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diff --git a/lib/generic/set.h b/lib/generic/set.h
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+++ b/lib/generic/set.h
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+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/**
+ * @file set.h
+ * @brief A set abstraction implemented on top of map.
+ *
+ * @note The API is based on map.h, see it for more examples.
+ *
+ * # Example usage:
+ *
+ * @code{.c}
+ *      set_t set = set_make(NULL);
+ *
+ *      // Insert keys
+ *      if (set_add(&set, "princess") != 0 ||
+ *          set_add(&set, "prince")   != 0 ||
+ *          set_add(&set, "leia")     != 0) {
+ *          fail();
+ *      }
+ *
+ *      // Test membership
+ *      if (set_contains(&set, "leia")) {
+ *          success();
+ *      }
+ *
+ *      // Prefix search
+ *      int i = 0;
+ *      int count(const char *s, void *n) { (*(int *)n)++; return 0; }
+ *      if (set_walk_prefixed(set, "princ", count, &i) == 0) {
+ *          printf("%d matches\n", i);
+ *      }
+ *
+ *      // Delete
+ *      if (set_del(&set, "badkey") != 0) {
+ *          fail(); // No such key
+ *      }
+ *
+ *      // Clear the set
+ *      set_clear(&set);
+ * @endcode
+ *
+ * \addtogroup generics
+ * @{
+ */
+
+#pragma once
+
+#include <stddef.h>
+#include "map.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef map_t set_t;
+typedef int (set_walk_cb)(const char *, void *);
+
+/*! Creates an new, empty critbit set */
+#define set_make \
+	map_make
+
+/*! Returns non-zero if set contains str */
+#define set_contains(set, str) \
+	map_contains((set), (str))
+
+/*! Inserts str into set.  Returns 0 if new, 1 if already present, or ENOMEM. */
+#define set_add(set, str) \
+	map_set((set), (str), (void *)1)
+
+/*! Deletes str from the set, returns 0 on suceess */
+#define set_del(set, str) \
+	map_del((set), (str))
+
+/*! Clears the given set */
+#define set_clear(set) \
+	map_clear(set)
+
+/*! Calls callback for all strings in map  */
+#define set_walk(set, callback, baton) \
+	map_walk_prefixed((set), "", (callback), (baton))
+
+/*! Calls callback for all strings in set with the given prefix  */
+#define set_walk_prefixed(set, prefix, callback, baton) \
+	map_walk_prefixed((set), (prefix), (callback), (baton))
+
+
+#ifdef __cplusplus
+}
+#endif
+
+/** @} */