internal.util.SdmxWebDriverLoader Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of sdmx-dl-api Show documentation

Easily download official statistics - API

There is a newer version: 3.0.0-beta.13

package internal.util;

import internal.sdmxdl.web.spi.FailsafeSdmxWebDriver;
import java.lang.Iterable;
import java.lang.Long;
import java.lang.Override;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.ServiceLoader;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.Consumer;
import java.util.stream.Collectors;
import java.util.stream.StreamSupport;
import sdmxdl.web.spi.SdmxWebDriver;

/**
 * Custom service loader for {@link sdmxdl.web.spi.SdmxWebDriver}.
 * 
This class is thread-safe.
 * Properties:
 * 

 * Quantifier: MULTIPLE
 * Fallback: null
 * Preprocessing: wrapper: internal.sdmxdl.web.spi.FailsafeSdmxWebDriver filters:[isAvailable] sorters:[getRank]
 * Mutability: NONE
 * Singleton: false
 * Name: internal.util.SdmxWebDriverLoader
 * Backend: null
 * Cleaner: null
 * 
 */
public final class SdmxWebDriverLoader {
  private final Iterable source = ServiceLoader.load(SdmxWebDriver.class);

  private final List resource = doLoad();

  private Spliterator spliterator() {
    return new Spliterators.AbstractSpliterator(Long.MAX_VALUE, 0) {
      final Iterator delegate = source.iterator();

      @Override
      public boolean tryAdvance(Consumer action) {
        if (delegate.hasNext()) {
          action.accept((SdmxWebDriver) delegate.next());
          return true;
        }
        return false;
      }
    };
  }

  private List doLoad() {
    return StreamSupport.stream(spliterator(), false)
        .map(FailsafeSdmxWebDriver::wrap)
        .map(SdmxWebDriver.class::cast)
        .filter(SdmxWebDriver::isAvailable)
        .sorted(Collections.reverseOrder(Comparator.comparingInt(SdmxWebDriver::getRank)))
        .collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
  }

  /**
   * Gets a list of {@link sdmxdl.web.spi.SdmxWebDriver} instances.
   * 
This method is thread-safe.
   * @return the current non-null value
   */
  public List get() {
    return resource;
  }

  /**
   * Gets a list of {@link sdmxdl.web.spi.SdmxWebDriver} instances.
   * 
This is equivalent to the following code: new SdmxWebDriverLoader().get()
   * 
Therefore, the returned value might be different at each call.
   * 
This method is thread-safe.
   * @return a non-null value
   */
  public static List load() {
    return new SdmxWebDriverLoader().get();
  }
}