/*
* Primitive Collections for Java.
* Copyright (C) 2002 S�ren Bak
*
* 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 bak.pcj.set;
import bak.pcj.CharCollection;
import bak.pcj.CharIterator;
import bak.pcj.hash.CharHashFunction;
import bak.pcj.hash.DefaultCharHashFunction;
import bak.pcj.util.Exceptions;
import java.io.Serializable;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
/**
* This class represents open addressing hash table based sets of char values.
* Unlike the Java Collections <tt>HashSet</tt> instances of this class
* are not backed up by a map. It is implemented using a simple open addressing
* hash table where the keys are stored directly as entries.
*
* @see CharOpenHashSet
* @see java.util.HashSet
*
* @author Søren Bak
* @version 1.3 22-08-2003 20:19
* @since 1.0
*/
public class CharOpenHashSet extends AbstractCharSet implements CharSet, Cloneable, Serializable {
/** Constant indicating relative growth policy. */
private static final int GROWTH_POLICY_RELATIVE = 0;
/** Constant indicating absolute growth policy. */
private static final int GROWTH_POLICY_ABSOLUTE = 1;
/**
* The default growth policy of this set.
* @see #GROWTH_POLICY_RELATIVE
* @see #GROWTH_POLICY_ABSOLUTE
*/
private static final int DEFAULT_GROWTH_POLICY = GROWTH_POLICY_RELATIVE;
/** The default factor with which to increase the capacity of this set. */
public static final double DEFAULT_GROWTH_FACTOR = 1.0;
/** The default chunk size with which to increase the capacity of this set. */
public static final int DEFAULT_GROWTH_CHUNK = 10;
/** The default capacity of this set. */
public static final int DEFAULT_CAPACITY = 11;
/** The default load factor of this set. */
public static final double DEFAULT_LOAD_FACTOR = 0.75;
/**
* The hash function used to hash keys in this set.
* @serial
*/
private CharHashFunction keyhash;
/**
* The size of this set.
* @serial
*/
private int size;
/**
* The hash table backing up this set. Contains set values directly.
* Due to the use of a secondary hash function, the length of this
* array must be a prime.
*/
private transient char[] data;
/** The states of each cell in the keys[]. */
private transient byte[] states;
private static final byte EMPTY = 0;
private static final byte OCCUPIED = 1;
private static final byte REMOVED = 2;
/** The number of entries in use (removed or occupied). */
private transient int used;
/**
* The growth policy of this set (0 is relative growth, 1 is absolute growth).
* @serial
*/
private int growthPolicy;
/**
* The growth factor of this set, if the growth policy is
* relative.
* @serial
*/
private double growthFactor;
/**
* The growth chunk size of this set, if the growth policy is
* absolute.
* @serial
*/
private int growthChunk;
/**
* The load factor of this set.
* @serial
*/
private double loadFactor;
/**
* The next size at which to expand the keys[].
* @serial
*/
private int expandAt;
private CharOpenHashSet(CharHashFunction keyhash, int capacity, int growthPolicy, double growthFactor, int growthChunk, double loadFactor) {
if (keyhash == null)
Exceptions.nullArgument("hash function");
if (capacity < 0)
Exceptions.negativeArgument("capacity", String.valueOf(capacity));
if (growthFactor <= 0.0)
Exceptions.negativeOrZeroArgument("growthFactor", String.valueOf(growthFactor));
if (growthChunk <= 0)
Exceptions.negativeOrZeroArgument("growthChunk", String.valueOf(growthChunk));
if (loadFactor <= 0.0)
Exceptions.negativeOrZeroArgument("loadFactor", String.valueOf(loadFactor));
this.keyhash = keyhash;
capacity = bak.pcj.hash.Primes.nextPrime(capacity);
data = new char[capacity];
this.states = new byte[capacity];
size = 0;
expandAt = (int)Math.round(loadFactor*capacity);
used = 0;
this.growthPolicy = growthPolicy;
this.growthFactor = growthFactor;
this.growthChunk = growthChunk;
this.loadFactor = loadFactor;
}
private CharOpenHashSet(int capacity, int growthPolicy, double growthFactor, int growthChunk, double loadFactor) {
this(DefaultCharHashFunction.INSTANCE, capacity, growthPolicy, growthFactor, growthChunk, loadFactor);
}
/**
* Creates a new hash set with capacity 11, a relative
* growth factor of 1.0, and a load factor of 75%.
