/*******************************************************************************
* Copyright (c) 2009-2013 CWI
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* * Arnold Lankamp - Arnold.Lankamp@cwi.nl
* * Anya Helene Bagge - anya@ii.uib.no
*******************************************************************************/
package org.rascalmpl.parser.gtd.util;
import java.util.Iterator;
@SuppressWarnings("unchecked")
public class HashMap<K, V>{
private Entry<K, V>[] entries;
private int hashMask;
private int bitSize = 2;
private int threshold;
private int load;
public HashMap(){
super();
int nrOfEntries = 1 << bitSize;
hashMask = nrOfEntries - 1;
// Only 0.15% of uses actually have entries, so only allocate if needed (Anya, 2012-09-15)
entries = null;
threshold = nrOfEntries;
load = 0;
}
private void rehash(){
int nrOfEntries = 1 << (++bitSize);
int newHashMask = nrOfEntries - 1;
Entry<K, V>[] oldEntries = entries;
Entry<K, V>[] newEntries = new Entry[nrOfEntries];
Entry<K, V> currentEntryRoot = new Entry<K, V>(null, null, 0, null);
Entry<K, V> shiftedEntryRoot = new Entry<K, V>(null, null, 0, null);
int oldSize = oldEntries.length;
for(int i = oldSize - 1; i >= 0; --i){
Entry<K, V> e = oldEntries[i];
if(e != null){
Entry<K, V> lastCurrentEntry = currentEntryRoot;
Entry<K, V> lastShiftedEntry = shiftedEntryRoot;
int lastPosition = -1;
do{
int position = e.hash & newHashMask;
if(position == i){
if(position != lastPosition) lastCurrentEntry.next = e;
lastCurrentEntry = e;
}else{
if(position != lastPosition) lastShiftedEntry.next = e;
lastShiftedEntry = e;
}
e = e.next;
}while(e != null);
lastCurrentEntry.next = null;
lastShiftedEntry.next = null;
newEntries[i] = currentEntryRoot.next;
newEntries[i | oldSize] = shiftedEntryRoot.next;
}
}
threshold <<= 1;
entries = newEntries;
hashMask = newHashMask;
}
private void ensureCapacity(){
if(entries == null) {
entries = new Entry[1 << bitSize];
}
else if(load >= threshold){
rehash();
}
}
public V put(K key, V value){
ensureCapacity();
int hash = key.hashCode();
int position = hash & hashMask;
Entry<K, V> currentStartEntry = entries[position];
if(currentStartEntry != null){
Entry<K, V> entry = currentStartEntry;
do{
if(hash == entry.hash && entry.key.equals(key)){
V oldValue = entry.value;
entry.value = value;
return oldValue;
}
}while((entry = entry.next) != null);
}
entries[position] = new Entry<K, V>(key, value, hash, currentStartEntry);
++load;
return null;
}
public void putUnsafe(K key, V value){
ensureCapacity();
int hash = key.hashCode();
int position = hash & hashMask;
entries[position] = new Entry<K, V>(key, value, hash, entries[position]);
++load;
}
public V remove(K key){
if(entries == null)
return null;
int hash = key.hashCode();
int position = hash & hashMask;
Entry<K, V> previous = null;
Entry<K, V> currentStartEntry = entries[position];
if(currentStartEntry != null){
Entry<K, V> entry = currentStartEntry;
do{
if(hash == entry.hash && entry.key.equals(key)){
if(previous == null){
entries[position] = entry.next;
}else{
previous.next = entry.next;
}
--load;
return entry.value;
}
previous = entry;
}while((entry = entry.next) != null);
}
return null;
}
public V get(K key){
if(entries == null)
return null;
int hash = key.hashCode();
int position = hash & hashMask;
Entry<K, V> entry = entries[position];
while(entry != null){
if(hash == entry.hash && key.equals(entry.key)) return entry.value;
entry = entry.next;
}
return null;
}
public int size(){
return load;
}
public void clear(){
if(entries != null)
entries = new Entry[entries.length];
load = 0;
}
public Iterator<Entry<K, V>> entryIterator(){
return new EntryIterator<K, V>(this);
}
public Iterator<V> valueIterator(){
return new ValueIterator<K, V>(this);
}
private static class EntryIterator<K, V> implements Iterator<Entry<K, V>>{
private final Entry<K, V>[] data;
private Entry<K, V> current;
private int index;
public EntryIterator(HashMap<K, V> hashMap){
super();
data = hashMap.entries;
index = data.length - 1;
if(hashMap.entries != null)
current = new Entry<K, V>(null, null, -1, data[index]);
else
current = null;
locateNext();
}
private void locateNext(){
Entry<K, V> next = current.next;
if(next != null){
current = next;
return;
}
for(int i = index - 1; i >= 0 ; i--){
Entry<K, V> entry = data[i];
if(entry != null){
current = entry;
index = i;
return;
}
}
current = null;
index = 0;
}
public boolean hasNext(){
return (current != null);
}
public Entry<K, V> next(){
if(!hasNext()) throw new UnsupportedOperationException("There are no more elements in this iterator.");
Entry<K, V> entry = current;
locateNext();
return entry;
}
public void remove(){
throw new UnsupportedOperationException("This iterator doesn't support removal.");
}
}
private static class ValueIterator<K, V> implements Iterator<V>{
private final Entry<K, V>[] data;
private Entry<K, V> current;
private int index;
public ValueIterator(HashMap<K, V> hashMap){
super();
data = hashMap.entries;
index = data.length - 1;
if(data != null) {
current = new Entry<K, V>(null, null, -1, data[index]);
locateNext();
}
else
current = null;
}
private void locateNext(){
Entry<K, V> next = current.next;
if(next != null){
current = next;
return;
}
for(int i = index - 1; i >= 0 ; i--){
Entry<K, V> entry = data[i];
if(entry != null){
current = entry;
index = i;
return;
}
}
current = null;
index = 0;
}
public boolean hasNext(){
return (current != null);
}
public V next(){
if(!hasNext()) throw new UnsupportedOperationException("There are no more elements in this iterator.");
Entry<K, V> entry = current;
locateNext();
return entry.value;
}
public void remove(){
throw new UnsupportedOperationException("This iterator doesn't support removal.");
}
}
public static class Entry<K, V>{
public final int hash;
public final K key;
public V value;
public Entry<K, V> next;
public Entry(K key, V value, int hash, Entry<K, V> next){
super();
this.key = key;
this.value = value;
this.hash = hash;
this.next = next;
}
}
}