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Library providing immutable/persistent collection classes for
Java. While collections are immutable they provide methods for
adding and removing values by creating new modified copies of
themselves. Each copy shares almost all of its structure with
other copies to minimize memory consumption.
///###////////////////////////////////////////////////////////////////////////
//
// Burton Computer Corporation
// http://www.burton-computer.com
//
// Copyright (c) 2017, Burton Computer Corporation
// All rights reserved.
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//
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// notice, this list of conditions and the following disclaimer in
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package org.javimmutable.collections;
import javax.annotation.Nonnull;
import java.util.Iterator;
import java.util.Objects;
import java.util.Spliterator;
import java.util.function.Predicate;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
/**
* Interface for classes that can produce java.util.Streams and are also Iterable. The default stream
* creation implementations use spliterator().
*/
public interface IterableStreamable
extends SplitableIterable,
Streamable
{
/**
* Overridden here to require implementations to return a SplitableIterator rather than
* a basic Iterator. This is necessary to allow composition of new objects from methods
* like keys() and values().
*/
@Nonnull
@Override
SplitableIterator iterator();
/**
* @return characteristics value used when creating Spliterators
*/
int getSpliteratorCharacteristics();
/**
* Default implementation that creates a Spliterator from a newly created Iterator.
*/
@Nonnull
@Override
default Spliterator spliterator()
{
return iterator().spliterator(getSpliteratorCharacteristics());
}
@Nonnull
default Stream stream()
{
return StreamSupport.stream(spliterator(), false);
}
@Nonnull
default Stream parallelStream()
{
return StreamSupport.stream(spliterator(), true);
}
/**
* Count the total number of elements in iterator.
*
* @return total number of elements in iterator.
*/
default int count()
{
int answer = 0;
for (T ignored : this) {
answer += 1;
}
return answer;
}
/**
* Apply the predicate to every element in iterator order and return number of times
* predicate returned true.
*
* @param predicate test applied to each element
* @return number of times predicate returned true
*/
default int count(@Nonnull Predicate predicate)
{
int answer = 0;
for (T value : this) {
if (predicate.test(value)) {
answer += 1;
}
}
return answer;
}
/**
* Apply the predicate to every element in iterator order and return true if the
* predicate returns true for all elements. Iteration of elements stops immediately
* if predicate returns false. Returns true if there are no elements.
*
* @param predicate test to apply to each element
* @return true if no elements to process or predicate returned true for all elements, otherwise false
*/
default boolean allMatch(@Nonnull Predicate predicate)
{
for (T value : this) {
if (!predicate.test(value)) {
return false;
}
}
return true;
}
/**
* Apply the predicate to every element in iterator order and return true if the
* predicate returns true for any element. Iteration of elements stops immediately
* if predicate returns true. Returns false if there are no elements.
*
* @param predicate test to apply to each element
* @return false if no elements to process or predicate returned false for all elements, otherwise true
*/
default boolean anyMatch(@Nonnull Predicate predicate)
{
for (T value : this) {
if (predicate.test(value)) {
return true;
}
}
return false;
}
/**
* Apply the predicate to every element in iterator order until the predicate returns true.
*
* @param predicate test to apply to each element
* @return empty if predicate always returns false otherwise Holder containing value for which predicate returned true
*/
default Holder first(@Nonnull Predicate predicate)
{
for (T value : this) {
if (predicate.test(value)) {
return Holders.of(value);
}
}
return Holders.of();
}
/**
* Add all elements to the collection.
*
* @param collection collection to accumulate the values
* @return the collection after all elements have been processed
*/
default > C collect(@Nonnull C collection)
{
for (T value : this) {
collection = collection.insert(value);
}
return collection;
}
/**
* Add the first maxToCollect elements to the collection
*
* @param collection collection to accumulate the values
* @return the collection after all elements have been processed
*/
default > C collect(int maxToCollect,
@Nonnull C collection)
{
final Iterator iterator = iterator();
for (int i = 0; i < maxToCollect && iterator.hasNext(); ++i) {
collection = collection.insert(iterator.next());
}
return collection;
}
/**
* Apply the predicate to every element in iterator order and add any elements for which
* predicate returns true to the collection.
*
* @param collection collection to accumulate the values
* @param predicate predicate applied to each element
* @return the collection after all elements have been processed
*/
default > C collect(@Nonnull C collection,
@Nonnull Predicate predicate)
{
for (T value : this) {
if (predicate.test(value)) {
collection = collection.insert(value);
}
}
return collection;
}
/**
* Apply the predicate to every element in iterator order and add any elements for which
* predicate returns true to the collection. Iteration stops if maxToCollect values have
* been added to collection.
