/*
 
* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
 
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 
*
 
* This code is free software; you can redistribute it and/or modify it
 
* under the terms of the GNU General Public License version 2 only, as
 
* published by the Free Software Foundation.
  
Oracle designates this
 
* particular file as subject to the "Classpath" exception as provided
 
* by Oracle in the LICENSE file that accompanied this code.
 
*
 
* This code is distributed in the hope that it will be useful, but WITHOUT
 
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 
* FITNESS FOR A PARTICULAR PURPOSE.
  
See the GNU General Public License
 
* version 2 for more details (a copy is included in the LICENSE file that
 
* accompanied this code).
 
*
 
* You should have received a copy of the GNU General Public License version
 
* 2 along with this work; if not, write to the Free Software Foundation,
 
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 
*
 
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 
* or visit www.oracle.com if you need additional information or have any
 
* questions.
 
*/
package java.util.stream;

import java.util.Arrays;
import java.util.IntSummaryStatistics;
import java.util.Objects;
import java.util.OptionalDouble;
import java.util.OptionalInt;
import java.util.PrimitiveIterator;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.BiConsumer;
import java.util.function.Function;
import java.util.function.IntBinaryOperator;
import java.util.function.IntConsumer;
import java.util.function.IntFunction;
import java.util.function.IntPredicate;
import java.util.function.IntSupplier;
import java.util.function.IntToDoubleFunction;
import java.util.function.IntToLongFunction;
import java.util.function.IntUnaryOperator;
import java.util.function.ObjIntConsumer;
import java.util.function.Supplier;

/**
 
* A sequence of primitive int-valued elements supporting sequential and parallel
 
* aggregate operations.
  
This is the {@code int} primitive specialization of
 
* {@link Stream}.
 
*
 
* <p>The following example illustrates an aggregate operation using
 
* {@link Stream} and {@link IntStream}, computing the sum of the weights of the
 
* red widgets:
 
*
 
* <pre>{@code
 
*
     
int sum = widgets.stream()
 
*
                      
.filter(w -> w.getColor() == RED)
 
*
                      
.mapToInt(w -> w.getWeight())
 
*
                      
.sum();
 
* }</pre>
 
*
 
* See the class documentation for {@link Stream} and the package documentation
 
* for<a href="package-summary.html">java.util.stream</a>
 
for additional
 
* specification of streams, stream operations, stream pipelines, and
 
* parallelism.
 
*
 
* @since 1.8
 
* @see Stream
 
* @see<a href="package-summary.html">java.util.stream</a>
 
*/

public interface IntStream extends BaseStream<Integer, IntStream> {

    
/**
     
* Returns a stream consisting of the elements of this stream that match
     
* the given predicate.
     
*
     
* <p>This is an <a href="package-summary.html#StreamOps">intermediate
     
* operation</a>.
     
*
     
* @param predicate a
 
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
                  
<a href="package-summary.html#Statelessness">stateless</a>
     
*
                  
predicate to apply to each element to determine if it
     
*
                  
should be included
     
* @return the new stream
     
*/

    
IntStream filter(IntPredicate predicate);

    
/**
     
* Returns a stream consisting of the results of applying the given
     
* function to the elements of this stream.
     
*
     
* <p>This is an <a href="package-summary.html#StreamOps">intermediate
     
* operation</a>.
     
*
     
* @param mapper a
 
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
               
<a href="package-summary.html#Statelessness">stateless</a>
     
*
               
function to apply to each element
     
* @return the new stream
     
*/

    
IntStream map(IntUnaryOperator mapper);

    
/**
     
* Returns an object-valued {@code Stream} consisting of the results of
     
* applying the given function to the elements of this stream.
     
*
     
* <p>This is an <a href="package-summary.html#StreamOps">
     
*intermediate operation</a>.
     
*
     
* @param <U> the element type of the new stream
     
* @param mapper a
 
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
               
<a href="package-summary.html#Statelessness">stateless</a>
     
*
               
function to apply to each element
     
* @return the new stream
     
*/

    
<U> Stream<U> mapToObj(IntFunction<? extends U> mapper);

    
/**
     
* Returns a {@code LongStream} consisting of the results of applying the
     
* given function to the elements of this stream.
     
