479 lines
14 KiB
PHP
479 lines
14 KiB
PHP
<?php
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// $Id$
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/**
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* @file
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* Search query extender and helper functions.
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*/
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/**
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* Do a query on the full-text search index for a word or words.
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*
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* This function is normally only called by each module that supports the
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* indexed search (and thus, implements hook_update_index()).
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*
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* Results are retrieved in two logical passes. However, the two passes are
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* joined together into a single query. And in the case of most simple
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* queries the second pass is not even used.
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*
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* The first pass selects a set of all possible matches, which has the benefit
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* of also providing the exact result set for simple "AND" or "OR" searches.
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*
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* The second portion of the query further refines this set by verifying
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* advanced text conditions (such as negative or phrase matches).
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*
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* The used query object has the tag 'search_$type' and can be further extended
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* with hook_query_alter().
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*/
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class SearchQuery extends SelectQueryExtender {
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/**
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* The search query that is used for searching.
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*
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* @var string
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*/
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protected $searchExpression;
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/**
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* Type of search.
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*
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* This maps to the value of the type column in search_index.
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*
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* @var string
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*/
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protected $type;
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/**
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* Positive and negative search keys.
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*
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* @var array
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*/
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protected $keys = array('positive' => array(), 'negative' => array());
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/**
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* Indicates if the first pass query requires complex conditions (LIKE).
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*
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* @var boolean.
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*/
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protected $simple = TRUE;
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/**
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* Conditions that are used for exact searches.
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*
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* This is always used for the second pass query but not for the first pass,
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* unless $this->simple is FALSE.
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*
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* @var DatabaseCondition
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*/
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protected $conditions;
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/**
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* Indicates how many matches for a search query are necessary.
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*
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* @var int
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*/
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protected $matches = 0;
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/**
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* Array of search words.
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*
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* These words have to match against {search_index}.word.
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*
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* @var array
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*/
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protected $words = array();
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/**
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* Multiplier for the normalized search score.
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*
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* This value is calculated by the first pass query and multiplied with the
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* actual score of a specific word to make sure that the resulting calculated
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* score is between 0 and 1.
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*
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* @var float
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*/
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protected $normalize;
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/**
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* Indicates if the first pass query has been executed.
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*
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* @var boolean
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*/
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protected $executedFirstPass = FALSE;
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/**
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* Stores score expressions.
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*
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* @var array
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*/
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protected $scores = array();
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/**
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* Stores arguments for score expressions.
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*
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* @var array
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*/
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protected $scoresArguments = array();
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/**
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* Total value of all the multipliers.
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*
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* @var array
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*/
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protected $multiply = array();
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/**
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* Search items for the given search query string and type.
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*
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* @param $query
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* A search query string, that can contain options.
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* @param $type
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* The type of search, this maps to {search_index}.type.
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* @return
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* The SearchQuery object.
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*/
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public function searchExpression($expression, $type) {
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$this->searchExpression = $expression;
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$this->type = $type;
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return $this;
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}
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/**
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* Apply a search option and remove it from the search query string.
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*
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* These options are in the form option:value,value2,value3.
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*
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* @param $option
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* Name of the option.
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* @param $column
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* Name of the db column to which the value should be applied.
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* @return
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* TRUE if at least a value for that option has been found, FALSE if not.
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*/
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public function setOption($option, $column) {
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if ($values = search_expression_extract($this->searchExpression, $option)) {
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$or = db_or();
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foreach (explode(',', $values) as $value) {
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$or->condition($column, $value);
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}
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$this->condition($or);
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$this->searchExpression = search_expression_insert($this->searchExpression, $option);
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return TRUE;
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}
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return FALSE;
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}
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/**
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* Parse a search query into SQL conditions.
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*
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* We build two queries that matches the dataset bodies.
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*/
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protected function parseSearchExpression() {
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// Matchs words optionally prefixed by a dash. A word in this case is
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// something between two spaces, optionally quoted.
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preg_match_all('/ (-?)("[^"]+"|[^" ]+)/i', ' ' . $this->searchExpression , $keywords, PREG_SET_ORDER);
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if (count($keywords) == 0) {
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return;
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}
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// Classify tokens.
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$or = FALSE;
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$warning = '';
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foreach ($keywords as $match) {
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$phrase = FALSE;
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// Strip off phrase quotes.