*
* @param collection collection to accumulate the values
* @param predicate predicate applied to each element
* @return the collection after all elements have been processed
*/
default > C collect(int maxToCollect,
@Nonnull C collection,
@Nonnull Predicate predicate)
{
final Iterator iterator = iterator();
while (maxToCollect > 0 && iterator.hasNext()) {
final T value = iterator.next();
if (predicate.test(value)) {
collection = collection.insert(value);
maxToCollect -= 1;
}
}
return collection;
}
/**
* Apply the transform function to all elements in iterator order and add each transformed
* value to the specified collection.
*
* @param collection collection to accumulate the transformed values
* @param transform transformation applied to each element
* @return the collection after all elements have been processed
*/
default > C transform(@Nonnull C collection,
@Nonnull Func1 transform)
{
for (T value : this) {
collection = collection.insert(transform.apply(value));
}
return collection;
}
/**
* Apply the transform function to all elements in iterator order and add the contents of
* non-empty Holders to the specified collection. Stops iteration and returns immediately
* if maxToCollect values have been added to the collection.
*
* @param maxToCollect maximum number of values to add to collection
* @param collection collection to accumulate the transformed values
* @param transform transformation applied to each element
* @return the collection after all elements have been processed
*/
default > C transform(int maxToCollect,
@Nonnull C collection,
@Nonnull Func1 transform)
{
final Iterator iterator = iterator();
while (maxToCollect > 0 && iterator.hasNext()) {
final T value = iterator.next();
collection = collection.insert(transform.apply(value));
maxToCollect -= 1;
}
return collection;
}
/**
* Apply the transform function to all elements in iterator order and add the contents of
* non-empty Holders to the specified collection.
*
* @param collection collection to accumulate the transformed values
* @param transform transformation applied to each element
* @return the collection after all elements have been processed
*/
default > C transformSome(@Nonnull C collection,
@Nonnull Func1> transform)
{
for (T value : this) {
Holder transformed = transform.apply(value);
if (transformed.isFilled()) {
collection = collection.insert(transformed.getValue());
}
}
return collection;
}
/**
* Apply the transform function to all elements in iterator order and add the contents of
* non-empty Holders to the specified collection. Stops iteration and returns immediately
* if maxToCollect values have been added to the collection.
*
* @param maxToCollect maximum number of values to add to collection
* @param collection collection to accumulate the transformed values
* @param transform transformation applied to each element
* @return the collection after all elements have been processed
*/
default > C transformSome(int maxToCollect,
@Nonnull C collection,
@Nonnull Func1> transform)
{
final Iterator iterator = iterator();
while (maxToCollect > 0 && iterator.hasNext()) {
final T value = iterator.next();
Holder transformed = transform.apply(value);
if (transformed.isFilled()) {
collection = collection.insert(transformed.getValue());
maxToCollect -= 1;
}
}
return collection;
}
/**
* Apply the predicate to all elements in iterator order and add the elements to
* the specified collections based on predicate return value. All elements for which predicate
* returns true are added to matched. All others are added to unmatched. Resulting
* collections are packaged into Partitions object and returned.
*
* @param matched collection to accumulate the matched elements
* @param unmatched collection to accumulate the unmatched elements
* @param predicate predicate applied to each element
* @return Partitions containing (matched,unmatched)
*/
default > Partitions partition(@Nonnull C matched,
@Nonnull C unmatched,
@Nonnull Predicate predicate)
{
for (T value : this) {
if (predicate.test(value)) {
matched = matched.insert(value);
} else {
unmatched = unmatched.insert(value);
}
}
return new Partitions<>(matched, unmatched);
}
/**
* Apply the specified accumulator to all elements in iterator order calling the accumulator function
* for each element. The first call to accumulator is passed the first element in the sequence.
* All remaining calls to accumulator are passed the result from the previous call.
*
* @param accumulator method called to compute result
* @return empty Holder if the sequence is empty, otherwise Holder containing result from last call to accumulator
*/
default Holder reduce(Func2 accumulator)
{
Iterator iterator = iterator();
if (!iterator.hasNext()) {
return Holders.of();
}
T answer = iterator.next();
while (iterator.hasNext()) {
answer = accumulator.apply(answer, iterator.next());
}
return Holders.of(answer);
}
class Partitions
{
private final T matched;
private final T unmatched;
public Partitions(T matched,
T unmatched)
{
this.matched = matched;
this.unmatched = unmatched;
}
public T getMatched()
{
return matched;
}
public T getUnmatched()
{
return unmatched;
}
@Override
public boolean equals(Object o)
{
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Partitions that = (Partitions)o;
return Objects.equals(matched, that.matched) &&
Objects.equals(unmatched, that.unmatched);
}
@Override
public int hashCode()
{
return Objects.hash(matched, unmatched);
}
}
}