include/geometry/simpleStats.h

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/*********************************************************************
** Copyright (c) 2004 MAK Technologies, Inc.
** All rights reserved.
*********************************************************************/
/*********************************************************************
** $RCSfile: simpleStats.h,v $ $Revision: 1.5 $ $State: Exp $
*********************************************************************/

#ifndef simpleStats_H_
#define simpleStats_H_

//
// A simple class for maintaining statistics/instrumentation.
// This class intentionally does not provide support for more complex
// computations, nor does it maintain a list of N number of items added.  
// This is to ensure that its performance is O(1) and its usage cost low 
// enough for use in the most performance critical areas of code. (unlike
// code that has been instrumented by a profiler).
// @note This class is intended ONLY for use with types that support being
// initialized by a constructor taking in 0 as a parameter.  Obviously, this
// is intended for use with the basic arithmetic types, such as int and float.
// Additionally, the average must be reportable as a double, as specifying a
// separate template parameter just to specify the return type of the average
// function seemed overly complex.
//
template <typename T>
class DtSimpleStats
{
public:
   DtSimpleStats() : myCount(0), mySum(0), myMin(0), myMax(0) {};
   
   virtual ~DtSimpleStats() {};

   // Adds the specified item.  Causes the count, total, and possibly
   // the min and max to be updated as well.
   void addItem(const T& item);

   // @return The current total divided by the current count.
   double getAverage() const { return mySum/myCount; }
   
   // @return The current min item added.  If no item has been added,
   // returns the default for the specified typename T
   const T& getMin() const { return myMin; }
   
   // @return The current max item added.  If no item has been added,
   // returns the default for the specified typename T
   const T& getMax() const { return myMax; }
   
   // @return The sum of all items added so far
   const T& getSum() const { return mySum; }

   // @return The current number of items added.
   unsigned int getCount() const { return myCount; }

   // Clears the object back to its initial state.
   void clear();

private:
   // Not implemented
   DtSimpleStats(const DtSimpleStats& original);
   DtSimpleStats& operator=(const DtSimpleStats& original);
   

   unsigned int   myCount;
   T     mySum;
   T     myMin;
   T     myMax;
};


//------------------------------------------------------
//  INLINE METHODS
//------------------------------------------------------
template <typename T>
void DtSimpleStats<T>::addItem(const T& item)
{
   ++myCount;
   mySum += item;
   if (myMax < item || 
       myCount == 1)
   {
      myMax = item;
   }
   if (myMin > item || 
       myCount == 1)
   {
      myMin = item;
   }
}


template <typename T>
void DtSimpleStats<T>::clear()
{
   myCount = 0;
   mySum = 0;
   myMin = 0;
   myMax = 0;
}

#endif