TrieUtils.java

package org.limewire.collection;

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

import org.limewire.collection.Trie.Cursor;



/**
 * Miscellaneous utilities for Tries. See <a 
 * href="http://en.wikipedia.org/wiki/Trie">Trie</a> for more information.
 */
public final class TrieUtils {
    
    private TrieUtils() {}
    
    public static <K,V> List<V> select(Trie<K,V> trie, K key, int count) {
        return select(trie, key, count, null);
    }
    
    public static <K,V> List<V> select(Trie<K,V> trie, K key, 
                int count, final Cursor<K,V> cursor) {
        
        final int size = Math.min(trie.size(), count);
        final List<V> values = new ArrayList<V>(size);
        
        trie.select(key, new Cursor<K,V>() {
            public Cursor.SelectStatus select(Entry<? extends K, ? extends V> entry) {
                if (cursor == null || cursor.select(entry) == Cursor.SelectStatus.EXIT) {
                    values.add(entry.getValue());
                }
                
                return values.size() >= size ? Cursor.SelectStatus.EXIT : Cursor.SelectStatus.CONTINUE;
            }
        });
        
        return values;
    }
}