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/* 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) 2003-2015 Paolo Boldi and 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.Comparator;
import it.unimi.dsi.fastutil.IndirectPriorityQueue;
import it.unimi.dsi.fastutil.ints.IntArrays;
import it.unimi.dsi.fastutil.AbstractIndirectPriorityQueue;
import java.util.NoSuchElementException;
/** A type-specific array-based semi-indirect priority queue.
*
* Instances of this class use as reference list a reference array, which must be provided to each constructor, and represent a priority queue using a backing array of integer
* indices—all operations are performed directly on the array. The array is enlarged as needed, but it is never shrunk. Use the {@link #trim()} method to reduce its size, if necessary.
*
*
This implementation is extremely inefficient, but it is difficult to beat when the size of the queue is very small. Moreover, it allows to enqueue several time the same index, without
* limitations. */
public class ObjectArrayIndirectPriorityQueue extends AbstractIndirectPriorityQueue implements IndirectPriorityQueue {
/** The reference array. */
protected K refArray[];
/** The backing array. */
protected int array[] = IntArrays.EMPTY_ARRAY;
/** The number of elements in this queue. */
protected int size;
/** The type-specific comparator used in this queue. */
protected Comparator c;
/** The first index, cached, if {@link #firstIndexValid} is true. */
protected int firstIndex;
/** Whether {@link #firstIndex} contains a valid value. */
protected boolean firstIndexValid;
/** Creates a new empty queue without elements with a given capacity and comparator.
*
* @param refArray the reference array.
* @param capacity the initial capacity of this queue.
* @param c the comparator used in this queue, or null for the natural order. */
public ObjectArrayIndirectPriorityQueue( K[] refArray, int capacity, Comparator c ) {
if ( capacity > 0 ) this.array = new int[ capacity ];
this.refArray = refArray;
this.c = c;
}
/** Creates a new empty queue with given capacity and using the natural order.
*
* @param refArray the reference array.
* @param capacity the initial capacity of this queue. */
public ObjectArrayIndirectPriorityQueue( K[] refArray, int capacity ) {
this( refArray, capacity, null );
}
/** Creates a new empty queue with capacity equal to the length of the reference array and a given comparator.
*
* @param refArray the reference array.
* @param c the comparator used in this queue, or null for the natural order. */
public ObjectArrayIndirectPriorityQueue( K[] refArray, Comparator c ) {
this( refArray, refArray.length, c );
}
/** Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.
*
* @param refArray the reference array. */
public ObjectArrayIndirectPriorityQueue( K[] refArray ) {
this( refArray, refArray.length, null );
}
/** Wraps a given array in a queue using a given comparator.
*
* The queue returned by this method will be backed by the given array.
*
* @param refArray the reference array.
* @param a an array of indices into refArray.
* @param size the number of elements to be included in the queue.
* @param c the comparator used in this queue, or null for the natural order. */
public ObjectArrayIndirectPriorityQueue( final K[] refArray, final int[] a, int size, final Comparator c ) {
this( refArray, 0, c );
this.array = a;
this.size = size;
}
/** Wraps a given array in a queue using a given comparator.
*
*
The queue returned by this method will be backed by the given array.
*
* @param refArray the reference array.
* @param a an array of indices into refArray.
* @param c the comparator used in this queue, or null for the natural order. */
public ObjectArrayIndirectPriorityQueue( final K[] refArray, final int[] a, final Comparator c ) {
this( refArray, a, a.length, c );
}
/** Wraps a given array in a queue using the natural order.
*
*
The queue returned by this method will be backed by the given array.
*
* @param refArray the reference array.
* @param a an array of indices into refArray.
* @param size the number of elements to be included in the queue. */
public ObjectArrayIndirectPriorityQueue( final K[] refArray, final int[] a, int size ) {
this( refArray, a, size, null );
}
/** Wraps a given array in a queue using the natural order.
*
*
The queue returned by this method will be backed by the given array.
*
* @param refArray the reference array.
