<?php

/**

 * Zend Framework

 *

 * LICENSE

 *

 * This source file is subject to the new BSD license that is bundled

 * with this package in the file LICENSE.txt.

 * It is also available through the world-wide-web at this URL:

 * http://framework.zend.com/license/new-bsd

 * If you did not receive a copy of the license and are unable to

 * obtain it through the world-wide-web, please send an email

 * to license@zend.com so we can send you a copy immediately.

 *

 * @category   Zend

 * @package    Zend_Search_Lucene

 * @subpackage Search

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 * @version    $Id: Weight.php 20096 2010-01-06 02:05:09Z bkarwin $

 */

/**

 * Calculate query weights and build query scorers.

 *

 * A Weight is constructed by a query Query->createWeight().

 * The sumOfSquaredWeights() method is then called on the top-level

 * query to compute the query normalization factor Similarity->queryNorm(float).

 * This factor is then passed to normalize(float).  At this point the weighting

 * is complete.

 *

 * @category   Zend

 * @package    Zend_Search_Lucene

 * @subpackage Search

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

abstract class Zend_Search_Lucene_Search_Weight

{

    /**

     * Normalization factor.

     * This value is stored only for query expanation purpose and not used in any other place

     *

     * @var float

     */

    protected $_queryNorm;

    /**

     * Weight value

     *

     * Weight value may be initialized in sumOfSquaredWeights() or normalize()

     * because they both are invoked either in Query::_initWeight (for top-level query) or

     * in corresponding methods of parent query's weights

     *

     * @var float

     */

    protected $_value;

    /**

     * The weight for this query.

     *

     * @return float

     */

    public function getValue()

    {

        return $this->_value;

    }

    /**

     * The sum of squared weights of contained query clauses.

     *

     * @return float

     */

    abstract public function sumOfSquaredWeights();

    /**

     * Assigns the query normalization factor to this.

     *

     * @param $norm

     */

    abstract public function normalize($norm);

}