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package org.glassfish.jersey.internal.util.collection;
/**
* A collection of {@link Ref reference} factory & utility methods.
*
* @author Marek Potociar (marek.potociar at oracle.com)
*/
public final class Refs {
private Refs() {
// preventing instantiation
}
/**
* Immutable {@link Ref} implementation.
*/
private static final class ImmutableRefImpl<T> implements Ref<T> {
private final T reference;
ImmutableRefImpl(final T value) {
this.reference = value;
}
@Override
public T get() {
return reference;
}
@Override
public void set(final T value) throws IllegalStateException {
throw new IllegalStateException("This implementation of Ref interface is immutable.");
}
@Override
public String toString() {
return "ImmutableRefImpl{"
+ "reference=" + reference
+ '}';
}
@Override
public boolean equals(final Object obj) {
if (obj == null) {
return false;
}
if (!(obj instanceof Ref)) {
return false;
}
Object otherRef = ((Ref) obj).get();
return this.reference == otherRef || (this.reference != null && this.reference.equals(otherRef));
}
@Override
public int hashCode() {
int hash = 5;
hash = 47 * hash + (this.reference != null ? this.reference.hashCode() : 0);
return hash;
}
}
/**
* Default (mutable) {@link Ref} implementation. This implementation is not thread-safe.
*/
private static final class DefaultRefImpl<T> implements Ref<T> {
private T reference;
DefaultRefImpl() {
this.reference = null;
}
DefaultRefImpl(final T value) {
this.reference = value;
}
@Override
public T get() {
return reference;
}
@Override
public void set(final T value) throws IllegalStateException {
this.reference = value;
}
@Override
public String toString() {
return "DefaultRefImpl{"
+ "reference=" + reference
+ '}';
}
@Override
public boolean equals(final Object obj) {
if (obj == null) {
return false;
}
if (!(obj instanceof Ref)) {
return false;
}
Object otherRef = ((Ref) obj).get();
T ref = this.reference;
return ref == otherRef || (ref != null && ref.equals(otherRef));
}
@Override
public int hashCode() {
int hash = 5;
hash = 47 * hash + (this.reference != null ? this.reference.hashCode() : 0);
return hash;
}
}
/**
* Thread-safe {@link Ref} implementation.
*/
private static final class ThreadSafeRefImpl<T> implements Ref<T> {
private volatile T reference;
ThreadSafeRefImpl() {
this.reference = null;
}
ThreadSafeRefImpl(final T value) {
this.reference = value;
}
@Override
public T get() {
return reference;
}
@Override
public void set(final T value) throws IllegalStateException {
this.reference = value;
}
@Override
public String toString() {
return "ThreadSafeRefImpl{"
+ "reference=" + reference
+ '}';
}
@Override
public boolean equals(final Object obj) {
if (obj == null) {
return false;
}
if (!(obj instanceof Ref)) {
return false;
}
Object otherRef = ((Ref) obj).get();
T localRef = this.reference;
return localRef == otherRef || (localRef != null && localRef.equals(otherRef));
}
@Override
public int hashCode() {
T localRef = this.reference;
int hash = 5;
hash = 47 * hash + (localRef != null ? localRef.hashCode() : 0);
return hash;
}
}
/**
* Construct a new mutable {@link Ref} instance referencing the given
* input value.
*
* @param <T> type of the referenced instance.
* @param value value of the newly constructed reference.
* @return a new mutable {@link Ref} instance referencing the given
* input value.
*/
public static <T> Ref<T> of(final T value) {
return new DefaultRefImpl<T>(value);
}
/**
* Construct a new empty mutable {@link Ref} instance.
*
* @param <T> type of the referenced instance.
* @return a new mutable empty {@link Ref} instance.
*/
public static <T> Ref<T> emptyRef() {
return new DefaultRefImpl<T>();
}
/**
* Construct a new empty mutable thread-safe {@link Ref} instance.
*
* @param <T> type of the referenced instance.
* @return a new mutable empty thread-safe {@link Ref} instance.
* @since 2.8
*/
public static <T> Ref<T> threadSafe() {
return new ThreadSafeRefImpl<T>();
}
/**
* Construct a new mutable thread-safe {@link Ref} instance referencing the given
* input value.
*
* @param <T> type of the referenced instance.
* @param value value of the newly constructed reference.
* @return a new mutable thread-safe {@link Ref} instance referencing the given
* input value.
* @since 2.8
*/
public static <T> Ref<T> threadSafe(final T value) {
return new ThreadSafeRefImpl<T>(value);
}
/**
* Construct a new immutable {@link Ref} instance referencing the given
* input value.
* <p/>
* Invoking a {@link Ref#set(java.lang.Object)} on the returned instance
* will result in a {@link IllegalStateException} being thrown.
*
* @param <T> type of the referenced instance.
* @param value value of the newly constructed reference.
* @return a new immutable {@link Ref} instance referencing the given
* input value.
*/
public static <T> Ref<T> immutableRef(final T value) {
return new ImmutableRefImpl<T>(value);
}
}