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if ($match[2]{0} == '"') {
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$match[2] = substr($match[2], 1, -1);
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$phrase = TRUE;
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$this->simple = FALSE;
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}
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// Simplify keyword according to indexing rules and external preprocessors.
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$words = search_simplify($match[2]);
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// Re-explode in case simplification added more words, except when
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// matching a phrase.
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$words = $phrase ? array($words) : preg_split('/ /', $words, -1, PREG_SPLIT_NO_EMPTY);
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// Negative matches.
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if ($match[1] == '-') {
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$this->keys['negative'] = array_merge($this->keys['negative'], $words);
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}
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// OR operator: instead of a single keyword, we store an array of all
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// OR'd keywords.
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elseif ($match[2] == 'OR' && count($this->keys['positive'])) {
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$last = array_pop($this->keys['positive']);
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// Starting a new OR?
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if (!is_array($last)) {
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$last = array($last);
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}
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$this->keys['positive'][] = $last;
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$or = TRUE;
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continue;
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}
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// AND operator: implied, so just ignore it.
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elseif ($match[2] == 'AND' || $match[2] == 'and') {
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$warning = $match[2];
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continue;
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}
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// Plain keyword.
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else {
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if ($match[2] == 'or') {
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$warning = $match[2];
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}
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if ($or) {
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// Add to last element (which is an array).
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$this->keys['positive'][count($this->keys['positive']) - 1] = array_merge($this->keys['positive'][count($this->keys['positive']) - 1], $words);
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}
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else {
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$this->keys['positive'] = array_merge($this->keys['positive'], $words);
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}
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}
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$or = FALSE;
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}
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// Convert keywords into SQL statements.
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$this->conditions = db_and();
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$simple_and = FALSE;
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$simple_or = FALSE;
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// Positive matches.
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foreach ($this->keys['positive'] as $key) {
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// Group of ORed terms.
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if (is_array($key) && count($key)) {
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$simple_or = TRUE;
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$any = FALSE;
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$queryor = db_or();
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foreach ($key as $or) {
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list($num_new_scores) = $this->parseWord($or);
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$any |= $num_new_scores;
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$queryor->condition('d.data', "% $or %", 'LIKE');
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}
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if (count($queryor)) {
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$this->conditions->condition($queryor);
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// A group of OR keywords only needs to match once.
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$this->matches += ($any > 0);
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}
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}
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// Single ANDed term.
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else {
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$simple_and = TRUE;
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list($num_new_scores, $num_valid_words) = $this->parseWord($key);
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$this->conditions->condition('d.data', "% $key %", 'LIKE');
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if (!$num_valid_words) {
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$this->simple = FALSE;
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}
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// Each AND keyword needs to match at least once.
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$this->matches += $num_new_scores;
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}
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}
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if ($simple_and && $simple_or) {
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$this->simple = FALSE;
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}
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// Negative matches.
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foreach ($this->keys['negative'] as $key) {
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$this->conditions->condition('d.data', "% $key %", 'NOT LIKE');
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$this->simple = FALSE;
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}
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if ($warning == 'or') {
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drupal_set_message(t('Search for either of the two terms with uppercase <strong>OR</strong>. For example, <strong>cats OR dogs</strong>.'));
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}
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}
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/**
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* Helper function for parseQuery().
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*/
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protected function parseWord($word) {
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$num_new_scores = 0;
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$num_valid_words = 0;
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// Determine the scorewords of this word/phrase.
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$split = explode(' ', $word);
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foreach ($split as $s) {
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$num = is_numeric($s);
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if ($num || drupal_strlen($s) >= variable_get('minimum_word_size', 3)) {
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$s = $num ? ((int)ltrim($s, '-0')) : $s;
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if (!isset($this->words[$s])) {
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$this->words[$s] = $s;
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$num_new_scores++;
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}
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$num_valid_words++;
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}
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}
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// Return matching snippet and number of added words.
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return array($num_new_scores, $num_valid_words);
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}
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/**
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* Execute the first pass query.
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*
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* This can either be done explicitly, so that additional scores and
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* conditions can be applied to the second pass query or implicitly by
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* addScore() or execute().
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*
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* @return
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* TRUE if search items exist, FALSE if not.