*
     
* <p>This is an <a href="package-summary.html#StreamOps">intermediate
     
* operation</a>.
     
*
     
* @param mapper a
 
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
               
<a href="package-summary.html#Statelessness">stateless</a>
     
*
               
function to apply to each element
     
* @return the new stream
     
*/

    
LongStream mapToLong(IntToLongFunction mapper);

    
/**
     
* Returns a {@code DoubleStream} consisting of the results of applying the
     
* given function to the elements of this stream.
     
*
     
* <p>This is an <a href="package-summary.html#StreamOps">intermediate
     
* operation</a>.
     
*
     
* @param mapper a
 
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
               
<a href="package-summary.html#Statelessness">stateless</a>
     
*
               
function to apply to each element
     
* @return the new stream
     
*/

    
DoubleStream mapToDouble(IntToDoubleFunction 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 java.util.stream.BaseStream#close() closed} after its contents
     
* have been placed into this stream.
  
(If a mapped stream is {@code null}
     
* an empty stream is used, instead.)
     
*
     
* <p>This is an <a href="package-summary.html#StreamOps">intermediate
     
* operation</a>.
     
*
     
* @param mapper a
 
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
               
<a href="package-summary.html#Statelessness">stateless</a>
     
*
               
function to apply to each element which produces an
     
*
               
{@code IntStream} of new values
     
* @return the new stream
     
* @see Stream#flatMap(Function)
     
*/

    
IntStream flatMap(IntFunction<? extends IntStream> mapper);

    
/**
     
* Returns a stream consisting of the distinct elements of this stream.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">stateful
     
* intermediate operation</a>.
     
*
     
* @return the new stream
     
*/

    
IntStream distinct();

    
/**
     
* Returns a stream consisting of the elements of this stream in sorted
     
* order.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">stateful
     
* intermediate operation</a>.
     
*
     
* @return the new stream
     
*/

    
IntStream sorted();

    
/**
     
* 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.
     
*
     
* <p>This is an <a href="package-summary.html#StreamOps">intermediate
     
* operation</a>.
     
*
     
* <p>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.
     
*
     
* @apiNote This method exists mainly to support debugging, where you want
     
* to see the elements as they flow past a certain point in a pipeline:
     
* <pre>{@code
     
*IntStream.of(1, 2, 3, 4)
     
*
         
.filter(e -> e > 2)
     
*
         
.peek(e -> System.out.println("Filtered value: " + e))
     
*
         
.map(e -> e * e)
     
*
         
.peek(e -> System.out.println("Mapped value: " + e))
     
*
         
.sum();
     
* }</pre>
     
*
     
* @param action a <a href="package-summary.html#NonInterference">
     
*
               
non-interfering</a> action to perform on the elements as
     
*
               
they are consumed from the stream
     
* @return the new stream
     
*/

    
IntStream peek(IntConsumer action);

    
/**
     
* Returns a stream consisting of the elements of this stream, truncated
     
* to be no longer than {@code maxSize} in length.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
     
* stateful intermediate operation</a>.
     
*
     
* @apiNote
     
* While {@code limit()} is generally a cheap operation on sequential
     
* stream pipelines, it can be quite expensive on ordered parallel pipelines,
     
* especially for large values of {@code maxSize}, since {@code limit(n)}
     
* is constrained to return not just any <em>n</em> elements, but the
     
* <em>first n</em> elements in the encounter order.
  
Using an unordered
     
* stream source (such as {@link #generate(IntSupplier)}) or removing the
     
* ordering constraint with
 
 
may result in significant
     
* speedups of {@code limit()} in parallel pipelines, if the semantics of
     
* your situation permit.
  
If consistency with encounter order is required,
     
* and you are experiencing poor performance or memory utilization with
     
* {@code limit()} in parallel pipelines, switching to sequential execution
     
* with
 
 
may improve performance.
     
*
     
* @param maxSize the number of elements the stream should be limited to
     
* @return the new stream
     
* @throws IllegalArgumentException if {@code maxSize} is negative
     
*/

    
IntStream 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.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">stateful
     
* intermediate operation</a>.
     
