/*******************************************************************************
* ALMA - Atacama Large Millimeter Array
* Copyright (c) ESO - European Southern Observatory, 2011
* (in the framework of the ALMA collaboration).
* All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*******************************************************************************/
package com.cosylab.acs.maci.manager;
/**
* <p>A hash map that uses primitive ints for the key and values instead of objects.</p>
* NOTE: this implementatio is not synced, client has to care of that.
*
* <p>This implemenation is based on original java implementation.</p>
* @author <a href="mailto:matej.sekoranjaATcosylab.com">Matej Sekoranja</a>
* @version $id$
* @see java.util.HashMap
*/
public class IntHashMap {
/**
* The hash table data.
*/
private transient Entry table[];
/**
* The total number of entries in the hash table.
*/
private transient int count;
/**
* The table is rehashed when its size exceeds this threshold. (The
* value of this field is (int)(capacity * loadFactor).)
*
* @serial
*/
private int threshold;
/**
* The load factor for the hashtable.
*
* @serial
*/
private float loadFactor;
/**
* <p>Innerclass that acts as a datastructure to create a new entry in the
* table.</p>
*/
private static class Entry {
int hash;
int key;
int value;
Entry next;
/**
* <p>Create a new entry with the given values.</p>
*
* @param hash The code used to hash the object with
* @param key The key used to enter this in the table
* @param value The value for this key
* @param next A reference to the next entry in the table
*/
protected Entry(int hash, int key, int value, Entry next) {
initialize(hash, key, value, next);
}
/**
* <p>Set given values.</p>
*
* @param hash The code used to hash the object with
* @param key The key used to enter this in the table
* @param value The value for this key
* @param next A reference to the next entry in the table
*/
public void initialize(int hash, int key, int value, Entry next) {
this.hash = hash;
this.key = key;
this.value = value;
this.next = next;
}
}
/**
* <p>Constructs a new, empty hashtable with a default capacity and load
* factor, which is <code>20</code> and <code>0.75</code> respectively.</p>
*/
public IntHashMap() {
this(20, 0.75f);
}
/**
* <p>Constructs a new, empty hashtable with the specified initial capacity
* and default load factor, which is <code>0.75</code>.</p>
*
* @param initialCapacity the initial capacity of the hashtable.
* @throws IllegalArgumentException if the initial capacity is less
* than zero.
*/
public IntHashMap(int initialCapacity) {
this(initialCapacity, 0.75f);
}
/**
* <p>Constructs a new, empty hashtable with the specified initial
* capacity and the specified load factor.</p>
*
* @param initialCapacity the initial capacity of the hashtable.
* @param loadFactor the load factor of the hashtable.
* @throws IllegalArgumentException if the initial capacity is less
* than zero, or if the load factor is nonpositive.
*/
public IntHashMap(int initialCapacity, float loadFactor) {
super();
if (initialCapacity < 0) {
throw new IllegalArgumentException("Illegal Capacity: " + initialCapacity);
}
if (loadFactor <= 0) {
throw new IllegalArgumentException("Illegal Load: " + loadFactor);
}
if (initialCapacity == 0) {
initialCapacity = 1;
}
this.loadFactor = loadFactor;
table = new Entry[initialCapacity];
threshold = (int) (initialCapacity * loadFactor);
}
/**
* <p>Returns the number of keys in this hashtable.</p>
*
* @return the number of keys in this hashtable.
*/
public int size() {
return count;
}
/**
* <p>Tests if this hashtable maps no keys to values.</p>
*
* @return <code>true</code> if this hashtable maps no keys to values;
* <code>false</code> otherwise.
*/
public boolean isEmpty() {
return count == 0;
}
/**
* <p>Tests if some key maps into the specified value in this hashtable.
* This operation is more expensive than the <code>containsKey</code>
* method.</p>
*
* <p>Note that this method is identical in functionality to containsValue,
* (which is part of the Map interface in the collections framework).</p>
*
* @param value a value to search for.
* @return <code>true</code> if and only if some key maps to the
* <code>value</code> argument in this hashtable as
* determined by the <tt>equals</tt> method;
* <code>false</code> otherwise.
* @throws NullPointerException if the value is <code>null</code>.
* @see #containsKey(int)
* @see #containsValue(Object)
* @see java.util.Map
*/
public boolean contains(int value) {
Entry tab[] = table;
for (int i = tab.length; i-- > 0;) {
for (Entry e = tab[i]; e != null; e = e.next) {
if (e.value == value) {
return true;
}
}
}
return false;
}
/**
* <p>Returns <code>true</code> if this HashMap maps one or more keys
* to this value.</p>
*
* <p>Note that this method is identical in functionality to contains
* (which predates the Map interface).</p>
*
* @param value value whose presence in this HashMap is to be tested.
