/*
 * Copyright (c) 2007, DoodleProject
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 * the documentation and/or other materials provided with the
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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 */

package jhplot.math.num.random;


/**
 * Base continuous random variable that provides a
 * {@link RNG) instance as a source for uniform random numbers.
 * 
 * @since 1.3
 * @version $Revision: 1.3 $ $Date: 2007/11/18 23:51:19 $
 */
public abstract class AbstractDiscreteRandomVariable implements
    DiscreteRandomVariable {

    /** the source random number generator. */
    private RNG source;

    /**
     * Create a random variable with the given source generator.
     * 
     * @param rng the source generator.
     */
    protected AbstractDiscreteRandomVariable(RNG rng) {
        super();
        setSource(rng);
    }

    /**
     * Access the source generator.
     * 
     * @return the source generator.
     */
    protected RNG getSource() {
        return source;
    }

    /**
     * Access the next random number from the source generator.
     * 
     * @return the next random number.
     */
    protected double nextRandomNumber() {
        return getSource().nextRandomNumber();
    }

    /**
     * Modify the source generator.
     * 
     * @param delegate the new source generator.
     */
    private void setSource(RNG delegate) {
        if (delegate == null) {
            throw new IllegalArgumentException("source can not be null.");
        }
        this.source = delegate;
    }
}