/////////////////////////////////////////////////////////////////////////////
// temp.cpp - demonstrate performance implications of temporary objects
//
// Jim Fawcett, CSE691 - SW Modeling & Analysis, Fall 2000
/////////////////////////////////////////////////////////////////////////////
// Platform: Dell XPS1000, Windows 2000 Professional, SP1

#pragma warning(disable : 4786)
#include <iostream>
#include <string>
#include "..\timer.h"
using namespace std;

/////////////////////////////////////////////////////////////////////////////
// class that creates a temporary when assigned a string

class createTemp {

  public:
    createTemp() { }
    createTemp(string &s) : _s(s) { }
    createTemp& operator=(const createTemp &ct);

  private:
    string _s;
};

createTemp& createTemp::operator =(const createTemp &ct) {

  if(this == &ct)
    return *this;
  _s = ct._s;
  return *this;
}

/////////////////////////////////////////////////////////////////////////////
// class that does not create a temporary when assigned a string

class noTemp {

  public:
    noTemp() { }
    noTemp(string &s) : _s(s) { }
    noTemp& operator=(string &s);

  private:
    string _s;
};

noTemp& noTemp::operator =(string &s) {

  if((void*)this == (void*)(&s))
    return *this;
  _s = s;
  return *this;
}

//

/////////////////////////////////////////////////////////////////////////////
// assign string to class object

template<class T>
void assign(T &t1, string &s) {

  t1 = s;
}

/////////////////////////////////////////////////////////////////////////////
// function to time function calls

template<class U, class V> 
clock_t timeFunction(void(*pFunc)(U u, V v), U u, V v, int N) {

  timer t;
  t.start();
  int i;
  for(i=0; i<N; i++)
    pFunc(u,v);
  t.stop();

  cout << "\n  type of argument is " << typeid(u).name();

  cout << "\n  time to call function " << N << " times = " 
       << t.elapsed() << " milliseconds" << endl;
  
  return t.elapsed();
}

/////////////////////////////////////////////////////////////////////////////
// test stub

void main() {

  cout << "\n  Demo Performance - with and without temporaries "
       << "\n =================================================\n";

  const int N = 500000;

  createTemp ct;
  string s = "This is a moderately long, but not terribly long string";

  timeFunction<createTemp&,string&>(assign<createTemp>, ct, s, N);
 
  noTemp nt;
  timeFunction<noTemp&,string&>(assign<noTemp>, nt, s, N);

  cout << "\n\n";
}