/* This file is part of the Joshua Machine Translation System.
 * 
 * Joshua 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 library; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */
/*
 * This file is based on the edu.umd.clip.mt.PhrasePair class from
 * the University of Maryland's umd-hadoop-mt-0.01 project. That
 * project is released under the terms of the Apache License 2.0,
 * but with special permission for the Joshua Machine Translation
 * System to release modifications under the LGPL version 2.1. LGPL
 * version 3 requires no special permission since it is compatible
 * with Apache License 2.0
 */
package joshua.subsample;
// TODO: if we generalize the Alignment class, we could move this
//       to joshua.util.sentence.

import joshua.corpus.Phrase;


/**
 * Phrase-aligned tuple class associating an F phrase, E phrase,
 * and (possibly null) word-alignments. This is primarily for
 * maintaining sentence-alignment.
 *
 * @author UMD (Jimmy Lin, Chris Dyer, et al.)
 * @author wren ng thornton <wren@users.sourceforge.net>
 * @version $LastChangedDate: 2009-05-20 02:38:46 -0500 (Wed, 20 May 2009) $
 */
public class PhrasePair {
	// Making these final requires Java6, not Java5
	private final Phrase    f;
	private final Phrase    e;
	private final Alignment a;
	
//===============================================================
// Constructors
//===============================================================
	public PhrasePair(Phrase f_, Phrase e_) { this(f_, e_, null); }
	
	public PhrasePair(Phrase f, Phrase e, Alignment a) {
		this.f = f;
		this.e = e;
		this.a = a;
	}
	
//===============================================================
// Attributes
//===============================================================
	public Phrase    getF()         { return f; }
	public Phrase    getE()         { return e; }
	public Alignment getAlignment() { return a; }
	
//===============================================================
// Methods
//===============================================================
	public float ratioFtoE() {
		return ((float)this.f.size()) / ((float)this.e.size());
	}
}