/**
* Copyright 2014 Netflix, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package rx.internal.operators;
import java.util.
NoSuchElementException;
import rx.
Observable.
Operator;
import rx.
Subscriber;
import rx.internal.producers.
SingleProducer;
import rx.plugins.
RxJavaHooks;
/**
* If the Observable completes after emitting a single item that matches a
* predicate, return an Observable containing that item. If it emits more than
* one such item or no item, throw an IllegalArgumentException.
* @param <T> the value type
*/
public final class
OperatorSingle<T> implements
Operator<T, T> {
private final boolean
hasDefaultValue;
private final T
defaultValue;
static final class
Holder {
final static
OperatorSingle<?>
INSTANCE = new
OperatorSingle<
Object>();
}
/**
* Returns a singleton instance of OperatorSingle (if the stream is empty or has
* more than one element an error will be emitted) that is cast to the generic type.
*
* @param <T> the value type
* @return a singleton instance of an Operator that will emit a single value only unless the stream has zero or more than one element in which case it will emit an error.
*/
@
SuppressWarnings("unchecked")
public static <T>
OperatorSingle<T>
instance() {
return (
OperatorSingle<T>)
Holder.
INSTANCE;
}
OperatorSingle() {
this(false, null);
}
public
OperatorSingle(T
defaultValue) {
this(true,
defaultValue);
}
private
OperatorSingle(boolean
hasDefaultValue, final T
defaultValue) {
this.
hasDefaultValue =
hasDefaultValue;
this.
defaultValue =
defaultValue;
}
@
Override
public
Subscriber<? super T>
call(final
Subscriber<? super T>
child) {
final
ParentSubscriber<T>
parent = new
ParentSubscriber<T>(
child,
hasDefaultValue,
defaultValue);
child.
add(
parent);
return
parent;
}
static final class
ParentSubscriber<T> extends
Subscriber<T> {
private final
Subscriber<? super T>
child;
private final boolean
hasDefaultValue;
private final T
defaultValue;
private T
value;
private boolean
isNonEmpty;
private boolean
hasTooManyElements;
ParentSubscriber(
Subscriber<? super T>
child, boolean
hasDefaultValue,
T
defaultValue) {
this.
child =
child;
this.
hasDefaultValue =
hasDefaultValue;
this.
defaultValue =
defaultValue;
request(2); // could go unbounded, but test expect this
}
@
Override
public void
onNext(T
value) {
if (!
hasTooManyElements) {
if (
isNonEmpty) {
hasTooManyElements = true;
child.
onError(new
IllegalArgumentException("Sequence contains too many elements"));
unsubscribe();
} else {
this.
value =
value;
isNonEmpty = true;
}
}
}
@
Override
public void
onCompleted() {
if (!
hasTooManyElements) {
if (
isNonEmpty) {
child.
setProducer(new
SingleProducer<T>(
child,
value));
} else {
if (
hasDefaultValue) {
child.
setProducer(new
SingleProducer<T>(
child,
defaultValue));
} else {
child.
onError(new
NoSuchElementException("Sequence contains no elements"));
}
}
}
// Otherwise we have already sent an onError message
}
@
Override
public void
onError(
Throwable e) {
if (
hasTooManyElements) {
RxJavaHooks.
onError(
e);
return;
}
child.
onError(
e);
}
}
}