public class OrderedSet<K>
extends java.lang.Object
implements java.util.SortedSet<K>, java.io.Serializable, java.lang.Cloneable
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.
Modifier and Type | Field and 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 and Description |
---|
OrderedSet()
Creates a new hash set with initial expected
DEFAULT_INITIAL_SIZE elements and
DEFAULT_LOAD_FACTOR as load factor. |
OrderedSet(java.util.Collection<? extends K> c)
Creates a new hash set with
DEFAULT_LOAD_FACTOR as load
factor copying a given collection. |
OrderedSet(java.util.Collection<? extends K> c,
CrossHash.IHasher hasher)
Creates a new hash set with
DEFAULT_LOAD_FACTOR as load
factor copying a given collection. |
OrderedSet(java.util.Collection<? extends K> c,
float f)
Creates a new hash set copying a given collection.
|
OrderedSet(java.util.Collection<? extends K> c,
float f,
CrossHash.IHasher hasher)
Creates a new hash set copying a given collection.
|
OrderedSet(CrossHash.IHasher hasher)
Creates a new hash set with
DEFAULT_LOAD_FACTOR as load
factor. |
OrderedSet(int expected)
Creates a new hash set with
DEFAULT_LOAD_FACTOR as load
factor. |
OrderedSet(int expected,
CrossHash.IHasher hasher)
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(java.util.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(java.util.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,
CrossHash.IHasher hasher)
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,
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,
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.
|
Modifier and Type | Method and Description |
---|---|
boolean |
add(K k) |
boolean |
addAll(java.util.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() |
java.lang.Object |
clone()
Returns a deep copy of this map.
|
java.util.Comparator<? super K> |
comparator() |
boolean |
contains(java.lang.Object k) |
boolean |
containsAll(java.util.Collection<?> c)
Checks whether this collection contains all elements from the given
collection.
|
boolean |
equals(java.lang.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(java.lang.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.
|
java.util.SortedSet<K> |
headSet(K to) |
int |
indexOf(java.lang.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() |
java.util.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(java.lang.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(java.lang.Object k) |
boolean |
remove(java.lang.Object o) |
boolean |
removeAll(java.util.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(java.util.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(java.util.Comparator<? super K> comparator)
Sorts this whole OrderedSet using the supplied Comparator.
|
void |
sort(java.util.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. |
java.util.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.
|
java.util.SortedSet<K> |
tailSet(K from) |
java.lang.Object[] |
toArray() |
<T> T[] |
toArray(T[] a) |
java.lang.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.
|
protected K[] key
protected int mask
protected boolean containsNull
protected IntVLA order
reorder(int...)
and other methods.protected int n
protected int maxFill
f
.protected int size
public final float f
public static final int DEFAULT_INITIAL_SIZE
public static final float DEFAULT_LOAD_FACTOR
public static final float FAST_LOAD_FACTOR
public static final float VERY_FAST_LOAD_FACTOR
protected final CrossHash.IHasher hasher
public OrderedSet(int expected, float f)
The actual table size will be the least power of two greater than expected
/f
.
expected
- the expected number of elements in the hash set.f
- the load factor.public OrderedSet(int expected)
DEFAULT_LOAD_FACTOR
as load
factor.expected
- the expected number of elements in the hash set.public OrderedSet()
DEFAULT_INITIAL_SIZE
elements and
DEFAULT_LOAD_FACTOR
as load factor.public OrderedSet(java.util.Collection<? extends K> c, float f)
c
- a Collection
to be copied into the new hash set.f
- the load factor.public OrderedSet(java.util.Collection<? extends K> c)
DEFAULT_LOAD_FACTOR
as load
factor copying a given collection.c
- a Collection
to be copied into the new hash set.public OrderedSet(java.util.Iterator<? extends K> i, float f)
i
- a type-specific iterator whose elements will fill the set.f
- the load factor.public OrderedSet(java.util.Iterator<? extends K> i)
DEFAULT_LOAD_FACTOR
as load
factor using elements provided by a type-specific iterator.i
- a type-specific iterator whose elements will fill the set.public OrderedSet(K[] a, int offset, int length, float f)
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.public OrderedSet(K[] a, int offset, int length)
DEFAULT_LOAD_FACTOR
as load
factor and fills it with the elements of a given array.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.public OrderedSet(K[] a, float f)
a
- an array to be copied into the new hash set.f
- the load factor.public OrderedSet(K[] a)
DEFAULT_LOAD_FACTOR
as load
factor copying the elements of an array.a
- an array to be copied into the new hash set.public OrderedSet(int expected, float f, CrossHash.IHasher hasher)
The actual table size will be the least power of two greater than expected
/f
.
