diff -r 99a34860c105 -r d938228c382e src/ucx/cx/map.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/ucx/cx/map.h	Sun Nov 06 15:53:32 2022 +0100
@@ -0,0 +1,270 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *
+ *   2. Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in the
+ *      documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+/**
+ * \file map.h
+ * \brief Interface for map implementations.
+ * \author Mike Becker
+ * \author Olaf Wintermann
+ * \version 3.0
+ * \copyright 2-Clause BSD License
+ */
+
+#ifndef UCX_MAP_H
+#define UCX_MAP_H
+
+#include "common.h"
+#include "allocator.h"
+#include "iterator.h"
+#include "hash_key.h"
+
+#ifdef    __cplusplus
+extern "C" {
+#endif
+
+/** Type for the UCX map. */
+typedef struct cx_map_s CxMap;
+
+/** Type for a map entry. */
+typedef struct cx_map_entry_s CxMapEntry;
+
+/** Type for map class definitions. */
+typedef struct cx_map_class_s cx_map_class;
+
+/** Structure for the UCX map. */
+struct cx_map_s {
+    /** The map class definition. */
+    cx_map_class *cl;
+    /** An allocator that is used for the map elements. */
+    CxAllocator *allocator;
+    /** The number of elements currently stored. */
+    size_t size;
+    // TODO: elemsize + a flag if values shall be copied to the map
+};
+
+/**
+ * The class definition for arbitrary maps.
+ */
+struct cx_map_class_s {
+    /**
+     * Deallocates the entire memory.
+     */
+    __attribute__((__nonnull__))
+    void (*destructor)(struct cx_map_s *map);
+
+    /**
+     * Removes all elements.
+     */
+    __attribute__((__nonnull__))
+    void (*clear)(struct cx_map_s *map);
+
+    /**
+     * Add or overwrite an element.
+     */
+    __attribute__((__nonnull__))
+    int (*put)(
+            CxMap *map,
+            CxHashKey key,
+            void *value
+    );
+
+    /**
+     * Returns an element.
+     */
+    __attribute__((__nonnull__, __warn_unused_result__))
+    void *(*get)(
+            CxMap const *map,
+            CxHashKey key
+    );
+
+    /**
+     * Removes an element.
+     */
+    __attribute__((__nonnull__, __warn_unused_result__))
+    void *(*remove)(
+            CxMap *map,
+            CxHashKey key
+    );
+
+    /**
+     * Iterator over the key/value pairs.
+     */
+    __attribute__((__nonnull__, __warn_unused_result__))
+    CxIterator (*iterator)(CxMap *map);
+
+    /**
+     * Iterator over the keys.
+     */
+    __attribute__((__nonnull__, __warn_unused_result__))
+    CxIterator (*iterator_keys)(CxMap *map);
+
+    /**
+     * Iterator over the values.
+     */
+    __attribute__((__nonnull__, __warn_unused_result__))
+    CxIterator (*iterator_values)(CxMap *map);
+};
+
+/**
+ * A map entry.
+ */
+struct cx_map_entry_s {
+    /**
+     * A pointer to the key.
+     */
+    CxHashKey const *key;
+    /**
+     * A pointer to the value.
+     */
+    void *value;
+};
+
+
+/**
+ * Deallocates the memory of the specified map.
+ *
+ * @param map the map to be destroyed
+ */
+__attribute__((__nonnull__))
+static inline void cxMapDestroy(CxMap *map) {
+    // TODO: likely to add auto-free feature for contents in the future
+    map->cl->destructor(map);
+}
+
+
+/**
+ * Clears a map by removing all elements.
+ *
+ * @param map the map to be cleared
+ */
+__attribute__((__nonnull__))
+static inline void cxMapClear(CxMap *map) {
+    map->cl->clear(map);
+}
+
+/**
+ * Puts a key/value-pair into the map.
+ *
+ * @param map the map
+ * @param key the key
+ * @param value the value
+ * @return 0 on success, non-zero value on failure
+ */
+__attribute__((__nonnull__))
+static inline int cxMapPut(
+        CxMap *map,
+        CxHashKey key,
+        void *value
+) {
+    return map->cl->put(map, key, value);
+}
+
+/**
+ * Retrieves a value by using a key.
+ *
+ * @param map the map
+ * @param key the key
+ * @return the value
+ */
+__attribute__((__nonnull__, __warn_unused_result__))
+static inline void *cxMapGet(
+        CxMap const *map,
+        CxHashKey key
+) {
+    return map->cl->get(map, key);
+}
+
+/**
+ * Removes a key/value-pair from the map by using the key.
+ *
+ * @param map the map
+ * @param key the key
+ * @return the removed value
+ */
+__attribute__((__nonnull__, __warn_unused_result__))
+static inline void *cxMapRemove(
+        CxMap *map,
+        CxHashKey key
+) {
+    return map->cl->remove(map, key);
+}
+
+// TODO: set-like map operations (union, intersect, difference)
+
+/**
+ * Creates a value iterator for a map.
+ *
+ * \note An iterator iterates over all elements successively. Therefore the order
+ * highly depends on the map implementation and may change arbitrarily when the contents change.
+ *
+ * @param map the map to create the iterator for
+ * @return an iterator for the currently stored values
+ */
+__attribute__((__nonnull__, __warn_unused_result__))
+static inline CxIterator cxMapIteratorValues(CxMap *map) {
+    return map->cl->iterator_values(map);
+}
+
+/**
+ * Creates a key iterator for a map.
+ *
+ * The elements of the iterator are keys of type CxHashKey.
+ *
+ * \note An iterator iterates over all elements successively. Therefore the order
+ * highly depends on the map implementation and may change arbitrarily when the contents change.
+ *
+ * @param map the map to create the iterator for
+ * @return an iterator for the currently stored keys
+ */
+__attribute__((__nonnull__, __warn_unused_result__))
+static inline CxIterator cxMapIteratorKeys(CxMap *map) {
+    return map->cl->iterator_keys(map);
+}
+
+/**
+ * Creates an iterator for a map.
+ *
+ * The elements of the iterator are key/value pairs of type CxMapEntry.
+ *
+ * \note An iterator iterates over all elements successively. Therefore the order
+ * highly depends on the map implementation and may change arbitrarily when the contents change.
+ *
+ * @param map the map to create the iterator for
+ * @return an iterator for the currently stored entries
+ * @see cxMapIteratorKeys()
+ * @see cxMapIteratorValues()
+ */
+__attribute__((__nonnull__, __warn_unused_result__))
+static inline CxIterator cxMapIterator(CxMap *map) {
+    return map->cl->iterator(map);
+}
+
+#ifdef    __cplusplus
+}
+#endif
+
+#endif // UCX_MAP_H
\ No newline at end of file