diff -r 862ab606ee06 -r 04c9f8d8f03b ucx/cx/collection.h
--- a/ucx/cx/collection.h	Sun Feb 16 17:38:07 2025 +0100
+++ b/ucx/cx/collection.h	Tue Feb 25 21:12:11 2025 +0100
@@ -26,11 +26,11 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 /**
- * \file collection.h
- * \brief Common definitions for various collection implementations.
- * \author Mike Becker
- * \author Olaf Wintermann
- * \copyright 2-Clause BSD License
+ * @file collection.h
+ * @brief Common definitions for various collection implementations.
+ * @author Mike Becker
+ * @author Olaf Wintermann
+ * @copyright 2-Clause BSD License
  */
 
 #ifndef UCX_COLLECTION_H
@@ -92,17 +92,69 @@
      * instead of copies of the actual objects.
      */
     bool store_pointer;
+    /**
+     * Indicates if this collection is guaranteed to be sorted.
+     * Note that the elements can still be sorted, even when the collection is not aware of that.
+     */
+    bool sorted;
 };
 
 /**
  * Use this macro to declare common members for a collection structure.
+ *
+ * @par Example Use
+ * @code
+ * struct MyCustomSet {
+ *     CX_COLLECTION_BASE;
+ *     MySetElements *data;
+ * }
+ * @endcode
  */
 #define CX_COLLECTION_BASE struct cx_collection_s collection
 
 /**
+ * Returns the number of elements currently stored.
+ *
+ * @param c a pointer to a struct that contains #CX_COLLECTION_BASE
+ * @return (@c size_t) the number of currently stored elements
+ */
+#define cxCollectionSize(c) ((c)->collection.size)
+
+/**
+ * Returns the size of one element.
+ *
+ * If #cxCollectionStoresPointers() returns true, this is the size of a pointer.
+ *
+ * @param c a pointer to a struct that contains #CX_COLLECTION_BASE
+ * @return (@c size_t) the size of one element in bytes
+ */
+#define cxCollectionElementSize(c) ((c)->collection.elem_size)
+
+/**
+ * Indicates whether this collection only stores pointers instead of the actual data.
+ *
+ * @param c a pointer to a struct that contains #CX_COLLECTION_BASE
+ * @retval true if this collection stores only pointers to data
+ * @retval false if this collection stores the actual element's data
+ */
+#define cxCollectionStoresPointers(c) ((c)->collection.store_pointer)
+
+/**
+ * Indicates whether the collection can guarantee that the stored elements are currently sorted.
+ *
+ * This may return false even when the elements are sorted.
+ * It is totally up to the implementation of the collection whether it keeps track of the order of its elements.
+ *
+ * @param c a pointer to a struct that contains #CX_COLLECTION_BASE
+ * @retval true if the elements are currently sorted wrt. the collection's compare function
+ * @retval false if the order of elements is unknown
+ */
+#define cxCollectionSorted(c) ((c)->collection.sorted)
+
+/**
  * Sets a simple destructor function for this collection.
  *
- * @param c the collection
+ * @param c a pointer to a struct that contains #CX_COLLECTION_BASE
  * @param destr the destructor function
  */
 #define cxDefineDestructor(c, destr) \
@@ -111,7 +163,7 @@
 /**
  * Sets a simple destructor function for this collection.
  *
- * @param c the collection
+ * @param c a pointer to a struct that contains #CX_COLLECTION_BASE
  * @param destr the destructor function
  */
 #define cxDefineAdvancedDestructor(c, destr, data) \
@@ -124,8 +176,11 @@
  * Usually only used by collection implementations. There should be no need
  * to invoke this macro manually.
  *
- * @param c the collection
- * @param e the element
+ * When the collection stores pointers, those pointers are directly passed
+ * to the destructor. Otherwise, a pointer to the element is passed.
+ *
+ * @param c a pointer to a struct that contains #CX_COLLECTION_BASE
+ * @param e the element (the type is @c void* or @c void** depending on context)
  */
 #define cx_invoke_simple_destructor(c, e) \
     (c)->collection.simple_destructor((c)->collection.store_pointer ? (*((void **) (e))) : (e))
@@ -136,8 +191,11 @@
  * Usually only used by collection implementations. There should be no need
  * to invoke this macro manually.
  *
- * @param c the collection
- * @param e the element
+ * When the collection stores pointers, those pointers are directly passed
+ * to the destructor. Otherwise, a pointer to the element is passed.
+ *
+ * @param c a pointer to a struct that contains #CX_COLLECTION_BASE
+ * @param e the element (the type is @c void* or @c void** depending on context)
  */
 #define cx_invoke_advanced_destructor(c, e) \
     (c)->collection.advanced_destructor((c)->collection.destructor_data, \
@@ -150,8 +208,11 @@
  * Usually only used by collection implementations. There should be no need
  * to invoke this macro manually.
  *
- * @param c the collection
- * @param e the element
+ * When the collection stores pointers, those pointers are directly passed
+ * to the destructor. Otherwise, a pointer to the element is passed.
+ *
+ * @param c a pointer to a struct that contains #CX_COLLECTION_BASE
+ * @param e the element (the type is @c void* or @c void** depending on context)
  */
 #define cx_invoke_destructor(c, e) \
     if ((c)->collection.simple_destructor) cx_invoke_simple_destructor(c,e); \