make the elements of ref_filter_cbdata
pointers. We can now use the information given by the users
to obtain our own ref_filter_cbdata structure. Changes are made to
support the change in ref_filter_cbdata structure.

Make 'for-each-ref' use this API.

Helped-by: Junio C Hamano <gitster@pobox.com>
Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/for-each-ref.c b/builtin/for-each-ref.c
index 637fc4a..7919206 100644
--- a/builtin/for-each-ref.c
+++ b/builtin/for-each-ref.c
@@ -16,7 +16,8 @@
 	const char *format = "%(objectname) %(objecttype)\t%(refname)";
 	struct ref_sorting *sorting = NULL, **sorting_tail = &sorting;
 	int maxcount = 0, quote_style = 0;
-	struct ref_filter_cbdata ref_cbdata;
+	struct ref_array array;
+	struct ref_filter filter;
 
 	struct option opts[] = {
 		OPT_BIT('s', "shell", &quote_style,
@@ -54,16 +55,16 @@
 	/* for warn_ambiguous_refs */
 	git_config(git_default_config, NULL);
 
-	memset(&ref_cbdata, 0, sizeof(ref_cbdata));
-	ref_cbdata.filter.name_patterns = argv;
-	for_each_rawref(ref_filter_handler, &ref_cbdata);
+	memset(&array, 0, sizeof(array));
+	memset(&filter, 0, sizeof(filter));
+	filter.name_patterns = argv;
+	filter_refs(&array, &filter, FILTER_REFS_ALL | FILTER_REFS_INCLUDE_BROKEN);
+	ref_array_sort(sorting, &array);
 
-	ref_array_sort(sorting, &ref_cbdata.array);
-
-	if (!maxcount || ref_cbdata.array.nr < maxcount)
-		maxcount = ref_cbdata.array.nr;
+	if (!maxcount || array.nr < maxcount)
+		maxcount = array.nr;
 	for (i = 0; i < maxcount; i++)
-		show_ref_array_item(ref_cbdata.array.items[i], format, quote_style);
-	ref_array_clear(&ref_cbdata.array);
+		show_ref_array_item(array.items[i], format, quote_style);
+	ref_array_clear(&array);
 	return 0;
 }