Hashtable: hide implementation of Hashtable and HashtableItem

Hashtable.c

@@ -19,6 +19,20 @@ in the source distribution for its full text.
 #include "XUtils.h"
 
 
+typedef struct HashtableItem_ {
+   ht_key_t key;
+   unsigned int probe;
+   void* value;
+} HashtableItem;
+
+struct Hashtable_ {
+   unsigned int size;
+   HashtableItem* buckets;
+   unsigned int items;
+   bool owner;
+};
+
+
 #ifndef NDEBUG
 
 static void Hashtable_dump(const Hashtable* this) {

Hashtable.h

@@ -14,18 +14,7 @@ typedef unsigned int ht_key_t;
 
 typedef void(*Hashtable_PairFunction)(ht_key_t key, void* value, void* userdata);
 
-typedef struct HashtableItem_ {
-   ht_key_t key;
-   unsigned int probe;
-   void* value;
-} HashtableItem;
-
-typedef struct Hashtable_ {
-   unsigned int size;
-   HashtableItem* buckets;
-   unsigned int items;
-   bool owner;
-} Hashtable;
+typedef struct Hashtable_ Hashtable;
 
 #ifndef NDEBUG