Assert.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.test;
 
import java.util.ArrayList;
import java.util.List;
 
import ca.uqac.lif.synthia.GiveUpException;
import ca.uqac.lif.synthia.NoMoreElementException;
import ca.uqac.lif.synthia.Picker;
import ca.uqac.lif.synthia.Shrinkable;
import ca.uqac.lif.synthia.random.RandomFloat;
 
/**
 * @ingroup Examples
 * @author sylvain
 *
 * @param <T>
 */
public class Assert<T>
{
    protected static final int MAX_STARTS = 100;
 
    protected static final int MAX_CYCLES = 100;
 
    protected static final int MAX_TRIES = 10;
 
    protected Shrinkable<T> m_input;
 
    protected List<T> m_shrunk;
 
    protected Picker<Float> m_decision;
 
    public Assert(Shrinkable<T> input, Picker<Float> decision)
    {
        super();
        m_input = input;
        m_shrunk = new ArrayList<T>();
        m_decision = decision;
    }
 
    public Assert(Shrinkable<T> input)
    {
        this(input, RandomFloat.instance);
    }
 
    public List<T> getIterations()
    {
        return m_shrunk;
    }
 
    public T getInitial()
    {
        if (m_shrunk.isEmpty())
        {
            return null;
        }
        return m_shrunk.get(0);
    }
 
    public T getShrunk()
    {
        if (m_shrunk.isEmpty())
        {
            return null;
        }
        return m_shrunk.get(m_shrunk.size() - 1);
    }
 
    @SuppressWarnings("unchecked")
    public boolean check()
    {
        T best = null;
        for (int start_cnt = 0; start_cnt < MAX_STARTS; start_cnt++)
        {
            List<T> shrunk = new ArrayList<T>();
            T o = null;
            boolean found = false;
            try
            {
                for (int i = 0; i < MAX_TRIES; i++)
                {
                    o = m_input.pick();
                    if (!evaluate(o))
                    {
                        found = true;
                        break;
                    }
                }
                shrunk.add(o);
            }
            catch (GiveUpException e)
            {
                continue;
            }
            catch (NoMoreElementException e)
            {
                continue;
            }
            if (!found)
            {
                continue;
            }
            Shrinkable<T> p = m_input.shrink(o, m_decision, 1);
            try
            {
                for (int i = 0; i < MAX_CYCLES; i++)
                {
                    boolean new_found = false;
                    for (float magnitude = 0.25f; !new_found && magnitude <= 1; magnitude += 0.25f)
                    {
                        p = p.shrink(o, m_decision, magnitude);
                        int j;
                        for (j = 0; j < MAX_TRIES; j++)
                        {
                            o = p.pick();
                            if (!evaluate(o))
                            {
                                shrunk.add(o);
                                new_found = true;
                                break;
                            }
                        }
                    }
                }
            }
            catch (NoMoreElementException e)
            {
                // Nothing to do
            }
            if (!(o instanceof Comparable))
            {
                // No point in trying to find "best" input
                m_shrunk = shrunk;
                break;
            }
            if (!shrunk.isEmpty())
            {
                Comparable<T> new_o = (Comparable<T>) shrunk.get(shrunk.size() - 1);
                if (best == null || new_o.compareTo(best) < 0)
                {
                    // Found a "smaller" input
                    m_shrunk = shrunk;
                    best = shrunk.get(shrunk.size() - 1);
                }               
            }
        }
        return m_shrunk.isEmpty();
    }
 
    protected boolean evaluate(T o)
    {
        return true;
    }
}