*/
public CharOpenHashSet() {
this(DEFAULT_CAPACITY);
}
/**
* Creates a new hash set with the same elements as a specified
* collection.
*
* @param c
* the collection whose elements to add to the new
* set.
*
* @throws NullPointerException
* if <tt>c</tt> is <tt>null</tt>.
*/
public CharOpenHashSet(CharCollection c) {
this();
addAll(c);
}
/**
* Creates a new hash set with the same elements as the specified
* array.
*
* @param a
* the array whose elements to add to the new
* set.
*
* @throws NullPointerException
* if <tt>a</tt> is <tt>null</tt>.
*
* @since 1.1
*/
public CharOpenHashSet(char[] a) {
this();
for (int i = 0; i < a.length; i++)
add(a[i]);
}
/**
* Creates a new hash set with a specified capacity, a relative
* growth factor of 1.0, and a load factor of 75%.
*
* @param capacity
* the initial capacity of the set.
*
* @throws IllegalArgumentException
* if <tt>capacity</tt> is negative.
*/
public CharOpenHashSet(int capacity) {
this(capacity, DEFAULT_GROWTH_POLICY, DEFAULT_GROWTH_FACTOR, DEFAULT_GROWTH_CHUNK, DEFAULT_LOAD_FACTOR);
}
/**
* Creates a new hash set with a capacity of 11, a relative
* growth factor of 1.0, and a specified load factor.
*
* @param loadFactor
* the load factor of the set.
*
* @throws IllegalArgumentException
* if <tt>loadFactor</tt> is negative or zero.
*/
public CharOpenHashSet(double loadFactor) {
this(DEFAULT_CAPACITY, DEFAULT_GROWTH_POLICY, DEFAULT_GROWTH_FACTOR, DEFAULT_GROWTH_CHUNK, loadFactor);
}
/**
* Creates a new hash set with a specified capacity and
* load factor, and a relative growth factor of 1.0.
*
* @param capacity
* the initial capacity of the set.
*
* @param loadFactor
* the load factor of the set.
*
* @throws IllegalArgumentException
* if <tt>capacity</tt> is negative;
* if <tt>loadFactor</tt> is not positive.
*/
public CharOpenHashSet(int capacity, double loadFactor) {
this(capacity, DEFAULT_GROWTH_POLICY, DEFAULT_GROWTH_FACTOR, DEFAULT_GROWTH_CHUNK, loadFactor);
}
/**
* Creates a new hash set with a specified capacity,
* load factor, and relative growth factor.
*
* <p>The set capacity increases to <tt>capacity()*(1+growthFactor)</tt>.
* This strategy is good for avoiding many capacity increases, but
* the amount of wasted memory is approximately the size of the set.
*
* @param capacity
* the initial capacity of the set.
*
* @param loadFactor
* the load factor of the set.
*
* @param growthFactor
* the relative amount with which to increase the
* the capacity when a capacity increase is needed.
*
* @throws IllegalArgumentException
* if <tt>capacity</tt> is negative;
* if <tt>loadFactor</tt> is not positive;
* if <tt>growthFactor</tt> is not positive.
*/
public CharOpenHashSet(int capacity, double loadFactor, double growthFactor) {
this(capacity, GROWTH_POLICY_RELATIVE, growthFactor, DEFAULT_GROWTH_CHUNK, loadFactor);
}
/**
* Creates a new hash set with a specified capacity,
* load factor, and absolute growth factor.
*
* <p>The set capacity increases to <tt>capacity()+growthChunk</tt>.
* This strategy is good for avoiding wasting memory. However, an
* overhead is potentially introduced by frequent capacity increases.
