/* RandomInt.doc documents RandomInt, a pseudo-random integer class.
 *
 * Written by: Joel C. Adams, Spring, 1993, at Calvin College.
 * Written for: C++: An Introduction To Computing.
 * Revised: Spring 1997, for C++: An Introduction To Computing 2e.
 * Revised: Summer 2001, for C++: An Introduction To Computing 3e.
 *
 * Usage: to generate a...
 *  nondeterministic sequence of 'random' numbers in 0..RAND_MAX:
 *     RandomInt rint1;       
 *  deterministic sequence of 'random' numbers in 0..RAND_MAX:
 *     RandomInt rint2(a);
 *  nondeterministic sequence of 'random' numbers in b..c:
 *     RandomInt rint3(b, c);       
 *  deterministic sequence of 'random' numbers in b..c:
 *     RandomInt rint2(a, b, c);
 *
 * Caution: RandomInt objects are NOT autonomous, but SHARE the ANSI-C
 *  standard random number generator rand().  For most applications,
 *  this will have no effect.  However, if a program defines an unseeded
 *  RandomInt r1, and later defines a seeded RandomInt r2, then the
 *  number-sequence for r1 will be 'random' prior to the definition
 *  of r2, but deterministic following the definition of r2 (because r2's
 *  re-seeding the random number generator affects the numbers of r1).
 *
 * Class Invariant: myRandomValue contains a 'random' number
 *                 between myLowerBound and myUpperBound (inclusive).
 ********************************************************************/

// ***** RandomInt.h **************************************************

#ifndef RANDOMINT
#define RANDOMINT
#include <iostream>
#include <cstdlib>
#include <cassert>
#include <ctime>
using namespace std;

class RandomInt
{ 
 public:                                       // INTERFACE:
                                               //  constructors
  RandomInt();                                 //    default values
  RandomInt(int low, int high);                //    bounded
  RandomInt(int seedValue);                    //    seeded 
  RandomInt(int seedValue, int low, int high); //    seeded & bounded
                                               //  output:
  void print(ostream & out) const;             //    member (<< below)
                                               //  generate next:
  RandomInt generate();                        //    default bounds
  RandomInt generate(int low, int high);       //    new bounds
                                               //  type-conversion
  operator int();                              //    RandomInt-to-int

 private:                                      // PRIVATE SECTION:
                                               //  utility functions
  void initialize(int low, int high);          //   unseeded initializer
  void seededInitialize(int seedValue,         //   seeded initializer
                        int low, int high);
  int nextRandomInt();                         //   formula encapsulation

  int myLowerBound,                            //  the minimum random value
      myUpperBound,                            //  the maximum random value
      myRandomValue;                           //  the current random value

  static bool generatorInitialized;            //  initialization flag
};


/*********************************************************************
 * Initialize a RandomInt to a number within default bounds.         *
 * Postcondition: myLowerBound == 0 && myUpperBound == RAND_MAX &&   *
 *                 srand() has been seeded (using time()) &&         *
 *                 myRandomValue contains a 'random' number.         *
 *********************************************************************/
inline RandomInt::RandomInt()
{
  initialize(0, RAND_MAX);
}

/*********************************************************************
 * Initialize a RandomInt to a number within specified bounds.       *
 * Precondition: 0 <= low && low < high.                             *
 * Postcondition: myLowerBound == low && myUpperBound == high &&     *
 *                 srand() has been seeded (using time()) &&         *
 *                 myRandomValue contains a 'random' number.         *
 *********************************************************************/
inline RandomInt::RandomInt(int low, int high)
{
  assert(0 <= low);
  assert(low < high);
  initialize(low, high);
}

/*********************************************************************
 * Initialize a RandomInt to a number within default bounds,         *
 *     using a specified seed value.                                 *
 * Postcondition: myLowerBound == 0 && myUpperBound == RAND_MAX &&   *
 *                 srand() has been seeded (using seedValue) &&      *
 *                 myRandomValue contains a 'random' number.         *
 *********************************************************************/
inline RandomInt::RandomInt(int seedValue)
{
  assert(seedValue >= 0);
  seededInitialize(seedValue, 0, RAND_MAX);
}

