squidpony.squidmath.OrderedSet<K>

All Implemented Interfaces:: Serializable, Cloneable, Iterable<K>, Collection<K>, Set<K>, SortedSet<K>

Direct Known Subclasses:: EnumOrderedSet

public class OrderedSet<K>
extends Object
implements SortedSet<K>, Serializable, Cloneable

A generic linked hash set with with a fast implementation, originally from fastutil as ObjectLinkedOpenHashSet but modified to support indexed access of items, reordering, and optional hash strategies for array keys (which fastutil does differently).

Instances of this class use a hash table to represent a set. The table is filled up to a specified load factor, and then doubled in size to accommodate new entries. If the table is emptied below one fourth of the load factor, it is halved in size. However, halving is not performed when deleting entries from an iterator, as it would interfere with the iteration process.

Note that clear() does not modify the hash table size. Rather, a family of trimming methods lets you control the size of the table; this is particularly useful if you reuse instances of this class.

Iterators generated by this set will enumerate elements in the same order in which they have been added to the set (addition of elements already present in the set does not change the iteration order). Note that this order has nothing in common with the natural order of the keys. The order is kept by means of an array list, represented via an IntVLA parallel to the table that can be modified with methods like shuffle(IRNG).

This class implements the interface of a sorted set, so to allow easy access of the iteration order: for instance, you can get the first element in iteration order with first() without having to create an iterator; however, this class partially violates the SortedSet contract because all subset methods throw an exception and comparator() returns always null.

Additional methods, such as addAndMoveToFirst(), make it easy to use instances of this class as a cache (e.g., with LRU policy).

This class allows approximately constant-time lookup of keys or values by their index in the ordering, which can allow some novel usage of the data structure. OrderedSet can be used like a list of unique elements, keeping order like a list does but also allowing rapid checks for whether an item exists in the OrderedSet, and OrderedMap can be used like that but with values associated as well (where OrderedSet uses contains(), OrderedMap uses containsKey()). You can also set the item at a position with addAt(Object, int), or alter an item while keeping index the same with alter(Object, Object). Reordering works here too, both with completely random orders from shuffle(IRNG) or with a previously-generated ordering from reorder(int...) (you can produce such an ordering for a given size and reuse it across multiple Ordered data structures with IRNG.randomOrdering(int)).

You can pass an CrossHash.IHasher instance such as CrossHash.generalHasher as an extra parameter to most of this class' constructors, which allows the OrderedSet to use arrays (usually primitive arrays) as items. If you expect only one type of array, you can use an instance like CrossHash.intHasher to hash int arrays, or the aforementioned generalHasher to hash most kinds of arrays (it can't handle most multi-dimensional arrays well). If you aren't using array items, you don't need to give an IHasher to the constructor and can ignore this feature.

Thank you, Sebastiano Vigna, for making FastUtil available to the public with such high quality.
See https://github.com/vigna/fastutil for the original library.

Author:: Sebastiano Vigna (responsible for all the hard parts), Tommy Ettinger (mostly responsible for squashing several layers of parent classes into one monster class)
See Also:: Serialized Form

Field Summary

Fields
Modifier and Type	Field	Description
`protected boolean`	`containsNull`	Whether this set contains the key zero.
`static int`	`DEFAULT_INITIAL_SIZE`	The initial default size of a hash table.
`static float`	`DEFAULT_LOAD_FACTOR`	The default load factor of a hash table.
`float`	`f`	The acceptable load factor.
`static float`	`FAST_LOAD_FACTOR`	The load factor for a (usually small) table that is meant to be particularly fast.
`protected CrossHash.IHasher`	`hasher`
`protected K[]`	`key`	The array of keys.
`protected int`	`mask`	The mask for wrapping a position counter.
`protected int`	`maxFill`	Threshold after which we rehash.
`protected int`	`n`	The current table size.
`protected IntVLA`	`order`	An IntVLA (variable-length int sequence) that stores the positions in the key array of specific keys, with the positions in insertion order.
`protected int`	`size`	Number of entries in the set (including the key zero, if present).
`static float`	`VERY_FAST_LOAD_FACTOR`	The load factor for a (usually very small) table that is meant to be extremely fast.

