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package it.unimi.dsi.util;
/*
* DSI utilities
*
* Copyright (C) 2006-2009 Sebastiano Vigna
*
* 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 Lesser 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.
*
*/
import it.unimi.dsi.fastutil.objects.ObjectOpenHashSet;
import it.unimi.dsi.lang.MutableString;
import it.unimi.dsi.fastutil.io.FastByteArrayOutputStream;
import it.unimi.dsi.io.OutputBitStream;
import java.io.IOException;
/** A set of interned mutable strings.
*
* This class extends {@link it.unimi.dsi.fastutil.objects.ObjectOpenHashSet} by
* providing an {@link #intern(MutableString)} method with a semantics similar to
* that of {@link String#intern()}.
*/
public class InternedMutableStringSet extends ObjectOpenHashSet {
public final static class Term extends MutableString {
private static final long serialVersionUID = 0L;
public int lastDocument;
public int lastPosition = -1;
public final FastByteArrayOutputStream fbaos = new FastByteArrayOutputStream( 1 );
public final OutputBitStream obs = new OutputBitStream( fbaos, 0 );
public Term( MutableString s ) {
super( s );
}
public void addOccurrence( int document, int position ) throws IOException {
obs.writeDelta( document - lastDocument );
if ( document != lastDocument ) lastPosition = -1;
obs.writeDelta( position - lastPosition - 1 );
lastDocument = document;
lastPosition = position;
}
}
private static final long serialVersionUID = 0L;
private int free;
private int p;
private int count;
private byte[] state;
public InternedMutableStringSet() {
super();
}
public InternedMutableStringSet( final int n, final float f ) {
super( n, f );
}
public InternedMutableStringSet( final int n ) {
super( n );
}
/** Returns an interned, canonical copy contained in this set of the specified mutable string.
*
* The semantics of this method is essentially the same as that of
* {@link java.util.Collection#add(Object)}, but
* this method will return a mutable string
* equal to s currently in this set. The string will
* never be s, as in the case s is
* not in this set a {@linkplain MutableString#compact() compact copy}
* of s will be stored instead.
*
*
The purpose of this method is similar to that of {@link String#intern()},
* but obviously here the user has much greater control.
*
* @param s the mutable string that must be interned.
* @return the mutable string equal to s stored in this set.
*/
public Term intern( final MutableString s ) {
// Duplicate code from add()--keep in line!
final int i = findInsertionPoint( s );
if ( i < 0 ) return (Term)(key[ -( i + 1 ) ]);
if ( state[ i ] == FREE ) free--;
state[ i ] = OCCUPIED;
final Term t = (Term)( key[ i ] = new Term( s ) );
if ( ++count >= maxFill ) {
int newP = Math.min( p + growthFactor(), PRIMES.length - 1 );
// Just to be sure that size changes when p is very small.
while( PRIMES[ newP ] == PRIMES[ p ] ) newP++;
rehash( newP ); // Table too filled, let's rehash
}
if ( free == 0 ) rehash( p );
return t;
}
//Copied from add(...) in the fastutil 6.5.11
private int findInsertionPoint(MutableString k) {
int pos = ( (k) == null ? 0x87fcd5c : it.unimi.dsi.fastutil.HashCommon.murmurHash3( (k).hashCode() ^ mask ) ) & mask;
// There's always an unused entry.
while( used[ pos ] ) {
if ( ( (key[ pos ]) == null ? (k) == null : (key[ pos ]).equals(k) ) ) return pos;
pos = ( pos + 1 ) & mask;
}
// TODO Auto-generated method stub
return pos;
}
}