org.meeuw.i18n.regions.RegionService Maven / Gradle / Ivy
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Provides the service loader for Regions, and some utilities to deal with regions generally
package org.meeuw.i18n.regions;
import java.util.*;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import javax.annotation.Priority;
import org.checkerframework.checker.nullness.qual.NonNull;
import org.meeuw.i18n.regions.spi.RegionProvider;
/**
* The singleton service providing information about the registered regions.
* @author Michiel Meeuwissen
* @since 0.1
*/
public class RegionService {
private static final Logger logger = Logger.getLogger(RegionService.class.getName());
private static final RegionService INSTANCE = new RegionService();
private boolean inited = false;
private List> providers;
private RegionService() {
}
/**
* The singleton of this class.
*/
public static RegionService getInstance() {
INSTANCE.initIfNeeded();
return INSTANCE;
}
/**
* Searches all available {@link RegionProvider}s for a region with given code and class.
* @param code The (ISO) code
* @param lenient Whether matching should be lenient or strict. Lenient matching may e.g. be case insensitive or matching on former codes
* @param clazz The subclass or sub interface of {@link Region} which is searched
* @param checker An extra predicate to which the region must match
* @param The type of the requested Region type
*
* @return an optional of region. Empty if not found.
*/
@SuppressWarnings("unchecked")
public Optional getByCode(@NonNull String code, boolean lenient, @NonNull Class clazz, @NonNull Predicate checker) {
for (RegionProvider provider : getProviders()) {
if (provider.canProvide(clazz)) {
try {
Optional byCode = provider.getByCode(code, lenient);
if (byCode.isPresent()) {
if (clazz.isInstance(byCode.get()) && checker.test(byCode.get())) {
return (Optional) byCode;
}
}
} catch (Exception e) {
logger.warning(() -> "Exception from " + provider + " for code " + code);
}
}
}
return Optional.empty();
}
/**
* A defaulting version of {@link #getByCode(String, boolean, Class, Predicate)}. The predicate is implicitly always true.
*/
public Optional getByCode(@NonNull String code, boolean lenient, @NonNull Class clazz) {
return getByCode(code, lenient, clazz, (c) -> true);
}
/**
* A defaulting version of {@link #getByCode(String, boolean, Class, Predicate)}. No predicate, lenient matching.
*/
public Optional getByCode(@NonNull String code, @NonNull Class clazz) {
return getByCode(code, true, clazz);
}
/**
*
*/
public Optional getByCode(@NonNull String s, boolean lenient) {
return getByCode(s, lenient, Region.class);
}
/**
* Searches all available {@link RegionProvider}s for a region with given code and class. This is a defaulting
* version of {@link #getByCode(String, Class)}, where the second argument is {@link Region}, and hence it will search Regions of all types.
* @return an optional of region. Empty if not found.
*/
public Optional getByCode(String s) {
return getByCode(s, true);
}
/**
* Returns a stream of all known instances of Region. Filtered by class.
*
* You could also use {@link #values()} and then simply {@link Stream#filter(Predicate)}, but the advantage of this method is that {@link RegionProvider}'s which say they cannot {@link RegionProvider#canProvide(Class)} the given class are not even consulted.
*
* @param clazz The class (a subclass or interface of {@link Region}
* @param
*/
public Stream values(Class clazz) {
Spliterator spliterator = new Spliterator() {
private final Iterator> iterator = getProviders().iterator();
private Spliterator values;
@Override
public boolean tryAdvance(Consumer action) {
while (values == null || !values.tryAdvance(action)) {
if (iterator.hasNext()) {
RegionProvider rp = iterator.next();
if (rp.canProvide(clazz)) {
values = (Spliterator) rp.values().spliterator();
}
} else {
return false;
}
}
return true;
}
@Override
public Spliterator trySplit() {
return null;
}
@Override
public long estimateSize() {
return Long.MAX_VALUE;
}
@Override
public int characteristics() {
return IMMUTABLE;
}
};
return StreamSupport.stream(spliterator, false).filter(clazz::isInstance);
}
/**
* @return A stream of all known {@link Region} instances of one of the given {@link Region.Type}.
*/
public Stream values(Region.Type... types) {
Set set = new HashSet<>(Arrays.asList(types));
return values().filter(r -> set.contains(r.getType()));
}
/**
* @return A stream of all known {@link Region} instances.
*/
public Stream values() {
return values(Region.class);
}
/**
* @return The providers currently registered
*/
public List> getProviders() {
return Collections.unmodifiableList(providers);
}
/**
*/
public > Optional getProvider(Class clazz) {
return (Optional) providers.stream().filter(clazz::isInstance).findFirst();
}
private void initIfNeeded() {
if (! inited) {
boolean init = false;
synchronized(this) {
if (! inited) {
final ServiceLoader loader = ServiceLoader.load(RegionProvider.class);
List> list = new ArrayList<>();
loader.iterator().forEachRemaining(list::add);
list.sort(priorityComparator());
providers = Collections.unmodifiableList(list);
inited = true;
init = true;
}
}
if (init) {
// run in separate thread to avoid dead locks
new Thread(() ->
logger.log(Level.FINE, "RegionService has {0}", providers)
).start();
}
}
}
private static Comparator priorityComparator() {
return (o1, o2) -> {
try {
final Priority p1 = o1 == null ? null : o1.getClass().getAnnotation(Priority.class);
final int v1 = p1 != null ? p1.value() : 100;
final Priority p2 = o2 == null ? null : o2.getClass().getAnnotation(Priority.class);
final int v2 = p2 != null ? p2.value() : 100;
return v1 - v2;
} catch (NoClassDefFoundError ncdfe) {
logger.log(Level.INFO, "{0}:{1} region services {2} {3} are unordered", new Object[]{ncdfe.getClass(), ncdfe.getMessage(), o1, o2});
String sn1 = o1 == null ? null : o1.getClass().getSimpleName();
String sn2 = o2 == null ? null : o2.getClass().getSimpleName();
return Objects.compare(sn1, sn2, Comparator.naturalOrder());
}
};
}
}
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