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/*
* Copyright (C) 2002-2022 Sebastiano Vigna
*
* 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 it.unimi.dsi.fastutil.ints;
import java.util.Collection;
import static it.unimi.dsi.fastutil.Size64.sizeOf;
/** A type-specific {@link Collection}; provides some additional methods
* that use polymorphism to avoid (un)boxing.
*
* Additionally, this class defines strengthens (again) {@link #iterator()}.
*
*
This interface specifies reference equality semantics (members will be compared equal with
* {@code ==} instead of {@link Object#equals(Object) equals}), which may result in breaks in contract
* if attempted to be used with non reference-equality semantics based {@link Collection}s. For example, a
* {@code aReferenceCollection.equals(aObjectCollection)} may return different a different result then
* {@code aObjectCollection.equals(aReferenceCollection)}, in violation of {@link Object#equals equals}'s
* contract requiring it being symmetric.
*
* @see Collection
*/
public interface IntCollection extends Collection, IntIterable {
/** Returns a type-specific iterator on the elements of this collection.
*
* @apiNote This specification strengthens the one given in
* {@link java.lang.Iterable#iterator()}, which was already
* strengthened in the corresponding type-specific class,
* but was weakened by the fact that this interface extends {@link Collection}.
*
* @return a type-specific iterator on the elements of this collection.
*/
@Override
IntIterator iterator();
/** Returns a primitive iterator on the elements of this collection.
*
*
This method is identical to {@link #iterator()}, as the type-specific
* iterator is already compatible with the JDK's primitive iterators.
* It only exists for compatibility with the other primitive types' {@code Collection}s
* that have use for widened iterators.
*
* @return a primitive iterator on the elements of this collection.
* @since 8.5.0
*/
@Override
default IntIterator intIterator() { return iterator(); }
// If you change these default spliterator methods, you will likely need to update Iterable, List, Set, and SortedSet too
/** Returns a type-specific spliterator on the elements of this collection.
*
*
See {@link java.util.Collection#spliterator()} for more documentation on the requirements
* of the returned spliterator.
*
* @apiNote This specification strengthens the one given in
* {@link java.util.Collection#spliterator()}.
*
Also, this is generally the only {@code spliterator} method subclasses should override.
*
* @implSpec The default implementation returns a late-binding spliterator (see
* {@link java.util.Spliterator Spliterator} for documentation on what binding policies mean)
* that wraps this instance's type specific {@link #iterator}.
*
Additionally, it reports {@link java.util.Spliterator#SIZED Spliterator.SIZED}
*
* @implNote As this default implementation wraps the iterator, and {@link java.util.Iterator}
* is an inherently linear API, the returned spliterator will yield limited performance gains
* when run in parallel contexts, as the returned spliterator's
* {@link java.util.Spliterator#trySplit() trySplit()} will have linear runtime.
*
* @return a type-specific spliterator on the elements of this collection.
* @since 8.5.0
*/
@Override
default IntSpliterator spliterator() {
return IntSpliterators.asSpliterator(
iterator(), sizeOf(this), IntSpliterators.COLLECTION_SPLITERATOR_CHARACTERISTICS);
}
/** Returns a primitive spliterator on the elements of this collection.
*
*
This method is identical to {@link #spliterator()}, as the type-specific
* spliterator is already compatible with the JDK's primitive spliterators.
* It only exists for compatibility with the other primitive types' {@code Collection}s
* that have use for widened spliterators.
*
* @return a primitive spliterator on the elements of this collection.
* @since 8.5.0
*/
@Override
default IntSpliterator intSpliterator() { return spliterator(); }
/** Ensures that this collection contains the specified element (optional operation).
* @see Collection#add(Object)
*/
boolean add(int key);
/** Returns {@code true} if this collection contains the specified element.
* @see Collection#contains(Object)
*/
boolean contains(int key);
/** Removes a single instance of the specified element from this
* collection, if it is present (optional operation).
*
*
Note that this method should be called {@link java.util.Collection#remove(Object) remove()}, but the clash
* with the similarly named index-based method in the {@link java.util.List} interface
* forces us to use a distinguished name. For simplicity, the set interfaces reinstates
* {@code remove()}.
*
* @see Collection#remove(Object)
*/
boolean rem(int key);
/** {@inheritDoc}
* @deprecated Please use the corresponding type-specific method instead.
*/
@Deprecated
@Override
default boolean add(final Integer key) {
return add((key).intValue());
}
/** {@inheritDoc}
* @deprecated Please use the corresponding type-specific method instead.
*/
@Deprecated
@Override
default boolean contains(final Object key) {
if (key == null) return false;
return contains(((Integer)(key)).intValue());
}
/** {@inheritDoc}
* @deprecated Please use (and implement) the {@code rem()} method instead.
*/
@Deprecated
@Override
default boolean remove(final Object key) {
if (key == null) return false;
return rem(((Integer)(key)).intValue());
}
/** Returns a primitive type array containing the items of this collection.
* @return a primitive type array containing the items of this collection.