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 implementationspublic OrderedSet(CrossHash.IHasher hasher)
DEFAULT_LOAD_FACTOR
as load
factor.hasher
- used to hash items; typically only needed when K is an array, where CrossHash has implementationspublic OrderedSet(int expected, CrossHash.IHasher hasher)
DEFAULT_LOAD_FACTOR
as load
factor.hasher
- used to hash items; typically only needed when K is an array, where CrossHash has implementationspublic OrderedSet(java.util.Collection<? extends K> c, float f, CrossHash.IHasher hasher)
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 implementationspublic OrderedSet(java.util.Collection<? extends K> c, CrossHash.IHasher hasher)
DEFAULT_LOAD_FACTOR
as load
factor copying a given collection.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 implementationspublic OrderedSet(K[] a, int offset, int length, float f, CrossHash.IHasher hasher)
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.public OrderedSet(K[] a, int offset, int length, CrossHash.IHasher hasher)
DEFAULT_LOAD_FACTOR
as load
factor and fills it with the elements of a given array.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.public OrderedSet(K[] a, float f, CrossHash.IHasher hasher)
a
- an array to be copied into the new hash set.f
- the load factor.public OrderedSet(K[] a, CrossHash.IHasher hasher)
DEFAULT_LOAD_FACTOR
as load
factor copying the elements of an array.a
- an array to be copied into the new hash set.public boolean addAll(java.util.Collection<? extends K> c)
public boolean addAll(K[] a)
public boolean add(K k)
public boolean addAt(K k, int idx)
public K addOrGet(K k)
This is equivalent to (but faster than) doing a:
K exist = set.get(k); if (exist == null) { set.add(k); exist = k; }
protected final void shiftKeys(int pos)
pos
- a starting position.protected boolean rem(java.lang.Object k)
public boolean remove(java.lang.Object o)
public K removeFirst()
java.util.NoSuchElementException
- is this set is empty.public K removeLast()
java.util.NoSuchElementException
- is this set is empty.public boolean addAndMoveToFirst(K k)
k
- the key.public boolean addAndMoveToLast(K k)
k
- the key.public K get(java.lang.Object k)
null
.null
.public boolean contains(java.lang.Object k)
protected int positionOf(java.lang.Object k)
public int indexOf(java.lang.Object k)
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.k
- a key or possible key that this should find the index ofpublic boolean swap(K left, K right)
left
- an item that should be present in this OrderedSetright
- an item that should be present in this OrderedSetpublic boolean swapIndices(int left, int right)
public void clear()
public int size()
public boolean containsAll(java.util.Collection<?> c)
public boolean retainAll(java.util.Collection<?> c)
public boolean removeAll(java.util.Collection<?> c)
public boolean isEmpty()
protected int fixOrder(int i)
i
- the index of an entry.protected void fixOrder(int s, int d)
s
- the source position.d
- the destination position.public K first()
first
in interface java.util.SortedSet<K>
public K last()
last
in interface java.util.SortedSet<K>
public java.util.SortedSet<K> tailSet(K from)
tailSet
in interface java.util.SortedSet<K>
public java.util.SortedSet<K> headSet(K to)
headSet
in interface java.util.SortedSet<K>
public java.util.SortedSet<K> subSet(K from, K to)
subSet
in interface java.util.SortedSet<K>
public java.util.Comparator<? super K> comparator()
comparator
in interface java.util.SortedSet<K>
public java.util.ListIterator<K> iterator()
public boolean trim()
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.
trim(int)
public boolean trim(int n)
Let N be the smallest table size that can hold max(n,
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.
size()
)
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.
n
- the threshold for the trimming.trim()
protected void rehash(int newN)
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.
newN
- the new sizepublic java.lang.Object clone()
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.
clone
in class java.lang.Object
public int hashCode()
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.
public long hash64()
public static int maxFill(int n, float f)
n
- the size of the backing array.f
- the load factor.public static long maxFill(long n, float f)
n
- the size of the backing array.f
- the load factor.public static int arraySize(int expected, float f)
Math.ceil( expected / f )
.expected
- the expected number of elements in a hash table.f
- the load factor.java.lang.IllegalArgumentException
- if the necessary size is larger than 230.public java.lang.Object[] toArray()
public <T> T[] toArray(T[] a)
public java.lang.String toString()
toString
in class java.lang.Object
public boolean equals(java.lang.Object o)
public K getAt(int idx)
idx
- the index in the iteration order of the key to fetchpublic boolean removeAt(int idx)
idx
- the index in the iteration order of the item to removepublic K randomItem(IRNG rng)
rng
- used to generate a random index for a valuepublic OrderedSet<K> shuffle(IRNG rng)
rng
- used to generate a random orderingpublic OrderedSet<K> reorder(int... ordering)
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.
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.
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 orderingpublic boolean alter(K original, K replacement)
original
- a K value that will be removed from this Set if present, and its iteration index rememberedreplacement
- another K value that will replace original at the remembered indexpublic boolean alterAt(int index, K replacement)
index
- an index to replace the K item atreplacement
- another K value that will replace the original at the remembered indexpublic void sort(java.util.Comparator<? super K> comparator)
comparator
- a Comparator that can be used on the same type this uses for its keys (may need wildcards)public void sort(java.util.Comparator<? super K> comparator, int start, int end)
start
up to (but not including) the
index end
, using the supplied Comparator.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()
public void reverse()
Copyright © Eben Howard 2012–2022. All rights reserved.