package de.unisiegen.tpml.core.util ;


import java.util.Collection ;
import java.util.Iterator ;


/**
 * Static class, which provides several static utility functions for handling
 * integers and related constructs.
 * 
 * @author Benedikt Meurer
 * @version $Rev$
 * @see java.lang.Integer
 */
public final class IntegerUtilities
{
  /**
   * Transforms a <code>Collection</code> of <code>Integer</code> instances
   * to a simple <code>int</code> array.
   * 
   * @param collection a <code>Collection</code> of <code>Integer</code>s.
   * @return an <code>int</code> array with the values from the specified
   *         <code>collection</code>.
   */
  public static int [ ] toArray ( Collection < Integer > collection )
  {
    // check if we have an empty collection here
    if ( collection.isEmpty ( ) ) return EMPTY_ARRAY ;
    // transform the collection into an array
    int [ ] array = new int [ collection.size ( ) ] ;
    Iterator < Integer > iterator = collection.iterator ( ) ;
    for ( int n = 0 ; iterator.hasNext ( ) ; ++ n )
      array [ n ] = iterator.next ( ).intValue ( ) ;
    return array ;
  }


  /**
   * A shared, empty and immutable integer array, which can be used to avoid
   * allocating empty integer arrays whenever one needs to present an empty
   * integer array.
   */
  public static final int [ ] EMPTY_ARRAY = new int [ 0 ] ;
}