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/*
* Copyright (c) 2000, 2020, Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.util.stream;
import com.tangosol.util.function.Remote;
import java.util.DoubleSummaryStatistics;
import java.util.OptionalDouble;
import java.util.PrimitiveIterator;
import java.util.Spliterator;
import java.util.function.BiConsumer;
import java.util.function.DoubleBinaryOperator;
import java.util.function.DoubleConsumer;
import java.util.function.DoubleFunction;
import java.util.function.DoublePredicate;
import java.util.function.DoubleToIntFunction;
import java.util.function.DoubleToLongFunction;
import java.util.function.DoubleUnaryOperator;
import java.util.function.Function;
import java.util.function.ObjDoubleConsumer;
import java.util.function.Supplier;
/**
* A sequence of primitive double-valued elements supporting sequential and parallel
* aggregate operations. This is the {@code double} primitive specialization of
* {@link RemoteStream}.
*
* The following example illustrates an aggregate operation using
* {@link RemoteStream} and {@link RemoteDoubleStream}, computing the sum of the weights of the
* red widgets:
*
*
{@code
* double sum = widgets.stream()
* .filter(w -> w.getColor() == RED)
* .mapToDouble(w -> w.getWeight())
* .sum();
* }
*
* This interface is an extension of {@code java.util.stream.DoubleStream} that
* captures lambdas used as method arguments as serializable lambdas.
*
* @author as 2014.09.11
* @since 12.2.1
*
* @see RemoteStream
* @see com.tangosol.util.stream
*/
public interface RemoteDoubleStream
extends java.util.stream.DoubleStream, BaseRemoteStream
{
/**
* Returns a stream consisting of the elements of this stream that match
* the given predicate.
*
* This is an intermediate operation.
*
* @param predicate a non-interfering, stateless
* predicate to apply to each element to determine if it
* should be included
*
* @return the new stream
*/
RemoteDoubleStream filter(DoublePredicate predicate);
/**
* Returns a stream consisting of the elements of this stream that match
* the given predicate.
*
* This is an intermediate operation.
*
* @param predicate a non-interfering, stateless
* predicate to apply to each element to determine if it
* should be included
*
* @return the new stream
*/
default RemoteDoubleStream filter(Remote.DoublePredicate predicate)
{
return filter((DoublePredicate) predicate);
}
/**
* Returns a stream consisting of the results of applying the given
* function to the elements of this stream.
*
* This is an intermediate operation.
*
* @param mapper a non-interfering, stateless
* function to apply to each element
*
* @return the new stream
*/
RemoteDoubleStream map(DoubleUnaryOperator mapper);
/**
* Returns a stream consisting of the results of applying the given
* function to the elements of this stream.
*
* This is an intermediate operation.
*
* @param mapper a non-interfering, stateless
* function to apply to each element
*
* @return the new stream
*/
default RemoteDoubleStream map(Remote.DoubleUnaryOperator mapper)
{
return map((DoubleUnaryOperator) mapper);
}
/**
* Returns an object-valued {@code Stream} consisting of the results of
* applying the given function to the elements of this stream.
*
* This is an intermediate operation.
*
* @param the element type of the new stream
* @param mapper a non-interfering, stateless
* function to apply to each element
*
* @return the new stream
*/
RemoteStream mapToObj(DoubleFunction mapper);
/**
* Returns an object-valued {@code Stream} consisting of the results of
* applying the given function to the elements of this stream.
*
* This is an intermediate operation.
*
* @param the element type of the new stream
* @param mapper a non-interfering, stateless
* function to apply to each element
*
* @return the new stream
*/
default RemoteStream mapToObj(Remote.DoubleFunction mapper)
{
return mapToObj((DoubleFunction) mapper);
}
/**
* Returns an {@code IntStream} consisting of the results of applying the
* given function to the elements of this stream.
*
* This is an intermediate operation.
*
* @param mapper a non-interfering, stateless
* function to apply to each element
*
* @return the new stream
*/
RemoteIntStream mapToInt(DoubleToIntFunction mapper);
/**
* Returns an {@code IntStream} consisting of the results of applying the
* given function to the elements of this stream.
