com.ajjpj.afoundation.collection.immutable.ALongHashMap Maven / Gradle / Ivy
package com.ajjpj.afoundation.collection.immutable;
import com.ajjpj.afoundation.collection.AEquality;
import com.ajjpj.afoundation.function.AFunction1;
import java.io.Serializable;
import java.util.*;
/**
* This is an {@link com.ajjpj.afoundation.collection.immutable.AHashMap} that is specialized for keys of type long, i.e. primitive numbers rather than objects. It duplicates its API
* to support both efficient primitive 'long' values and generified 'Long's,
*
* @author arno
*/
public class ALongHashMap extends AbstractAMap {
private static final int LEVEL_INCREMENT = 10;
transient private Integer cachedHashcode = null; // intentionally not volatile: This class is immutable, so recalculating per thread works
private static final ALongHashMap EMPTY = new ALongHashMap ();
/**
* Returns an empty ALongHashMap instance. Calling this factory method instead of
* the constructor allows internal reuse of empty map instances since they are immutable.
*/
@SuppressWarnings("unchecked")
public static ALongHashMap empty() {
return EMPTY;
}
public static ALongHashMap fromJavaUtilMap(Map map) {
ALongHashMap result = empty ();
for(Map.Entry entry: map.entrySet()) {
result = result.updated(entry.getKey().longValue (), entry.getValue());
}
return result;
}
/**
* Returns an ALongHashMap initialized from separate 'keys' and 'values' collections. Both collections
* are iterated exactly once and are expected to have the same size.
*/
public static ALongHashMap fromKeysAndValues(Iterable keys, Iterable values) {
final Iterator ki = keys.iterator();
final Iterator vi = values.iterator();
ALongHashMap result = ALongHashMap.empty ();
while(ki.hasNext()) {
final Number key = ki.next();
final V value = vi.next();
result = result.updated(key.longValue (), value);
}
return result;
}
/**
* Returns an ALongHashMap instance initialized from a collection of
* keys and a function. For each element of the keys collection, the function is called once to
* determine the corresponding value, and the pair is then stored in the map.
*/
@SuppressWarnings("unused")
public static ALongHashMap fromKeysAndFunction(Iterable keys, AFunction1 f) throws E {
final Iterator ki = keys.iterator();
ALongHashMap result = empty ();
while(ki.hasNext()) {
final K key = ki.next();
final V value = f.apply(key);
result = result.updated(key.longValue (), value);
}
return result;
}
private ALongHashMap () {
}
@Override public AEquality keyEquality () {
return AEquality.NATURAL_ORDER;
}
@Override public AMap clear () {
return null;
}
@Override public int size() {
return 0;
}
public boolean containsKey(long key) {
return get(key).isDefined();
}
@Override public AOption get (Long key) {
return get (key.longValue ());
}
public AOption get(long key) {
return doGet(key, computeHash(key), 0);
}
@Override public V getRequired (Long key) {
return getRequired (key.longValue());
}
public V getRequired (long key) {
return get(key).get();
}
@Override public ALongHashMap updated (Long key, V value) {
return updated (key.longValue (), value);
}
public ALongHashMap updated (long key, V value) {
return doUpdated(key, computeHash(key), 0, value);
}
@Override public ALongHashMap removed (Long key) {
return removed (key.longValue ());
}
public ALongHashMap removed (long key) {
return doRemoved(key, computeHash(key), 0);
}
@Override
public Iterator> iterator() {
return new Iterator> () {
final ALongMapIterator inner = longIterator ();
@Override public boolean hasNext () {
return inner.hasNext ();
}
@Override public AMapEntry next () {
inner.next ();
return inner;
}
@Override public void remove () {
throw new UnsupportedOperationException ();
}
};
}
public ALongMapIterator longIterator() { //TODO test this - and all map iterator() implementations
return new LongIteratorImpl<> (this);
}
@Override public ASet keys() {
return new ALongHashSet (this);
}
/**
* @param level number of least significant bits of the hash to discard for local hash lookup. This mechanism
* is used to create a 64-way hash trie - level increases by 10 at each level
*/
AOption doGet(long key, long hash, int level) {
return AOption.none();
}
ALongHashMap doUpdated(long key, long hash, int level, V value) {
return new LongHashMap1<> (key, hash, value);
}
ALongHashMap doRemoved(long key, long hash, int level) {
return this;
}
private static long computeHash (long key) { //TODO better spread function?
