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Functional Java is an open source library that supports closures for the Java programming language
package fj.data;
import fj.*;
import fj.function.Effect1;
import java.util.Collection;
import java.util.Iterator;
import static fj.P.p;
import static fj.data.Option.fromNull;
/**
* A mutable hash map providing O(1) lookup.
*
* @version %build.number%
* @see java.util.HashMap
*/
public final class HashMap implements Iterable {
private final class Key {
private final K k;
private final Equal e;
private final Hash h;
Key(final K k, final Equal e, final Hash h) {
this.k = k;
this.e = e;
this.h = h;
}
K k() {
return k;
}
@SuppressWarnings({"unchecked"})
public boolean equals(final Object o) {
return o instanceof Key && e.eq(k, (K) ((Key) o).k());
}
public int hashCode() {
return h.hash(k);
}
}
/**
* Returns an iterator for this map's keys. This method exists to permit the use in a for-each loop.
*
* @return A iterator for this map's keys.
*/
public Iterator iterator() {
return keys().iterator();
}
private final java.util.HashMap, V> m;
private final Equal e;
private final Hash h;
/**
* Construct a hash map with the given equality and hashing strategy.
*
* @param e The equality strategy.
* @param h The hashing strategy.
*/
public HashMap(final Equal e, final Hash h) {
m = new java.util.HashMap, V>();
this.e = e;
this.h = h;
}
public HashMap(java.util.Map map, final Equal e, final Hash h) {
this(e, h);
for (K key : map.keySet()) {
set(key, map.get(key));
}
}
/**
* Construct a hash map with the given equality and hashing strategy.
*
* @param e The equality strategy.
* @param h The hashing strategy.
* @param initialCapacity The initial capacity.
*/
public HashMap(final Equal e, final Hash h, final int initialCapacity) {
m = new java.util.HashMap, V>(initialCapacity);
this.e = e;
this.h = h;
}
public HashMap(java.util.Map map) {
this(map, Equal.anyEqual(), Hash.anyHash());
}
/**
* Construct a hash map 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 HashMap(final Equal e, final Hash h, final int initialCapacity, final float loadFactor) {
m = new java.util.HashMap, V>(initialCapacity, loadFactor);
this.e = e;
this.h = h;
}
/**
* Construct a hash map that uses {@link Object#equals} and {@link Object#hashCode}.
*
* @return A new hash map that uses {@link Object#equals} and {@link Object#hashCode}.
*/
public static HashMap hashMap() {
final Equal e = Equal.anyEqual();
final Hash h = Hash.anyHash();
return new HashMap(e, h);
}
/**
* Compare two key values for equality using the underlying equality strategy.
*
* @param k1 One key value to compare.
* @param k2 The other key value to compare.
* @return true if the two key values are equal, false otherwise.
*/
public boolean eq(final K k1, final K k2) {
return e.eq(k1, k2);
}
/**
* Compute the hash of the given key value using the underlying hashing strategy.
*
* @param k The key value to computer the hash of.
* @return The hash of the given key value.
*/
public int hash(final K k) {
return h.hash(k);
}
/**
* Returns a potential value that the given key maps to.
*
* @param k The key to look up in the hash map.
* @return A potential value for the given key.
*/
public Option get(final K k) {
return fromNull(m.get(new Key(k, e, h)));
}
/**
* A curried version of {@link #get(Object)}.
*
* @return A curried version of {@link #get(Object)}.
*/
public F> get() {
return new F>() {
public Option f(final K k) {
return get(k);
}
};
}
/**
* Clear all entries from this hash map.
*/
public void clear() {
m.clear();
}
/**
* Determines if the given key value exists in this hash map.
*
* @param k The key value to look for in this hash map.
* @return true if this hash map contains the given key, false otherwise.
*/
public boolean contains(final K k) {
return m.containsKey(new Key(k, e, h));
}
/**
* Returns all key entries in this hash map.
*
* @return All key entries in this hash map.
*/
public List keys() {
final List.Buffer b = new List.Buffer();
for (final Key k : m.keySet()) {
b.snoc(k.k());
}
return b.toList();
}
/**
* Returns all values in this hash map.
*
* @return All values in this hash map.
*/
public List values() {
return keys().map(new F() {
public V f(final K k) {
return m.get(new Key(k, e, h));
}
});
}
/**
* Determines if this hash map has any entries.
*
* @return true if this hash map has no entries, false otherwise.
*/
public boolean isEmpty() {
return m.isEmpty();
}
/**
* Returns the number of entries in this hash map.
*
* @return The number of entries in this hash map.
*/
public int size() {
return m.size();
}
/**
* Inserts the given key and value association into the hash map.
*
* @param k The key to insert.
* @param v The value to insert.
*/
public void set(final K k, final V v) {
if (v != null) {
m.put(new Key(k, e, h), v);
}
}
/**
* Deletes the entry in the hash map that corresponds to the given key.
*
* @param k The key to delete from this hash map.
*/
public void delete(final K k) {
m.remove(new Key(k, e, h));
}
/**
* Deletes the entry in the hash map that corresponds to the given key and returns any associated value.
*
* @param k The key to delete from this hash map.
* @return The value that was associated with the given key, if there was one.
*/
public Option getDelete(final K k) {
return fromNull(m.remove(new Key(k, e, h)));
}
public HashMap map(F keyFunction,
F valueFunction,
Equal equal, Hash hash) {
final HashMap hashMap = new HashMap(equal, hash);
for (K key : keys()) {
final A newKey = keyFunction.f(key);
final B newValue = valueFunction.f(get(key).some());
hashMap.set(newKey, newValue);
}
return hashMap;
}
public HashMap map(F keyFunction,
F valueFunction) {
return map(keyFunction, valueFunction, Equal.anyEqual(), Hash.anyHash());
}
public HashMap map(F, P2> function, Equal equal, Hash hash) {
return from(toStream().map(function), equal, hash);
}
public HashMap map(F, P2> function) {
return from(toStream().map(function));
}
public HashMap mapKeys(F keyFunction, Equal equal, Hash hash) {
return map(keyFunction, Function.identity(), equal, hash);
}
public HashMap mapKeys(F function) {
return mapKeys(function, Equal.anyEqual(), Hash.anyHash());
}
public HashMap mapValues(F function) {
return map(Function.identity(), function, e, h);
}
public void foreachDoEffect(Effect1> effect) {
toStream().foreachDoEffect(effect);
}
public void foreach(F, Unit> function) {
toStream().foreach(function);
}
public List> toList() {
return keys().map(k -> p(k, get(k).some()));
}
/**
* Projects an immutable collection of this hash map.
*
* @return An immutable collection of this hash map.
*/
public Collection> toCollection() {
return toList().toCollection();
}
public Stream> toStream() {
return toList().toStream();
}
public Option> toOption() {
return toList().toOption();
}
public Array> toArray() {
return toList().toArray();
}
public java.util.Map toMap() {
final java.util.HashMap result = new java.util.HashMap();
for (K key : keys()) {
result.put(key, get(key).some());
}
return result;
}
public static HashMap from(Iterable> entries) {
return from(entries, Equal.anyEqual(), Hash.anyHash());
}
public static HashMap from(Iterable> entries, Equal equal, Hash hash) {
final HashMap map = new HashMap(equal, hash);
for (P2 entry : entries) {
map.set(entry._1(), entry._2());
}
return map;
}
}