*
* This is an intermediate operation.
*
* @param mapper a non-interfering, stateless
* function to apply to each element
*
* @return the new stream
*/
default RemoteIntStream mapToInt(Remote.DoubleToIntFunction mapper)
{
return mapToInt((DoubleToIntFunction) mapper);
}
/**
* Returns a {@code LongStream} consisting of the results of applying the
* given function to the elements of this stream.
*
* This is an intermediate operation.
*
* @param mapper a non-interfering, stateless
* function to apply to each element
*
* @return the new stream
*/
RemoteLongStream mapToLong(DoubleToLongFunction mapper);
/**
* Returns a {@code LongStream} consisting of the results of applying the
* given function to the elements of this stream.
*
* This is an intermediate operation.
*
* @param mapper a non-interfering, stateless
* function to apply to each element
*
* @return the new stream
*/
default RemoteLongStream mapToLong(Remote.DoubleToLongFunction mapper)
{
return mapToLong((DoubleToLongFunction) mapper);
}
/**
* Returns a stream consisting of the results of replacing each element of
* this stream with the contents of a mapped stream produced by applying
* the provided mapping function to each element. Each mapped stream is
* {@link BaseRemoteStream#close() closed} after its contents have been placed
* into this stream. (If a mapped stream is {@code null} an empty stream
* is used, instead.)
*
* This is an intermediate operation.
*
* @param mapper a non-interfering, stateless
* function to apply to each element which produces a
* {@code DoubleStream} of new values
*
* @return the new stream
*
* @see RemoteStream#flatMap(Function)
*/
RemoteDoubleStream flatMap(DoubleFunction mapper);
/**
* Returns a stream consisting of the results of replacing each element of
* this stream with the contents of a mapped stream produced by applying
* the provided mapping function to each element. Each mapped stream is
* {@link BaseRemoteStream#close() closed} after its contents have been placed
* into this stream. (If a mapped stream is {@code null} an empty stream
* is used, instead.)
*
* This is an intermediate operation.
*
* @param mapper a non-interfering, stateless
* function to apply to each element which produces a
* {@code DoubleStream} of new values
*
* @return the new stream
*
* @see RemoteStream#flatMap(Function)
*/
default RemoteDoubleStream flatMap(Remote.DoubleFunction mapper)
{
return flatMap((DoubleFunction) mapper);
}
/**
* Returns a stream consisting of the elements of this stream, additionally
* performing the provided action on each element as elements are consumed
* from the resulting stream.
*
* This is an intermediate operation.
*
* For parallel stream pipelines, the action may be called at
* whatever time and in whatever thread the element is made available by the
* upstream operation. If the action modifies shared state,
* it is responsible for providing the required synchronization.
*
* @param action a non-interfering action to perform on the elements as
* they are consumed from the stream
*
* @return the new stream
*/
RemoteDoubleStream peek(DoubleConsumer action);
/**
* Returns a stream consisting of the elements of this stream, additionally
* performing the provided action on each element as elements are consumed
* from the resulting stream.
*
* This is an intermediate operation.
*
* For parallel stream pipelines, the action may be called at
* whatever time and in whatever thread the element is made available by the
* upstream operation. If the action modifies shared state,
* it is responsible for providing the required synchronization.
*
* @param action a non-interfering action to perform on the elements as
* they are consumed from the stream
*
* @return the new stream
*/
default RemoteDoubleStream peek(Remote.DoubleConsumer action)
{
return peek((DoubleConsumer) action);
}
/**
* Returns a stream consisting of the distinct elements of this stream. The
* elements are compared for equality according to
* {@link java.lang.Double#compare(double, double)}.
*
* This is a stateful intermediate operation.
*
* @return the result stream
*/
java.util.stream.DoubleStream distinct();
/**
* Returns a stream consisting of the elements of this stream in sorted
* order. The elements are compared for equality according to
* {@link java.lang.Double#compare(double, double)}.
*
* This is a stateful intermediate operation.
