Mutate.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.util;
 
import ca.uqac.lif.synthia.Picker;
 
/**
 * Transforms an object from a picker by selecting a mutator and applying it
 * to an object. Concretely, this picker is instantiated by
 * providing two things:
 * <ol>
 * <li>An arbitrary {@link Picker} producing the objects of type <tt>T</tt>
 * to transform</li>
 * <li>Another picker providing a {@link Mutator} for objects of type
 * <tt>T</tt></li>
 * </ol>
 * On each call to {@link Picker#pick() pick()}, an object and a mutator
 * are obtained, and the mutator is applied to the object. The resulting
 * "mutated" object is then returned.
 * <p>
 * As with any other picker, both sources are arbitrary. For example, one
 * could use a {@link Choice} picker to provide a randomly-selected mutation
 * from a set of choices to apply to each object.
 * 
 * @param <T> The type of the objects transformed by this picker
 * @ingroup API
 */
public class Mutate<T> extends Mutator<T>
{
    /**
     * Mutates input objects
     */
    /*@ non_null @*/ protected Picker<Mutator<T>> m_mutations;
 
    public Mutate(/*@ non_null @*/ Picker<? extends T> picker, /*@ non_null @*/ Picker<Mutator<T>> mutations)
    {
        super(picker);
        m_mutations = mutations;
    }
 
    @Override
    public T pick()
    {
        Mutator<T> mutator = m_mutations.pick();
        mutator.setPicker(m_picker);
        return mutator.pick();
    }
 
    @Override
    public Picker<T> duplicate(boolean with_state)
    {
        return new Mutate<T>(m_picker.duplicate(with_state), m_mutations.duplicate(with_state));
    }
}