Filter: Add literal for empty set

Add literal for empty set [], which works both for tree-based sets
and prefix sets by using existing constant promotion mechanism.

Minor changes by committer.

1 files changed, 4 insertions, 4 deletions

diff --git a/filter/data.h b/filter/data.h
index 8cba8c0e..221e4229 100644
--- a/filter/data.h
+++ b/filter/data.h
@@ -279,11 +279,11 @@ int val_in_range(const struct f_val *v1, const struct f_val *v2);
 
 int clist_set_type(const struct f_tree *set, struct f_val *v);
 static inline int eclist_set_type(const struct f_tree *set)
-{ return set->from.type == T_EC; }
+{ return !set || set->from.type == T_EC; }
 static inline int lclist_set_type(const struct f_tree *set)
-{ return set->from.type == T_LC; }
+{ return !set || set->from.type == T_LC; }
 static inline int path_set_type(const struct f_tree *set)
-{ return set->from.type == T_INT; }
+{ return !set || set->from.type == T_INT; }
 
 const struct adata *clist_filter(struct linpool *pool, const struct adata *list, const struct f_val *set, int pos);
 const struct adata *eclist_filter(struct linpool *pool, const struct adata *list, const struct f_val *set, int pos);
@@ -299,7 +299,7 @@ undef_value(struct f_val v)
     (v.val.ad == &null_adata);
 }
 
-extern const struct f_val f_const_empty_path, f_const_empty_clist, f_const_empty_eclist, f_const_empty_lclist;
+extern const struct f_val f_const_empty_path, f_const_empty_clist, f_const_empty_eclist, f_const_empty_lclist, f_const_empty_prefix_set;
 
 enum filter_return f_eval(const struct f_line *expr, struct linpool *tmp_pool, struct f_val *pres);