Subversion-Projekte lars-tiefland.prado

<?php

/**

 * Zend Framework

 *

 * LICENSE

 *

 * This source file is subject to version 1.0 of the Zend Framework

 * license, that is bundled with this package in the file LICENSE, and

 * is available through the world-wide-web at the following URL:

 * http://www.zend.com/license/framework/1_0.txt. If you did not receive

 * a copy of the Zend Framework license and are unable to obtain it

 * through the world-wide-web, please send a note to license@zend.com

 * so we can mail you a copy immediately.

 *

 * @package    Zend_Search_Lucene

 * @subpackage Search

 * @copyright  Copyright (c) 2005-2006 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://www.zend.com/license/framework/1_0.txt Zend Framework License version 1.0

 */

/**

 * Zend_Search_Lucene_Search_Query

 */

require_once 'Zend/Search/Lucene/Search/Query.php';

/**

 * Zend_Search_Lucene_Search_Weight_MultiTerm

 */

require_once 'Zend/Search/Lucene/Search/Weight/Phrase.php';

/**

 * A Query that matches documents containing a particular sequence of terms.

 *

 * @package    Zend_Search_Lucene

 * @subpackage Search

 * @copyright  Copyright (c) 2005-2006 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://www.zend.com/license/framework/1_0.txt Zend Framework License version 1.0

 */

class Zend_Search_Lucene_Search_Query_Phrase extends Zend_Search_Lucene_Search_Query

{

    /**

     * Terms to find.

     * Array of Zend_Search_Lucene_Index_Term objects.

     *

     * @var array

     */

    private $_terms;

    /**

     * Term positions (relative positions of terms within the phrase).

     * Array of integers

     *

     * @var array

     */

    private $_offsets;

    /**

     * Sets the number of other words permitted between words in query phrase.

     * If zero, then this is an exact phrase search.  For larger values this works

     * like a WITHIN or NEAR operator.

     *

     * The slop is in fact an edit-distance, where the units correspond to

     * moves of terms in the query phrase out of position.  For example, to switch

     * the order of two words requires two moves (the first move places the words

     * atop one another), so to permit re-orderings of phrases, the slop must be

     * at least two.

     * More exact matches are scored higher than sloppier matches, thus search

     * results are sorted by exactness.

     *

     * The slop is zero by default, requiring exact matches.

     *

     * @var unknown_type

     */

    private $_slop;

    /**

     * Result vector.

     * Bitset or array of document IDs

     * (depending from Bitset extension availability).

     *

     * @var mixed

     */

    private $_resVector = null;

    /**

     * Terms positions vectors.

     * Array of Arrays:

     * term1Id => (docId => array( pos1, pos2, ... ), ...)

     * term2Id => (docId => array( pos1, pos2, ... ), ...)

     *

     * @var array

     */

    private $_termsPositions = array();

    /**

     * Class constructor.  Create a new prase query.

     *

     * @param string $field    Field to search.

     * @param array  $terms    Terms to search Array of strings.

     * @param array  $offsets  Relative term positions. Array of integers.

     * @throws Zend_Search_Lucene_Exception

     */

    public function __construct($terms = null, $offsets = null, $field = null)

    {

        $this->_slop = 0;

        if (is_array($terms)) {

            $this->_terms = array();

            foreach ($terms as $termId => $termText) {

                $this->_terms[$termId] = ($field !== null)? new Zend_Search_Lucene_Index_Term($termText, $field):

                                                            new Zend_Search_Lucene_Index_Term($termText);

            }

        } else if ($terms === null) {

            $this->_terms = array();

        } else {

            throw new Zend_Search_Lucene_Exception('terms argument must be array of strings or null');

        }

        if (is_array($offsets)) {

            if (count($this->_terms) != count($offsets)) {

                throw new Zend_Search_Lucene_Exception('terms and offsets arguments must have the same size.');

            }

            $this->_offsets = $offsets;

        } else if ($offsets === null) {

            $this->_offsets = array();

            foreach ($this->_terms as $termId => $term) {

                $position = count($this->_offsets);

                $this->_offsets[$termId] = $position;

            }

        } else {

            throw new Zend_Search_Lucene_Exception('offsets argument must be array of strings or null');

        }

    }

    /**

     * Set slop

     *

     * @param integer $slop

     */

    public function setSlop($slop)

    {

        $this->_slop = $slop;

    }

    /**

     * Get slop

     *

     * @return integer

     */

    public function getSlop()

    {

        return $this->_slop;

    }

    /**

     * Adds a term to the end of the query phrase.