*
     
* @apiNote
     
* While {@code skip()} is generally a cheap operation on sequential
     
* stream pipelines, it can be quite expensive on ordered parallel pipelines,
     
* especially for large values of {@code n}, since {@code skip(n)}
     
* is constrained to skip not just any <em>n</em> elements, but the
     
* <em>first n</em> elements in the encounter order.
  
Using an unordered
     
* stream source (such as {@link #generate(IntSupplier)}) or removing the
     
* ordering constraint with
 
 
may result in significant
     
* speedups of {@code skip()} in parallel pipelines, if the semantics of
     
* your situation permit.
  
If consistency with encounter order is required,
     
* and you are experiencing poor performance or memory utilization with
     
* {@code skip()} in parallel pipelines, switching to sequential execution
     
* with
 
 
may improve performance.
     
*
     
* @param n the number of leading elements to skip
     
* @return the new stream
     
* @throws IllegalArgumentException if {@code n} is negative
     
*/

    
IntStream skip(long n);

    
/**
     
* Performs an action for each element of this stream.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">terminal
     
* operation</a>.
     
*
     
* <p>For parallel stream pipelines, this operation does <em>not</em>
     
* 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 <a href="package-summary.html#NonInterference">
     
*
               
non-interfering</a> action to perform on the elements
     
*/

    
void forEach(IntConsumer 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.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">terminal
     
* operation</a>.
     
*
     
* @param action a <a href="package-summary.html#NonInterference">
     
*
               
non-interfering</a> action to perform on the elements
     
* @see #forEach(IntConsumer)
     
*/

    
void forEachOrdered(IntConsumer action);

    
/**
     
* Returns an array containing the elements of this stream.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">terminal
     
* operation</a>.
     
*
     
* @return an array containing the elements of this stream
     
*/

    
int[] toArray();

    
/**
     
* Performs a
 
<a href="package-summary.html#Reduction">reduction</a>
 
on the
     
* elements of this stream, using the provided identity value and an
     
*
 
<a href="package-summary.html#Associativity">associative</a>
     
* accumulation function, and returns the reduced value.
  
This is equivalent
     
* to:
     
* <pre>{@code
     
*int result = identity;
     
*for (int element : this stream)
     
*
         
result = accumulator.applyAsInt(result, element)
     
*return result;
     
* }</pre>
     
*
     
* but is not constrained to execute sequentially.
     
*
     
* <p>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
     
*
 
<a href="package-summary.html#Associativity">associative</a>
 
function.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">terminal
     
* operation</a>.
     
*
     
* @apiNote Sum, min, max, and average are all special cases of reduction.
     
* Summing a stream of numbers can be expressed as:
     
*
     
* <pre>{@code
     
*int sum = integers.reduce(0, (a, b) -> a+b);
     
* }</pre>
     
*
     
* or more compactly:
     
*
     
* <pre>{@code
     
*int sum = integers.reduce(0, Integer::sum);
     
* }</pre>
     
*
     
* <p>While this may seem a more roundabout way to perform an aggregation
     
* compared to simply mutating a running total in a loop, reduction
     
* operations parallelize more gracefully, without needing additional
     
* synchronization and with greatly reduced risk of data races.
     
*
     
* @param identity the identity value for the accumulating function
     
* @param op an
 
<a href="package-summary.html#Associativity">associative</a>,
     
*
           
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
           
<a href="package-summary.html#Statelessness">stateless</a>
     
*
           
function for combining two values
     
* @return the result of the reduction
     
*
 

     
*
 

     
*
 

     
*
 

     
*/

    
int reduce(int identity, IntBinaryOperator op);

    
/**
     
* Performs a
 
<a href="package-summary.html#Reduction">reduction</a>
 
on the
     
* elements of this stream, using an
     
*
 
<a href="package-summary.html#Associativity">associative</a>
 
accumulation
     
* function, and returns an {@code OptionalInt} describing the reduced value,
     
* if any. This is equivalent to:
     
* <pre>{@code
     
*boolean foundAny = false;
     
*int result = null;
     
*for (int element : this stream) {
     
*
         
if (!foundAny) {
     
*
             
foundAny = true;
     
*
             
result = element;
     
*
         
}
     
*
         
else
     
*
             
result = accumulator.applyAsInt(result, element);
     
*}
     
*return foundAny ? OptionalInt.of(result) : OptionalInt.empty();
     
* }</pre>
     
*
     
* but is not constrained to execute sequentially.
     
