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The Berkeley parser analyzes the grammatical structure of natural language using probabilistic context-free grammars (PCFGs).

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/**
 * 
 */
package edu.berkeley.nlp.PCFGLA;

import java.util.ArrayList;
import java.util.List;

import edu.berkeley.nlp.util.PriorityQueue;

/**
 * @author petrov
 *
 */
public class LazyList {
	List sortedBegining;
	PriorityQueue fringe;
	int nSorted, nFringe;
	boolean[] grammarTags;
//	double bestScore;
	
	public LazyList(boolean[] tags){
		sortedBegining = new ArrayList();
		fringe = new PriorityQueue();
		nSorted = 0;
		nFringe = 0;
		grammarTags = tags;
//		bestScore = Double.NEGATIVE_INFINITY;
	}
	
	public int sortedListSize(){
		return nSorted;
	}
	
	public void addToFringe(HyperEdge el){
		fringe.add(el, el.score);
		nFringe++;
	}
	
//	public void addToSorted(HyperEdge el){
//		sortedBegining.add(el);
//		nSorted++;
//	}

	public HyperEdge getKbest(int k){
		if (k>nSorted){
			System.out.println("Don't have this element yet");
			return null;
//		} else if (k==nSorted&&(k==0||!fringe.hasNext())){
//			return null;
		} else if (k==nSorted){ // extract the next best
			expandNextBest();
		}
		if (k==nSorted) return null;
		return sortedBegining.get(k);
	}
	
	public void expandNextBest(){
		while (fringe.hasNext()) {
			HyperEdge edge = fringe.next();
			boolean isNew = true;
			for (HyperEdge alreadyIn : sortedBegining){
				if (alreadyIn.differsInPOSatMost(edge,grammarTags)) {
					isNew = false;
					break;
				}
			}
			if (isNew){
				sortedBegining.add(edge);
				nFringe--;
				nSorted++;
				break;
			}
		}
	}
	
	
}