* Added optional allocator template parameter.

* Added optional parameter "void** oldTable" to Resize(). If given the old
  allocation for the table is returned instead of freeing it.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35278 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/util/OpenHashTable.h

@@ -31,18 +31,44 @@
 		typedef int		KeyType;
 		typedef	Foo		ValueType;
 
-		HashTableDefinition(const HashTableDefinition&) {}
+		size_t HashKey(int key) const
+		{
+			return key >> 1;
+		}
 
-		size_t HashKey(int key) const { return key >> 1; }
+		size_t Hash(Foo* value) const
-		size_t Hash(Foo* value) const { return HashKey(value->bar); }
+		{
-		bool Compare(int key, Foo* value) const { return value->bar == key; }
+			return HashKey(value->bar);
-		Foo*& GetLink(Foo* value) const { return value->fNext; }
+		}
+
+		bool Compare(int key, Foo* value) const
+		{
+			return value->bar == key;
+		}
+
+		Foo*& GetLink(Foo* value) const
+		{
+			return value->fNext;
+		}
 	};
 */
 
 
+struct MallocAllocator {
+	void* Allocate(size_t size) const
+	{
+		return malloc(size);
+	}
+
+	void Free(void* memory) const
+	{
+		free(memory);
+	}
+};
+
+
 template<typename Definition, bool AutoExpand = true,
-	bool CheckDuplicates = false>
+	bool CheckDuplicates = false, typename Allocator = MallocAllocator>
 class BOpenHashTable {
 public:
 	typedef BOpenHashTable<Definition, AutoExpand, CheckDuplicates> HashTable;
@@ -51,9 +77,7 @@ public:
 
 	static const size_t kMinimumSize = 8;
 
-	// we use malloc() / free() for allocation. If in the future this
+	// All allocations are of power of 2 lengths.
-	// is revealed to be insufficient we can switch to a template based
-	// allocator. All allocations are of power of 2 lengths.
 
 	// regrowth factor: 200 / 256 = 78.125%
 	//                   50 / 256 = 19.53125%
@@ -75,9 +99,19 @@ public:
 	{
 	}
 
+	BOpenHashTable(const Definition& definition, const Allocator& allocator)
+		:
+		fDefinition(definition),
+		fAllocator(allocator),
+		fTableSize(0),
+		fItemCount(0),
+		fTable(NULL)
+	{
+	}
+
 	~BOpenHashTable()
 	{
-		free(fTable);
+		fAllocator.Free(fTable);
 	}
 
 	status_t Init(size_t initialSize = kMinimumSize)
@@ -259,15 +293,18 @@ public:
 		unless \a force is \c true, in which case the supplied allocation is
 		used in any event.
 		Otherwise \c true is returned.
+		If \a oldTable is non-null and resizing is successful, the old table
+		will not be freed, but will be returned via this parameter instead.
 	*/
-	bool Resize(void* allocation, size_t size, bool force = false)
+	bool Resize(void* allocation, size_t size, bool force = false,
+		void** oldTable = NULL)
 	{
 		if (!force && size != ResizeNeeded()) {
-			free(allocation);
+			fAllocator.Free(allocation);
 			return false;
 		}
 
-		_Resize((ValueType**)allocation, size / sizeof(ValueType*));
+		_Resize((ValueType**)allocation, size / sizeof(ValueType*), oldTable);
 		return true;
 	}
 
@@ -356,7 +393,7 @@ protected:
 	bool _Resize(size_t newSize)
 	{
 		ValueType** newTable
-			= (ValueType**)malloc(sizeof(ValueType*) * newSize);
+			= (ValueType**)fAllocator.Allocate(sizeof(ValueType*) * newSize);
 		if (newTable == NULL)
 			return false;
 
@@ -364,7 +401,7 @@ protected:
 		return true;
 	}
 
-	void _Resize(ValueType** newTable, size_t newSize)
+	void _Resize(ValueType** newTable, size_t newSize, void** oldTable = NULL)
 	{
 		for (size_t i = 0; i < newSize; i++)
 			newTable[i] = NULL;
@@ -379,7 +416,10 @@ protected:
 				}
 			}
 
-			free(fTable);
+			if (oldTable != NULL)
+				*oldTable = fTable;
+			else
+				fAllocator.Free(fTable);
 		}
 
 		fTableSize = newSize;
@@ -406,6 +446,7 @@ protected:
 	}
 
 	Definition		fDefinition;
+	Allocator		fAllocator;
 	size_t			fTableSize;
 	size_t			fItemCount;
 	ValueType**		fTable;