*
     
* <p>The {@code accumulator} function must be an
     
*
 
<a href="package-summary.html#Associativity">associative</a>
 
function.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">terminal
     
* operation</a>.
     
*
     
* @param op an
 
<a href="package-summary.html#Associativity">associative</a>,
     
*
           
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
           
<a href="package-summary.html#Statelessness">stateless</a>
     
*
           
function for combining two values
     
* @return the result of the reduction
     
* @see #reduce(int, IntBinaryOperator)
     
*/

    
OptionalInt reduce(IntBinaryOperator op);

    
/**
     
* Performs a <a href="package-summary.html#MutableReduction">mutable
     
* reduction</a> 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:
     
* <pre>{@code
     
*R result = supplier.get();
     
*for (int element : this stream)
     
*
         
accumulator.accept(result, element);
     
*return result;
     
* }</pre>
     
*
     
* <p>Like {@link #reduce(int, IntBinaryOperator)}, {@code collect} operations
     
* can be parallelized without requiring additional synchronization.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">terminal
     
* operation</a>.
     
*
     
* @param <R> 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
 
<a href="package-summary.html#Associativity">associative</a>,
     
*
                    
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
                    
<a href="package-summary.html#Statelessness">stateless</a>
     
*
                    
function for incorporating an additional element into a result
     
* @param combiner an
 
<a href="package-summary.html#Associativity">associative</a>,
     
*
                    
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
                    
<a href="package-summary.html#Statelessness">stateless</a>
     
*
                    
function for combining two values, which must be
     
*
                    
compatible with the accumulator function
     
* @return the result of the reduction
     
* @see Stream#collect(Supplier, BiConsumer, BiConsumer)
     
*/

    
<R> R collect(Supplier<R> supplier,
                  
ObjIntConsumer<R> accumulator,
                  
BiConsumer<R, R> combiner);

    
/**
     
* Returns the sum of elements in this stream.
  
This is a special case
     
* of a
 
<a href="package-summary.html#Reduction">reduction</a>
     
* and is equivalent to:
     
* <pre>{@code
     
*return reduce(0, Integer::sum);
     
* }</pre>
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">terminal
     
* operation</a>.
     
*
     
* @return the sum of elements in this stream
     
*/

    
int sum();

    
/**
     
* Returns an {@code OptionalInt} describing the minimum element of this
     
* stream, or an empty optional if this stream is empty.
  
This is a special
     
* case of a
 
<a href="package-summary.html#Reduction">reduction</a>
     
* and is equivalent to:
     
* <pre>{@code
     
*return reduce(Integer::min);
     
* }</pre>
     
*
     
* <p>This is a
 
<a href="package-summary.html#StreamOps">terminal operation</a>.
     
*
     
* @return an {@code OptionalInt} containing the minimum element of this
     
* stream, or an empty {@code OptionalInt} if the stream is empty
     
*/

    
OptionalInt min();

    
/**
     
* Returns an {@code OptionalInt} describing the maximum element of this
     
* stream, or an empty optional if this stream is empty.
  
This is a special
     
* case of a
 
<a href="package-summary.html#Reduction">reduction</a>
     
* and is equivalent to:
     
* <pre>{@code
     
*return reduce(Integer::max);
     
* }</pre>
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">terminal
     
* operation</a>.
     
*
     
* @return an {@code OptionalInt} containing the maximum element of this
     
* stream, or an empty {@code OptionalInt} if the stream is empty
     
*/

    
OptionalInt max();

    
/**
     
* Returns the count of elements in this stream.
  
This is a special case of
     
* a
 
<a href="package-summary.html#Reduction">reduction</a>
 
and is
     
* equivalent to:
     
* <pre>{@code
     
*return mapToLong(e -> 1L).sum();
     
* }</pre>
     
*
     
* <p>This is a
 
<a href="package-summary.html#StreamOps">terminal operation</a>.
     