long h = key;
h = h + ~(h << 18);
h = h ^ (h >>> 28);
h = h + (h << 8);
return h ^ (h >>> 20);
}
@SuppressWarnings("unchecked")
private static ALongHashMap[] createArray(int size) {
return new ALongHashMap[size];
}
@Override
public String toString() {
final StringBuilder result = new StringBuilder("{");
boolean first = true;
for(AMapEntry e: this) {
if(first) {
first = false;
}
else {
result.append(", ");
}
result.append(e.getKey ()).append("->").append(e.getValue());
}
result.append("}");
return result.toString();
}
/**
* very internal method. It assumes hash0 != hash1.
*/
private static LongHashTrieMap mergeLeafMaps (long hash0, ALongHashMap elem0, long hash1, ALongHashMap elem1, int level, int size) {
final int index0 = (int) ((hash0 >>> level) & 0x3f);
final int index1 = (int) ((hash1 >>> level) & 0x3f);
if(index0 != index1) {
final long bitmap = (1L << index0) | (1L << index1);
final ALongHashMap[] elems = createArray(2);
if(index0 < index1) {
elems[0] = elem0;
elems[1] = elem1;
}
else {
elems[0] = elem1;
elems[1] = elem0;
}
return new LongHashTrieMap<>(bitmap, elems, size);
}
else {
final ALongHashMap[] elems = createArray(1);
final long bitmap = (1L << index0);
// try again, based on the
elems[0] = mergeLeafMaps(hash0, elem0, hash1, elem1, level + LEVEL_INCREMENT, size);
return new LongHashTrieMap<>(bitmap, elems, size);
}
}
static class LongIteratorImpl implements ALongMapIterator { //TODO test this - and all 'iterator()' methods for all maps
private final Deque> stack = new ArrayDeque<> ();
private LongHashMap1 current;
LongIteratorImpl (ALongHashMap root) {
if (root.nonEmpty ()) {
stack.push (root);
}
}
@Override public boolean hasNext () {
return !stack.isEmpty ();
}
@Override public void next () {
ALongHashMap next;
try {
while (true) {
next = stack.pop ();
if (next.getClass () == LongHashMap1.class) {
current = (LongHashMap1) next;
break;
}
for (ALongHashMap child: ((LongHashTrieMap) next).elems) {
stack.push (child);
}
}
}
catch (Exception e) { // avoid the 'empty' check to put the penalty on the exceptional rather than the regular case
current = null;
throw new NoSuchElementException ();
}
}
@Override public long getLongKey () {
try {
return current.key;
}
catch (Exception e) { // avoid the 'null' check to put the penalty on the exceptional rather than the regular case
throw new NoSuchElementException ();
}
}
@Override public Long getKey () {
return getLongKey ();
}
@Override public V getValue () {
try {
return current.value;
}
catch (Exception e) { // avoid the 'null' check to put the penalty on the exceptional rather than the regular case
throw new NoSuchElementException ();
}
}
}
static class LongHashMap1 extends ALongHashMap {
private final long key;
private final long hash;
private final V value;
LongHashMap1(long key, long hash, V value) {
super();
this.key = key;
this.hash = hash;
this.value = value;
}
@Override public int size() {
return 1;
}
@Override AOption doGet(long key, long hash, int level) {
if(this.key == key) {
return AOption.some (value);
}
return AOption.none();
}
@Override ALongHashMap doUpdated(long key, long hash, int level, V value) {
if (key == this.key) {
if(this.value == value) {
return this;
}
else {
return new LongHashMap1<>(key, hash, value);
}
}
else {
// find a level where they don't collide
