RandomInteger.java

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/*
    Synthia, a data structure generator
    Copyright (C) 2019-2020 Laboratoire d'informatique formelle
    Université du Québec à Chicoutimi, Canada
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published
    by the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package ca.uqac.lif.synthia.random;
 
import ca.uqac.lif.synthia.Picker;
import ca.uqac.lif.synthia.Reactive;
import ca.uqac.lif.synthia.Shrinkable;
import ca.uqac.lif.synthia.util.NothingPicker;
 
/**
 * Picks an integer uniformly in an interval.
 * 
 * @ingroup API
 */
public class RandomInteger extends RandomPicker<Integer> implements Shrinkable<Integer>, Reactive<Integer,Integer>
{
    /**
     * The lower bound of the interval
     */
    protected int m_min;
    
    /**
     * The higher bound of the interval
     */
    protected int m_max;
 
    /**
     * Default constructor
     */
    public RandomInteger()
    {
        super();
        setInterval(0,1);
    }
 
 
    /**
     * Creates a new instance of the picker.
     * @param min The lower bound of the interval
     * @param max The higher bound of the interval
     */
    public RandomInteger(int min, int max)
    {
        super();
        setInterval(min, max);
    }
 
    /**
     * Protected constructor used to duplicate the picker.
     * @param min The lower bound of the interval.
     * @param max The higher bound of the interval.
     * @param seed The initial seed of the random genarator.
     * @param random The random generator.
     */
    protected RandomInteger(int min, int max, int seed, Random random)
    {
        m_min = min;
        m_max = max;
        m_seed = seed;
        m_random = random;
    }
    
    /**
     * Sets the interval in which integers are picked
     * @param min The lower bound of the interval
     * @param max The higher bound of the interval
     */
    public RandomInteger setInterval(int min, int max)
    {
        m_min = min;
        m_max = max;
        return this;
    }
    
    /**
     * Sets the maximum bound for values of this picker.
     * @param max The higher bound of the interval
     */
    @Override
    public void tell(Integer max)
    {
        m_max = max;
    }
 
    @Override
    public RandomInteger setSeed(int seed)
    {
        super.setSeed(seed);
        return this;
    }
 
 
    /**
     * Picks a random integer. Typically, this method is expected to return non-null
     * objects; a <tt>null</tt> return value is used to signal that no more
     * objects will be produced. That is, once this method returns
     * <tt>null</tt>, it should normally return <tt>null</tt> on all subsequent
     * calls.
     * @return The random integer
     */
    @Override
    public Integer pick() 
    {
        return m_random.nextInt(m_max - m_min) + m_min;
    }
 
 
    /**
     * Creates a copy of the RandomInteger picker.
     * @param with_state If set to <tt>false</tt>, the returned copy is set to
     * the class' initial state (i.e. same thing as calling the picker's
     * constructor). If set to <tt>true</tt>, the returned copy is put into the
     * same internal state as the object it is copied from.
     * @return The copy of the RandomInteger picker
     */
    @Override
    public RandomInteger duplicate(boolean with_state)
    {
        RandomInteger copy = new RandomInteger(m_min, m_max, m_seed, m_random.Duplicate());
        if (!with_state)
        {
            copy.reset();
        }
        return copy;
    }
    
    @Override
    public Shrinkable<Integer> shrink(Integer element, Picker<Float> decision, float magnitude)
    {
        if(element <= m_min)
        {
            return new NothingPicker<Integer>();
        }
        else
        {
            
            int new_bound = (int) (element * magnitude);
            if (new_bound <= m_min)
            {
                new_bound = m_min + 1;              
            }
            return new RandomInteger(m_min, new_bound, m_seed, m_random.Duplicate());
        }
    }
    
    @Override
    public String toString()
    {
        return "RandomInteger [" + m_min + "," + m_max + "]";
    }
 
 
    @Override
    public Shrinkable<Integer> shrink(Integer o)
    {
        return shrink(o, RandomFloat.instance, 1);
    }
}