*
* @param capacity
* the initial capacity of the set.
*
* @param loadFactor
* the load factor of the set.
*
* @param growthChunk
* the absolute amount with which to increase the
* the capacity when a capacity increase is needed.
*
* @throws IllegalArgumentException
* if <tt>capacity</tt> is negative;
* if <tt>loadFactor</tt> is not positive;
* if <tt>growthChunk</tt> is not positive.
*/
public CharOpenHashSet(int capacity, double loadFactor, int growthChunk) {
this(capacity, GROWTH_POLICY_ABSOLUTE, DEFAULT_GROWTH_FACTOR, growthChunk, loadFactor);
}
// ---------------------------------------------------------------
// Constructors with hash function argument
// ---------------------------------------------------------------
/**
* Creates a new hash set with capacity 11, a relative
* growth factor of 1.0, and a load factor of 75%.
*
* @param keyhash
* the hash function to use when hashing keys.
*
* @throws NullPointerException
* if <tt>keyhash</tt> is <tt>null</tt>.
*/
public CharOpenHashSet(CharHashFunction keyhash) {
this(keyhash, DEFAULT_CAPACITY, DEFAULT_GROWTH_POLICY, DEFAULT_GROWTH_FACTOR, DEFAULT_GROWTH_CHUNK, DEFAULT_LOAD_FACTOR);
}
/**
* Creates a new hash set with a specified capacity, a relative
* growth factor of 1.0, and a load factor of 75%.
*
* @param keyhash
* the hash function to use when hashing keys.
*
* @param capacity
* the initial capacity of the set.
*
* @throws IllegalArgumentException
* if <tt>capacity</tt> is negative.
*
* @throws NullPointerException
* if <tt>keyhash</tt> is <tt>null</tt>.
*/
public CharOpenHashSet(CharHashFunction keyhash, int capacity) {
this(keyhash, capacity, DEFAULT_GROWTH_POLICY, DEFAULT_GROWTH_FACTOR, DEFAULT_GROWTH_CHUNK, DEFAULT_LOAD_FACTOR);
}
/**
* Creates a new hash set with a capacity of 11, a relative
* growth factor of 1.0, and a specified load factor.
*
* @param keyhash
* the hash function to use when hashing keys.
*
* @param loadFactor
* the load factor of the set.
*
* @throws IllegalArgumentException
* if <tt>loadFactor</tt> is negative or zero.
*
* @throws NullPointerException
* if <tt>keyhash</tt> is <tt>null</tt>.
*/
public CharOpenHashSet(CharHashFunction keyhash, double loadFactor) {
this(keyhash, DEFAULT_CAPACITY, DEFAULT_GROWTH_POLICY, DEFAULT_GROWTH_FACTOR, DEFAULT_GROWTH_CHUNK, loadFactor);
}
/**
* Creates a new hash set with a specified capacity and
* load factor, and a relative growth factor of 1.0.
*
* @param keyhash
* the hash function to use when hashing keys.
*
* @param capacity
* the initial capacity of the set.
*
* @param loadFactor
* the load factor of the set.
*
* @throws IllegalArgumentException
* if <tt>capacity</tt> is negative;
* if <tt>loadFactor</tt> is not positive.
*
* @throws NullPointerException
* if <tt>keyhash</tt> is <tt>null</tt>.
*/
public CharOpenHashSet(CharHashFunction keyhash, int capacity, double loadFactor) {
this(keyhash, capacity, DEFAULT_GROWTH_POLICY, DEFAULT_GROWTH_FACTOR, DEFAULT_GROWTH_CHUNK, loadFactor);
}
/**
* Creates a new hash set with a specified capacity,
* load factor, and relative growth factor.
*
* <p>The set capacity increases to <tt>capacity()*(1+growthFactor)</tt>.
* This strategy is good for avoiding many capacity increases, but
* the amount of wasted memory is approximately the size of the set.
*
* @param keyhash
* the hash function to use when hashing keys.