*
* @return the result stream
*/
java.util.stream.DoubleStream sorted();
/**
* Returns a stream consisting of the elements of this stream, truncated
* to be no longer than {@code maxSize} in length.
*
* This is a short-circuiting stateful intermediate operation.
*
* @param maxSize the number of elements the stream should be limited to
*
* @return the new stream
*
* @throws IllegalArgumentException if {@code maxSize} is negative
*/
java.util.stream.DoubleStream limit(long maxSize);
/**
* Returns a stream consisting of the remaining elements of this stream
* after discarding the first {@code n} elements of the stream.
* If this stream contains fewer than {@code n} elements then an
* empty stream will be returned.
*
* This is a stateful intermediate operation.
*
* @param n the number of leading elements to skip
*
* @return the new stream
*
* @throws IllegalArgumentException if {@code n} is negative
*/
java.util.stream.DoubleStream skip(long n);
/**
* Performs an action for each element of this stream.
*
* This is a terminal operation.
*
* For parallel stream pipelines, this operation does not
* guarantee to respect the encounter order of the stream, as doing so
* would sacrifice the benefit of parallelism. For any given element, the
* action may be performed at whatever time and in whatever thread the
* library chooses. If the action accesses shared state, it is
* responsible for providing the required synchronization.
*
* @param action a non-interfering action to perform on the elements
*/
void forEach(DoubleConsumer action);
/**
* Performs an action for each element of this stream, guaranteeing that
* each element is processed in encounter order for streams that have a
* defined encounter order.
*
* This is a terminal operation.
*
* @param action a non-interfering action to perform on the elements
*
* @see #forEach(DoubleConsumer)
*/
void forEachOrdered(DoubleConsumer action);
/**
* Returns an array containing the elements of this stream.
*
* This is a terminal operation.
*
* @return an array containing the elements of this stream
*/
double[] toArray();
/**
* Performs a reduction on the elements of this stream, using the
* provided identity value and an associative accumulation function,
* and returns the reduced value. This is equivalent to:
*
{@code
* double result = identity;
* for (double element : this stream)
* result = accumulator.applyAsDouble(result, element)
* return result;
* }
*
* but is not constrained to execute sequentially.
*
* The {@code identity} value must be an identity for the accumulator
* function. This means that for all {@code x},
* {@code accumulator.apply(identity, x)} is equal to {@code x}.
* The {@code accumulator} function must be an associative function.
*
* This is a terminal operation.
*
* @param identity the identity value for the accumulating function
* @param op an associative, non-interfering, stateless
* function for combining two values
*
* @return the result of the reduction
*
* @see #sum()
* @see #min()
* @see #max()
* @see #average()
*/
double reduce(double identity, DoubleBinaryOperator op);
/**
* Performs a reduction on the elements of this stream, using the
* provided identity value and an associative accumulation function,
* and returns the reduced value. This is equivalent to:
*
{@code
* double result = identity;
* for (double element : this stream)
* result = accumulator.applyAsDouble(result, element)
* return result;
* }
*
* but is not constrained to execute sequentially.
*
* The {@code identity} value must be an identity for the accumulator
* function. This means that for all {@code x},
* {@code accumulator.apply(identity, x)} is equal to {@code x}.
* The {@code accumulator} function must be an associative function.
*
* This is a terminal operation.
*
* @param identity the identity value for the accumulating function
* @param op an associative, non-interfering, stateless
* function for combining two values
*
* @return the result of the reduction
*
* @see #sum()
* @see #min()
* @see #max()
* @see #average()
*/
default double reduce(double identity, Remote.DoubleBinaryOperator op)
{
return reduce(identity, (DoubleBinaryOperator) op);
}
/**
* Performs a reduction on the elements of this stream, using an
* associative accumulation function, and returns an
* {@code OptionalDouble} describing the reduced value, if any. This is
* equivalent to:
*
{@code
* boolean foundAny = false;
* double result = null;
* for (double element : this stream) {
* if (!foundAny) {
* foundAny = true;
* result = element;
* }
* else
* result = accumulator.applyAsDouble(result, element);
* }
* return foundAny ? OptionalDouble.of(result) : OptionalDouble.empty();
* }
*
* but is not constrained to execute sequentially.
