package com.googlecode.objectify;
import java.io.Serializable;
import com.googlecode.objectify.Key;
import com.googlecode.objectify.NotFoundException;;
/**
* <p>GWT emulation of the Ref<?> class. Not complete; there's a lot we can't do client-side.</p>
*
* @author Jeff Schnitzer <jeff@infohazard.org>
*/
public class Ref<T> implements Serializable, Comparable<Ref<T>>
{
private static final long serialVersionUID = 1L;
Key<T> key;
T value;
/** */
public static <T> Ref<T> create(Key<T> key) {
if (key == null)
throw new NullPointerException("Cannot create a Ref from a null key");
return new Ref<T>(key);
}
/** */
public static <T> Ref<T> create(Key<T> key, T value) {
return new Ref<T>(key, value);
}
/** Doesn't set the key! Dangerous. */
public static <T> Ref<T> create(T value) {
return new Ref<T>(value);
}
/** */
public Ref(Key<T> key) {
this.key = key;
}
/** */
public Ref(T value) {
this.value = value;
}
/** */
public Ref(Key<T> key, T value) {
this.key = key;
this.value = value;
}
/**
*/
public Key<T> key() {
if (key == null)
throw new IllegalStateException("This ref was created without a key, and we cannot determine keys on the GWT client-side");
return key;
}
/**
*/
public T get() {
return value;
}
/**
*/
public T getValue() {
return value;
}
/**
*/
final public Key<T> getKey() {
return key();
}
/**
*/
final public Key<T> safeKey() {
Key<T> k = this.key();
if (k == null)
throw new NotFoundException();
else
return k;
}
/**
*/
final public T safeGet() {
T t = this.get();
if (t == null)
throw new NotFoundException(key());
else
return t;
}
/** Comparison is based on key */
@Override
public int compareTo(Ref<T> o) {
return this.key().compareTo(o.key());
}
/** Equality comparison is based on key equivalence */
@Override
public boolean equals(Object obj) {
return obj != null && obj instanceof Ref && key().equals(((Ref<?>)obj).key());
}
/** Type-safe comparison for key equivalence */
public boolean equivalent(Ref<T> other) {
return equals(other);
}
/** Type safe comparison for key equivalence */
public boolean equivalent(Key<T> other) {
return key().equivalent(other);
}
/** Hash code is simply that of key */
@Override
public int hashCode() {
return key().hashCode();
}
/** Renders some info about the key */
@Override
public String toString() {
return this.getClass().getSimpleName() + "(" + key() + ")";
}
}