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	/*
	* Copyright (c) 1998, 2018, 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
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	* 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
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	package java.util;

	/**
	* A {@link Set} that further provides a <i>total ordering</i> on its elements.
	* The elements are ordered using their {@linkplain Comparable natural
	* ordering}, or by a {@link Comparator} typically provided at sorted
	* set creation time. The set's iterator will traverse the set in
	* ascending element order. Several additional operations are provided
	* to take advantage of the ordering. (This interface is the set
	* analogue of {@link SortedMap}.)
	*
	* <p>All elements inserted into a sorted set must implement the {@code Comparable}
	* interface (or be accepted by the specified comparator). Furthermore, all
	* such elements must be <i>mutually comparable</i>: {@code e1.compareTo(e2)}
	* (or {@code comparator.compare(e1, e2)}) must not throw a
	* {@code ClassCastException} for any elements {@code e1} and {@code e2} in
	* the sorted set. Attempts to violate this restriction will cause the
	* offending method or constructor invocation to throw a
	* {@code ClassCastException}.
	*
	* <p>Note that the ordering maintained by a sorted set (whether or not an
	* explicit comparator is provided) must be <i>consistent with equals</i> if
	* the sorted set is to correctly implement the {@code Set} interface. (See
	* the {@code Comparable} interface or {@code Comparator} interface for a
	* precise definition of <i>consistent with equals</i>.) This is so because
	* the {@code Set} interface is defined in terms of the {@code equals}
	* operation, but a sorted set performs all element comparisons using its
	* {@code compareTo} (or {@code compare}) method, so two elements that are
	* deemed equal by this method are, from the standpoint of the sorted set,
	* equal. The behavior of a sorted set <i>is</i> well-defined even if its
	* ordering is inconsistent with equals; it just fails to obey the general
	* contract of the {@code Set} interface.
	*
	* <p>All general-purpose sorted set implementation classes should
	* provide four "standard" constructors: 1) A void (no arguments)
	* constructor, which creates an empty sorted set sorted according to
	* the natural ordering of its elements. 2) A constructor with a
	* single argument of type {@code Comparator}, which creates an empty
	* sorted set sorted according to the specified comparator. 3) A
	* constructor with a single argument of type {@code Collection},
	* which creates a new sorted set with the same elements as its
	* argument, sorted according to the natural ordering of the elements.
	* 4) A constructor with a single argument of type {@code SortedSet},
	* which creates a new sorted set with the same elements and the same
	* ordering as the input sorted set. There is no way to enforce this
	* recommendation, as interfaces cannot contain constructors.
	*
	* <p>Note: several methods return subsets with restricted ranges.
	* Such ranges are <i>half-open</i>, that is, they include their low
	* endpoint but not their high endpoint (where applicable).
	* If you need a <i>closed range</i> (which includes both endpoints), and
	* the element type allows for calculation of the successor of a given
	* value, merely request the subrange from {@code lowEndpoint} to
	* {@code successor(highEndpoint)}. For example, suppose that {@code s}
	* is a sorted set of strings. The following idiom obtains a view
	* containing all of the strings in {@code s} from {@code low} to
	* {@code high}, inclusive:<pre>
	* SortedSet<String> sub = s.subSet(low, high+"\0");</pre>
	*
	* A similar technique can be used to generate an <i>open range</i> (which
	* contains neither endpoint). The following idiom obtains a view
	* containing all of the Strings in {@code s} from {@code low} to
	* {@code high}, exclusive:<pre>
	* SortedSet<String> sub = s.subSet(low+"\0", high);</pre>
	*
	* <p>This interface is a member of the
	* <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
	* Java Collections Framework</a>.
	*
	* @param <E> the type of elements maintained by this set
	*
	* @author Josh Bloch
	* @see Set
	* @see TreeSet
	* @see SortedMap
	* @see Collection
	* @see Comparable
	* @see Comparator
	* @see ClassCastException
	* @since 1.2
	*/

	public interface SortedSet<E> extends Set<E> {
	/**
	* Returns the comparator used to order the elements in this set,
	* or {@code null} if this set uses the {@linkplain Comparable
	* natural ordering} of its elements.
	*
	* @return the comparator used to order the elements in this set,
	* or {@code null} if this set uses the natural ordering
	* of its elements
	*/
	Comparator<? super E> comparator();

