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JSR 354 provides an API for representing, transporting, and performing comprehensive calculations with Money and Currency. This module provides a forward compatible backport of the API.

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/*
 * CREDIT SUISSE IS WILLING TO LICENSE THIS SPECIFICATION TO YOU ONLY UPON THE CONDITION THAT YOU
 * ACCEPT ALL OF THE TERMS CONTAINED IN THIS AGREEMENT. PLEASE READ THE TERMS AND CONDITIONS OF THIS
 * AGREEMENT CAREFULLY. BY DOWNLOADING THIS SPECIFICATION, YOU ACCEPT THE TERMS AND CONDITIONS OF
 * THE AGREEMENT. IF YOU ARE NOT WILLING TO BE BOUND BY IT, SELECT THE "DECLINE" BUTTON AT THE
 * BOTTOM OF THIS PAGE. Specification: JSR-354 Money and Currency API ("Specification") Copyright
 * (c) 2012-2013, Credit Suisse All rights reserved.
 */
package javax.money.spi;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.ServiceLoader;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * This class implements the (default) {@link ServiceProvider} interface and hereby uses the JDK
 * {@link java.util.ServiceLoader} to load the services required.
 *
 * @author Anatole Tresch
 */
class DefaultServiceProvider implements ServiceProvider {
    /** List of services loaded, per class. */
    private final ConcurrentHashMap> servicesLoaded = new ConcurrentHashMap>();

    @Override
    public int getPriority() {
        return 0;
    }

    /**
     * Loads and registers services.
     *
     * @param serviceType
     *            The service type.
     * @param 
     *            the concrete type.
     * @return the items found, never {@code null}.
     */
    @Override
    public  List getServices(final Class serviceType) {
        @SuppressWarnings("unchecked")
        List found = (List) servicesLoaded.get(serviceType);
        if (found != null) {
            return found;
        }

        return loadServices(serviceType);
    }

    @Override
    public  T getService(Class serviceType) {
        List servicesFound = getServices(serviceType);
        if(servicesFound.isEmpty()){
            return null;
        }
        return servicesFound.get(0);
    }

    /**
     * Loads and registers services.
     *
     * @param   serviceType  The service type.
     * @param             the concrete type.
     *
     * @return  the items found, never {@code null}.
     */
    private  List loadServices(final Class serviceType) {
        List services = new ArrayList();
        try {
            for (T t : ServiceLoader.load(serviceType)) {
                services.add(t);
            }
            @SuppressWarnings("unchecked")
            final List previousServices = (List) servicesLoaded.putIfAbsent(serviceType, (List