RandomSubString.java

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package ca.uqac.lif.synthia.string;
 
import ca.uqac.lif.synthia.Picker;
import ca.uqac.lif.synthia.Seedable;
import ca.uqac.lif.synthia.Shrinkable;
import ca.uqac.lif.synthia.random.RandomBoolean;
import ca.uqac.lif.synthia.random.RandomFloat;
import ca.uqac.lif.synthia.random.RandomPicker;
import ca.uqac.lif.synthia.util.NothingPicker;
 
/**
 * {@link RandomPicker} that produces random substrings from an original one.
 * @author Marc-Antoine Plourde
 * @ingroup API
 */
public class RandomSubString implements Shrinkable<String>, Seedable
{
 
    /**
     * The string used to generate substrings.
     */
    protected String m_string;
 
    /**
     * A {@link RandomBoolean} picker to select if we pick a character or not.
     */
    protected RandomBoolean m_charSelect;
 
    /**
     * Private constructor used by the {@link #duplicate(boolean)} method.
     *
     * @param s The {@link #m_string} attribute.
     * @param char_select The {@link #m_charSelect} attribute.
     */
    private RandomSubString(String s, RandomBoolean char_select)
    {
        m_string = s;
        m_charSelect = char_select;
    }
 
    /**
     * Public constructor used to create a new instance of the class.
     *
     * @param s The string used to generate substrings.
     */
    public RandomSubString(String s)
    {
        m_string = s;
        m_charSelect = new RandomBoolean();
    }
 
    /**
     * Create a new {@link RandomSubString} picker based on a given string. If this given string is
     * empty, the method will return a {@link NothingPicker}. The new instance will also have the same
     * internal states for the {@link #m_charSelect} attributes as the original one.
     *
     * @param element The string used by the new {@link RandomSubString} picker to produce substrings.
     *
     * @return The new instance of the class or a {@link NothingPicker}.
     */
    @Override
    public Shrinkable<String> shrink(String element, Picker<Float> decision, float magnitude)
    {
        if (element.isEmpty())
        {
            return new NothingPicker<String>();
        }
        else
        {
            return new RandomSubString(element, m_charSelect.duplicate(true));
        }
    }
 
    @Override
    public void reset()
    {
        m_charSelect.reset();
    }
 
    @Override
    public String pick()
    {
        boolean initial_bool = m_charSelect.pick();
        boolean picked_bool = initial_bool;
        StringBuilder substring = new StringBuilder();
        int i =0;
        while ((initial_bool == picked_bool) && (i < m_string.length()))
        {
            if(initial_bool)
            {
                substring.append(m_string.charAt(i));
            }
            picked_bool = m_charSelect.pick();
            i++;
        }
 
        if(!initial_bool)
        {
            while ((picked_bool) && (i < m_string.length()))
            {
                substring.append(m_string.charAt(i));
                picked_bool = m_charSelect.pick();
                i++;
            }
        }
 
        return substring.toString();
    }
 
    @Override
    public Picker<String> duplicate(boolean with_state)
    {
        return new RandomSubString(m_string, m_charSelect.duplicate(with_state));
    }
 
    @Override
    public RandomSubString setSeed(int seed)
    {
        m_charSelect.setSeed(seed);
        return this;
    }
 
    @Override
    public Shrinkable<String> shrink(String o)
    {
        return shrink(o, RandomFloat.instance, 1);
    }
}