Constructor Summary

Constructors
Constructor	Description
`OrderedSet()`	Creates a new hash set with initial expected `DEFAULT_INITIAL_SIZE` elements and `DEFAULT_LOAD_FACTOR` as load factor.
`OrderedSet(int expected)`	Creates a new hash set with `DEFAULT_LOAD_FACTOR` as load factor.
`OrderedSet(int expected, float f)`	Creates a new hash map.
`OrderedSet(int expected, float f, CrossHash.IHasher hasher)`	Creates a new hash map.
`OrderedSet(int expected, CrossHash.IHasher hasher)`	Creates a new hash set with `DEFAULT_LOAD_FACTOR` as load factor.
`OrderedSet(Collection<? extends K> c)`	Creates a new hash set with `DEFAULT_LOAD_FACTOR` as load factor copying a given collection.
`OrderedSet(Collection<? extends K> c, float f)`	Creates a new hash set copying a given collection.
`OrderedSet(Collection<? extends K> c, float f, CrossHash.IHasher hasher)`	Creates a new hash set copying a given collection.
`OrderedSet(Collection<? extends K> c, CrossHash.IHasher hasher)`	Creates a new hash set with `DEFAULT_LOAD_FACTOR` as load factor copying a given collection.
`OrderedSet(Iterator<? extends K> i)`	Creates a new hash set with `DEFAULT_LOAD_FACTOR` as load factor using elements provided by a type-specific iterator.
`OrderedSet(Iterator<? extends K> i, float f)`	Creates a new hash set using elements provided by a type-specific iterator.
`OrderedSet(K[] a)`	Creates a new hash set with `DEFAULT_LOAD_FACTOR` as load factor copying the elements of an array.
`OrderedSet(K[] a, float f)`	Creates a new hash set copying the elements of an array.
`OrderedSet(K[] a, float f, CrossHash.IHasher hasher)`	Creates a new hash set copying the elements of an array.
`OrderedSet(K[] a, int offset, int length)`	Creates a new hash set with `DEFAULT_LOAD_FACTOR` as load factor and fills it with the elements of a given array.
`OrderedSet(K[] a, int offset, int length, float f)`	Creates a new hash set and fills it with the elements of a given array.
`OrderedSet(K[] a, int offset, int length, float f, CrossHash.IHasher hasher)`	Creates a new hash set and fills it with the elements of a given array.
`OrderedSet(K[] a, int offset, int length, CrossHash.IHasher hasher)`	Creates a new hash set with `DEFAULT_LOAD_FACTOR` as load factor and fills it with the elements of a given array.
`OrderedSet(K[] a, CrossHash.IHasher hasher)`	Creates a new hash set with `DEFAULT_LOAD_FACTOR` as load factor copying the elements of an array.
`OrderedSet(CrossHash.IHasher hasher)`	Creates a new hash set with `DEFAULT_LOAD_FACTOR` as load factor.