* @see Collection#toArray()
*/
int[] toIntArray();
/** Returns a primitive type array containing the items of this collection.
*
*
Note that, contrarily to {@link Collection#toArray(Object[])}, this
* methods just writes all elements of this collection: no special
* value will be added after the last one.
*
* @param a if this array is big enough, it will be used to store this collection.
* @return a primitive type array containing the items of this collection.
* @see Collection#toArray(Object[])
* @deprecated Please use {@code toArray()} instead—this method is redundant and will be removed in the future.
*/
@Deprecated
default int[] toIntArray(int a[]) {
return toArray(a);
}
/** Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.
*
*
Note that, contrarily to {@link Collection#toArray(Object[])}, this
* methods just writes all elements of this collection: no special
* value will be added after the last one.
*
* @param a if this array is big enough, it will be used to store this collection.
* @return a primitive type array containing the items of this collection.
* @see Collection#toArray(Object[])
*/
int[] toArray(int a[]);
/** Adds all elements of the given type-specific collection to this collection.
*
* @param c a type-specific collection.
* @see Collection#addAll(Collection)
* @return {@code true} if this collection changed as a result of the call.
*/
boolean addAll(IntCollection c);
/** Checks whether this collection contains all elements from the given type-specific collection.
*
* @param c a type-specific collection.
* @see Collection#containsAll(Collection)
* @return {@code true} if this collection contains all elements of the argument.
*/
boolean containsAll(IntCollection c);
/** Remove from this collection all elements in the given type-specific collection.
*
* @param c a type-specific collection.
* @see Collection#removeAll(Collection)
* @return {@code true} if this collection changed as a result of the call.
*/
boolean removeAll(IntCollection c);
/** {@inheritDoc}
* @deprecated Please use the corresponding type-specific method instead.
*/
@Deprecated
@Override
default boolean removeIf(final java.util.function.Predicate filter) {
return removeIf(
filter instanceof java.util.function.IntPredicate ?
((java.util.function.IntPredicate) filter) :
(java.util.function.IntPredicate) key -> filter.test(Integer.valueOf(key)));
}
/** Remove from this collection all elements which satisfy the given predicate.
*
* @param filter a predicate which returns {@code true} for elements to be
* removed.
* @see Collection#removeIf(java.util.function.Predicate)
* @return {@code true} if any elements were removed.
* @apiNote Implementing classes should generally override this method, and take the default
* implementation of the other overloads which will delegate to this method (after proper
* conversions).
*/
default boolean removeIf(final java.util.function.IntPredicate filter) {
java.util.Objects.requireNonNull(filter);
boolean removed = false;
final IntIterator each = iterator();
while (each.hasNext()) {
if (filter.test(each.nextInt())) {
each.remove();
removed = true;
}
}
return removed;
}
// Because our primitive Predicate interface extends both the JDK's primitive
// and object Predicate interfaces, calling this method with it would be ambiguous.
// This overload exists to pass it to the proper primitive overload.
/** Remove from this collection all elements which satisfy the given predicate.
*
*
WARNING: Overriding this method is almost always a mistake, as this
* overload only exists to disambiguate. Instead, override the {@code removeIf()} overload
* that uses the JDK's primitive predicate type (e.g. {@link java.util.function.IntPredicate}).
*
*
If Java supported final default methods, this would be one, but sadly it does not.
*
*
If you checked and are overriding the version with {@code java.util.function.XPredicate}, and
* still see this warning, then your IDE is incorrectly conflating this method with the proper
* method to override, and you can safely ignore this message.
*
* @param filter a predicate which returns {@code true} for elements to be
* removed.
* @see Collection#removeIf(java.util.function.Predicate)
* @return {@code true} if any elements were removed.
*/
default boolean removeIf(final IntPredicate filter) {
return removeIf((java.util.function.IntPredicate) filter);
}
/** Retains in this collection only elements from the given type-specific collection.
*
* @param c a type-specific collection.
* @see Collection#retainAll(Collection)
* @return {@code true} if this collection changed as a result of the call.
*/
boolean retainAll(IntCollection c);
/** {@inheritDoc}
* @deprecated Please use the corresponding type-specific method instead.
*/
@Deprecated
@Override
default java.util.stream.Stream stream() { return Collection.super.stream(); }
/** Return a primitive stream over the elements, performing widening casts if needed.
* @return a primitive stream over the elements.
* @see Collection#stream()
* @see java.util.stream.IntStream
*/
default java.util.stream.IntStream intStream() {
return java.util.stream.StreamSupport.intStream(intSpliterator(), false);
}
/** {@inheritDoc}
* @deprecated Please use the corresponding type-specific method instead.
*/
@Deprecated
@Override
default java.util.stream.Stream parallelStream() { return Collection.super.parallelStream(); }
/** Return a parallel primitive stream over the elements, performing widening casts if needed.
* @return a parallel primitive stream over the elements.
* @see Collection#parallelStream()
* @see java.util.stream.IntStream
*/
default java.util.stream.IntStream intParallelStream() {
return java.util.stream.StreamSupport.intStream(intSpliterator(), true);
}
}