// exception2.cpp			By: Aiman Hanna -  ©1993-2006 Aiman Hanna

// Again, exceptions are run-time program anomalies. Programmers 
// generally develop their own style for handling exceptions. 
// This program shows some example of these styles to handle a situation 
// where the new operator (request for dynamic memory allocations fails. 
 

// Key Points:		1) "non-standard" ways for handling exceptions


#include "exception2.h"


int NSHandle1( )
{
	int *ptr1 = new int[999999999];

	if (ptr1 == 0)		// same as if (ptr == NULL) 
	{
		cerr << "Could not allocate needed memory" << endl;
		cout << "Function will return immediately" << endl; 
		return (-1);
	}

	cout << "Allocation is fine. " << endl;
	delete [] ptr1;
	return 0;
}


int NSHandle2( )
{
	// This is the worst and most common. Just trust that it won't happen

	char *ptr1 = new char[30];
	
	// just use the assumed allocated space
	strcpy(ptr1, "I am always lucky"); 
	cout <<endl << ptr1 << endl;;

	// delete the assumed allocated space
	delete [] ptr1;
	return 0;
}


ProducerConsumer::ProducerConsumer()
{
	// An empty element of the array will have a negative value (that is -1)
	for (int i = 0; i < 10; i++)
		buff[i] = -1;

}


bool ProducerConsumer::isEmpty()
{

	if (buff[0] == -1)
		return true;

return false;
}


bool ProducerConsumer::isFull()
{

	if (buff[9] != -1)
		return true;

return false;
}



bool ProducerConsumer::produceItem( int item )
{
	if (isFull())
		return false;		
	int i = 0;
	while (buff[i++] != -1);
		buff[i - 1] = item;
	return true;
}



bool ProducerConsumer::consumeItem( )
{
	// finds the last full element and consume it (set it to -1) 
	if (isEmpty())
		return false;		

	int i = 0, item = -1;
	while ( (i < 10) && (buff[i] != -1) ) 
		i++;
	
	item = buff[i-1];
	buff[i-1] = -1;
	return true;
	
}




void ProducerConsumer::displayBuffContents()
{
	cout << "\nThe buffer contents at this point are: " << endl;
	for (int i= 0; i < 10; i++)
		cout << buff[i] << "  ";
	cout << endl << endl;

}





int main()
{
	int i = NSHandle1( );
	if (i == -1) 
			cerr << "Function NSHandle1( ) returned with allocation error" << endl << endl;

	NSHandle2( );

	ProducerConsumer pc1;
	if (pc1.consumeItem( ) == false)
	{
		cerr << "Could not consume. Buffer is empty" << endl << endl;;

	}

	for (i = 0; i < 13; i++)
		{
			if(pc1.produceItem(i * 5) == false)		// i*5 is just a value 
				cerr << "Could not produce. Buffer is full" << endl;

			if ((i == 7) || (i ==8) || (i ==9))		// just show the buffer contents at these three points
				pc1.displayBuffContents();

		}

	
	for (i = 0; i < 13; i++)
		{
			if (pc1.consumeItem() == false)	
				cerr << "Could not consume. Buffer is empty" << endl;
			
			if ((i == 7) || (i ==8) || (i ==9))		// just show the buffer contents at these last three points
				pc1.displayBuffContents();
		}
	return 0;
}


	
	


// The result of running the program
/*

Could not allocate needed memory
Function will return immediately
Function NSHandle1( ) returned with allocation error


I am always lucky
Could not consume. Buffer is empty


The buffer contents at this point are:
0  5  10  15  20  25  30  35  -1  -1


The buffer contents at this point are:
0  5  10  15  20  25  30  35  40  -1


The buffer contents at this point are:
0  5  10  15  20  25  30  35  40  45

Could not produce. Buffer is full
Could not produce. Buffer is full
Could not produce. Buffer is full

The buffer contents at this point are:
0  5  -1  -1  -1  -1  -1  -1  -1  -1


The buffer contents at this point are:
0  -1  -1  -1  -1  -1  -1  -1  -1  -1


The buffer contents at this point are:
-1  -1  -1  -1  -1  -1  -1  -1  -1  -1

Could not consume. Buffer is empty
Could not consume. Buffer is empty
Could not consume. Buffer is empty
*/