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package org.apidesign.codeinjection;

import java.util.Iterator;

import java.util.ServiceLoader;

import org.apidesign.codeinjection.spi.CountDownExtender;

/** Second version to {@link CountDownImplV1} - imagine someone wants to

 * reimplement {@link #down()} method to decrement by two not just by one.

 * You do not like that idea at all, but you do not want to prevent such

 * behaviour. You just do not want to maintain such bloody code. What can

 * you do? You need to allow <b>code injection</b> via the

 * {@link CountDownExtender} class!

 *

 * @author Jaroslav Tulach <jtulach@netbeans.org>

 */

final class CountDownImplV2 extends CountDown {

    private int cnt;

    CountDownImplV2(int initial) {

        this.cnt = initial;

    }

// BEGIN: codeinjection.v2

    public void down() {

        Iterator<CountDownExtender> it;

        it = ServiceLoader.load(CountDownExtender.class).iterator();

        if (it.hasNext()) {

            // injected behaviour

            cnt = it.next().decrement(cnt);

        } else {

            // common behaviour of 1.0 version

            cnt--;

        }

    }

    public boolean isDown() {

        return cnt <= 0;

    }

// END: codeinjection.v2

}