package umontreal.iro.lecuyer.randvar;
import umontreal.iro.lecuyer.rng.*;
import umontreal.iro.lecuyer.probdist.*;


/**
 * This class implements a random variate generator for the 
 * uniform distribution over integers, over the interval [i, j].
 * Its mass function is
 * 
 * 

 * 

 * p(x) = 1/(j - i + 1)         for x = i, i + 1,…, j
 * 

 * and 0 elsewhere.
 * 
 */
public class UniformIntGen extends RandomVariateGenInt  {
   protected int left;     // the left limit of the interval
   protected int right;    // the right limit of the interval
    



   /**
    * Creates a uniform random variate generator over the integers
    *   in the closed interval [i, j], using stream s.
    * 
    */
   public UniformIntGen (RandomStream s, int i, int j)  {
      super (s, new UniformIntDist (i, j));
      setParams (i, j);
   }


   /**
    * Creates a new generator for the distribution dist, using 
    *     stream s.
    * 
    */
   public UniformIntGen (RandomStream s, UniformIntDist dist)  {
      super (s, dist);
      if (dist != null)
         setParams (dist.getI(), dist.getJ());
   }


   /**
    * Generates a new uniform random variate over the interval
    *    [i, j], using stream s, by inversion.
    * 
    */
   public static int nextInt (RandomStream s, int i, int j)  {
      return UniformIntDist.inverseF (i, j, s.nextDouble());
   }


   /**
    * Returns the parameter i.
    * 
    */
   public int getI() {
      return left;
   }
 

   /**
    * Returns the parameter j.
    * 
    * 
    */
   public int getJ() {
      return right;
   }


   protected  void setParams (int i, int j) {
      if (j < i)
        throw new IllegalArgumentException ("j < i");
      left = i;
      right = j;
   }
}