*
* The {@code accumulator} function must be an associative function.
*
* This is a terminal operation.
*
* @param op an associative, non-interfering, stateless
* function for combining two values
*
* @return the result of the reduction
*
* @see #reduce(double, DoubleBinaryOperator)
*/
OptionalDouble reduce(DoubleBinaryOperator op);
/**
* Performs a reduction on the elements of this stream, using an
* associative accumulation function, and returns an
* {@code OptionalDouble} describing the reduced value, if any. This is
* equivalent to:
*
{@code
* boolean foundAny = false;
* double result = null;
* for (double element : this stream) {
* if (!foundAny) {
* foundAny = true;
* result = element;
* }
* else
* result = accumulator.applyAsDouble(result, element);
* }
* return foundAny ? OptionalDouble.of(result) : OptionalDouble.empty();
* }
*
* but is not constrained to execute sequentially.
*
* The {@code accumulator} function must be an associative function.
*
* This is a terminal operation.
*
* @param op an associative, non-interfering, stateless
* function for combining two values
*
* @return the result of the reduction
*
* @see #reduce(double, DoubleBinaryOperator)
*/
default OptionalDouble reduce(Remote.DoubleBinaryOperator op)
{
return reduce((DoubleBinaryOperator) op);
}
/**
* Performs a mutable reduction operation on the elements of this
* stream. A mutable reduction is one in which the reduced value is a mutable
* result container, such as an {@code ArrayList}, and elements are incorporated
* by updating the state of the result rather than by replacing the result.
*
* This produces a result equivalent to:
*
{@code
* R result = supplier.get();
* for (double element : this stream)
* accumulator.accept(result, element);
* return result;
* }
*
* Like {@link #reduce(double, DoubleBinaryOperator)}, {@code collect}
* operations can be parallelized without requiring additional
* synchronization.
*
* This is a terminal operation.
*
* @param type of the result
* @param supplier a function that creates a new result container. For a
* parallel execution, this function may be called
* multiple times and must return a fresh value each time.
* @param accumulator an associative, non-interfering,
* stateless function for incorporating an
* additional element into a result
* @param combiner an associative, non-interfering,
* stateless function for combining two values,
* which must be compatible with the accumulator function
*
* @return the result of the reduction
*
* @see RemoteStream#collect(Supplier, BiConsumer, BiConsumer)
*/
R collect(Supplier supplier,
ObjDoubleConsumer accumulator,
BiConsumer combiner);
/**
* Performs a mutable reduction operation on the elements of this
* stream. A mutable reduction is one in which the reduced value is a mutable
* result container, such as an {@code ArrayList}, and elements are incorporated
* by updating the state of the result rather than by replacing the result.
*
* This produces a result equivalent to:
*
{@code
* R result = supplier.get();
* for (double element : this stream)
* accumulator.accept(result, element);
* return result;
* }
*
* Like {@link #reduce(double, DoubleBinaryOperator)}, {@code collect}
* operations can be parallelized without requiring additional
* synchronization.
*
* This is a terminal operation.
*
* @param type of the result
* @param supplier a function that creates a new result container. For a
* parallel execution, this function may be called
* multiple times and must return a fresh value each time.
* @param accumulator an associative, non-interfering,
* stateless function for incorporating an
* additional element into a result
* @param combiner an associative, non-interfering,
* stateless function for combining two values,
* which must be compatible with the accumulator function
*
* @return the result of the reduction
*
* @see RemoteStream#collect(Supplier, BiConsumer, BiConsumer)
*/
default R collect(Remote.Supplier supplier,
Remote.ObjDoubleConsumer accumulator,
Remote.BiConsumer combiner)
{
return collect((Supplier) supplier,
(ObjDoubleConsumer) accumulator,
(BiConsumer) combiner);
}
/**
* Returns the sum of elements in this stream.
