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/*
* Copyright 2016 Google 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 java.util.stream;
import static javaemul.internal.InternalPreconditions.checkState;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Optional;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.Spliterators.AbstractSpliterator;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.BinaryOperator;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.IntFunction;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.function.ToDoubleFunction;
import java.util.function.ToIntFunction;
import java.util.function.ToLongFunction;
import java.util.function.UnaryOperator;
/**
* See
* the official Java API doc for details.
*
* @param the type of data being streamed
*/
public interface Stream extends BaseStream> {
/**
* See
* the official Java API doc for details.
*/
interface Builder extends Consumer {
@Override
void accept(T t);
default Stream.Builder add(T t) {
accept(t);
return this;
}
Stream build();
}
static Stream.Builder builder() {
return new Builder() {
private ArrayList items = new ArrayList<>();
@Override
public void accept(T t) {
checkState(items != null, "Builder already built");
items.add(t);
}
@Override
@SuppressWarnings("unchecked")
public Stream build() {
checkState(items != null, "Builder already built");
Stream stream = items.stream();
items = null;
return stream;
}
};
}
static Stream concat(Stream a, Stream b) {
// This is nearly the same as flatMap, but inlined, wrapped around a single spliterator of
// these two objects, and without close() called as the stream progresses. Instead, close is
// invoked as part of the resulting stream's own onClose, so that either can fail without
// affecting the other, and correctly collecting suppressed exceptions.
// TODO replace this flatMap-ish spliterator with one that directly combines the two root
// streams
Spliterator> spliteratorOfStreams =
Arrays.asList(a, b).spliterator();
AbstractSpliterator spliterator =
new Spliterators.AbstractSpliterator(Long.MAX_VALUE, 0) {
Spliterator next;
@Override
public boolean tryAdvance(Consumer action) {
// look for a new spliterator
while (advanceToNextSpliterator()) {
// if we have one, try to read and use it
if (next.tryAdvance(action)) {
return true;
} else {
// failed, null it out so we can find another
next = null;
}
}
return false;
}
private boolean advanceToNextSpliterator() {
while (next == null) {
if (!spliteratorOfStreams.tryAdvance(
n -> {
if (n != null) {
next = n.spliterator();
}
})) {
return false;
}
}
return true;
}
};
Stream result = new StreamImpl(null, spliterator);
return result.onClose(a::close).onClose(b::close);
}
static Stream empty() {
return new StreamImpl.Empty(null);
}
static Stream generate(Supplier s) {
AbstractSpliterator spliterator =
new Spliterators.AbstractSpliterator(
Long.MAX_VALUE, Spliterator.IMMUTABLE | Spliterator.ORDERED) {
@Override
public boolean tryAdvance(Consumer action) {
action.accept(s.get());
return true;
}
};
return StreamSupport.stream(spliterator, false);
}
static Stream iterate(T seed, UnaryOperator f) {
AbstractSpliterator spliterator =
new Spliterators.AbstractSpliterator(
Long.MAX_VALUE, Spliterator.IMMUTABLE | Spliterator.ORDERED) {
private T next = seed;
@Override
public boolean tryAdvance(Consumer action) {
action.accept(next);
next = f.apply(next);
return true;
}
};
return StreamSupport.stream(spliterator, false);
}
static Stream of(T t) {
// TODO consider a splittable that returns only a single value, either for use here or in the
// singleton collection types
return Collections.singleton(t).stream();
}
static Stream of(T... values) {
return Arrays.stream(values);
}
boolean allMatch(Predicate predicate);
boolean anyMatch(Predicate predicate);
R collect(Collector collector);
R collect(
Supplier supplier, BiConsumer accumulator, BiConsumer combiner);
long count();
Stream distinct();
Stream filter(Predicate predicate);
Optional findAny();
Optional findFirst();
Stream flatMap(Function> mapper);
DoubleStream flatMapToDouble(Function mapper);
IntStream flatMapToInt(Function mapper);
LongStream flatMapToLong(Function mapper);
void forEach(Consumer action);
void forEachOrdered(Consumer action);
Stream limit(long maxSize);
Stream map(Function mapper);
DoubleStream mapToDouble(ToDoubleFunction mapper);
IntStream mapToInt(ToIntFunction mapper);
LongStream mapToLong(ToLongFunction mapper);
Optional max(Comparator comparator);
Optional min(Comparator comparator);
boolean noneMatch(Predicate predicate);
Stream peek(Consumer action);
Optional reduce(BinaryOperator accumulator);
T reduce(T identity, BinaryOperator accumulator);
U reduce(U identity, BiFunction accumulator, BinaryOperator combiner);
Stream skip(long n);
Stream sorted();
Stream sorted(Comparator comparator);
Object[] toArray();
A[] toArray(IntFunction generator);
}