	/**
	* Returns a view of the portion of this set whose elements range
	* from {@code fromElement}, inclusive, to {@code toElement},
	* exclusive. (If {@code fromElement} and {@code toElement} are
	* equal, the returned set is empty.) The returned set is backed
	* by this set, so changes in the returned set are reflected in
	* this set, and vice-versa. The returned set supports all
	* optional set operations that this set supports.
	*
	* <p>The returned set will throw an {@code IllegalArgumentException}
	* on an attempt to insert an element outside its range.
	*
	* @param fromElement low endpoint (inclusive) of the returned set
	* @param toElement high endpoint (exclusive) of the returned set
	* @return a view of the portion of this set whose elements range from
	* {@code fromElement}, inclusive, to {@code toElement}, exclusive
	* @throws ClassCastException if {@code fromElement} and
	* {@code toElement} cannot be compared to one another using this
	* set's comparator (or, if the set has no comparator, using
	* natural ordering). Implementations may, but are not required
	* to, throw this exception if {@code fromElement} or
	* {@code toElement} cannot be compared to elements currently in
	* the set.
	* @throws NullPointerException if {@code fromElement} or
	* {@code toElement} is null and this set does not permit null
	* elements
	* @throws IllegalArgumentException if {@code fromElement} is
	* greater than {@code toElement}; or if this set itself
	* has a restricted range, and {@code fromElement} or
	* {@code toElement} lies outside the bounds of the range
	*/
	SortedSet<E> subSet(E fromElement, E toElement);

	/**
	* Returns a view of the portion of this set whose elements are
	* strictly less than {@code toElement}. The returned set is
	* backed by this set, so changes in the returned set are
	* reflected in this set, and vice-versa. The returned set
	* supports all optional set operations that this set supports.
	*
	* <p>The returned set will throw an {@code IllegalArgumentException}
	* on an attempt to insert an element outside its range.
	*
	* @param toElement high endpoint (exclusive) of the returned set
	* @return a view of the portion of this set whose elements are strictly
	* less than {@code toElement}
	* @throws ClassCastException if {@code toElement} is not compatible
	* with this set's comparator (or, if the set has no comparator,
	* if {@code toElement} does not implement {@link Comparable}).
	* Implementations may, but are not required to, throw this
	* exception if {@code toElement} cannot be compared to elements
	* currently in the set.
	* @throws NullPointerException if {@code toElement} is null and
	* this set does not permit null elements
	* @throws IllegalArgumentException if this set itself has a
	* restricted range, and {@code toElement} lies outside the
	* bounds of the range
	*/
	SortedSet<E> headSet(E toElement);

	/**
	* Returns a view of the portion of this set whose elements are
	* greater than or equal to {@code fromElement}. The returned
	* set is backed by this set, so changes in the returned set are
	* reflected in this set, and vice-versa. The returned set
	* supports all optional set operations that this set supports.
	*
	* <p>The returned set will throw an {@code IllegalArgumentException}
	* on an attempt to insert an element outside its range.
	*
	* @param fromElement low endpoint (inclusive) of the returned set
	* @return a view of the portion of this set whose elements are greater
	* than or equal to {@code fromElement}
	* @throws ClassCastException if {@code fromElement} is not compatible
	* with this set's comparator (or, if the set has no comparator,
	* if {@code fromElement} does not implement {@link Comparable}).
	* Implementations may, but are not required to, throw this
	* exception if {@code fromElement} cannot be compared to elements
	* currently in the set.
	* @throws NullPointerException if {@code fromElement} is null
	* and this set does not permit null elements
	* @throws IllegalArgumentException if this set itself has a
	* restricted range, and {@code fromElement} lies outside the
	* bounds of the range
	*/
	SortedSet<E> tailSet(E fromElement);

	/**
	* Returns the first (lowest) element currently in this set.
	*
	* @return the first (lowest) element currently in this set
	* @throws NoSuchElementException if this set is empty
	*/
	E first();

	/**
	* Returns the last (highest) element currently in this set.
	*
	* @return the last (highest) element currently in this set
	* @throws NoSuchElementException if this set is empty
	*/
	E last();

	/**
	* Creates a {@code Spliterator} over the elements in this sorted set.
	*
	* <p>The {@code Spliterator} reports {@link Spliterator#DISTINCT},
	* {@link Spliterator#SORTED} and {@link Spliterator#ORDERED}.
	* Implementations should document the reporting of additional
	* characteristic values.
	*
	* <p>The spliterator's comparator (see
	* {@link java.util.Spliterator#getComparator()}) must be {@code null} if
	* the sorted set's comparator (see {@link #comparator()}) is {@code null}.
	* Otherwise, the spliterator's comparator must be the same as or impose the
	* same total ordering as the sorted set's comparator.
	*
	* @implSpec
	* The default implementation creates a
	* <em><a href="Spliterator.html#binding">late-binding</a></em> spliterator
	* from the sorted set's {@code Iterator}. The spliterator inherits the
	* <em>fail-fast</em> properties of the set's iterator. The
	* spliterator's comparator is the same as the sorted set's comparator.
	* <p>
	* The created {@code Spliterator} additionally reports
	* {@link Spliterator#SIZED}.
	*
	* @implNote
	* The created {@code Spliterator} additionally reports
	* {@link Spliterator#SUBSIZED}.
	*
	* @return a {@code Spliterator} over the elements in this sorted set
	* @since 1.8
	*/
	@Override
	default Spliterator<E> spliterator() {
	return new Spliterators.IteratorSpliterator<E>(
	this, Spliterator.DISTINCT \| Spliterator.SORTED \| Spliterator.ORDERED) {
	@Override
	public Comparator<? super E> getComparator() {
	return SortedSet.this.comparator();
	}
	};
	}
	}

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