in commons/src/main/java/org/apache/causeway/commons/collections/Can_Singleton.java [52:457]
record Can_Singleton<T>(T element) implements Can<T> {
@Override
public Optional<T> getSingleton() {
return Optional.of(element);
}
@Override
public Cardinality getCardinality() {
return Cardinality.ONE;
}
@Override
public Stream<T> stream() {
return Stream.of(element);
}
@Override
public Stream<T> parallelStream() {
return Stream.of(element);
}
@Override
public Optional<T> getFirst() {
return getSingleton();
}
@Override
public Optional<T> getLast() {
return getSingleton();
}
@Override
public Optional<T> get(final int elementIndex) {
return getSingleton();
}
@Override
public int size() {
return 1;
}
@Override
public boolean contains(final @Nullable T element) {
return Objects.equals(this.element, element);
}
@Override
public Iterator<T> iterator(final int skip, final int limit) {
return skip<1
&& limit>0
? iterator()
: Collections.<T>emptyList().iterator();
}
@Override
public Iterator<T> iterator() {
return Collections.singletonList(element).iterator();
}
@Override
public Can<T> sorted(final @NonNull Comparator<? super T> c) {
return this;
}
@Override
public Can<T> distinct() {
return this;
}
@Override
public Can<T> distinct(final @NonNull BiPredicate<T, T> equality) {
return this;
}
@Override
public Can<T> reverse() {
return this;
}
@Override
public Iterator<T> reverseIterator() {
return iterator();
}
@Override
public Can<T> reduce(final @NonNull BinaryOperator<T> accumulator) {
return this; // reduction of singleton acts as identity operation
}
@Override
public void forEach(final @NonNull Consumer<? super T> action) {
action.accept(this.element);
}
@Override
public Can<T> filter(final @Nullable Predicate<? super T> predicate) {
if(predicate==null) {
return this; // identity
}
return predicate.test(element)
? this // identity
: Can.empty();
}
@Override
public <R> void zip(final Iterable<R> zippedIn, final BiConsumer<? super T, ? super R> action) {
action.accept(element, zippedIn.iterator().next());
}
@Override
public <R, Z> Can<R> zipMap(final Iterable<Z> zippedIn, final BiFunction<? super T, ? super Z, R> mapper) {
var next = mapper.apply(element, zippedIn.iterator().next());
return next!=null
? new Can_Singleton<>(next)
: Can.empty();
}
@Override
public <R, Z> Stream<R> zipStream(final @NonNull Iterable<Z> zippedIn, final BiFunction<? super T, ? super Z, R> mapper) {
var next = mapper.apply(element, zippedIn.iterator().next());
return next!=null
? Stream.of(next)
: Stream.empty();
}
@Override
public Can<T> add(final @Nullable T element) {
return element!=null
? Can.ofStream(Stream.of(this.element, element)) // append
: this;
}
@Override
public Can<T> addAll(final @Nullable Can<T> other) {
if(other==null
|| other.isEmpty()) {
return this;
}
if(other.isCardinalityOne()) {
return add(other.getSingleton().orElseThrow(_Exceptions::unexpectedCodeReach));
}
var newElements = new ArrayList<T>(other.size()+1);
newElements.add(element);
other.forEach(newElements::add);
return _CanFactory.ofNonNullElements(newElements);
}
@Override
public Can<T> add(final int index, final @Nullable T element) {
if(element==null) {
return this; // no-op
}
if(index==0) {
return Can.ofStream(Stream.of(element, this.element)); // insert before
}
if(index==1) {
return Can.ofStream(Stream.of(this.element, element)); // append
}
throw new IndexOutOfBoundsException(
"cannot add to singleton with index other than 0 or 1; got " + index);
}
@Override
public Can<T> replace(final int index, final @Nullable T element) {
if(index!=0) {
throw new IndexOutOfBoundsException(
"cannot replace on singleton with index other than 0; got " + index);
}
return element!=null
? Can.ofSingleton(element)
: Can.empty();
}
@Override
public Can<T> remove(final int index) {
if(index==0) {
return Can.empty();
}
throw new IndexOutOfBoundsException(
"cannot remove from singleton with index other than 0; got " + index);
}
@Override
public Can<T> remove(final @Nullable T element) {
if(this.element.equals(element)) {
return Can.empty();
}
return this;
}
@Override
public Can<T> pickByIndex(final @Nullable int... indices) {
if(indices==null
||indices.length==0) {
return Can.empty();
}
int pickCount = 0; // actual size of the returned Can<T>
for(int index:indices) {
if(index==0) {
++pickCount;
}
}
if(pickCount==0) {
return Can.empty();
}
if(pickCount==1) {
return this;
}
var newElements = new ArrayList<T>(pickCount);
for(int i=0; i<pickCount; i++) {
newElements.add(element);
}
return _CanFactory.ofNonNullElements(newElements);
}
@Override
public Can<T> pickByIndex(final @Nullable IntStream intStream) {