Method Summary

Modifier and Type	Method	Description
`boolean`	`add(K k)`
`boolean`	`addAll(Collection<? extends K> c)`
`boolean`	`addAll(K[] a)`
`boolean`	`addAndMoveToFirst(K k)`	Adds a key to the set; if the key is already present, it is moved to the first position of the iteration order.
`boolean`	`addAndMoveToLast(K k)`	Adds a key to the set; if the key is already present, it is moved to the last position of the iteration order.
`boolean`	`addAt(K k, int idx)`
`K`	`addOrGet(K k)`	Add a random element if not present, get the existing value if already present.
`boolean`	`alter(K original, K replacement)`	Changes a K, original, to another, replacement, while keeping replacement at the same point in the ordering.
`boolean`	`alterAt(int index, K replacement)`	Changes the K at the given index to replacement while keeping replacement at the same point in the ordering.
`static int`	`arraySize(int expected, float f)`	Returns the least power of two smaller than or equal to 2³⁰ and larger than or equal to `Math.ceil( expected / f )`.
`void`	`clear()`
`Object`	`clone()`	Returns a deep copy of this map.
`Comparator<? super K>`	`comparator()`
`boolean`	`contains(Object k)`
`boolean`	`containsAll(Collection<?> c)`	Checks whether this collection contains all elements from the given collection.
`boolean`	`equals(Object o)`
`K`	`first()`	Returns the first element of this set in iteration order.
`protected int`	`fixOrder(int i)`	Modifies the link vector so that the given entry is removed.
`protected void`	`fixOrder(int s, int d)`	Modifies the ordering for a shift from s to d.
`K`	`get(Object k)`	Returns the element of this set that is equal to the given key, or `null`.
`K`	`getAt(int idx)`	Gets the item at the given index in the iteration order in constant time (random-access).
`long`	`hash64()`
`int`	`hashCode()`	Returns a hash code for this set.
`SortedSet<K>`	`headSet(K to)`
`int`	`indexOf(Object k)`	Gets the position in the ordering of the given key, though not as efficiently as some data structures can do it (e.g.
`boolean`	`isEmpty()`
`ListIterator<K>`	`iterator()`
`K`	`last()`	Returns the last element of this set in iteration order.
`static int`	`maxFill(int n, float f)`	Returns the maximum number of entries that can be filled before rehashing.
`static long`	`maxFill(long n, float f)`	Returns the maximum number of entries that can be filled before rehashing.
`protected int`	`positionOf(Object k)`
`K`	`randomItem(IRNG rng)`	Gets a random value from this OrderedSet in constant time, using the given IRNG to generate a random number.
`protected void`	`rehash(int newN)`	Rehashes the map.
`protected boolean`	`rem(Object k)`
`boolean`	`remove(Object o)`
`boolean`	`removeAll(Collection<?> c)`	Remove from this collection all elements in the given collection.
`boolean`	`removeAt(int idx)`	Removes the item at the given index in the iteration order in not-exactly constant time (though it still should be efficient).
`K`	`removeFirst()`	Removes the first key in iteration order.
`K`	`removeLast()`	Removes the the last key in iteration order.
`OrderedSet<K>`	`reorder(int... ordering)`	Given an array or varargs of replacement indices for this OrderedSet's iteration order, reorders this so the first item in the returned version is the same as `getAt(ordering[0])` (with some care taken for negative or too-large indices), the second item in the returned version is the same as `getAt(ordering[1])`, etc.
`boolean`	`retainAll(Collection<?> c)`	Retains in this collection only elements from the given collection.
`void`	`reverse()`	Reverses the iteration order in linear time.
`protected void`	`shiftKeys(int pos)`	Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.
`OrderedSet<K>`	`shuffle(IRNG rng)`	Randomly alters the iteration order for this OrderedSet using the given IRNG to shuffle.
`int`	`size()`
`void`	`sort(Comparator<? super K> comparator)`	Sorts this whole OrderedSet using the supplied Comparator.
`void`	`sort(Comparator<? super K> comparator, int start, int end)`	Sorts a sub-range of this OrderedSet from what is currently the index `start` up to (but not including) the index `end`, using the supplied Comparator.
`SortedSet<K>`	`subSet(K from, K to)`
`boolean`	`swap(K left, K right)`	Swaps the positions in the ordering for the given items, if they are both present.
`boolean`	`swapIndices(int left, int right)`	Swaps the given indices in the ordering, if they are both ints between 0 and size.
`SortedSet<K>`	`tailSet(K from)`
`Object[]`	`toArray()`
`<T> T[]`	`toArray(T[] a)`
`String`	`toString()`
`boolean`	`trim()`	Rehashes the map, making the table as small as possible.
`boolean`	`trim(int n)`	Rehashes this map if the table is too large.

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream, toArray

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface java.util.SortedSet

spliterator

Field Details
- key
  
  protected K[] key
  
  The array of keys.
- mask
  
  protected int mask
  
  The mask for wrapping a position counter.
- containsNull
  
  protected boolean containsNull
  
  Whether this set contains the key zero.
- order
  
  protected IntVLA order
  
  An IntVLA (variable-length int sequence) that stores the positions in the key array of specific keys, with the positions in insertion order. The order can be changed with reorder(int...) and other methods.
- n
  
  protected int n
  
  The current table size.
- maxFill
  
  protected int maxFill
  
  Threshold after which we rehash. It must be the table size times f.
- size
  
  protected int size
  
  Number of entries in the set (including the key zero, if present).
- f
  
  public final float f
  
  The acceptable load factor.
- DEFAULT_INITIAL_SIZE
  
  public static final int DEFAULT_INITIAL_SIZE
  
  The initial default size of a hash table.
  