final ALongHashMap that = new LongHashMap1<>(key, hash, value);
return mergeLeafMaps(this.hash, this, hash, that, level, 2);
}
}
@Override ALongHashMap doRemoved(long key, long hash, int level) {
if (key == this.key) {
return empty();
}
else {
return this;
}
}
}
static class LongHashTrieMap extends ALongHashMap {
final long bitmap;
final ALongHashMap[] elems;
final int size;
LongHashTrieMap (long bitmap, ALongHashMap[] elems, int size) {
this.bitmap = bitmap;
this.elems = elems;
this.size = size;
}
@Override public int size() {
return size;
}
@Override
AOption doGet(long key, long hash, int level) {
final int index = (int) ((hash >>> level) & 0x3f);
if (bitmap == - 1) {
return elems[index & 0x3f].doGet(key, hash, level + LEVEL_INCREMENT);
}
final long mask = 1L << index;
if ((bitmap & mask) != 0) {
final int offset = Long.bitCount (bitmap & (mask - 1));
return elems[offset].doGet(key, hash, level + LEVEL_INCREMENT);
}
return AOption.none();
}
@Override ALongHashMap doUpdated(long key, long hash, int level, V value) {
final int index = (int) ((hash >>> level) & 0x3f);
final long mask = (1L << index);
final int offset = Long.bitCount(bitmap & (mask - 1));
if ((bitmap & mask) != 0) {
final ALongHashMap sub = elems[offset];
final ALongHashMap subNew = sub.doUpdated(key, hash, level + LEVEL_INCREMENT, value);
if(subNew == sub) {
return this;
}
else {
final ALongHashMap[] elemsNew = createArray(elems.length);
System.arraycopy(elems, 0, elemsNew, 0, elems.length);
elemsNew[offset] = subNew;
return new LongHashTrieMap<> (bitmap, elemsNew, size + (subNew.size() - sub.size()));
}
}
else {
final ALongHashMap[] elemsNew = createArray(elems.length + 1);
System.arraycopy(elems, 0, elemsNew, 0, offset);
elemsNew[offset] = new LongHashMap1<>(key, hash, value);
System.arraycopy(elems, offset, elemsNew, offset + 1, elems.length - offset);
return new LongHashTrieMap<>(bitmap | mask, elemsNew, size + 1);
}
}
@Override ALongHashMap doRemoved (long key, long hash, int level) {
final int index = (int) ((hash >>> level) & 0x3f);
final long mask = 1L << index;
final int offset = Long.bitCount (bitmap & (mask - 1));
if ((bitmap & mask) != 0) {
final ALongHashMap sub = elems[offset];
final ALongHashMap subNew = sub.doRemoved(key, hash, level + LEVEL_INCREMENT);
if (subNew == sub) {
return this;
}
else if (subNew.isEmpty()) {
final long bitmapNew = bitmap ^ mask;
if (bitmapNew != 0) {
final ALongHashMap[] elemsNew = createArray(elems.length - 1);
System.arraycopy(elems, 0, elemsNew, 0, offset);
System.arraycopy(elems, offset + 1, elemsNew, offset, elems.length - offset - 1);
final int sizeNew = size - sub.size();
if (elemsNew.length == 1 && ! (elemsNew[0] instanceof LongHashTrieMap)) {
return elemsNew[0];
}
else {
return new LongHashTrieMap<>(bitmapNew, elemsNew, sizeNew);
}
}
else {
return ALongHashMap.empty ();
}
}
else if(elems.length == 1 && ! (subNew instanceof LongHashTrieMap)) {
return subNew;
}
else {
final ALongHashMap[] elemsNew = createArray(elems.length);
System.arraycopy(elems, 0, elemsNew, 0, elems.length);
elemsNew[offset] = subNew;
final int sizeNew = size + (subNew.size() - sub.size());
return new LongHashTrieMap<>(bitmap, elemsNew, sizeNew);
}
} else {
return this;
}
}
}
}
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