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game/shared/entitydatainstantiator.h

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+//=============================================================================//
+
+#ifndef ENTITYDATAINSTANTIATOR_H
+#define ENTITYDATAINSTANTIATOR_H
+#ifdef _WIN32
+#pragma once
+#endif
+
+#include "utlhash.h"
+
+#include "tier0/memdbgon.h"
+
+// This is the hash key type, but it could just as easily be and int or void *
+class CBaseEntity;
+
+//-----------------------------------------------------------------------------
+// Purpose: 
+//-----------------------------------------------------------------------------
+abstract_class IEntityDataInstantiator
+{
+public:
+	virtual ~IEntityDataInstantiator() {};
+
+	virtual void *GetDataObject( const CBaseEntity *instance ) = 0;
+	virtual void *CreateDataObject( const CBaseEntity *instance ) = 0;
+	virtual void DestroyDataObject( const CBaseEntity *instance ) = 0;
+};
+
+//-----------------------------------------------------------------------------
+// Purpose: 
+//-----------------------------------------------------------------------------
+template <class T>
+class CEntityDataInstantiator : public IEntityDataInstantiator
+{
+public:
+	CEntityDataInstantiator() : 
+		m_HashTable( 64, 0, 0, CompareFunc, KeyFunc )
+	{
+	}
+
+	virtual void *GetDataObject( const CBaseEntity *instance )
+	{
+		UtlHashHandle_t handle; 
+		HashEntry entry;
+		entry.key = instance;
+		handle = m_HashTable.Find( entry );
+
+		if ( handle != m_HashTable.InvalidHandle() )
+		{
+			return (void *)m_HashTable[ handle ].data;
+		}
+
+		return NULL;
+	}
+
+	virtual void *CreateDataObject( const CBaseEntity *instance )
+	{
+		UtlHashHandle_t handle; 
+		HashEntry entry;
+		entry.key = instance;
+		handle = m_HashTable.Find( entry );
+
+		// Create it if not already present
+		if ( handle == m_HashTable.InvalidHandle() )
+		{
+			handle = m_HashTable.Insert( entry );
+			Assert( handle != m_HashTable.InvalidHandle() );
+			m_HashTable[ handle ].data = new T;
+	
+			// FIXME: We'll have to remove this if any objects we instance have vtables!!!
+			Q_memset( m_HashTable[ handle ].data, 0, sizeof( T ) );
+		}
+
+		return (void *)m_HashTable[ handle ].data;
+	}
+
+	virtual void DestroyDataObject( const CBaseEntity *instance )
+	{
+		UtlHashHandle_t handle; 
+		HashEntry entry;
+		entry.key = instance;
+		handle = m_HashTable.Find( entry );
+
+		if ( handle != m_HashTable.InvalidHandle() )
+		{
+			delete m_HashTable[ handle ].data;
+			m_HashTable.Remove( handle );
+		}
+	}
+
+private:
+
+	struct HashEntry
+	{
+		HashEntry()
+		{
+			key = NULL;
+			data = NULL;
+		}
+
+		const CBaseEntity *key;
+		T				*data;
+	};
+
+	static bool CompareFunc( const HashEntry &src1, const HashEntry &src2 )
+	{
+		return ( src1.key == src2.key );
+	}
+
+
+	static unsigned int KeyFunc( const HashEntry &src )
+	{
+		// Shift right to get rid of alignment bits and border the struct on a 16 byte boundary
+		return (unsigned int)src.key;
+	}
+
+	CUtlHash< HashEntry >	m_HashTable;
+};
+
+#include "tier0/memdbgoff.h"
+
+#endif // ENTITYDATAINSTANTIATOR_H