TopNList.java

package org.tallison.lucene.syns;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

class TopNList<E extends Valuable> {
    private List<E> list = null;
    private int max = -1;
    private ValueComparator comp = null;


    public TopNList(int max){
        this(max, new DescendingValueComparator());
    }
    private TopNList(int max, ValueComparator comp){
        this.max = max;
        this.comp = comp;
        list = new ArrayList<E>(max);
    }



    public double bottomValue(){
        if (list.size() == 0){
            return Double.MIN_VALUE;
        }
        return list.get(list.size()-1).getValue();
    }
    public boolean willAdd(Valuable newObj){
        if (list.size() < max)
            return true;

      return comp.compare(newObj, list.get(list.size() - 1)) < 0;

    }
    public void add(E newObj){
        if (list.size() == max){
            if (comp.compare(newObj, list.get(list.size()-1)) >= 0){
                return;
            }
        }
        int insert = -1;

        //this could be sped up with binary search
        for (int i = 0; i < list.size(); i++){
            if (comp.compare(newObj, list.get(i)) < 0){
                insert = i;
                break;
            }
        }
        insert = (insert < 0) ? list.size() : insert;
        list.add(insert, newObj);
        if (list.size() > max)
            list.remove(max);
    }
    public List<E> getList(){
        return list;
    }
    public String toString(){
        return list.toString();
    }

    public static void main(String[] args){
        //def m = [ 'cat' : 4, 'bison' : 5, 'dog' : 6,
        //'aardvark' : 15, 'the' : 120, 'a' : 50, 'centipede' : 1]

        Map<String, Integer> m = new HashMap<String, Integer>();
        m.put("z", 150);
        m.put("y", 115);
        m.put("x", 110);
        m.put("cat2", 4);
        m.put("bison", 5);
        m.put("dog",6);
        m.put("aardvark",15);
        m.put("the",120);
        TopNList<TermDoublePair> list = new TopNList<TermDoublePair>(3, new DescendingValueComparator());
        for (Map.Entry<String, Integer> e : m.entrySet()){
            System.out.println("adding " + e.getKey() + " " +e.getValue());
            list.add(new TermDoublePair(e.getKey(), e.getValue()));
        }
        System.out.println(list);


    }
}