     * The relative position of the term is specified explicitly or the one immediately

     * after the last term added.

     *

     * @param Zend_Search_Lucene_Index_Term $term

     * @param integer $position

     */

    public function addTerm(Zend_Search_Lucene_Index_Term $term, $position = null) {

        if ((count($this->_terms) != 0)&&(end($this->_terms)->field != $term->field)) {

            throw new Zend_Search_Lucene_Exception('All phrase terms must be in the same field: ' .

                                                   $term->field . ':' . $term->text);

        }

        $this->_terms[] = $term;

        if ($position !== null) {

            $this->_offsets[] = $position;

        } else if (count($this->_offsets) != 0) {

            $this->_offsets[] = end($this->_offsets) + 1;

        } else {

            $this->_offsets[] = 0;

        }

    }

    /**

     * Returns query term

     *

     * @return array

     */

    public function getTerms()

    {

        return $this->_terms;

    }

    /**

     * Set weight for specified term

     *

     * @param integer $num

     * @param Zend_Search_Lucene_Search_Weight_Term $weight

     */

    public function setWeight($num, $weight)

    {

        $this->_weights[$num] = $weight;

    }

    /**

     * Constructs an appropriate Weight implementation for this query.

     *

     * @param Zend_Search_Lucene $reader

     * @return Zend_Search_Lucene_Search_Weight

     */

    protected function _createWeight($reader)

    {

        return new Zend_Search_Lucene_Search_Weight_Phrase($this, $reader);

    }

    /**

     * Calculate result vector

     *

     * @param Zend_Search_Lucene $reader

     */

    private function _calculateResult($reader)

    {

        if (extension_loaded('bitset')) {

            foreach( $this->_terms as $termId=>$term ) {

                if($this->_resVector === null) {

                    $this->_resVector = bitset_from_array($reader->termDocs($term));

                } else {

                    $this->_resVector = bitset_intersection(

                                $this->_resVector,

                                bitset_from_array($reader->termDocs($term)) );

                }

                $this->_termsPositions[$termId] = $reader->termPositions($term);

            }

        } else {

            foreach( $this->_terms as $termId=>$term ) {

                if($this->_resVector === null) {

                    $this->_resVector = array_flip($reader->termDocs($term));

                } else {

                    $termDocs = array_flip($reader->termDocs($term));

                    foreach($this->_resVector as $key=>$value) {

                        if (!isset( $termDocs[$key] )) {

                            unset( $this->_resVector[$key] );

                        }

                    }

                }

                $this->_termsPositions[$termId] = $reader->termPositions($term);

            }

        }

    }

    /**

     * Score calculator for exact phrase queries (terms sequence is fixed)

     *

     * @param integer $docId

     * @return float

     */

    public function _exactPhraseFreq($docId)

    {

        $freq = 0;

        // Term Id with lowest cardinality

        $lowCardTermId = null;

        // Calculate $lowCardTermId

        foreach ($this->_terms as $termId => $term) {

            if ($lowCardTermId === null ||

                count($this->_termsPositions[$termId][$docId]) <

                count($this->_termsPositions[$lowCardTermId][$docId]) ) {

                    $lowCardTermId = $termId;

                }

        }

        // Walk through positions of the term with lowest cardinality

        foreach ($this->_termsPositions[$lowCardTermId][$docId] as $lowCardPos) {

            // We expect phrase to be found

            $freq++;

            // Walk through other terms

            foreach ($this->_terms as $termId => $term) {

                if ($termId != $lowCardTermId) {

                    $expectedPosition = $lowCardPos +

                                            ($this->_offsets[$termId] -

                                             $this->_offsets[$lowCardTermId]);

                    if (!in_array($expectedPosition, $this->_termsPositions[$termId][$docId])) {

                        $freq--;  // Phrase wasn't found.