*
     
* @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.
  
This is a
     
* special case of a
     
*
 
<a href="package-summary.html#Reduction">reduction</a>.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">terminal
     
* operation</a>.
     
*
     
* @return an {@code OptionalDouble} containing the average element of this
     
* stream, or an empty optional if the stream is empty
     
*/

    
OptionalDouble average();

    
/**
     
* Returns an {@code IntSummaryStatistics} describing various
     
* summary data about the elements of this stream.
  
This is a special
     
* case of a
 
<a href="package-summary.html#Reduction">reduction</a>.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">terminal
     
* operation</a>.
     
*
     
* @return an {@code IntSummaryStatistics} describing various summary data
     
* about the elements of this stream
     
*/

    
IntSummaryStatistics 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.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
     
* terminal operation</a>.
     
*
     
* @apiNote
     
* This method evaluates the <em>existential quantification</em> of the
     
* predicate over the elements of the stream (for some x P(x)).
     
*
     
* @param predicate a
 
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
                  
<a href="package-summary.html#Statelessness">stateless</a>
     
*
                  
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(IntPredicate 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.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
     
* terminal operation</a>.
     
*
     
* @apiNote
     
* This method evaluates the <em>universal quantification</em> of the
     
* predicate over the elements of the stream (for all x P(x)).
  
If the
     
* stream is empty, the quantification is said to be <em>vacuously
     
* satisfied</em> and is always {@code true} (regardless of P(x)).
     
*
     
* @param predicate a
 
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
                  
<a href="package-summary.html#Statelessness">stateless</a>
     
*
                  
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(IntPredicate 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.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
     
* terminal operation</a>.
     
*
     
* @apiNote
     
* This method evaluates the <em>universal quantification</em> of the
     
* negated predicate over the elements of the stream (for all x ~P(x)).
  
If
     
* the stream is empty, the quantification is said to be vacuously satisfied
     
* and is always {@code true}, regardless of P(x).
     
*
     
* @param predicate a
 
<a href="package-summary.html#NonInterference">non-interfering</a>,
     
*
                  
<a href="package-summary.html#Statelessness">stateless</a>
     
*
                  
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(IntPredicate predicate);

    
/**
     
* Returns an {@link OptionalInt} describing the first element of this
     
* stream, or an empty {@code OptionalInt} if the stream is empty.
  
If the
     
* stream has no encounter order, then any element may be returned.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
     
* terminal operation</a>.
     
*
     
* @return an {@code OptionalInt} describing the first element of this stream,
     
* or an empty {@code OptionalInt} if the stream is empty
     
*/

    
OptionalInt findFirst();

    
/**
     
* Returns an {@link OptionalInt} describing some element of the stream, or
     
* an empty {@code OptionalInt} if the stream is empty.
     
*
     
* <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
     
* terminal operation</a>.
     
*
     
* <p>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
 
 
instead.)
     
*
     
* @return an {@code OptionalInt} describing some element of this stream, or
     
* an empty {@code OptionalInt} if the stream is empty
     
*
 

     
*/

    
OptionalInt findAny();

    
/**
     
* Returns a {@code LongStream} consisting of the elements of this stream,
     
* converted to {@code long}.
     
*
     
* <p>This is an <a href="package-summary.html#StreamOps">intermediate
     
* operation</a>.
     
*
     
* @return a {@code LongStream} consisting of the elements of this stream,
     
* converted to {@code long}
     
*/

    
LongStream asLongStream();

    
/**
     
* Returns a {@code DoubleStream} consisting of the elements of this stream,
     
* converted to {@code double}.
     
*
     
* <p>This is an <a href="package-summary.html#StreamOps">intermediate
     
* operation</a>.
     
*
     
* @return a {@code DoubleStream} consisting of the elements of this stream,
     
* converted to {@code double}
     
*/

    
DoubleStream asDoubleStream();

    
/**
     
* Returns a {@code Stream} consisting of the elements of this stream,
     
* each boxed to an {@code Integer}.
     