  See Also:
  
  Constant Field Values
- DEFAULT_LOAD_FACTOR
  
  public static final float DEFAULT_LOAD_FACTOR
  
  The default load factor of a hash table.
  
  See Also:
  
  Constant Field Values
- FAST_LOAD_FACTOR
  
  public static final float FAST_LOAD_FACTOR
  
  The load factor for a (usually small) table that is meant to be particularly fast.
  
  See Also:
  
  Constant Field Values
- VERY_FAST_LOAD_FACTOR
  
  public static final float VERY_FAST_LOAD_FACTOR
  
  The load factor for a (usually very small) table that is meant to be extremely fast.
  
  See Also:
  
  Constant Field Values
- hasher
  
  protected final CrossHash.IHasher hasher
Constructor Details
- OrderedSet
  
  public OrderedSet(int expected, float f)
  
  Creates a new hash map.
  
  The actual table size will be the least power of two greater than expected/f.
  
  Parameters:
  
  expected - the expected number of elements in the hash set.
  
  f - the load factor.
- OrderedSet
  
  public OrderedSet(int expected)
  
  Creates a new hash set with DEFAULT_LOAD_FACTOR as load factor.
  
  Parameters:
  
  expected - the expected number of elements in the hash set.
- OrderedSet
  
  public OrderedSet()
  
  Creates a new hash set with initial expected DEFAULT_INITIAL_SIZE elements and DEFAULT_LOAD_FACTOR as load factor.
- OrderedSet
  
  public OrderedSet(Collection<? extends K> c, float f)
  
  Creates a new hash set copying a given collection.
  
  Parameters:
  
  c - a Collection to be copied into the new hash set.
  
  f - the load factor.
- OrderedSet
  
  public OrderedSet(Collection<? extends K> c)
  
  Creates a new hash set with DEFAULT_LOAD_FACTOR as load factor copying a given collection.
  
  Parameters:
  
  c - a Collection to be copied into the new hash set.
- OrderedSet
  
  public OrderedSet(Iterator<? extends K> i, float f)
  
  Creates a new hash set using elements provided by a type-specific iterator.
  
  Parameters:
  
  i - a type-specific iterator whose elements will fill the set.
  
  f - the load factor.
- OrderedSet
  
  public OrderedSet(Iterator<? extends K> i)
  
  Creates a new hash set with DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.
  
  Parameters:
  
  i - a type-specific iterator whose elements will fill the set.
- OrderedSet
  
  public OrderedSet(K[] a, int offset, int length, float f)
  
  Creates a new hash set and fills it with the elements of a given array.
  
  Parameters:
  
  a - an array whose elements will be used to fill the set.
  
  offset - the first element to use.
  
  length - the number of elements to use.
  
  f - the load factor.
- OrderedSet
  
  public OrderedSet(K[] a, int offset, int length)
  
  Creates a new hash set with DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array.
  
  Parameters:
  
  a - an array whose elements will be used to fill the set.
  
  offset - the first element to use.
  
  length - the number of elements to use.
- OrderedSet
  
  public OrderedSet(K[] a, float f)
  
  Creates a new hash set copying the elements of an array.
  
  Parameters:
  
  a - an array to be copied into the new hash set.
  
  f - the load factor.
- OrderedSet
  
  public OrderedSet(K[] a)
  
  Creates a new hash set with DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.
  
  Parameters:
  
  a - an array to be copied into the new hash set.
- OrderedSet
  
  public OrderedSet(int expected, float f, CrossHash.IHasher hasher)
  
  Creates a new hash map.
  
  The actual table size will be the least power of two greater than expected/f.
  
  Parameters:
  
  expected - the expected number of elements in the hash set.
  
  f - the load factor.
  
  hasher - used to hash items; typically only needed when K is an array, where CrossHash has implementations
- OrderedSet
  
  public OrderedSet(CrossHash.IHasher hasher)
  
  Creates a new hash set with DEFAULT_LOAD_FACTOR as load factor.
  