                        break;

                    }

                }

            }

        }

        return $freq;

    }

    /**

     * Score calculator for sloppy phrase queries (terms sequence is fixed)

     *

     * @param integer $docId

     * @param Zend_Search_Lucene $reader

     * @return float

     */

    public function _sloppyPhraseFreq($docId, Zend_Search_Lucene $reader)

    {

        $freq = 0;

        $phraseQueue = array();

        $phraseQueue[0] = array(); // empty phrase

        $lastTerm = null;

        // Walk through the terms to create phrases.

        foreach ($this->_terms as $termId => $term) {

            $queueSize = count($phraseQueue);

            $firstPass = true;

            // Walk through the term positions.

            // Each term position produces a set of phrases.

            foreach ($this->_termsPositions[$termId][$docId] as $termPosition ) {

                if ($firstPass) {

                    for ($count = 0; $count < $queueSize; $count++) {

                        $phraseQueue[$count][$termId] = $termPosition;

                    }

                } else {

                    for ($count = 0; $count < $queueSize; $count++) {

                        if ($lastTerm !== null &&

                            abs( $termPosition - $phraseQueue[$count][$lastTerm] -

                                 ($this->_offsets[$termId] - $this->_offsets[$lastTerm])) > $this->_slop) {

                            continue;

                        }

                        $newPhraseId = count($phraseQueue);

                        $phraseQueue[$newPhraseId]          = $phraseQueue[$count];

                        $phraseQueue[$newPhraseId][$termId] = $termPosition;

                    }

                }

                $firstPass = false;

            }

            $lastTerm = $termId;

        }

        foreach ($phraseQueue as $phrasePos) {

            $minDistance = null;

            for ($shift = -$this->_slop; $shift <= $this->_slop; $shift++) {

                $distance = 0;

                $start = reset($phrasePos) - reset($this->_offsets) + $shift;

                foreach ($this->_terms as $termId => $term) {

                    $distance += abs($phrasePos[$termId] - $this->_offsets[$termId] - $start);

                    if($distance > $this->_slop) {

                        break;

                    }

                }

                if ($minDistance === null || $distance < $minDistance) {

                    $minDistance = $distance;

                }

            }

            if ($minDistance <= $this->_slop) {

                $freq += $reader->getSimilarity()->sloppyFreq($minDistance);

            }

        }

        return $freq;

    }

    /**

     * Score specified document

     *

     * @param integer $docId

     * @param Zend_Search_Lucene $reader

     * @return float

     */

    public function score($docId, $reader)

    {

        // optimize zero-term case

        if (count($this->_terms) == 0) {

            return 0;

        }

        if($this->_resVector === null) {

            $this->_calculateResult($reader);

            $this->_initWeight($reader);

        }

        if ( (extension_loaded('bitset')) ?

                bitset_in($this->_resVector, $docId) :

                isset($this->_resVector[$docId])  ) {

            if ($this->_slop == 0) {

                $freq = $this->_exactPhraseFreq($docId);

            } else {

                $freq = $this->_sloppyPhraseFreq($docId, $reader);

            }

/*

            return $reader->getSimilarity()->tf($freq) *

                   $this->_weight->getValue() *

                   $reader->norm($docId, reset($this->_terms)->field);

*/

            if ($freq != 0) {

                $tf = $reader->getSimilarity()->tf($freq);

                $weight = $this->_weight->getValue();

                $norm = $reader->norm($docId, reset($this->_terms)->field);

                return $tf*$weight*$norm;

            }

        } else {

            return 0;

        }

    }

}