*
     
* <p>This is an <a href="package-summary.html#StreamOps">intermediate
     
* operation</a>.
     
*
     
* @return a {@code Stream} consistent of the elements of this stream,
     
* each boxed to an {@code Integer}
     
*/

    
Stream<Integer> boxed();

    
@Override
    
IntStream sequential
();

    
@Override
    
IntStream parallel
();

    
@Override
    
PrimitiveIterator.OfInt iterator
();

    
@Override
    
Spliterator.OfInt spliterator
();

    
// Static factories

    
/**
     
* Returns a builder for an {@code IntStream}.
     
*
     
* @return a stream builder
     
*/

    
public static Builder builder() {
        
return new Streams.IntStreamBuilderImpl();
    
}

    
/**
     
* Returns an empty sequential {@code IntStream}.
     
*
     
* @return an empty sequential stream
     
*/

    
public static IntStream empty() {
        
return StreamSupport.intStream(Spliterators.emptyIntSpliterator(), false);
    
}

    
/**
     
* Returns a sequential {@code IntStream} containing a single element.
     
*
     
* @param t the single element
     
* @return a singleton sequential stream
     
*/

    
public static IntStream of(int t) {
        
return StreamSupport.intStream(new Streams.IntStreamBuilderImpl(t), false);
    
}

    
/**
     
* Returns a sequential ordered stream whose elements are the specified values.
     
*
     
* @param values the elements of the new stream
     
* @return the new stream
     
*/

    
public static IntStream of(int... values) {
        
return Arrays.stream(values);
    
}

    
/**
     
* Returns an infinite sequential ordered {@code IntStream} produced by iterative
     
* application of a function {@code f} to an initial element {@code seed},
     
* producing a {@code Stream} consisting of {@code seed}, {@code f(seed)},
     
* {@code f(f(seed))}, etc.
     
*
     
* <p>The first element (position {@code 0}) in the {@code IntStream} will be
     
* the provided {@code seed}.
  
For {@code n > 0}, the element at position
     
* {@code n}, will be the result of applying the function {@code f} to the
     
* element at position {@code n - 1}.
     
*
     
* @param seed the initial element
     
* @param f a function to be applied to the previous element to produce
     
*
          
a new element
     
* @return A new sequential {@code IntStream}
     
*/

    
public static IntStream iterate(final int seed, final IntUnaryOperator f) {
        
Objects.requireNonNull(f);
        
final PrimitiveIterator.OfInt iterator = new PrimitiveIterator.OfInt() {
            
int t = seed;

            
@Override
            
public boolean hasNext() {
                
return true;
            
}

            
@Override
            
public int nextInt() {
                
int v = t;
                
t = f.applyAsInt(t);
                
return v;
            
}
        
};
        
return StreamSupport.intStream(Spliterators.spliteratorUnknownSize(
                
iterator,
                
Spliterator.ORDERED | Spliterator.IMMUTABLE | Spliterator.NONNULL), false);
    
}

    
/**
     
* Returns an infinite sequential unordered stream where each element is
     
* generated by the provided {@code IntSupplier}.
  
This is suitable for
     
* generating constant streams, streams of random elements, etc.
     
*
     
* @param s the {@code IntSupplier} for generated elements
     
* @return a new infinite sequential unordered {@code IntStream}
     
*/

    
public static IntStream generate(IntSupplier s) {
        
Objects.requireNonNull(s);
        
return StreamSupport.intStream(
                
new StreamSpliterators.InfiniteSupplyingSpliterator.OfInt(Long.MAX_VALUE, s), false);
    
}

    
/**
     
* Returns a sequential ordered {@code IntStream} from {@code startInclusive}
     
* (inclusive) to {@code endExclusive} (exclusive) by an incremental step of
     
* {@code 1}.
     
