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Counter.hpp

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/*==========================================================================
 * Copyright (c) 2001 Carnegie Mellon University.  All Rights Reserved.
 *
 * Use of the Lemur Toolkit for Language Modeling and Information Retrieval
 * is subject to the terms of the software license set forth in the LICENSE
 * file included with this software, and also available at
 * http://www.lemurproject.org/license.html
 *
 *==========================================================================
*/


#ifndef _COUNTER_HPP
#define _COUNTER_HPP



class Counter {
public:

  virtual ~Counter() {}
  // access functions
  
  virtual double count(int eventIndex) const= 0;
  virtual double sum() const= 0;
  
  virtual void startIteration() const= 0;
  virtual bool hasMore() const= 0;
  virtual void nextCount(int &eventIndex, double &count) const= 0;
};

class ModifiableCounter : public Counter {
public: 
  // manipulation functions
  virtual ~ModifiableCounter() {}
  virtual void incCount(int eventIndex, double count) = 0;
  virtual void setCount(int eventIndex, double count)  = 0;
};


template<class T>
class ArrayCounter : public ModifiableCounter {
public:
  
  ArrayCounter(int size) : sz(size), ct(new T[size]), total(0) {
    for (int i=0; i<size; i++) ct[i]=0;
  }
  virtual ~ArrayCounter() { delete [] ct;}

  virtual double count(int eventIndex) const{
    return ct[eventIndex];
  }

  virtual double sum() const{
    return total;
  }

  virtual void incCount(int eventIndex, double count) {
    ct[eventIndex] += (T)count;
    total += (T)count;
  }

  virtual void setCount(int eventIndex, double count) {
    total = total - ct[eventIndex]+ (T)count;
    ct[eventIndex] = (T)count;
  }


  virtual void startIteration() const{
    pos=0;
  }

  virtual bool hasMore() const{
    while ((pos < sz) && (ct[pos] == 0))
      pos++;
    return (pos<sz); 
  }

  virtual void nextCount(int &eventIndex, double &count) const{
    eventIndex = pos;
    count = ct[pos];
    pos++;
  }

protected:
  T *ct;
  int sz;
  T total;
  mutable int pos;
};

#endif /* _COUNTER_HPP */

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