*
* @param capacity
* the initial capacity of the set.
*
* @param loadFactor
* the load factor of the set.
*
* @param growthFactor
* the relative amount with which to increase the
* the capacity when a capacity increase is needed.
*
* @throws IllegalArgumentException
* if <tt>capacity</tt> is negative;
* if <tt>loadFactor</tt> is not positive;
* if <tt>growthFactor</tt> is not positive.
*
* @throws NullPointerException
* if <tt>keyhash</tt> is <tt>null</tt>.
*/
public CharOpenHashSet(CharHashFunction keyhash, int capacity, double loadFactor, double growthFactor) {
this(keyhash, capacity, GROWTH_POLICY_RELATIVE, growthFactor, DEFAULT_GROWTH_CHUNK, loadFactor);
}
/**
* Creates a new hash set with a specified capacity,
* load factor, and absolute growth factor.
*
* @param keyhash
* the hash function to use when hashing keys.
*
* <p>The set capacity increases to <tt>capacity()+growthChunk</tt>.
* This strategy is good for avoiding wasting memory. However, an
* overhead is potentially introduced by frequent capacity increases.
*
* @param capacity
* the initial capacity of the set.
*
* @param loadFactor
* the load factor of the set.
*
* @param growthChunk
* the absolute amount with which to increase the
* the capacity when a capacity increase is needed.
*
* @throws IllegalArgumentException
* if <tt>capacity</tt> is negative;
* if <tt>loadFactor</tt> is not positive;
* if <tt>growthChunk</tt> is not positive.
*
* @throws NullPointerException
* if <tt>keyhash</tt> is <tt>null</tt>.
*/
public CharOpenHashSet(CharHashFunction keyhash, int capacity, double loadFactor, int growthChunk) {
this(keyhash, capacity, GROWTH_POLICY_ABSOLUTE, DEFAULT_GROWTH_FACTOR, growthChunk, loadFactor);
}
// ---------------------------------------------------------------
// Hash table management
// ---------------------------------------------------------------
private void ensureCapacity(int elements) {
if (elements >= expandAt) {
int newcapacity;
if (growthPolicy == GROWTH_POLICY_RELATIVE)
newcapacity = (int)(data.length * (1.0 + growthFactor));
else
newcapacity = data.length + growthChunk;
if (newcapacity*loadFactor < elements)
newcapacity = (int)Math.round(((double)elements/loadFactor));
newcapacity = bak.pcj.hash.Primes.nextPrime(newcapacity);
expandAt = (int)Math.round(loadFactor*newcapacity);
char[] newdata = new char[newcapacity];
byte[] newstates = new byte[newcapacity];
used = 0;
// re-hash
for (int i = 0; i < data.length; i++) {
if (states[i] == OCCUPIED) {
used++;
char v = data[i];
// first hash
int h = Math.abs(keyhash.hash(v));
int n = h % newcapacity;
if (newstates[n] == OCCUPIED) {
// second hash
int c = 1 + (h % (newcapacity - 2));
for (;;) {
n -= c;
if (n < 0)
n += newcapacity;
if (newstates[n] == EMPTY)
break;
}
}
newstates[n] = OCCUPIED;
newdata[n] = v;
}
}
data = newdata;
states = newstates;
}
}
// ---------------------------------------------------------------
// Operations not supported by abstract implementation
// ---------------------------------------------------------------
public boolean add(char v) {
ensureCapacity(used+1);
// first hash
int h = Math.abs(keyhash.hash(v));
int i = h % data.length;
if (states[i] == OCCUPIED) {
if (data[i] == v)
return false;
// second hash
int c = 1 + (h % (data.length - 2));
for (;;) {
i -= c;
if (i < 0)
i += data.length;
// Removed entries are re-used
if (states[i] == EMPTY || states[i] == REMOVED)
break;
if (states[i] == OCCUPIED && data[i] == v)
return false;
}
}
if (states[i] == EMPTY)
used++;
states[i] = OCCUPIED;
data[i] = v;
size++;
return true;
}
public CharIterator iterator() {
return new CharIterator() {
int nextEntry = nextEntry(0);
int lastEntry = -1;
int nextEntry(int index) {
while (index < data.length && states[index] != OCCUPIED)
index++;
return index;
}
public boolean hasNext() {
return nextEntry < data.length;
}
public char next() {
if (!hasNext())
Exceptions.endOfIterator();
lastEntry = nextEntry;
nextEntry = nextEntry(nextEntry+1);
return data[lastEntry];
}
public void remove() {
if (lastEntry == -1)
Exceptions.noElementToRemove();
states[lastEntry] = REMOVED;
size--;
lastEntry = -1;
}
};
}
public void trimToSize()
{ }
/**
* Returns a clone of this hash set.
