RandomPrefix.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.RandomFloat;
import ca.uqac.lif.synthia.random.RandomInteger;
import ca.uqac.lif.synthia.util.NothingPicker;
 
/**
 * Like {@link RandomSubString}, but this time, the {@link Picker} returns a prefix of the original
 * strings of randomly selected length. The {@link RandomSubString#m_charSelect} is replaced by a
 * {@link RandomInteger}.
 * 
 * @ingroup API
 */
public class RandomPrefix implements Shrinkable<String>, Seedable
{
 
    /**
     * {@link RandomInteger} picker to select the size of a generated prefix.
     */
    protected RandomInteger m_prefixSize;
 
    /**
     * The string used to generate prefixes.
     */
    protected String m_string;
 
    /**
     * Private constructor used by the {@link #duplicate(boolean)} method.
     *
     * @param string The {@link #m_string} attributes.
     * @param prefix_size The {@link #m_prefixSize} attributes.
     */
    protected RandomPrefix(String string, RandomInteger prefix_size)
    {
        m_string = string;
        m_prefixSize = prefix_size;
    }
 
    /**
     * Public constructor to create a new instance of this {@link Picker}.
     *
     * @param string The string used to generate prefixes.
     */
    public RandomPrefix(String string)
    {
        m_string = string;
        m_prefixSize = new RandomInteger(0, m_string.length()+1);
    }
 
    /**
     * Create a new {@link RandomPrefix} 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_prefixSize} attributes as the original one.
     *
     * @param element The string used by the new {@link RandomPrefix} 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<>();
        }
        return new RandomPrefix(element, m_prefixSize.duplicate(true));
    }
 
    @Override
    public void reset()
    {
        m_prefixSize.reset();
    }
 
    @Override
    public String pick()
    {
        return m_string.substring(0, m_prefixSize.pick());
    }
 
    @Override
    public RandomPrefix duplicate(boolean with_state)
    {
        return new RandomPrefix(m_string, m_prefixSize.duplicate(with_state));
    }
 
    @Override
    public RandomPrefix setSeed(int seed)
    {
        m_prefixSize.setSeed(seed);
        return this;
    }
 
    @Override
    public Shrinkable<String> shrink(String o)
    {
        return shrink(o, RandomFloat.instance, 1);
    }
}