*
* Summation is a special case of a reduction. If
* floating-point summation were exact, this method would be
* equivalent to:
*
*
{@code
* return reduce(0, Double::sum);
* }
*
* However, since floating-point summation is not exact, the above
* code is not necessarily equivalent to the summation computation
* done by this method.
*
* If any stream element is a NaN or the sum is at any point a NaN
* then the sum will be NaN.
*
* The value of a floating-point sum is a function both
* of the input values as well as the order of addition
* operations. The order of addition operations of this method is
* intentionally not defined to allow for implementation
* flexibility to improve the speed and accuracy of the computed
* result.
*
* In particular, this method may be implemented using compensated
* summation or other technique to reduce the error bound in the
* numerical sum compared to a simple summation of {@code double}
* values.
*
* This is a terminal operation.
*
* @return the sum of elements in this stream
*/
double sum();
/**
* Returns an {@code OptionalDouble} describing the minimum element of this
* stream, or an empty OptionalDouble if this stream is empty. The minimum
* element will be {@code Double.NaN} if any stream element was NaN. Unlike
* the numerical comparison operators, this method considers negative zero
* to be strictly smaller than positive zero. This is a special case of a
* reduction and is equivalent to:
*
{@code
* return reduce(Double::min);
* }
*
* This is a terminal operation.
*
* @return an {@code OptionalDouble} containing the minimum element of this
* stream, or an empty optional if the stream is empty
*/
OptionalDouble min();
/**
* Returns an {@code OptionalDouble} describing the maximum element of this
* stream, or an empty OptionalDouble if this stream is empty. The maximum
* element will be {@code Double.NaN} if any stream element was NaN. Unlike
* the numerical comparison operators, this method considers negative zero
* to be strictly smaller than positive zero. This is a special case of a
* reduction and is equivalent to:
*
{@code
* return reduce(Double::max);
* }
*
* This is a terminal operation.
*
* @return an {@code OptionalDouble} containing the maximum element of this
* stream, or an empty optional if the stream is empty
*/
OptionalDouble max();
/**
* Returns the count of elements in this stream. This is a special case of
* a reduction and is equivalent to:
*
{@code
* return mapToLong(e -> 1L).sum();
* }
*
* This is a terminal operation.
*
* @return the count of elements in this stream
*/
long count();
/**
* Returns an {@code OptionalDouble} describing the arithmetic
* mean of elements of this stream, or an empty optional if this
* stream is empty.
*
* If any recorded value is a NaN or the sum is at any point a NaN
* then the average will be NaN.
*
* The average returned can vary depending upon the order in
* which values are recorded.
*
* This method may be implemented using compensated summation or
* other technique to reduce the error bound in the {@link #sum
* numerical sum} used to compute the average.
*
* This is a terminal operation.
*
* @return an {@code OptionalDouble} containing the average element of this
* stream, or an empty optional if the stream is empty
*/
OptionalDouble average();
/**
* Returns a {@code DoubleSummaryStatistics} describing various summary data
* about the elements of this stream. This is a special case of a reduction.
*
* This is a terminal operation.
*
* @return a {@code DoubleSummaryStatistics} describing various summary data
* about the elements of this stream
*/
DoubleSummaryStatistics summaryStatistics();
/**
* Returns whether any elements of this stream match the provided
* predicate. May not evaluate the predicate on all elements if not
* necessary for determining the result. If the stream is empty then
* {@code false} is returned and the predicate is not evaluated.
*
* This is a short-circuiting terminal operation.
*
* @param predicate a non-interfering, stateless
* predicate to apply to elements of this stream
*
* @return {@code true} if any elements of the stream match the provided
* predicate, otherwise {@code false}
*/
boolean anyMatch(DoublePredicate predicate);
/**
* Returns whether any elements of this stream match the provided
* predicate. May not evaluate the predicate on all elements if not
* necessary for determining the result. If the stream is empty then
* {@code false} is returned and the predicate is not evaluated.
*
* This is a short-circuiting terminal operation.