  Parameters:
  
  hasher - used to hash items; typically only needed when K is an array, where CrossHash has implementations
- OrderedSet
  
  public OrderedSet(int expected, CrossHash.IHasher hasher)
  
  Creates a new hash set with DEFAULT_LOAD_FACTOR as load factor.
  
  Parameters:
  
  hasher - used to hash items; typically only needed when K is an array, where CrossHash has implementations
- OrderedSet
  
  public OrderedSet(Collection<? extends K> c, float f, CrossHash.IHasher hasher)
  
  Creates a new hash set copying a given collection.
  
  Parameters:
  
  c - a Collection to be copied into the new hash set.
  
  f - the load factor.
  
  hasher - used to hash items; typically only needed when K is an array, where CrossHash has implementations
- OrderedSet
  
  public OrderedSet(Collection<? extends K> c, CrossHash.IHasher hasher)
  
  Creates a new hash set with DEFAULT_LOAD_FACTOR as load factor copying a given collection.
  
  Parameters:
  
  c - a Collection to be copied into the new hash set.
  
  hasher - used to hash items; typically only needed when K is an array, where CrossHash has implementations
- OrderedSet
  
  public OrderedSet(K[] a, int offset, int length, float f, CrossHash.IHasher hasher)
  
  Creates a new hash set and fills it with the elements of a given array.
  
  Parameters:
  
  a - an array whose elements will be used to fill the set.
  
  offset - the first element to use.
  
  length - the number of elements to use.
  
  f - the load factor.
- OrderedSet
  
  public OrderedSet(K[] a, int offset, int length, CrossHash.IHasher hasher)
  
  Creates a new hash set with DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array.
  
  Parameters:
  
  a - an array whose elements will be used to fill the set.
  
  offset - the first element to use.
  
  length - the number of elements to use.
- OrderedSet
  
  public OrderedSet(K[] a, float f, CrossHash.IHasher hasher)
  
  Creates a new hash set copying the elements of an array.
  
  Parameters:
  
  a - an array to be copied into the new hash set.
  
  f - the load factor.
- OrderedSet
  
  public OrderedSet(K[] a, CrossHash.IHasher hasher)
  
  Creates a new hash set with DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.
  
  Parameters:
  
  a - an array to be copied into the new hash set.
Method Details
- addAll
  
  public boolean addAll(Collection<? extends K> c)
  
  Specified by:
  
  addAll in interface Collection<K>
  
  Specified by:
  
  addAll in interface Set<K>
- addAll
  
  public boolean addAll(K[] a)
- add
  
  public boolean add(K k)
  
  Specified by:
  
  add in interface Collection<K>
  
  Specified by:
  
  add in interface Set<K>
- addAt
  
  public boolean addAt(K k, int idx)
- addOrGet
  
  public K addOrGet(K k)
  Add a random element if not present, get the existing value if already present.
  This is equivalent to (but faster than) doing a:
  
  K exist = set.get(k); if (exist == null) { set.add(k); exist = k; }
- shiftKeys
  
  protected final void shiftKeys(int pos)
  
  Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.
  
  Parameters:
  
  pos - a starting position.
- rem
  
  protected boolean rem(Object k)
- remove
  
  public boolean remove(Object o)
  
  Specified by:
  
  remove in interface Collection<K>
  
  Specified by:
  
  remove in interface Set<K>
- removeFirst
  
  public K removeFirst()
  
  Removes the first key in iteration order.
  
  Returns:
  
  the first key.
  
  Throws:
  
  NoSuchElementException - is this set is empty.
- removeLast
  
  public K removeLast()
  
  Removes the the last key in iteration order.
  
  Returns:
  
  the last key.
  
  Throws:
  
  NoSuchElementException - is this set is empty.
- addAndMoveToFirst
  
  public boolean addAndMoveToFirst(K k)
  
  Adds a key to the set; if the key is already present, it is moved to the first position of the iteration order.
  
  Parameters:
  
  k - the key.
  
  Returns:
  
  true if the key was not present.
- addAndMoveToLast
  
  public boolean addAndMoveToLast(K k)
  
  Adds a key to the set; if the key is already present, it is moved to the last position of the iteration order.
  
  Parameters:
  
  k - the key.
  
  Returns:
  
  true if the key was not present.
- get
  
  public K get(Object k)
  
  Returns the element of this set that is equal to the given key, or null.
  
