src.it.unimi.dsi.fastutil.IndirectPriorityQueues Maven / Gradle / Ivy
package it.unimi.dsi.fastutil;
/*
* Copyright (C) 2003-2013 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.
*/
import java.util.Comparator;
import java.util.NoSuchElementException;
/** A class providing static methods and objects that do useful things with indirect priority queues.
*
* @see IndirectPriorityQueue
*/
public class IndirectPriorityQueues {
private IndirectPriorityQueues() {}
/** An immutable class representing the empty indirect priority queue.
*
* This class may be useful to implement your own in case you subclass
* {@link IndirectPriorityQueue}.
*/
@SuppressWarnings("rawtypes")
public static class EmptyIndirectPriorityQueue extends AbstractIndirectPriorityQueue {
protected EmptyIndirectPriorityQueue() {}
public void enqueue( final int i ) { throw new UnsupportedOperationException(); }
public int dequeue() { throw new NoSuchElementException(); }
public boolean isEmpty() { return true; }
public int size() { return 0; }
public boolean contains( int index ) { return false; }
public void clear() {}
public int first() { throw new NoSuchElementException(); }
public int last() { throw new NoSuchElementException(); }
public void changed() { throw new NoSuchElementException(); }
public void allChanged() {}
public Comparator comparator() { return null; }
public void changed( final int i ) { throw new IllegalArgumentException( "Index " + i + " is not in the queue" ); }
public boolean remove( final int i ) { return false; }
public int front( int[] a ) { return 0; }
}
/** An empty indirect priority queue (immutable).
*/
public final static EmptyIndirectPriorityQueue EMPTY_QUEUE = new EmptyIndirectPriorityQueue();
/** A synchronized wrapper class for indirect priority queues. */
public static class SynchronizedIndirectPriorityQueue implements IndirectPriorityQueue {
public static final long serialVersionUID = -7046029254386353129L;
final protected IndirectPriorityQueue q;
final protected Object sync;
protected SynchronizedIndirectPriorityQueue( final IndirectPriorityQueue q, final Object sync ) {
this.q = q;
this.sync = sync;
}
protected SynchronizedIndirectPriorityQueue( final IndirectPriorityQueue q ) {
this.q = q;
this.sync = this;
}
public void enqueue( int x ) { synchronized( sync ) { q.enqueue( x ); } }
public int dequeue() { synchronized( sync ) { return q.dequeue(); } }
public boolean contains( final int index ) { synchronized( sync ) { return q.contains( index ); } }
public int first() { synchronized( sync ) { return q.first(); } }
public int last() { synchronized( sync ) { return q.last(); } }
public boolean isEmpty() { synchronized( sync ) { return q.isEmpty(); } }
public int size() { synchronized( sync ) { return q.size(); } }
public void clear() { synchronized( sync ) { q.clear(); } }
public void changed() { synchronized( sync ) { q.changed(); } }
public void allChanged() { synchronized( sync ) { q.allChanged(); } }
public void changed( int i ) { synchronized( sync ) { q.changed( i ); } }
public boolean remove( int i ) { synchronized( sync ) { return q.remove( i ); } }
public Comparator comparator() { synchronized( sync ) { return q.comparator(); } }
public int front( int[] a ) { return q.front( a ); }
}
/** Returns a synchronized type-specific indirect priority queue backed by the specified type-specific indirect priority queue.
*
* @param q the indirect priority queue to be wrapped in a synchronized indirect priority queue.
* @return a synchronized view of the specified indirect priority queue.
*/
public static IndirectPriorityQueue synchronize( final IndirectPriorityQueue q ) { return new SynchronizedIndirectPriorityQueue( q ); }
/** Returns a synchronized type-specific indirect priority queue backed by the specified type-specific indirect priority queue, using an assigned object to synchronize.
*
* @param q the indirect priority queue to be wrapped in a synchronized indirect priority queue.
* @param sync an object that will be used to synchronize the access to the indirect priority queue.
* @return a synchronized view of the specified indirect priority queue.
*/
public static IndirectPriorityQueue synchronize( final IndirectPriorityQueue q, final Object sync ) { return new SynchronizedIndirectPriorityQueue( q, sync ); }
}