src.it.unimi.dsi.fastutil.objects.ObjectArraySet Maven / Gradle / Ivy
/* Generic definitions */
/* Assertions (useful to generate conditional code) */
/* Current type and class (and size, if applicable) */
/* Value methods */
/* Interfaces (keys) */
/* Interfaces (values) */
/* Abstract implementations (keys) */
/* Abstract implementations (values) */
/* Static containers (keys) */
/* Static containers (values) */
/* Implementations */
/* Synchronized wrappers */
/* Unmodifiable wrappers */
/* Other wrappers */
/* Methods (keys) */
/* Methods (values) */
/* Methods (keys/values) */
/* Methods that have special names depending on keys (but the special names depend on values) */
/* Equality */
/* Object/Reference-only definitions (keys) */
/* Object/Reference-only definitions (values) */
/*
* Copyright (C) 2007-2013 Sebastiano Vigna
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package it.unimi.dsi.fastutil.objects;
import java.util.Collection;
/** A simple, brute-force implementation of a set based on a backing array.
*
* The main purpose of this
* implementation is that of wrapping cleanly the brute-force approach to the storage of a very
* small number of items: just put them into an array and scan linearly to find an item.
*/
public class ObjectArraySet extends AbstractObjectSet implements java.io.Serializable, Cloneable {
private static final long serialVersionUID = 1L;
/** The backing array (valid up to {@link #size}, excluded). */
private transient Object[] a;
/** The number of valid entries in {@link #a}. */
private int size;
/** Creates a new array set using the given backing array. The resulting set will have as many elements as the array.
*
* It is responsibility of the caller that the elements of a are distinct.
*
* @param a the backing array.
*/
public ObjectArraySet( final Object[] a ) {
this.a = a;
size = a.length;
}
/** Creates a new empty array set.
*/
public ObjectArraySet() {
this.a = ObjectArrays.EMPTY_ARRAY;
}
/** Creates a new empty array set of given initial capacity.
*
* @param capacity the initial capacity.
*/
public ObjectArraySet( final int capacity ) {
this.a = new Object[ capacity ];
}
/** Creates a new array set copying the contents of a given collection.
* @param c a collection.
*/
public ObjectArraySet( ObjectCollection c ) {
this( c.size () );
addAll( c );
}
/** Creates a new array set copying the contents of a given set.
* @param c a collection.
*/
public ObjectArraySet( final Collection c ) {
this( c.size() );
addAll( c );
}
/** Creates a new array set using the given backing array and the given number of elements of the array.
*
* It is responsibility of the caller that the first size elements of a are distinct.
*
* @param a the backing array.
* @param size the number of valid elements in a.
*/
public ObjectArraySet( final Object[] a, final int size ) {
this.a = a;
this.size = size;
if ( size > a.length ) throw new IllegalArgumentException( "The provided size (" + size + ") is larger than or equal to the array size (" + a.length + ")" );
}
private int findKey( final Object o ) {
for( int i = size; i-- != 0; ) if ( ( (a[ i ]) == null ? (o) == null : (a[ i ]).equals(o) ) ) return i;
return -1;
}
@Override
@SuppressWarnings("unchecked")
public ObjectIterator iterator() {
return ObjectIterators.wrap( (K[]) a, 0, size );
}
@SuppressWarnings("unchecked")
public boolean contains( final Object k ) {
return findKey( k ) != -1;
}
public int size() {
return size;
}
@Override
@SuppressWarnings("unchecked")
public boolean remove( final Object k ) {
final int pos = findKey( k );
if ( pos == -1 ) return false;
final int tail = size - pos - 1;
for( int i = 0; i < tail; i++ ) a[ pos + i ] = a[ pos + i + 1 ];
size--;
a[ size ] = null;
return true;
}
@Override
public boolean add( final K k ) {
final int pos = findKey( k );
if ( pos != -1 ) return false;
if ( size == a.length ) {
final Object[] b = new Object[ size == 0 ? 2 : size * 2 ];
for( int i = size; i-- != 0; ) b[ i ] = a[ i ];
a = b;
}
a[ size++ ] = k;
return true;
}
@Override
public void clear() {
for( int i = size; i-- != 0; ) a[ i ] = null;
size = 0;
}
@Override
public boolean isEmpty() {
return size == 0;
}
/** Returns a deep copy of this set.
*
* This method performs a deep copy of this hash set; the data stored in the
* set, however, is not cloned. Note that this makes a difference only for object keys.
*
* @return a deep copy of this set.
*/
@SuppressWarnings("unchecked")
public ObjectArraySet clone() {
ObjectArraySet c;
try {
c = (ObjectArraySet )super.clone();
}
catch(CloneNotSupportedException cantHappen) {
throw new InternalError();
}
c.a = a.clone();
return c;
}
private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
s.defaultWriteObject();
for( int i = 0; i < size; i++ ) s.writeObject( a[ i ] );
}
@SuppressWarnings("unchecked")
private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
s.defaultReadObject();
a = new Object[ size ];
for( int i = 0; i < size; i++ ) a[ i ] = s.readObject();
}
}