*
* @param predicate a non-interfering, stateless
* predicate to apply to elements of this stream
*
* @return {@code true} if any elements of the stream match the provided
* predicate, otherwise {@code false}
*/
default boolean anyMatch(Remote.DoublePredicate predicate)
{
return anyMatch((DoublePredicate) predicate);
}
/**
* Returns whether all elements of this stream match the provided predicate.
* May not evaluate the predicate on all elements if not necessary for
* determining the result. If the stream is empty then {@code true} is
* returned and the predicate is not evaluated.
*
* This is a short-circuiting terminal operation.
*
* @param predicate a non-interfering, stateless
* predicate to apply to elements of this stream
*
* @return {@code true} if either all elements of the stream match the
* provided predicate or the stream is empty, otherwise {@code false}
*/
boolean allMatch(DoublePredicate predicate);
/**
* Returns whether all elements of this stream match the provided predicate.
* May not evaluate the predicate on all elements if not necessary for
* determining the result. If the stream is empty then {@code true} is
* returned and the predicate is not evaluated.
*
* This is a short-circuiting terminal operation.
*
* @param predicate a non-interfering, stateless
* predicate to apply to elements of this stream
*
* @return {@code true} if either all elements of the stream match the
* provided predicate or the stream is empty, otherwise {@code false}
*/
default boolean allMatch(Remote.DoublePredicate predicate)
{
return allMatch((DoublePredicate) predicate);
}
/**
* Returns whether no elements of this stream match the provided predicate.
* May not evaluate the predicate on all elements if not necessary for
* determining the result. If the stream is empty then {@code true} is
* returned and the predicate is not evaluated.
*
* This is a short-circuiting terminal operation.
*
* @param predicate a non-interfering, stateless
* predicate to apply to elements of this stream
*
* @return {@code true} if either no elements of the stream match the
* provided predicate or the stream is empty, otherwise {@code false}
*/
boolean noneMatch(DoublePredicate predicate);
/**
* Returns whether no elements of this stream match the provided predicate.
* May not evaluate the predicate on all elements if not necessary for
* determining the result. If the stream is empty then {@code true} is
* returned and the predicate is not evaluated.
*
* This is a short-circuiting terminal operation.
*
* @param predicate a non-interfering, stateless
* predicate to apply to elements of this stream
*
* @return {@code true} if either no elements of the stream match the
* provided predicate or the stream is empty, otherwise {@code false}
*/
default boolean noneMatch(Remote.DoublePredicate predicate)
{
return noneMatch((DoublePredicate) predicate);
}
/**
* Returns an {@link OptionalDouble} describing the first element of this
* stream, or an empty {@code OptionalDouble} if the stream is empty. If
* the stream has no encounter order, then any element may be returned.
*
* This is a short-circuiting terminal operation.
*
* @return an {@code OptionalDouble} describing the first element of this
* stream, or an empty {@code OptionalDouble} if the stream is empty
*/
OptionalDouble findFirst();
/**
* Returns an {@link OptionalDouble} describing some element of the stream,
* or an empty {@code OptionalDouble} if the stream is empty.
*
* This is a short-circuiting terminal operation.
*
*
The behavior of this operation is explicitly nondeterministic; it is
* free to select any element in the stream. This is to allow for maximal
* performance in parallel operations; the cost is that multiple invocations
* on the same source may not return the same result. (If a stable result
* is desired, use {@link #findFirst()} instead.)
*
* @return an {@code OptionalDouble} describing some element of this stream,
* or an empty {@code OptionalDouble} if the stream is empty
* @see #findFirst()
*/
OptionalDouble findAny();
/**
* Returns a {@code Stream} consisting of the elements of this stream,
* boxed to {@code Double}.
*
* This is an intermediate operation.
*
* @return a {@code Stream} consistent of the elements of this stream,
* each boxed to a {@code Double}
*/
RemoteStream boxed();
@Override
RemoteDoubleStream sequential();
@Override
RemoteDoubleStream parallel();
@Override
PrimitiveIterator.OfDouble iterator();
@Override
Spliterator.OfDouble spliterator();
}