* @return boolean <code>true</code> if the value is contained
* @see java.util.Map
* @since JDK1.2
*/
public boolean containsValue(int value) {
return contains(value);
}
/**
* <p>Tests if the specified object is a key in this hashtable.</p>
*
* @param key possible key.
* @return <code>true</code> if and only if the specified object is a
* key in this hashtable, as determined by the <tt>equals</tt>
* method; <code>false</code> otherwise.
* @see #contains(Object)
*/
public boolean containsKey(int key) {
Entry tab[] = table;
int hash = key;
int index = (hash & 0x7FFFFFFF) % tab.length;
for (Entry e = tab[index]; e != null; e = e.next) {
if (e.hash == hash) {
return true;
}
}
return false;
}
/**
* <p>Returns the value to which the specified key is mapped in this map.</p>
*
* @param key a key in the hashtable.
* @return the value to which the key is mapped in this hashtable;
* <code>-1</code> if the key is not mapped to any value in
* this hashtable.
* @see #put(int, Object)
*/
public int get(int key) {
Entry tab[] = table;
int hash = key;
int index = (hash & 0x7FFFFFFF) % tab.length;
for (Entry e = tab[index]; e != null; e = e.next) {
if (e.hash == hash) {
return e.value;
}
}
return -1;
}
/**
* <p>Increases the capacity of and internally reorganizes this
* hashtable, in order to accommodate and access its entries more
* efficiently.</p>
*
* <p>This method is called automatically when the number of keys
* in the hashtable exceeds this hashtable's capacity and load
* factor.</p>
*/
protected void rehash() {
int oldCapacity = table.length;
Entry oldMap[] = table;
int newCapacity = oldCapacity * 2 + 1;
Entry newMap[] = new Entry[newCapacity];
threshold = (int) (newCapacity * loadFactor);
table = newMap;
for (int i = oldCapacity; i-- > 0;) {
for (Entry old = oldMap[i]; old != null;) {
Entry e = old;
old = old.next;
int index = (e.hash & 0x7FFFFFFF) % newCapacity;
e.next = newMap[index];
newMap[index] = e;
}
}
}
/**
* <p>Maps the specified <code>key</code> to the specified
* <code>value</code> in this hashtable. The key cannot be
* <code>null</code>. </p>
*
* <p>The value can be retrieved by calling the <code>get</code> method
* with a key that is equal to the original key.</p>
*
* @param key the hashtable key.
* @param value the value.
* @return the previous value of the specified key in this hashtable,
* or <code>-1</code> if it did not have one.
* @throws NullPointerException if the key is <code>null</code>.
* @see #get(int)
*/
public int put(int key, int value) {
// Makes sure the key is not already in the hashtable.
Entry tab[] = table;
int hash = key;
int index = (hash & 0x7FFFFFFF) % tab.length;
for (Entry e = tab[index]; e != null; e = e.next) {
if (e.hash == hash) {
int old = e.value;
e.value = value;
return old;
}
}
if (count >= threshold) {
// Rehash the table if the threshold is exceeded
rehash();
tab = table;
index = (hash & 0x7FFFFFFF) % tab.length;
}
// Creates the new entry.
Entry e = new Entry(hash, key, value, tab[index]);
tab[index] = e;
count++;
return -1;
}
/**
* <p>Removes the key (and its corresponding value) from this
* hashtable.</p>
*
* <p>This method does nothing if the key is not present in the
* hashtable.</p>
*
* @param key the key that needs to be removed.
* @return the value to which the key had been mapped in this hashtable,
* or <code>-1</code> if the key did not have a mapping.
*/
public int remove(int key) {
Entry tab[] = table;
int hash = key;
int index = (hash & 0x7FFFFFFF) % tab.length;
for (Entry e = tab[index], prev = null; e != null; prev = e, e = e.next) {
if (e.hash == hash) {
if (prev != null) {
prev.next = e.next;
} else {
tab[index] = e.next;
}
count--;
int oldValue = e.value;
e.next = null;
return oldValue;
}
}
return -1;
}
/**
* <p>Clears this hashtable so that it contains no keys.</p>
*/
public void clear() {
Entry tab[] = table;
for (int index = tab.length; --index >= 0;)
tab[index] = null;
count = 0;
}
/**
* <p>Copies values to array. Note that array capacity has to be large enough.</p>
* @param arr array to be filled
* @param array (new if given not large enough) of values.
*/
public int[] toArray(int[] arr) {
if (arr == null || arr.length < count) {
arr = new int[count];
}
int pos = 0;
Entry tab[] = table;
for (int i = tab.length; i-- > 0;)
for (Entry e = tab[i]; e != null; e = e.next)
arr[pos++] = e.value;
return arr;
}
}