File size: 7.65Kb
<?php
/**
* Zend Framework (http://framework.zend.com/)
*
* @link http://github.com/zendframework/zf2 for the canonical source repository
* @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
* @package Zend_Search
*/
namespace ZendSearch\Lucene\Search\Query\Preprocessing;
use ZendSearch\Lucene;
use ZendSearch\Lucene\Analysis\Analyzer\Analyzer;
use ZendSearch\Lucene\Analysis\Analyzer\AnalyzerInterface;
use ZendSearch\Lucene\Index;
use ZendSearch\Lucene\Search\Highlighter\HighlighterInterface as Highlighter;
use ZendSearch\Lucene\Search\Query;
/**
* It's an internal abstract class intended to finalize ase a query processing after query parsing.
* This type of query is not actually involved into query execution.
*
* @category Zend
* @package Zend_Search_Lucene
* @subpackage Search
* @internal
*/
class Phrase extends AbstractPreprocessing
{
/**
* Phrase to find.
*
* @var string
*/
private $_phrase;
/**
* Phrase encoding (field name is always provided using UTF-8 encoding since it may be retrieved from index).
*
* @var string
*/
private $_phraseEncoding;
/**
* Field name.
*
* @var string
*/
private $_field;
/**
* 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 integer
*/
private $_slop;
/**
* Class constructor. Create a new preprocessing object for prase query.
*
* @param string $phrase Phrase to search.
* @param string $phraseEncoding Phrase encoding.
* @param string $fieldName Field name.
*/
public function __construct($phrase, $phraseEncoding, $fieldName)
{
$this->_phrase = $phrase;
$this->_phraseEncoding = $phraseEncoding;
$this->_field = $fieldName;
}
/**
* Set slop
*
* @param integer $slop
*/
public function setSlop($slop)
{
$this->_slop = $slop;
}
/**
* Get slop
*
* @return integer
*/
public function getSlop()
{
return $this->_slop;
}
/**
* Re-write query into primitive queries in the context of specified index
*
* @param \ZendSearch\Lucene\SearchIndexInterface $index
* @return \ZendSearch\Lucene\Search\Query\AbstractQuery
*/
public function rewrite(Lucene\SearchIndexInterface $index)
{
// Allow to use wildcards within phrases
// They are either removed by text analyzer or used as a part of keyword for keyword fields
//
// if (strpos($this->_phrase, '?') !== false || strpos($this->_phrase, '*') !== false) {
// require_once 'Zend/Search/Lucene/Search/QueryParserException.php';
// throw new Zend_Search_Lucene_Search_QueryParserException('Wildcards are only allowed in a single terms.');
// }
// Split query into subqueries if field name is not specified
if ($this->_field === null) {
$query = new Query\Boolean();
$query->setBoost($this->getBoost());
if (Lucene\Lucene::getDefaultSearchField() === null) {
$searchFields = $index->getFieldNames(true);
} else {
$searchFields = array(Lucene\Lucene::getDefaultSearchField());
}
foreach ($searchFields as $fieldName) {
$subquery = new Phrase($this->_phrase,
$this->_phraseEncoding,
$fieldName);
$subquery->setSlop($this->getSlop());
$query->addSubquery($subquery->rewrite($index));
}
$this->_matches = $query->getQueryTerms();
return $query;
}
// Recognize exact term matching (it corresponds to Keyword fields stored in the index)
// encoding is not used since we expect binary matching
$term = new Index\Term($this->_phrase, $this->_field);
if ($index->hasTerm($term)) {
$query = new Query\Term($term);
$query->setBoost($this->getBoost());
$this->_matches = $query->getQueryTerms();
return $query;
}
// tokenize phrase using current analyzer and process it as a phrase query
$tokens = Analyzer::getDefault()->tokenize($this->_phrase, $this->_phraseEncoding);
if (count($tokens) == 0) {
$this->_matches = array();
return new Query\Insignificant();
}
if (count($tokens) == 1) {
$term = new Index\Term($tokens[0]->getTermText(), $this->_field);
$query = new Query\Term($term);
$query->setBoost($this->getBoost());
$this->_matches = $query->getQueryTerms();
return $query;
}
//It's non-trivial phrase query
$position = -1;
$query = new Query\Phrase();
foreach ($tokens as $token) {
$position += $token->getPositionIncrement();
$term = new Index\Term($token->getTermText(), $this->_field);
$query->addTerm($term, $position);
$query->setSlop($this->getSlop());
}
$this->_matches = $query->getQueryTerms();
return $query;
}
/**
* Query specific matches highlighting
*
* @param Highlighter $highlighter Highlighter object (also contains doc for highlighting)
*/
protected function _highlightMatches(Highlighter $highlighter)
{
/** Skip fields detection. We don't need it, since we expect all fields presented in the HTML body and don't differentiate them */
/** Skip exact term matching recognition, keyword fields highlighting is not supported */
/** Skip wildcard queries recognition. Supported wildcards are removed by text analyzer */
// tokenize phrase using current analyzer and process it as a phrase query
$tokens = Analyzer::getDefault()->tokenize($this->_phrase, $this->_phraseEncoding);
if (count($tokens) == 0) {
// Do nothing
return;
}
if (count($tokens) == 1) {
$highlighter->highlight($tokens[0]->getTermText());
return;
}
//It's non-trivial phrase query
$words = array();
foreach ($tokens as $token) {
$words[] = $token->getTermText();
}
$highlighter->highlight($words);
}
/**
* Print a query
*
* @return string
*/
public function __toString()
{
// It's used only for query visualisation, so we don't care about characters escaping
if ($this->_field !== null) {
$query = $this->_field . ':';
} else {
$query = '';
}
$query .= '"' . $this->_phrase . '"';
if ($this->_slop != 0) {
$query .= '~' . $this->_slop;
}
if ($this->getBoost() != 1) {
$query .= '^' . round($this->getBoost(), 4);
}
return $query;
}
}