ComposeList.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.petitpoucet.AndNode;
import ca.uqac.lif.petitpoucet.NodeFactory;
import ca.uqac.lif.petitpoucet.Part;
import ca.uqac.lif.petitpoucet.PartNode;
import ca.uqac.lif.petitpoucet.function.ExplanationQueryable;
import ca.uqac.lif.petitpoucet.function.vector.NthElement;
import ca.uqac.lif.synthia.CannotShrinkException;
import ca.uqac.lif.synthia.Picker;
import ca.uqac.lif.synthia.Shrinkable;
import ca.uqac.lif.synthia.explanation.NthSuccessiveOutput;
import ca.uqac.lif.synthia.random.RandomFloat;
import ca.uqac.lif.synthia.util.Constant;
 
/**
 * 
 * @author Sylvain Hallé
 *
 * @param <T>
 * @ingroup API
 */
public class ComposeList<T> implements Picker<List<T>>, Shrinkable<List<T>>, ExplanationQueryable
{
    /**
     * The picker providing elements for the list.
     */
    /*@ non_null @*/ protected Picker<T> m_elements;
 
    /**
     * The picker deciding on the length of the list.
     */
    /*@ non_null @*/ protected Picker<Integer> m_length;
 
    /**
     * A list keeping track of the length of each list produced by the picker.
     * This list is used to answer calls to
     * {@link #getExplanation(Part, NodeFactory) getExplanation()}.
     */
    /*@ non_null @*/ protected List<Integer> m_lengths;
 
    /**
     * Creates a new instance of the picker.
     * @param elements The picker providing elements for the list
     * @param length The picker deciding on the length of the list
     */
    public ComposeList(Picker<T> elements, Picker<Integer> length)
    {
        super();
        m_elements = elements;
        m_length = length;
        m_lengths = new ArrayList<Integer>();
    }
    
    /**
     * Creates a new instance of the picker.
     * @param elements The picker providing elements for the list
     * @param length The fixed length of each list
     */
    public ComposeList(Picker<T> elements, int length)
    {
        this(elements, new Constant<Integer>(length));
    }
 
    @Override
    public void reset()
    {
        m_length.reset();
        m_elements.reset();
    }
 
    @Override
    public List<T> pick()
    {
        int len = m_length.pick();
        m_lengths.add(len);
        List<T> list = new ComparableList<T>();
        for (int i = 0; i < len; i++)
        {
            list.add(m_elements.pick());
        }
        return list;
    }
 
    @Override
    public ComposeList<T> duplicate(boolean with_state)
    {
        ComposeList<T> cl = new ComposeList<T>(m_elements.duplicate(with_state), m_length.duplicate(with_state));
        if (with_state)
        {
            cl.m_lengths.addAll(m_lengths);
        }
        return cl;
    }
 
    @Override
    public PartNode getExplanation(Part p)
    {
        return getExplanation(p, NodeFactory.getFactory());
    }
    
    @Override
    public String toString()
    {
        return "ComposeList";
    }
 
    @Override
    public PartNode getExplanation(Part p, NodeFactory f)
    {
        PartNode root = f.getPartNode(p, this);
        AndNode and = f.getAndNode();
        root.addChild(and);
        int index = NthSuccessiveOutput.mentionedOutput(p), part_index = NthElement.mentionedElement(p);
        if (index < 0 || index >= m_lengths.size())
        {
            return null; // Invalid part
        }
        int offset = 0;
        for (int i = 0; i < index; i++)
        {
            offset += m_lengths.size();
        }
        if (part_index < 0)
        {
            // p points at the whole list
            for (int i = 0; i < m_lengths.get(index); i++)
            {
                Part new_p = NthSuccessiveOutput.replaceOutIndexBy(p, offset + i);
                and.addChild(f.getPartNode(new_p, m_elements));
            }
            return root;
        }
        // p points at an element of the list
        if (part_index >= m_lengths.get(index))
        {
            // Nonexistent element
            return root;
        }
        Part new_p = NthSuccessiveOutput.removeNthElement(p);
        new_p = NthSuccessiveOutput.replaceOutIndexBy(new_p, offset + part_index);
        and.addChild(f.getPartNode(new_p, m_elements));
        return root;
    }
 
    @Override
    public Shrinkable<List<T>> shrink(List<T> o, Picker<Float> decision, float magnitude)
    {
        if (!(m_elements instanceof Shrinkable) || !(m_length instanceof Shrinkable))
        {
            throw new CannotShrinkException("Inner pickers are not shrinkable");
        }
        return new ComposeShrunkList<T>((Shrinkable<T>) m_elements, (Shrinkable<Integer>) m_length, o, decision, 1);
    }
 
    @Override
    public Shrinkable<List<T>> shrink(List<T> o)
    {
        return shrink(o, RandomFloat.instance, 1);
    }
}