* @param a an array of indices into refArray. */
public ObjectArrayIndirectPriorityQueue( final K[] refArray, final int[] a ) {
this( refArray, a, a.length );
}
/** Returns the index (in {@link #array}) of the smallest element. */
@SuppressWarnings("unchecked")
private int findFirst() {
if ( firstIndexValid ) return this.firstIndex;
firstIndexValid = true;
int i = size;
int firstIndex = --i;
K first = refArray[ array[ firstIndex ] ];
if ( c == null ) while ( i-- != 0 ) {
if ( ( ( (Comparable)( refArray[ array[ i ] ] ) ).compareTo( first ) < 0 ) ) first = refArray[ array[ firstIndex = i ] ];
}
else while ( i-- != 0 ) {
if ( c.compare( refArray[ array[ i ] ], first ) < 0 ) first = refArray[ array[ firstIndex = i ] ];
}
return this.firstIndex = firstIndex;
}
/** Returns the index (in {@link #array}) of the largest element. */
@SuppressWarnings("unchecked")
private int findLast() {
int i = size;
int lastIndex = --i;
K last = refArray[ array[ lastIndex ] ];
if ( c == null ) {
while ( i-- != 0 )
if ( ( ( (Comparable)( last ) ).compareTo( refArray[ array[ i ] ] ) < 0 ) ) last = refArray[ array[ lastIndex = i ] ];
}
else {
while ( i-- != 0 )
if ( c.compare( last, refArray[ array[ i ] ] ) < 0 ) last = refArray[ array[ lastIndex = i ] ];
}
return lastIndex;
}
protected final void ensureNonEmpty() {
if ( size == 0 ) throw new NoSuchElementException();
}
/** Ensures that the given index is a firstIndexValid reference.
*
* @param index an index in the reference array.
* @throws IndexOutOfBoundsException if the given index is negative or larger than the reference array length. */
protected void ensureElement( final int index ) {
if ( index < 0 ) throw new IndexOutOfBoundsException( "Index (" + index + ") is negative" );
if ( index >= refArray.length ) throw new IndexOutOfBoundsException( "Index (" + index + ") is larger than or equal to reference array size (" + refArray.length + ")" );
}
/** Enqueues a new element.
*
* Note that for efficiency reasons this method will not throw an exception when x is already in the queue. However, the queue state will become inconsistent and the
* following behaviour will not be predictable. */
@SuppressWarnings("unchecked")
public void enqueue( int x ) {
ensureElement( x );
if ( size == array.length ) array = IntArrays.grow( array, size + 1 );
if ( firstIndexValid ) {
if ( c == null ) {
if ( ( ( (Comparable)( refArray[ x ] ) ).compareTo( refArray[ array[ firstIndex ] ] ) < 0 ) ) firstIndex = size;
}
else if ( c.compare( refArray[ x ], refArray[ array[ firstIndex ] ] ) < 0 ) firstIndex = size;
}
else firstIndexValid = false;
array[ size++ ] = x;
}
public int dequeue() {
ensureNonEmpty();
final int firstIndex = findFirst();
final int result = array[ firstIndex ];
if ( --size != 0 ) System.arraycopy( array, firstIndex + 1, array, firstIndex, size - firstIndex );
firstIndexValid = false;
return result;
}
public int first() {
ensureNonEmpty();
return array[ findFirst() ];
}
public int last() {
ensureNonEmpty();
return array[ findLast() ];
}
public void changed() {
ensureNonEmpty();
firstIndexValid = false;
}
/** {@inheritDoc}
*
* Note that for efficiency reasons this method will not throw an exception when index is not in the queue. */
public void changed( int index ) {
ensureElement( index );
if ( index == firstIndex ) firstIndexValid = false;
}
public void allChanged() {
firstIndexValid = false;
}
public boolean remove( int index ) {
ensureElement( index );
final int[] a = array;
int i = size;
while ( i-- != 0 )
if ( a[ i ] == index ) break;
if ( i < 0 ) return false;
firstIndexValid = false;
if ( --size != 0 ) System.arraycopy( a, i + 1, a, i, size - i );
return true;
}
public int front( int[] a ) {
final K top = refArray[ array[ findFirst() ] ];
int i = size, c = 0;
while ( i-- != 0 )
if ( ( ( top ).equals( refArray[ array[ i ] ] ) ) ) a[ c++ ] = array[ i ];
return c;
}
public int size() {
return size;
}
public void clear() {
size = 0;
firstIndexValid = false;
}
/** Trims the backing array so that it has exactly {@link #size()} elements. */
public void trim() {
array = IntArrays.trim( array, size );
}
public Comparator comparator() {
return c;
}
public String toString() {
StringBuffer s = new StringBuffer();
s.append( "[" );
for ( int i = 0; i < size; i++ ) {
if ( i != 0 ) s.append( ", " );
s.append( refArray[ array[ i ] ] );
}
s.append( "]" );
return s.toString();
}
}