/*
* Copyright (c) 2011-2017 Pivotal Software Inc, All Rights Reserved.
*
* 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 reactor.core.publisher;
import java.util.
Objects;
import java.util.function.
BiFunction;
import java.util.function.
Supplier;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Fuseable;
import reactor.util.annotation.
Nullable;
/**
* Aggregates the source values with the help of an accumulator
* function and emits the the final accumulated value.
*
* @param <T> the source value type
* @param <R> the accumulated result type
*
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
MonoReduceSeed<T, R> extends
MonoFromFluxOperator<T, R>
implements
Fuseable {
final
Supplier<R>
initialSupplier;
final
BiFunction<R, ? super T, R>
accumulator;
MonoReduceSeed(
Flux<? extends T>
source,
Supplier<R>
initialSupplier,
BiFunction<R, ? super T, R>
accumulator) {
super(
source);
this.
initialSupplier =
Objects.
requireNonNull(
initialSupplier, "initialSupplier");
this.
accumulator =
Objects.
requireNonNull(
accumulator, "accumulator");
}
@
Override
public void
subscribe(
CoreSubscriber<? super R>
actual) {
R
initialValue;
try {
initialValue =
Objects.
requireNonNull(
initialSupplier.
get(),
"The initial value supplied is null");
}
catch (
Throwable e) {
Operators.
error(
actual,
Operators.
onOperatorError(
e,
actual.
currentContext()));
return;
}
source.
subscribe(new
ReduceSeedSubscriber<>(
actual,
accumulator,
initialValue));
}
static final class
ReduceSeedSubscriber<T, R> extends
Operators.
MonoSubscriber<T, R> {
final
BiFunction<R, ? super T, R>
accumulator;
Subscription s;
boolean
done;
ReduceSeedSubscriber(
CoreSubscriber<? super R>
actual,
BiFunction<R, ? super T, R>
accumulator,
R
value) {
super(
actual);
this.
accumulator =
accumulator;
this.
value =
value;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
TERMINATED) return
done;
if (
key ==
Attr.
PARENT) return
s;
return super.scanUnsafe(
key);
}
@
Override
public void
cancel() {
super.cancel();
s.
cancel();
}
@
Override
public void
setValue(R
value) {
// value already saved
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
validate(this.
s,
s)) {
this.
s =
s;
actual.
onSubscribe(this);
s.
request(
Long.
MAX_VALUE);
}
}
@
Override
public void
onNext(T
t) {
R
v;
try {
v =
Objects.
requireNonNull(
accumulator.
apply(
value,
t),
"The accumulator returned a null value");
}
catch (
Throwable e) {
onError(
Operators.
onOperatorError(this,
e,
t,
actual.
currentContext()));
return;
}
value =
v;
}
@
Override
public void
onError(
Throwable t) {
if (
done) {
Operators.
onErrorDropped(
t,
actual.
currentContext());
return;
}
done = true;
actual.
onError(
t);
}
@
Override
public void
onComplete() {
if (
done) {
return;
}
done = true;
complete(
value);
}
}
}