*
     
* @apiNote
     
* <p>An equivalent sequence of increasing values can be produced
     
* sequentially using a {@code for} loop as follows:
     
* <pre>{@code
     
*for (int i = startInclusive; i < endExclusive ; i++) { ... }
     
* }</pre>
     
*
     
* @param startInclusive the (inclusive) initial value
     
* @param endExclusive the exclusive upper bound
     
* @return a sequential {@code IntStream} for the range of {@code int}
     
*
         
elements
     
*/

    
public static IntStream range(int startInclusive, int endExclusive) {
        
if (startInclusive >= endExclusive) {
            
return empty();
        
} else {
            
return StreamSupport.intStream(
                    
new Streams.RangeIntSpliterator(startInclusive, endExclusive, false), false);
        
}
    
}

    
/**
     
* Returns a sequential ordered {@code IntStream} from {@code startInclusive}
     
* (inclusive) to {@code endInclusive} (inclusive) by an incremental step of
     
* {@code 1}.
     
*
     
* @apiNote
     
* <p>An equivalent sequence of increasing values can be produced
     
* sequentially using a {@code for} loop as follows:
     
* <pre>{@code
     
*for (int i = startInclusive; i <= endInclusive ; i++) { ... }
     
* }</pre>
     
*
     
* @param startInclusive the (inclusive) initial value
     
* @param endInclusive the inclusive upper bound
     
* @return a sequential {@code IntStream} for the range of {@code int}
     
*
         
elements
     
*/

    
public static IntStream rangeClosed(int startInclusive, int endInclusive) {
        
if (startInclusive > endInclusive) {
            
return empty();
        
} else {
            
return StreamSupport.intStream(
                    
new Streams.RangeIntSpliterator(startInclusive, endInclusive, true), false);
        
}
    
}

    
/**
     
* Creates a lazily concatenated stream whose elements are all the
     
* elements of the first stream followed by all the elements of the
     
* second stream.
  
The resulting stream is ordered if both
     
* of the input streams are ordered, and parallel if either of the input
     
* streams is parallel.
  
When the resulting stream is closed, the close
     
* handlers for both input streams are invoked.
     
*
     
* @implNote
     
* Use caution when constructing streams from repeated concatenation.
     
* Accessing an element of a deeply concatenated stream can result in deep
     
* call chains, or even {@code StackOverflowException}.
     
*
     
* @param a the first stream
     
* @param b the second stream
     
* @return the concatenation of the two input streams
     
*/

    
public static IntStream concat(IntStream a, IntStream b) {
        
Objects.requireNonNull(a);
        
Objects.requireNonNull(b);

        
Spliterator.OfInt split = new Streams.ConcatSpliterator.OfInt(
                
a.spliterator(), b.spliterator());
        
IntStream stream = StreamSupport.intStream(split, a.isParallel() || b.isParallel());
        
return stream.onClose(Streams.composedClose(a, b));
    
}

    
/**
     
* A mutable builder for an {@code IntStream}.
     
*
     
* <p>A stream builder has a lifecycle, which starts in a building
     
* phase, during which elements can be added, and then transitions to a built
     
* phase, after which elements may not be added.
  
The built phase
     
* begins when the {@link #build()} method is called, which creates an
     
* ordered stream whose elements are the elements that were added to the
     
* stream builder, in the order they were added.
     
*
     
* @see IntStream#builder()
     
* @since 1.8
     
*/

    
public interface Builder extends IntConsumer {

        
/**
         
* Adds an element to the stream being built.
         
*
         
* @throws IllegalStateException if the builder has already transitioned
         
* to the built state
         
*/

        
@Override
        
void accept(int t);

        
/**
         
* Adds an element to the stream being built.
         
*
         
* @implSpec
         
* The default implementation behaves as if:
         
* <pre>{@code
         
*
     
accept(t)
         
*
     
return this;
         
* }</pre>
         
*
         
* @param t the element to add
         
* @return {@code this} builder
         
* @throws IllegalStateException if the builder has already transitioned
         
* to the built state
         
*/

        
default Builder add(int t) {
            
accept(t);
            
return this;
        
}

        
/**
         
* Builds the stream, transitioning this builder to the built state.
         
* An {@code IllegalStateException} is thrown if there are further
         
* attempts to operate on the builder after it has entered the built
         
* state.
         
*
         
* @return the built stream
         
* @throws IllegalStateException if the builder has already transitioned to
         
* the built state
         
*/

        
IntStream build();
    
}
}