  Returns:
  
  the element of this set that is equal to the given key, or null.
- contains
  
  public boolean contains(Object k)
  
  Specified by:
  
  contains in interface Collection<K>
  
  Specified by:
  
  contains in interface Set<K>
- positionOf
  
  protected int positionOf(Object k)
- indexOf
  
  public int indexOf(Object k)
  
  Gets the position in the ordering of the given key, though not as efficiently as some data structures can do it (e.g. Arrangement can access ordering position very quickly but doesn't store other values on its own). Returns a value that is at least 0 if it found k, or -1 if k was not present.
  
  Parameters:
  
  k - a key or possible key that this should find the index of
  
  Returns:
  
  the index of k, if present, or -1 if it is not present in this OrderedSet
- swap
  
  public boolean swap(K left, K right)
  
  Swaps the positions in the ordering for the given items, if they are both present. Returns true if the ordering changed as a result of this call, or false if it stayed the same (which can be because left or right was not present, or because left and right are the same reference (so swapping would do nothing)).
  
  Parameters:
  
  left - an item that should be present in this OrderedSet
  
  right - an item that should be present in this OrderedSet
  
  Returns:
  
  true if this OrderedSet changed in ordering as a result of this call, or false otherwise
- swapIndices
  
  public boolean swapIndices(int left, int right)
  
  Swaps the given indices in the ordering, if they are both ints between 0 and size. Returns true if the ordering changed as a result of this call, or false if it stayed the same (which can be because left or right referred to an out-of-bounds index, or because left and right are equal (so swapping would do nothing)).
  
  Parameters:
  
  left - an index of an item in this OrderedSet, at least 0 and less than size()
  
  right - an index of an item in this OrderedSet, at least 0 and less than size()
  
  Returns:
  
  true if this OrderedSet changed in ordering as a result of this call, or false otherwise
- clear
  
  public void clear()
  
  Specified by:
  
  clear in interface Collection<K>
  
  Specified by:
  
  clear in interface Set<K>
- size
  
  public int size()
  
  Specified by:
  
  size in interface Collection<K>
  
  Specified by:
  
  size in interface Set<K>
- containsAll
  
  public boolean containsAll(Collection<?> c)
  
  Checks whether this collection contains all elements from the given collection.
  
  Specified by:
  
  containsAll in interface Collection<K>
  
  Specified by:
  
  containsAll in interface Set<K>
  
  Parameters:
  
  c - a collection.
  
  Returns:
  
  true if this collection contains all elements of the argument.
- retainAll
  
  public boolean retainAll(Collection<?> c)
  
  Retains in this collection only elements from the given collection.
  
  Specified by:
  
  retainAll in interface Collection<K>
  
  Specified by:
  
  retainAll in interface Set<K>
  
  Parameters:
  
  c - a collection.
  
  Returns:
  
  true if this collection changed as a result of the call.
- removeAll
  
  public boolean removeAll(Collection<?> c)
  
  Remove from this collection all elements in the given collection. If the collection is an instance of this class, it uses faster iterators.
  
  Specified by:
  
  removeAll in interface Collection<K>
  
  Specified by:
  
  removeAll in interface Set<K>
  
  Parameters:
  
  c - a collection.
  
  Returns:
  
  true if this collection changed as a result of the call.
- isEmpty
  
  public boolean isEmpty()
  
  Specified by:
  
  isEmpty in interface Collection<K>
  
  Specified by:
  
  isEmpty in interface Set<K>
- fixOrder
  
  protected int fixOrder(int i)
  
  Modifies the link vector so that the given entry is removed. This method will complete in linear time.
  
  Parameters:
  
  i - the index of an entry.
- fixOrder
  
  protected void fixOrder(int s, int d)
  
  Modifies the ordering for a shift from s to d.
  This method will complete in linear time or better.
  
  Parameters:
  
  s - the source position.
  
  d - the destination position.
- first
  
  public K first()
  
  Returns the first element of this set in iteration order.
  
  Specified by:
  
  first in interface SortedSet<K>
  
  Returns:
  
  the first element in iteration order.
- last
  
  public K last()
  
  Returns the last element of this set in iteration order.
  
