1 files changed, 53 insertions, 0 deletions
diff --git a/tag.c b/tag.c
new file mode 100644
index 0000000..e464dbc
--- /dev/null
+++ b/tag.c
@@ -0,0 +1,53 @@
+#include "tag.h"
+#include "link.h"
+
+static struct link *
+tagrefs_ffind(struct link *head, struct tag *tag)
+{
+	struct link *iter;
+
+	for (iter = head->next; iter; iter = iter->next) {
+		if (UPCAST(iter, struct tag_ref)->tag == tag)
+			return iter;
+	}
+
+	return NULL;
+}
+
+int
+tagrefs_incl(struct link *head, struct tag *tag)
+{
+	struct link *ref;
+
+	ref = tagrefs_ffind(head, tag);
+	return ref != NULL;
+}
+
+void
+tagrefs_add(struct link *head, struct tag *tag)
+{
+	struct tag_ref *ref;
+
+	if (tagrefs_incl(head, tag))
+		return;
+
+	ref = malloc(sizeof(struct tag_ref));
+	ASSERT(ref != NULL);
+	ref->link = LINK_EMPTY;
+	ref->tag = tag;
+	link_push_back(head, &ref->link);
+}
+
+void
+tagrefs_rm(struct link *head, struct tag *tag)
+{
+	struct link *ref;
+	struct tag_ref *tagref;
+
+	ref = tagrefs_ffind(head, tag);
+	if (!ref) return;
+
+	tagref = UPCAST(ref, struct tag_ref);
+	link_pop(ref);
+	free(tagref);
+}