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

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;

import static java.lang.annotation.RetentionPolicy.RUNTIME;

@Scope
@Documented
@Retention(RUNTIME)

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
     * 

                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)));

	<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>

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")

 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.project;

import javax.inject.Named;
import javax.inject.Singleton;

import java.io.FileNotFoundException;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

        Set<Artifact> artifactDependencies =
            resolver.resolve( project, Collections.singleton( Artifact.SCOPE_COMPILE ), session );
        assertEquals( 0, artifactDependencies.size() );

        artifactDependencies = resolver.resolve( project, Collections.singleton( Artifact.SCOPE_RUNTIME ), session );
        assertEquals( 1, artifactDependencies.size() );

 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven;

import javax.inject.Inject;
import javax.inject.Named;
import javax.inject.Singleton;

import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Set;

 */
package org.apache.maven.project;

import javax.inject.Inject;
import javax.inject.Named;
import javax.inject.Singleton;

import org.apache.maven.artifact.metadata.ArtifactMetadataSource;
import org.apache.maven.artifact.resolver.DefaultArtifactResolver;

@Named("classpath")
@Singleton
@Deprecated
public class TestArtifactResolver extends DefaultArtifactResolver {
    private ArtifactMetadataSource source;