*
* @return a clone of this hash set.
*
* @since 1.1
*/
public Object clone() {
try {
CharOpenHashSet c = (CharOpenHashSet)super.clone();
c.data = new char[data.length];
System.arraycopy(data, 0, c.data, 0, data.length);
c.states = new byte[data.length];
System.arraycopy(states, 0, c.states, 0, states.length);
return c;
} catch (CloneNotSupportedException e) {
Exceptions.cloning(); throw new RuntimeException();
}
}
// ---------------------------------------------------------------
// Operations overwritten for efficiency
// ---------------------------------------------------------------
public int size()
{ return size; }
public void clear() {
size = 0;
used = 0;
java.util.Arrays.fill(states, EMPTY);
}
public boolean contains(char v) {
int h = Math.abs(keyhash.hash(v));
int i = h % data.length;
if (states[i] != EMPTY) {
if (states[i] == OCCUPIED && data[i] == v)
return true;
// second hash
int c = 1 + (h % (data.length - 2));
for (;;) {
i -= c;
if (i < 0)
i += data.length;
if (states[i] == EMPTY)
return false;
if (states[i] == OCCUPIED && data[i] == v)
return true;
}
}
return false;
}
public int hashCode() {
int h = 0;
for (int i = 0; i < data.length; i++)
if (states[i] == OCCUPIED)
h += data[i];
return h;
}
public boolean remove(char v) {
int h = Math.abs(keyhash.hash(v));
int i = h % data.length;
if (states[i] != EMPTY) {
if (states[i] == OCCUPIED && data[i] == v) {
states[i] = REMOVED;
size--;
return true;
}
// second hash
int c = 1 + (h % (data.length - 2));
for (;;) {
i -= c;
if (i < 0)
i += data.length;
if (states[i] == EMPTY)
return false;
if (states[i] == OCCUPIED && data[i] == v) {
states[i] = REMOVED;
size--;
return true;
}
}
}
return false;
}
public char[] toArray(char[] a) {
if (a == null || a.length < size)
a = new char[size];
int p = 0;
for (int i = 0; i < data.length; i++)
if (states[i] == OCCUPIED)
a[p++] = data[i];
return a;
}
// ---------------------------------------------------------------
// Serialization
// ---------------------------------------------------------------
/**
* @serialData Default fields; the capacity of the
* set (<tt>int</tt>); the set's elements
* (<tt>char</tt>).
*
* @since 1.1
*/
private void writeObject(ObjectOutputStream s) throws IOException {
s.defaultWriteObject();
s.writeInt(data.length);
CharIterator i = iterator();
while (i.hasNext()) {
char x = i.next();
s.writeChar(x);
}
}
/**
* @since 1.1
*/
private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException {
s.defaultReadObject();
data = new char[s.readInt()];
states = new byte[data.length];
used = size;
for (int n = 0; n < size; n++) {
char v = s.readChar();
// first hash
int h = Math.abs(keyhash.hash(v));
int i = h % data.length;
if (states[i] == OCCUPIED) {
// second hash
int c = 1 + (h % (data.length - 2));
for (;;) {
i -= c;
if (i < 0)
i += data.length;
if (states[i] == EMPTY)
break;
}
}
states[i] = OCCUPIED;
data[i] = v;
}
}
}