/*********************************************************************
 * Initialize a RandomInt to a number within specified bounds        *
 *     using a specified seed value.                                 *
 * Precondition: 0 <= low && low < high.                             *
 * Postcondition: myLowerBound == low && myUpperBound == high &&     *
 *                 srand() has been seeded (using seedValue) &&      *
 *                 myRandomValue contains a 'random' number.         *
 *********************************************************************/
inline RandomInt::RandomInt(int seedValue, int low, int high)
{
  assert(seedValue >= 0);
  assert(0 <= low);
  assert(low < high);
  seededInitialize(seedValue, low, high);
}

/**********************************************************************
 * Output a RandomInt via an ostream (Function Member).               *
 * Precondition: out is an ostream.                                   *
 * Postcondition: myRandomValue has been inserted into out.           *
 **********************************************************************/
inline void RandomInt::print(ostream & out) const
{
  out << myRandomValue;
}

/**********************************************************************
 * Output a RandomInt via an ostream (Non-Function Member).           *
 * Precondition: out is an ostream,                                   *
 *                randInt is a RandomInt.                             *
 * Postcondition: randInt.myRandomValue has been inserted into out && *
 *                 ReturnValue == out.                                *
 **********************************************************************/
inline ostream & operator<< (ostream & out, const RandomInt & randInt)
{
  randInt.print(out);
  return out;
}

/*********************************************************************
 * Generate next random integer.                                     *
 * Precondition: srand() has been called to seed rand() &&           *
 *               myLowerBound has been initialized &&                *
 *               myUpperBound has been initialized.                  *
 * Postcondition: ReturnVal == a new 'random' number.                *
 *********************************************************************/
inline int RandomInt::nextRandomInt()
{
  return myLowerBound + rand() % (myUpperBound - myLowerBound + 1);
}

/**********************************************************************
 * Generate a new 'random' number within myLowerBound..myUpperBound.  *
 * Postcondition: myRandomValue has a new 'random' value &&           *
 *                ReturnValue == myself.                               *
 **********************************************************************/
inline RandomInt RandomInt::generate()
{
  myRandomValue = NextRandomInt();
  return *this;
}

/**********************************************************************
 * Convert RandomInt objects to int objects, where appropriate.       *
 * Precondition: A RandomInt has been used in a context defined       *
 *                for an int, but not for a RandomInt.                *
 * Postcondition: myRandomValue has been read and returned.           *
 **********************************************************************/
inline RandomInt::operator int() 
{
  return myRandomValue;
}


#endif


//******* RandomInt.cpp ********************************************

bool RandomInt::generatorInitialized = false;  // initialize the flag

/*********************************************************************
 * Initialize the data members and seed the random number generator  *
 *    using a default value (the clock).                             *
 * Precondition: 0 <= low && low < high.                             *
 * Postcondition: myLowerBound == low && myUpperBound == high &&     *
 *                 srand() has been seeded (using time()) &&         *
 *                 myRandomValue contains a 'random' number.         *
 *********************************************************************/
void RandomInt::initialize(int low, int high)
{
  myLowerBound = low;
  myUpperBound = high;

  if (!generatorInitialized)       // call srand() first time only
  {
     srand(long(time(0)));        // use clock for seed
     generatorInitialized = true;
  }

  myRandomValue = NextRandomInt();
}

/*********************************************************************
 * Initialize the data members and seed the random number generator  *
 *     using a specified value (seedValue).                          *
 * Precondition: 0 <= low && low < high.                             *
 * Postcondition: myLowerBound == low && myUpperBound == high &&     *
 *                 srand() has been seeded (using seedVal) &&        *
 *                 myRandomValue contains a 'random' number.         *
 *********************************************************************/
void RandomInt::seededInitialize(int seedValue, int low, int high)
{
  myLowerBound = low;
  myUpperBound = high;
  srand(seedValue);
  generatorInitialized = true;
  myRandomValue = nextRandomInt();
}

/**********************************************************************
 * Generate a new 'random' number within low..high.                   *
 * Precondition: 0 <= low && low < high.                              *
 * Postcondition: myRandomValue has a new 'random' value &&           *
 *               ReturnValue == myself.                               *
 **********************************************************************/
RandomInt RandomInt::generate(int low, int high)
{
  assert(0 <= low);
  assert(low < high);
  myLowerBound = low;
  myUpperBound = high;
  myRandomValue = nextRandomInt();
  return *this;
}