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The Trove library provides high speed regular and primitive
collections for Java.
///////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2001, Eric D. Friedman All Rights Reserved.
// Copyright (c) 2009, Rob Eden All Rights Reserved.
// Copyright (c) 2009, Jeff Randall 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 General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
///////////////////////////////////////////////////////////////////////////////
package gnu.trove.impl.hash;
import gnu.trove.procedure.TByteProcedure;
import gnu.trove.impl.HashFunctions;
import gnu.trove.impl.Constants;
import java.util.Arrays;
//////////////////////////////////////////////////
// THIS IS A GENERATED CLASS. DO NOT HAND EDIT! //
//////////////////////////////////////////////////
/**
* An open addressed hashing implementation for byte primitives.
*
* Created: Sun Nov 4 08:56:06 2001
*
* @author Eric D. Friedman, Rob Eden, Jeff Randall
* @version $Id: _E_Hash.template,v 1.1.2.6 2009/11/07 03:36:44 robeden Exp $
*/
abstract public class TByteHash extends TPrimitiveHash {
static final long serialVersionUID = 1L;
/** the set of bytes */
public transient byte[] _set;
/**
* value that represents null
*
* NOTE: should not be modified after the Hash is created, but is
* not final because of Externalization
*
*/
protected byte no_entry_value;
protected boolean consumeFreeSlot;
/**
* Creates a new TByteHash instance with the default
* capacity and load factor.
*/
public TByteHash() {
super();
no_entry_value = Constants.DEFAULT_BYTE_NO_ENTRY_VALUE;
//noinspection RedundantCast
if ( no_entry_value != ( byte ) 0 ) {
Arrays.fill( _set, no_entry_value );
}
}
/**
* Creates a new TByteHash instance whose capacity
* is the next highest prime above initialCapacity + 1
* unless that value is already prime.
*
* @param initialCapacity an int value
*/
public TByteHash( int initialCapacity ) {
super( initialCapacity );
no_entry_value = Constants.DEFAULT_BYTE_NO_ENTRY_VALUE;
//noinspection RedundantCast
if ( no_entry_value != ( byte ) 0 ) {
Arrays.fill( _set, no_entry_value );
}
}
/**
* Creates a new TByteHash instance with a prime
* value at or near the specified capacity and load factor.
*
* @param initialCapacity used to find a prime capacity for the table.
* @param loadFactor used to calculate the threshold over which
* rehashing takes place.
*/
public TByteHash( int initialCapacity, float loadFactor ) {
super(initialCapacity, loadFactor);
no_entry_value = Constants.DEFAULT_BYTE_NO_ENTRY_VALUE;
//noinspection RedundantCast
if ( no_entry_value != ( byte ) 0 ) {
Arrays.fill( _set, no_entry_value );
}
}
/**
* Creates a new TByteHash instance with a prime
* value at or near the specified capacity and load factor.
*
* @param initialCapacity used to find a prime capacity for the table.
* @param loadFactor used to calculate the threshold over which
* rehashing takes place.
* @param no_entry_value value that represents null
*/
public TByteHash( int initialCapacity, float loadFactor, byte no_entry_value ) {
super(initialCapacity, loadFactor);
this.no_entry_value = no_entry_value;
//noinspection RedundantCast
if ( no_entry_value != ( byte ) 0 ) {
Arrays.fill( _set, no_entry_value );
}
}
/**
* Returns the value that is used to represent null. The default
* value is generally zero, but can be changed during construction
* of the collection.
*
* @return the value that represents null
*/
public byte getNoEntryValue() {
return no_entry_value;
}
/**
* initializes the hashtable to a prime capacity which is at least
* initialCapacity + 1.
*
* @param initialCapacity an int value
* @return the actual capacity chosen
*/
protected int setUp( int initialCapacity ) {
int capacity;
capacity = super.setUp( initialCapacity );
_set = new byte[capacity];
return capacity;
}
/**
* Searches the set for val
*
* @param val an byte value
* @return a boolean value
*/
public boolean contains( byte val ) {
return index(val) >= 0;
}
/**
* Executes procedure for each element in the set.
*
* @param procedure a TObjectProcedure value
* @return false if the loop over the set terminated because
* the procedure returned false for some value.
*/
public boolean forEach( TByteProcedure procedure ) {
byte[] states = _states;
byte[] set = _set;
for ( int i = set.length; i-- > 0; ) {
if ( states[i] == FULL && ! procedure.execute( set[i] ) ) {
return false;
}
}
return true;
}
/**
* Releases the element currently stored at index.
*
* @param index an int value
*/
protected void removeAt( int index ) {
_set[index] = no_entry_value;
super.removeAt( index );
}
/**
* Locates the index of val.
*
* @param val an byte value
* @return the index of val or -1 if it isn't in the set.
*/
protected int index( byte val ) {
int hash, probe, index, length;
final byte[] states = _states;
final byte[] set = _set;
length = states.length;
hash = HashFunctions.hash( val ) & 0x7fffffff;
index = hash % length;
byte state = states[index];
if (state == FREE)
return -1;
if (state == FULL && set[index] == val)
return index;
return indexRehashed(val, index, hash, state);
}
int indexRehashed(byte key, int index, int hash, byte state) {
// see Knuth, p. 529
int length = _set.length;
int probe = 1 + (hash % (length - 2));
final int loopIndex = index;
do {
index -= probe;
if (index < 0) {
index += length;
}
state = _states[index];
//
if (state == FREE)
return -1;
//
if (key == _set[index] && state != REMOVED)
return index;
} while (index != loopIndex);
return -1;
}
/**
* Locates the index at which val can be inserted. if
* there is already a value equal()ing val in the set,
* returns that value as a negative integer.
*
* @param val an byte value
* @return an int value
*/
protected int insertKey( byte val ) {
int hash, index;
hash = HashFunctions.hash(val) & 0x7fffffff;
index = hash % _states.length;
byte state = _states[index];
consumeFreeSlot = false;
if (state == FREE) {
consumeFreeSlot = true;
insertKeyAt(index, val);
return index; // empty, all done
}
if (state == FULL && _set[index] == val) {
return -index - 1; // already stored
}
// already FULL or REMOVED, must probe
return insertKeyRehash(val, index, hash, state);
}
int insertKeyRehash(byte val, int index, int hash, byte state) {
// compute the double hash
final int length = _set.length;
int probe = 1 + (hash % (length - 2));
final int loopIndex = index;
int firstRemoved = -1;
/**
* Look until FREE slot or we start to loop
*/
do {
// Identify first removed slot
if (state == REMOVED && firstRemoved == -1)
firstRemoved = index;
index -= probe;
if (index < 0) {
index += length;
}
state = _states[index];
// A FREE slot stops the search
if (state == FREE) {
if (firstRemoved != -1) {
insertKeyAt(firstRemoved, val);
return firstRemoved;
} else {
consumeFreeSlot = true;
insertKeyAt(index, val);
return index;
}
}
if (state == FULL && _set[index] == val) {
return -index - 1;
}
// Detect loop
} while (index != loopIndex);
// We inspected all reachable slots and did not find a FREE one
// If we found a REMOVED slot we return the first one found
if (firstRemoved != -1) {
insertKeyAt(firstRemoved, val);
return firstRemoved;
}
// Can a resizing strategy be found that resizes the set?
throw new IllegalStateException("No free or removed slots available. Key set full?!!");
}
void insertKeyAt(int index, byte val) {
_set[index] = val; // insert value
_states[index] = FULL;
}
} // TByteHash