///////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2003-5 Jason Baldridge, Gann Bierner and
// University of Edinburgh (Michael White)
//
// 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.
//////////////////////////////////////////////////////////////////////////////
package opennlp.ccg.synsem;
import gnu.trove.*;
import java.util.*;
import opennlp.ccg.lexicon.Word;
/**
* A set of signs, unique up to surface words.
* Signs with lower derivational complexity are kept during insertion.
*
* @author Jason Baldridge
* @author Gann Bierner
* @author Michael White
* @version $Revision: 1.13 $, $Date: 2009/12/21 02:15:44 $
*/
public class SignHash extends THashSet {
private static final long serialVersionUID = 1L;
/** Hashing strategy that uses Sign's surfaceWordHashCode and surfaceWordEquals methods. */
protected static TObjectHashingStrategy surfaceWordHashingStrategy = new TObjectHashingStrategy() {
private static final long serialVersionUID = 1L;
public int computeHashCode(java.lang.Object o) {
return ((Sign)o).surfaceWordHashCode();
}
public boolean equals(java.lang.Object o1, java.lang.Object o2) {
return ((Sign)o1).surfaceWordEquals((Sign)o2);
}
};
/** Default constructor. */
public SignHash() { super(surfaceWordHashingStrategy); }
/**
* Constructor which adds one sign.
*/
public SignHash(Sign sign) {
this(); insert(sign);
}
/**
* Constructor which adds a collection of signs.
*/
public SignHash(Collection<Sign> c) {
this();
for (Sign s : c) insert(s);
}
/**
* Returns this as a set of signs.
*/
@SuppressWarnings("unchecked")
public Set<Sign> asSignSet() { return (Set<Sign>) this; }
/**
* Adds a sign, keeping the one with lower derivational complexity
* if there is an equivalent one there already; returns the old
* sign if it was displaced, the new sign if there was no equivalent
* old sign, or null if the sign was not actually added.
*/
public Sign insert(Sign sign) {
int pos = index(sign);
if (pos >= 0) {
Sign oldSign = (Sign) _set[pos];
if (oldSign == sign) return null;
if (sign.getDerivationHistory().compareTo(oldSign.getDerivationHistory()) < 0) {
_set[pos] = sign; return oldSign;
}
else return null;
}
else {
add(sign); return sign;
}
}
/** Returns the signs sorted by their words lexicographically. */
public List<Sign> getSignsSorted() {
ArrayList<Sign> retval = new ArrayList<Sign>(asSignSet());
Collections.sort(retval, signComparator);
return retval;
}
/** Comparator for signs to provide a persistent ordering. */
public static final Comparator<Sign> signComparator = new Comparator<Sign>() {
public int compare(Sign sign1, Sign sign2) {
return compareTo(sign1, sign2);
}
};
/** Compares signs by their derivation complexity, lists of words, then (somewhat desperately) cat hash codes. */
public static int compareTo(Sign sign1, Sign sign2) {
int cmp = 0;
cmp = sign1.getDerivationHistory().compareTo(sign2.getDerivationHistory());
if (cmp != 0) return cmp;
List<Word> words1 = sign1.getWords();
List<Word> words2 = sign2.getWords();
cmp = compareTo(words1, words2);
if (cmp != 0) return cmp;
// TODO: implement compareTo method on categories
int h1 = sign1.getCategory().hashCode();
int h2 = sign2.getCategory().hashCode();
if (h1 < h2) return -1;
if (h1 > h2) return 1;
return 0;
}
/** Compares lists of words lexicographically. */
public static int compareTo(List<Word> words1, List<Word> words2) {
int i=0;
while (i < words1.size() || i < words2.size()) {
if (i == words1.size()) return -1;
if (i == words2.size()) return 1;
Word w1 = words1.get(i); Word w2 = words2.get(i);
int cmp = w1.compareTo(w2);
if (cmp != 0) return cmp;
i++;
}
return 0;
}
}