MutateElement.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.collection;
 
import java.util.ArrayList;
import java.util.List;
 
import ca.uqac.lif.synthia.Picker;
import ca.uqac.lif.synthia.util.Constant;
import ca.uqac.lif.synthia.util.Mutator;
 
/**
 * Picker that selects an element of a list and applies the result of a mutator
 * on this element.
 *
 * @param <T> The type of the elements in the list
 * @ingroup API
 */
public class MutateElement<T> extends Mutator<List<T>>
{
    /**
     * A picker used to select the position of the first element.
     */
    protected Picker<Float> m_position;
    
    /**
     * A mutator picker to mutate elements of the list.
     */
    protected Picker<Mutator<? extends T>> m_mutator;
    
    /**
     * Creates a new instance of the picker.
     * @param picker The underlying picker producing the lists to transform
     * @param position A picker used to select the position of the first element
     * @param mutator A mutator picker to mutate elements of the list
     */
    public MutateElement(Picker<? extends List<T>> picker, Picker<Float> position, Picker<Mutator<? extends T>> mutator)
    {
        super(picker);
        m_position = position;
        m_mutator = mutator;
    }
 
    @SuppressWarnings("unchecked")
    @Override
    public List<T> pick()
    {
        List<T> list = m_picker.pick();
        int size = list.size();
        int position = (int) Math.floor(m_position.pick() * (double) size);
        T e = list.get(position);
        Mutator<T> m = (Mutator<T>) m_mutator.pick();
        m.setPicker(new Constant<T>(e));
        T e_m = m.pick();
        List<T> new_list = new ArrayList<T>(size);
        for (int i = 0; i < size; i++)
        {
            if (i == position)
            {
                new_list.add(e_m);
            }
            else
            {
                new_list.add(list.get(i));
            }
        }
        return new_list;
    }
    
    @Override
    public void reset()
    {
        m_position.reset();
        m_mutator.reset();
    }
 
    @Override
    public MutateElement<T> duplicate(boolean with_state)
    {
        return new MutateElement<T>(m_picker.duplicate(with_state), m_position.duplicate(with_state), m_mutator.duplicate(with_state));
    }
}