if(intStream==null) {
return Can.empty();
}
final long pickCountL = intStream.filter(index->index==0).count();
if(pickCountL==0L) {
return Can.empty();
}
if(pickCountL==1L) {
return this;
}
if(pickCountL>Integer.MAX_VALUE) {
throw _Exceptions.illegalArgument("pickCount %d is too large to fit into an int", pickCountL);
}
final int pickCount = (int) pickCountL;
var newElements = new ArrayList<T>(pickCount);
for(int i=0; i<pickCount; i++) {
newElements.add(element);
}
return _CanFactory.ofNonNullElements(newElements);
}
@Override
public Can<T> subCan(final int startInclusive) {
return startInclusive <= 0
? this
: Can.empty();
}
@Override
public Can<T> subCan(final int startInclusive, final int endExclusive) {
if (startInclusive >= endExclusive) {
return Can.empty();
}
return (startInclusive<=0
&& endExclusive>0)
? this
: Can.empty();
}
@Override
public Can<Can<T>> partitionInnerBound(final int maxInnerSize) {
if(maxInnerSize<1) {
throw _Exceptions.illegalArgument("maxInnerSize %d must be greater or equal to 1", maxInnerSize);
}
// a singular always fits into a single slot
return Can.of(this);
}
@Override
public Can<Can<T>> partitionOuterBound(final int outerSizeYield) {
if(outerSizeYield<1) {
throw _Exceptions.illegalArgument("outerSizeYield %d must be greater or equal to 1", outerSizeYield);
}
// a singular always fits into a single slot
return Can.of(this);
}
@Override
public int indexOf(final @Nullable T element) {
return this.element.equals(element) ? 0 : -1;
}
@Override
public boolean anyMatch(final Predicate<? super T> predicate) {
return predicate.test(element);
}
@Override
public boolean allMatch(final Predicate<? super T> predicate) {
return predicate.test(element);
}
@Override
public String toString() {
return "Can["+element+"]";
}
@Override
public boolean equals(final Object obj) {
if(obj instanceof Can) {
return ((Can<?>) obj).isEqualTo(this);
}
return false;
}
@Override
public int hashCode() {
return element.hashCode();
}
@Override
public int compareTo(final @Nullable Can<T> other) {
// when returning
// -1 ... this (singleton) is before other
// +1 ... this (singleton) is after other
if(other==null
|| other.isEmpty()) {
return 1; // all empty Cans are same and come first
}
final int firstElementComparison = _Objects.compareNonNull(
this.element,
other.getFirstElseFail());
if(firstElementComparison!=0
|| other.isCardinalityOne()) {
return firstElementComparison; // when both Cans are singletons, just compare by their contained values
}
// at this point firstElementComparison is 0 and other is of cardinality MULTIPLE
return -1; // singletons come before multi-cans
}
@Override
public List<T> toList() {
return Collections.singletonList(element); // serializable and immutable
}
@Override
public List<T> toArrayList() {
var list = _Lists.<T>newArrayList();
list.add(element);
return list;
}
@Override
public Set<T> toSet() {
return Collections.singleton(element); // serializable and immutable
}
@Override
public Set<T> toSet(final @NonNull Consumer<T> onDuplicated) {
return Collections.singleton(element); // serializable and immutable
}
@Override
public T[] toArray(final @NonNull Class<T> elementType) {
var array = _Casts.<T[]>uncheckedCast(Array.newInstance(elementType, 1));
array[0] = element;
return array;
}
@Override
public <K> Map<K, T> toMap(
final @NonNull Function<? super T, ? extends K> keyExtractor) {
return Map.of(keyExtractor.apply(element), element);
}
@Override
public <K, M extends Map<K, T>> Map<K, T> toMap(
final @NonNull Function<? super T, ? extends K> keyExtractor,
final @NonNull BinaryOperator<T> mergeFunction,
final @NonNull Supplier<M> mapFactory) {
return toMap(keyExtractor);
}
@Override
public <R, A> R collect(final @NonNull Collector<? super T, A, R> collector) {
var container = collector.supplier().get();
collector.accumulator().accept(container, element);
return collector.finisher().apply(container);
}
@Override
public <K> Map<K, Can<T>> groupBy(
final @NonNull Function<? super T, ? extends K> classifier) {
return Map.of(classifier.apply(element), this);
}
@Override
public <K, M extends Map<K, Can<T>>> Map<K, Can<T>> groupBy(
final @NonNull Function<? super T, ? extends K> classifier,
final @NonNull Supplier<M> mapFactory) {
return groupBy(classifier);
}
@Override
public String join(final @NonNull String delimiter) {
var str = element.toString();
return str!=null
? str
: "";
}
@Override
public String join(final @NonNull Function<? super T, String> toStringFunction, final @NonNull String delimiter) {
var str = toStringFunction.apply(element);
return str!=null
? str
: "";
}
}