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Functional Java is an open source library that supports closures for the Java programming language
package fj.data;
import fj.Equal;
import fj.Hash;
import fj.Unit;
import static fj.Equal.anyEqual;
import static fj.Hash.anyHash;
import static fj.Unit.unit;
import java.util.Collection;
import java.util.Iterator;
/**
* A mutable hash set that guarantees uniqueness of its elements providing O(1) lookup.
*
* @version %build.number%
* @see HashMap
*/
public final class HashSet implements Iterable {
/**
* Returns an iterator for this hash set. This method exists to permit the use in a for-each loop.
*
* @return A iterator for this hash set.
*/
public Iterator iterator() {
return toCollection().iterator();
}
private final HashMap m;
/**
* Construct a hash set with the given equality and hashing strategy.
*
* @param e The equality strategy.
* @param h The hashing strategy.
*/
public HashSet(final Equal e, final Hash h) {
m = new HashMap<>(e, h);
}
/**
* Construct a hash set with the given equality and hashing strategy.
*
* @param e The equality strategy.
* @param h The hashing strategy.
* @param initialCapacity The initial capacity.
*/
public HashSet(final Equal e, final Hash h, final int initialCapacity) {
m = new HashMap<>(e, h, initialCapacity);
}
/**
* Construct a hash set with the given equality and hashing strategy.
*
* @param e The equality strategy.
* @param h The hashing strategy.
* @param initialCapacity The initial capacity.
* @param loadFactor The load factor.
*/
public HashSet(final Equal e, final Hash h, final int initialCapacity, final float loadFactor) {
m = new HashMap<>(e, h, initialCapacity, loadFactor);
}
/**
* Compare two values for equality using the underlying equality strategy.
*
* @param a1 One value to compare.
* @param a2 The other value to compare.
* @return true if the two values are equal, false otherwise.
*/
public boolean eq(final A a1, final A a2) {
return m.eq(a1, a2);
}
/**
* Compute the hash of the given value using the underlying hashing strategy.
*
* @param a The value to computer the hash of.
* @return The hash of the given value.
*/
public int hash(final A a) {
return m.hash(a);
}
/**
* Creates a new HashSet using the given Equal and Hash
*/
public static HashSet empty(final Equal e, final Hash h) {
return new HashSet<>(e, h);
}
/**
* Creates an empty HashSet
*/
public static HashSet empty() {
return empty(anyEqual(), anyHash());
}
/**
* Create a HashSet from the Iterable.
*/
public static HashSet iterableHashSet(final Iterable it) {
return iterableHashSet(anyEqual(), anyHash(), it);
}
/**
* Create a HashSet from the Iterable.
*/
public static HashSet iterableHashSet(final Equal e, final Hash h, final Iterable it) {
final HashSet hs = empty(e, h);
for (A a: it) {
hs.set(a);
}
return hs;
}
/**
* Create a HashSet from the Iterator.
*/
public static HashSet iteratorHashSet(final Iterator it) {
return iterableHashSet(() -> it);
}
/**
* Create a HashSet from the Iterator.
*/
public static HashSet iteratorHashSet(final Equal e, final Hash h, final Iterator it) {
return iterableHashSet(e, h, () -> it);
}
/**
* Create a HashSet from the array.
*/
@SafeVarargs
public static HashSet arrayHashSet(final A...as) {
return iterableHashSet(Array.array(as));
}
/**
* Create a HashSet from the array.
*/
@SafeVarargs
public static HashSet arrayHashSet(final Equal e, final Hash h, final A...as) {
return iterableHashSet(e, h, Array.array(as));
}
/**
* Create a HashSet from the array.
*/
@SafeVarargs
public static HashSet hashSet(final A...as) {
return arrayHashSet(as);
}
/**
* Create a HashSet from the array.
*/
@SafeVarargs
public static HashSet hashSet(final Equal e, final Hash h, final A...as) {
return arrayHashSet(e, h, as);
}
/**
* Determines if this hash set contains the given element.
*
* @param a The element to look for in this hash set.
* @return true if this hash set contains the given element, false otherwise.
*/
public boolean contains(final A a) {
return m.contains(a);
}
/**
* Insert the given element into this hash set.
*
* @param a The element to insert.
*/
public void set(final A a) {
m.set(a, unit());
}
/**
* Clear all elements from this hash set.
*/
public void clear() {
m.clear();
}
/**
* Determines if this hash set contains any elements.
*
* @return true if this hash set contains no elements, false otherwise.
*/
public boolean isEmpty() {
return m.isEmpty();
}
/**
* Returns the number of entries in this hash set.
*
* @return The number of entries in this hash set.
*/
public int size() {
return m.size();
}
/**
* Deletes the given element from this hash set.
*
* @param a The element to delete from this hash set.
* @return true if this hash set contained the given element prior to deletion, false
* otherwise.
*/
public boolean delete(final A a) {
return m.getDelete(a).isSome();
}
/**
* Returns a list projection of this hash set.
*
* @return A list projection of this hash set.
*/
public List toList() {
return m.keys();
}
public java.util.List toJavaList() {
return toList().toJavaList();
}
public java.util.Set toJavaSet() {
return new java.util.HashSet<>(toCollection());
}
public static HashSet fromSet(java.util.Set s) {
return iterableHashSet(s);
}
/**
* Projects an immutable collection of this hash set.
*
* @return An immutable collection of this hash set.
*/
public Collection toCollection() {
return toList().toCollection();
}
}