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Editor/XT/Include/XTCallbacks.h

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+// XTCallbacks.h : header file
+//
+// This file is a part of the Xtreme Toolkit for MFC.
+// <20>1998-2003 Codejock Software, All Rights Reserved.
+//
+// This source code can only be used under the terms and conditions
+// outlined in the accompanying license agreement.
+//
+// support@codejock.com
+// http://www.codejock.com
+//
+//////////////////////////////////////////////////////////////////////
+
+#if !defined(__XTCALLBACKS_H__)
+#define __XTCALLBACKS_H__
+
+#if _MSC_VER > 1000
+#pragma once
+#endif // _MSC_VER > 1000
+
+// Summary: This class defines a point of listener/callback registration.
+//			Each listener can later be notified.
+template <class T, int MAXCOUNT>
+class  CXTCallbacks
+{
+public:
+
+	// Summary: A type of callback function, takes a parameter that is passed to notify() function
+	typedef void (CObject::*NOTIFYCB)(T caller);
+
+private:
+
+	// Summary: Callback descriptor
+	struct CXTCbParam
+	{
+		DWORD m_receipt;		// Registration receipt or 0 if this descriptor is not initialized yet
+		CObject* m_listener;	// Listener
+		NOTIFYCB m_cb;			// Callback
+		
+		CXTCbParam()
+		: m_listener(0)
+		, m_cb(0)
+		, m_receipt(0)
+		{ }		
+	};
+
+	DWORD	   m_signatureSeed;    // A seed for generating signatures
+	CXTCbParam m_params[MAXCOUNT]; // Array of registered callbacks, maxed out as specified in template declaration
+
+// Operations
+
+public:
+
+	CXTCallbacks()
+	: m_signatureSeed(0)
+	{}
+
+
+	// Input:	listener - a listener on which to invoke the callback
+	//			cb - listener's method to invoke
+	// Returns: Its registration receipt or 0 if no more space
+	// Summary:	Adds a callback, 
+	DWORD Add(CObject* listener, NOTIFYCB cb)
+	{
+		for (int i = 0; i < MAXCOUNT; i++)
+		{
+			if (!m_params[i].m_receipt)
+			{				
+				m_params[i].m_cb = cb;
+				m_params[i].m_listener = listener;
+				return (m_params[i].m_receipt = ++m_signatureSeed);
+			}
+		}
+		return 0;
+	}
+
+	// Input:	receipt - Registration receipt.
+	// Returns: true if the callback was actually removed.
+	// Summary:	Removes a callback by its registration receipt.
+	bool Remove(DWORD receipt)
+	{
+		for (int i = 0; i < MAXCOUNT; i++)
+		{
+			if (m_params[i].m_receipt == receipt)
+			{				
+				m_params[i].m_receipt = 0;
+				m_params[i].m_cb = 0;
+				m_params[i].m_listener = 0;
+				return true;
+			}
+		}
+		return false;
+	}
+
+	// Input:	listener - Callback listener.
+	// Returns: true if a callback(s) actually removed
+	// Summary:	Removes all callbacks registered with a given listener
+	bool Remove(CObject* listener)
+	{
+		bool removed = false;
+		for (int i = 0; i < MAXCOUNT; i++)
+		{
+			if (m_params[i].m_receipt &&
+				m_params[i].m_listener == listener)
+			{				
+				m_params[i].m_receipt = 0;
+				m_params[i].m_cb = 0;
+				m_params[i].m_listener = 0;
+				removed = true;
+			}
+		}
+		return removed;
+	}
+
+	// Input:	caller - Caller to notify listeners.
+	// Summary:	Notifies listeners
+	void Notify(T caller)
+	{
+		for (int i = 0; i < MAXCOUNT; i++)
+		{
+			if (m_params[i].m_receipt)
+			{				
+				(m_params[i].m_listener->*m_params[i].m_cb)(caller);
+			}
+		}
+	}
+};
+
+#endif // !defined(__XTCALLBACKS_H__)