  Specified by:
  
  last in interface SortedSet<K>
  
  Returns:
  
  the last element in iteration order.
- tailSet
  
  public SortedSet<K> tailSet(K from)
  
  Specified by:
  
  tailSet in interface SortedSet<K>
- headSet
  
  public SortedSet<K> headSet(K to)
  
  Specified by:
  
  headSet in interface SortedSet<K>
- subSet
  
  public SortedSet<K> subSet(K from, K to)
  
  Specified by:
  
  subSet in interface SortedSet<K>
- comparator
  
  public Comparator<? super K> comparator()
  
  Specified by:
  
  comparator in interface SortedSet<K>
- iterator
  
  public ListIterator<K> iterator()
  
  Specified by:
  
  iterator in interface Collection<K>
  
  Specified by:
  
  iterator in interface Iterable<K>
  
  Specified by:
  
  iterator in interface Set<K>
- trim
  
  public boolean trim()
  
  Rehashes the map, making the table as small as possible.
  
  This method rehashes the table to the smallest size satisfying the load factor. It can be used when the set will not be changed anymore, so to optimize access speed and size.
  
  If the table size is already the minimum possible, this method does nothing.
  
  Returns:
  
  true if there was enough memory to trim the map.
  
  See Also:
  
  trim(int)
- trim
  
  public boolean trim(int n)
  
  Rehashes this map if the table is too large.
  
  Let N be the smallest table size that can hold max(n,size()) entries, still satisfying the load factor. If the current table size is smaller than or equal to N, this method does nothing. Otherwise, it rehashes this map in a table of size N.
  
  This method is useful when reusing maps. Clearing a map leaves the table size untouched. If you are reusing a map many times, you can call this method with a typical size to avoid keeping around a very large table just because of a few large transient maps.
  
  Parameters:
  
  n - the threshold for the trimming.
  
  Returns:
  
  true if there was enough memory to trim the map.
  
  See Also:
  
  trim()
- rehash
  
  protected void rehash(int newN)
  
  Rehashes the map.
  
  This method implements the basic rehashing strategy, and may be overriden by subclasses implementing different rehashing strategies (e.g., disk-based rehashing). However, you should not override this method unless you understand the internal workings of this class.
  
  Parameters:
  
  newN - the new size
- clone
  
  public Object clone()
  
  Returns a deep copy of this map.
  
  This method performs a deep copy of this hash map; the data stored in the map, however, is not cloned. Note that this makes a difference only for object keys.
  
  Overrides:
  
  clone in class Object
  
  Returns:
  
  a deep copy of this map.
- hashCode
  
  public int hashCode()
  
  Returns a hash code for this set.
  This method overrides the generic method provided by the superclass. Since equals() is not overriden, it is important that the value returned by this method is the same value as the one returned by the overriden method.
  
  Specified by:
  
  hashCode in interface Collection<K>
  
  Specified by:
  
  hashCode in interface Set<K>
  
  Overrides:
  
  hashCode in class Object
  
  Returns:
  
  a hash code for this set.
- hash64
  
  public long hash64()
- maxFill
  
  public static int maxFill(int n, float f)
  
  Returns the maximum number of entries that can be filled before rehashing.
  
  Parameters:
  
  n - the size of the backing array.
  
  f - the load factor.
  
  Returns:
  
  the maximum number of entries before rehashing.
- maxFill
  
  public static long maxFill(long n, float f)
  
  Returns the maximum number of entries that can be filled before rehashing.
  
  Parameters:
  
  n - the size of the backing array.
  
  f - the load factor.
  
  Returns:
  
  the maximum number of entries before rehashing.
- arraySize
  
  public static int arraySize(int expected, float f)
  
  Returns the least power of two smaller than or equal to 2³⁰ and larger than or equal to Math.ceil( expected / f ).
  
  Parameters:
  
  expected - the expected number of elements in a hash table.
  
  f - the load factor.
  
  Returns:
  
  the minimum possible size for a backing array.
  
