Java 类com.google.inject.internal.CircularDependencyProxy 实例源码

@SuppressWarnings({"unchecked", "rawtypes" })
@Test
public void circularScopedValue() throws Exception {
  RequestScope requestScope = new RequestScope();
  Key<Object> key = Key.get(Object.class);
  try {
    new MockUnit(Provider.class, Map.class, CircularDependencyProxy.class)
        .expect(unit -> {
          Map scopedObjects = unit.get(Map.class);
          requestScope.enter(scopedObjects);
          expect(scopedObjects.get(key)).andReturn(null);
          expect(scopedObjects.containsKey(key)).andReturn(false);
        })
        .expect(unit -> {
          Provider provider = unit.get(Provider.class);
          expect(provider.get()).andReturn(unit.get(CircularDependencyProxy.class));
        })
        .run(unit -> {
          Object result = requestScope.<Object> scope(key, unit.get(Provider.class)).get();
          assertEquals(unit.get(CircularDependencyProxy.class), result);
        });
  } finally {
    requestScope.exit();
  }
}

@Override
public <T> Provider<T> scope(final Key<T> key, final Provider<T> unscoped) {
  return () -> {
    if (scope == null) {
      throw new OutOfScopeException("Not in scope");
    }

    Object value = scope.get(key);
    if (value == null) {
      T provided = unscoped.get();
      if (provided instanceof CircularDependencyProxy) {
        return provided;
      }
      value = (provided == null) ? NULL_SENTINEL : provided;
      scope.put(key, value);
    }

    @SuppressWarnings("unchecked")
    T result = (value != NULL_SENTINEL) ? (T) value : null;
    return result;
  };
}

/**
 * Returns true if the object is a proxy for a circular dependency, constructed by Guice because
 * it encountered a circular dependency. Scope implementations should be careful to <b>not cache
 * circular proxies</b>, because the proxies are not intended for general purpose use. (They are
 * designed just to fulfill the immediate injection, not all injections. Caching them can lead to
 * IllegalArgumentExceptions or ClassCastExceptions.)
 *
 * @since 4.0
 */
public static boolean isCircularProxy(Object object) {
  return object instanceof CircularDependencyProxy;
}

/**
 * Returns true if the object is a proxy for a circular dependency,
 * constructed by Guice because it encountered a circular dependency. Scope
 * implementations should be careful to <b>not cache circular proxies</b>,
 * because the proxies are not intended for general purpose use. (They are
 * designed just to fulfill the immediate injection, not all injections.
 * Caching them can lead to IllegalArgumentExceptions or ClassCastExceptions.)
 */
public static boolean isCircularProxy(Object object) {
  return object instanceof CircularDependencyProxy;
}

/**
 * Returns true if the object is a proxy for a circular dependency,
 * constructed by Guice because it encountered a circular dependency. Scope
 * implementations should be careful to <b>not cache circular proxies</b>,
 * because the proxies are not intended for general purpose use. (They are
 * designed just to fulfill the immediate injection, not all injections.
 * Caching them can lead to IllegalArgumentExceptions or ClassCastExceptions.)
 */
public static boolean isCircularProxy(Object object) {
  return object instanceof CircularDependencyProxy;
}