PickSmallerComparable.java

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/*
    Synthia, a data structure generator
    Copyright (C) 2019-2021 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.relative;
 
import ca.uqac.lif.synthia.Picker;
import ca.uqac.lif.synthia.PickerException;
import ca.uqac.lif.synthia.Shrinkable;
import ca.uqac.lif.synthia.random.RandomFloat;
 
/**
 * A variant of {@link PickIf} that selects an element if it is smaller than
 * a reference object. In order for the "smaller" condition to be evaluated,
 * the objects that are manipulated must implement the {@link Comparable}
 * interface.
 *   
 * @author Sylvain Hallé
 *
 * @param <T> The type of objects manipulated by this picker
 * @ingroup API
 */
public class PickSmallerComparable<T> extends PickIf<T> implements Shrinkable<T>
{
    /**
     * The reference object that candidate values are compared to.
     */
    protected Comparable<T> m_reference;
    
    /**
     * Creates a new instance of the picker.
     * @param source The source of objects
     * @param o The reference object that candidate values are compared to
     */
    @SuppressWarnings("unchecked")
    public PickSmallerComparable(Picker<? extends T> source, T o)
    {
        super(source);
        if (!(o instanceof Comparable))
        {
            throw new PickerException("Expected a comparable object");
        }
        m_reference = (Comparable<T>) o;
    }
 
    @SuppressWarnings("unchecked")
    @Override
    public PickSmallerComparable<T> duplicate(boolean with_state)
    {
        PickSmallerComparable<T> ps = new PickSmallerComparable<T>(m_picker.duplicate(with_state), (T) m_reference);
        super.copyInto(this, with_state);
        if (with_state)
        {
            ps.m_maxIteration = m_maxIteration;
        }
        return ps;
    }
 
    @Override
    public PickSmallerComparable<T> shrink(T o, Picker<Float> decision, float m)
    {
        PickSmallerComparable<T> ps = new PickSmallerComparable<T>(m_picker, (T) o);
        ps.m_maxIteration = m_maxIteration;
        return ps;
    }
 
    @Override
    protected boolean select(T element)
    {
        return m_reference.compareTo(element) > 0;
    }
 
    @Override
    public Shrinkable<T> shrink(T o)
    {
        return shrink(o, RandomFloat.instance, 1);
    }
}