package once

// Singleton contains a pointer to T that must be set once.
// Until the value is set all Get() calls will block.
type Singleton[T any] struct {
	v   *T
	set chan struct{}
}

// NewSingleton creates a new unset singleton.
func NewSingleton[T any]() *Singleton[T] {
	return &Singleton[T]{set: make(chan struct{}), v: nil}
}

// Get will return the singleton value.
func (s *Singleton[T]) Get() *T {
	<-s.set
	return s.v

/**
 * Denotes that a bean should be created as a singleton instance.
 * <p>
 * Singleton-scoped beans are instantiated once and reused throughout the entire
 * Maven execution. This scope should be used for stateless services or components
 * that can be safely shared across the entire build process.
 * <p>
 * Example usage:
 * <pre>
 * {@literal @}Singleton
 * public class GlobalConfiguration {
 *     // Implementation

import jcifs.config.PropertyConfiguration;

/**
 * Global singleton context
 *
 * @author mbechler
 *
 */
public class SingletonContext extends BaseContext implements CIFSContext {

    private static final Logger log = LoggerFactory.getLogger(SingletonContext.class);
    private static SingletonContext INSTANCE;

    /**
     * Initialize singleton context using custom properties
     *

	<component name="fessFileTransformer" class="org.codelibs.fess.crawler.transformer.FessFileTransformer" instance="singleton">
		<property name="name">"fessFileTransformer"</property>
	</component>

	<component name="fessStandardTransformer" class="org.codelibs.fess.crawler.transformer.FessStandardTransformer" instance="singleton">
		<property name="name">"fessStandardTransformer"</property>
	</component>

		<property name="name">"htmlTransformer"</property>
		<property name="featureMap">defaultFeatureMap</property>
		<property name="propertyMap">defaultPropertyMap</property>
		<property name="childUrlRuleMap">htmlUrlRuleMap</property>
	</component>

	<component name="textTransformer"
		class="org.codelibs.fess.crawler.transformer.impl.TextTransformer" instance="singleton">

                DependencyScope.COMPILE_ONLY.isTransitive(),
                singleton(CommonBuilds.PROJECT_PATH_MAIN, CommonBuilds.BUILD_PATH_COMPILE)));
        result.add(internalScopeManager.createDependencyScope(
                DependencyScope.TEST_RUNTIME.id(),
                DependencyScope.TEST_RUNTIME.isTransitive(),
                singleton(CommonBuilds.PROJECT_PATH_TEST, CommonBuilds.BUILD_PATH_RUNTIME)));

        .addEqualityGroup(
            singleton(1),
            union(singleton(1), singleton(1)),
            intersection(newHashSet(1, 2), newHashSet(1, 3)),
            difference(newHashSet(1, 2), newHashSet(2, 3)),
            symmetricDifference(newHashSet(1, 2, 3), newHashSet(2, 3)))
        .addEqualityGroup(
            singleton(2),
            union(singleton(2), singleton(2)),

import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static com.google.common.collect.testing.google.MultisetFeature.ENTRIES_ARE_VIEWS;
import static java.util.Collections.singleton;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.Multiset;
import com.google.common.collect.Multisets;
import com.google.common.collect.testing.features.CollectionFeature;

import javax.inject.Provider;
import javax.inject.Singleton;

import org.eclipse.aether.util.version.GenericVersionScheme;
import org.eclipse.aether.version.VersionScheme;

/**
 * Default version scheme provider: provides singleton {@link GenericVersionScheme} instance.
 *
 * @deprecated since 4.0.0, use {@code maven-api-impl} jar instead
 */
@Singleton
@Named
@Deprecated(since = "4.0.0")

    assertEquals(singleton("bar"), set);
    set.clear();
    assertTrue(set.isEmpty());
    assertEquals(singleton("foo"), sortedTable.rowKeySet());
  }

  public void testRowKeySetTailSet() {
    sortedTable = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    Set<String> set = sortedTable.rowKeySet().tailSet("cat");
    assertEquals(singleton("foo"), set);
    set.clear();