package proj.zoie.api.impl.util;
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
import it.unimi.dsi.fastutil.ints.IntCollection;
import it.unimi.dsi.fastutil.ints.IntIterator;
import it.unimi.dsi.fastutil.ints.IntSet;
import java.util.Collection;
import java.util.Iterator;
/**
* This class, a IntSet decorator, is for accelerating look-up by having a filter
* in front of the underlying IntSet. The filter is basically a Bloom filter.
* The hash table size and the hash function are tuned for fast calculation of hash values.
* The underlying IntSet should not be updated while this accelerator is in use.
*
* @author ymatsuda
*
*/
public class IntSetAccelerator implements IntSet
{
private final long[] _filter;
private final int _mask;
private final IntSet _set;
private final int MIXER = 2147482951; // a prime number
public IntSetAccelerator(IntSet set)
{
_set = set;
int mask = set.size()/4;
mask |= (mask >> 1);
mask |= (mask >> 2);
mask |= (mask >> 4);
mask |= (mask >> 8);
mask |= (mask >> 16);
_mask = mask;
_filter = new long[mask+1];
IntIterator iter = set.iterator();
while(iter.hasNext())
{
int h = iter.nextInt() * MIXER;
long bits = _filter[h & _mask];
bits |= ((1L << (h >>> 26)));
bits |= ((1L << ((h >> 20) & 0x3F)));
_filter[h & _mask] = bits;
}
}
public boolean contains(int val)
{
final int h = val * MIXER;
final long bits = _filter[h & _mask];
return (bits & (1L << (h >>> 26))) != 0 && (bits & (1L << ((h >> 20) & 0x3F))) != 0 && _set.contains(val);
}
public boolean contains(Object o)
{
return contains(((Integer)(o)).intValue());
}
public boolean containsAll(Collection<?> c)
{
final Iterator<?> i = c.iterator();
int n = c.size();
while(n-- != 0) if (!contains(i.next())) return false;
return true;
}
public boolean containsAll(IntCollection c)
{
final IntIterator i = c.iterator();
int n = c.size();
while(n-- != 0) if (!contains(i.nextInt())) return false;
return true;
}
public boolean add(int key)
{
throw new UnsupportedOperationException();
}
public boolean add(Integer o)
{
throw new UnsupportedOperationException();
}
public boolean addAll(Collection<? extends Integer> c)
{
throw new UnsupportedOperationException();
}
public boolean addAll(IntCollection c)
{
throw new UnsupportedOperationException();
}
public void clear()
{
throw new UnsupportedOperationException();
}
public boolean equals(Object o)
{
return _set.equals(o);
}
public int hashCode()
{
return _set.hashCode();
}
public IntIterator intIterator()
{
return _set.iterator();
}
public boolean isEmpty()
{
return _set.isEmpty();
}
public IntIterator iterator()
{
return _set.iterator();
}
public boolean rem(int key)
{
throw new UnsupportedOperationException();
}
public boolean remove(int key)
{
throw new UnsupportedOperationException();
}
public boolean remove(Object o)
{
throw new UnsupportedOperationException();
}
public boolean removeAll(Collection<?> c)
{
throw new UnsupportedOperationException();
}
public boolean removeAll(IntCollection c)
{
throw new UnsupportedOperationException();
}
public boolean retainAll(Collection<?> c)
{
throw new UnsupportedOperationException();
}
public boolean retainAll(IntCollection c)
{
throw new UnsupportedOperationException();
}
public int size()
{
return _set.size();
}
public Object[] toArray()
{
return _set.toArray();
}
public int[] toArray(int[] a)
{
return _set.toArray(a);
}
public <T> T[] toArray(T[] a)
{
return _set.toArray(a);
}
public int[] toIntArray()
{
return _set.toIntArray();
}
public int[] toIntArray(int[] a)
{
return _set.toIntArray(a);
}
}