  Throws:
  
  IllegalArgumentException - if the necessary size is larger than 2³⁰.
- toArray
  
  public Object[] toArray()
  
  Specified by:
  
  toArray in interface Collection<K>
  
  Specified by:
  
  toArray in interface Set<K>
- toArray
  
  public <T> T[] toArray(T[] a)
  
  Specified by:
  
  toArray in interface Collection<K>
  
  Specified by:
  
  toArray in interface Set<K>
- toString
  
  public String toString()
  
  Overrides:
  
  toString in class Object
- equals
  
  public boolean equals(Object o)
  
  Specified by:
  
  equals in interface Collection<K>
  
  Specified by:
  
  equals in interface Set<K>
  
  Overrides:
  
  equals in class Object
- getAt
  
  public K getAt(int idx)
  
  Gets the item at the given index in the iteration order in constant time (random-access).
  
  Parameters:
  
  idx - the index in the iteration order of the key to fetch
  
  Returns:
  
  the key at the index, if the index is valid, otherwise null
- removeAt
  
  public boolean removeAt(int idx)
  
  Removes the item at the given index in the iteration order in not-exactly constant time (though it still should be efficient).
  
  Parameters:
  
  idx - the index in the iteration order of the item to remove
  
  Returns:
  
  true if this Set was changed as a result of this call, or false if nothing changed.
- randomItem
  
  public K randomItem(IRNG rng)
  
  Gets a random value from this OrderedSet in constant time, using the given IRNG to generate a random number.
  
  Parameters:
  
  rng - used to generate a random index for a value
  
  Returns:
  
  a random value from this OrderedSet
- shuffle
  
  public OrderedSet<K> shuffle(IRNG rng)
  
  Randomly alters the iteration order for this OrderedSet using the given IRNG to shuffle.
  
  Parameters:
  
  rng - used to generate a random ordering
  
  Returns:
  
  this for chaining
- reorder
  
  public OrderedSet<K> reorder(int... ordering)
  
  Given an array or varargs of replacement indices for this OrderedSet's iteration order, reorders this so the first item in the returned version is the same as getAt(ordering[0]) (with some care taken for negative or too-large indices), the second item in the returned version is the same as getAt(ordering[1]), etc.
  Negative indices are considered reversed distances from the end of ordering, so -1 refers to the same index as ordering[ordering.length - 1]. If ordering is smaller than size(), only the indices up to the length of ordering will be modified. If ordering is larger than size(), only as many indices will be affected as size(), and reversed distances are measured from the end of this Set's entries instead of the end of ordering. Duplicate values in ordering will produce duplicate values in the returned Set.
  This method modifies this OrderedSet in-place and also returns it for chaining.
  
  Parameters:
  
  ordering - an array or varargs of int indices, where the nth item in ordering changes the nth item in this Set to have the value currently in this Set at the index specified by the value in ordering
  
  Returns:
  
  this for chaining, after modifying it in-place
- alter
  
  public boolean alter(K original, K replacement)
  
  Changes a K, original, to another, replacement, while keeping replacement at the same point in the ordering.
  
  Parameters:
  
  original - a K value that will be removed from this Set if present, and its iteration index remembered
  
  replacement - another K value that will replace original at the remembered index
  
  Returns:
  
  true if the Set changed, or false if it didn't (such as if the two arguments are equal, or replacement was already in the Set but original was not)
- alterAt
  
  public boolean alterAt(int index, K replacement)
  
  Changes the K at the given index to replacement while keeping replacement at the same point in the ordering.
  
  Parameters:
  
  index - an index to replace the K item at
  
  replacement - another K value that will replace the original at the remembered index
  
  Returns:
  
  true if the Set changed, or false if it didn't (such as if the replacement was already present at the given index)
- sort
  
  public void sort(Comparator<? super K> comparator)
  
  Sorts this whole OrderedSet using the supplied Comparator.
  
  Parameters:
  
  comparator - a Comparator that can be used on the same type this uses for its keys (may need wildcards)
- sort
  
  public void sort(Comparator<? super K> comparator, int start, int end)
  
  Sorts a sub-range of this OrderedSet from what is currently the index start up to (but not including) the index end, using the supplied Comparator.
  
  Parameters:
  
  comparator - a Comparator that can be used on the same type this uses for its keys (may need wildcards)
  
  start - the first index of a key to sort (the index can change after this)
  
  end - the exclusive bound on the indices to sort; often this is just size()
- reverse
  
  public void reverse()
  
  Reverses the iteration order in linear time.

Class OrderedSet<K>