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*/
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public function executeFirstPass() {
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$this->parseSearchExpression();
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if (count($this->words) == 0) {
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form_set_error('keys', format_plural(variable_get('minimum_word_size', 3), 'You must include at least one positive keyword with 1 character or more.', 'You must include at least one positive keyword with @count characters or more.'));
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return FALSE;
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}
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$this->executedFirstPass = TRUE;
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if (!empty($this->words)) {
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$or = db_or();
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foreach ($this->words as $word) {
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$or->condition('i.word', $word);
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}
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$this->condition($or);
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}
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// Build query for keyword normalization.
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$this->join('search_total', 't', 'i.word = t.word');
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$this
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->condition('i.type', $this->type)
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->groupBy('i.type')
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->groupBy('i.sid')
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->having('COUNT(*) >= :matches', array(':matches' => $this->matches));
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// Clone the query object to do the firstPass query;
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$first = clone $this->query;
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// For complex search queries, add the LIKE conditions to the first pass query.
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if (!$this->simple) {
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$first->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
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$first->condition($this->conditions);
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}
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// Calculate maximum keyword relevance, to normalize it.
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$first->addExpression('SUM(i.score * t.count)', 'calculated_score');
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$this->normalize = $first
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->range(0, 1)
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->orderBy('calculated_score', 'DESC')
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->execute()
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->fetchField();
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if ($this->normalize) {
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return TRUE;
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}
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return FALSE;
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}
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/**
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* Adds a custom score expression to the search query.
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*
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* Each score expression can optionally use a multiplicator and multiple
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* expressions are combined.
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*
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* @param $score
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* The score expression.
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* @param $arguments
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* Custom query arguments for that expression.
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* @param $multiply
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* If set, the score is multiplied with that value. Search query ensures
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* that the search scores are still normalized.
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*/
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public function addScore($score, $arguments = array(), $multiply = FALSE) {
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if ($multiply) {
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$i = count($this->multiply);
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$score = "CAST(:multiply_$i AS DECIMAL) * COALESCE(( " . $score . "), 0) / CAST(:total_$i AS DECIMAL)";
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$arguments[':multiply_' . $i] = $multiply;
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$this->multiply[] = $multiply;
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}
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$this->scores[] = $score;
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$this->scoresArguments += $arguments;
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return $this;
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}
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/**
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* Execute the search.
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*
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* If not already done, this executes the first pass query, then the complex
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* conditions are applied to the query including score expressions and
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* ordering.
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*
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* @return
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* FALSE if the first pass query returned no results and a database result
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* set if not.
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*/
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public function execute()
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{
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if (!$this->executedFirstPass) {
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$this->executeFirstPass();
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}
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if (!$this->normalize) {
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return new DatabaseStatementEmpty();
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}
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// Add conditions to query.
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$this->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
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$this->condition($this->conditions);
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if (empty($this->scores)) {
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// Add default score.
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$this->addScore('i.relevance');
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}
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if (count($this->getOrderBy()) == 0) {
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// Add default order.
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$this->orderBy('calculated_score', 'DESC');
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}
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if (count($this->multiply)) {
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// Add the total multiplicator as many times as requested to maintain
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// normalization as far as possible.
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$i = 0;
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$sum = array_sum($this->multiply);
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foreach ($this->multiply as $total) {
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$this->scoresArguments[':total_' . $i] = $sum;
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$i++;
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}
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}
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// Replace i.relevance pseudo-field with the actual, normalized value.
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$this->scores = str_replace('i.relevance', '(' . (1.0 / $this->normalize) . ' * i.score * t.count)', $this->scores);
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// Convert scores to an expression.
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$this->addExpression('SUM(' . implode(' + ', $this->scores) . ')', 'calculated_score', $this->scoresArguments);
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// Add tag and useful metadata.
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$this
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->addTag('search_' . $this->type)
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->addMetaData('normalize', $this->normalize)
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->fields('i', array('type', 'sid'));
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return $this->query->execute();
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}
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/**
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* Build the default count query for SearchQuery.
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*
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* Since SearchQuery always uses GROUP BY, we can default to a subquery. Also
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* adding the same conditions as execute() because countQuery() is called
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* first.
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*/
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public function countQuery() {
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// Clone the inner query.
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$inner = clone $this->query;
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// Add conditions to query.
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$inner->join('search_dataset', 'd', 'i.sid = d.sid AND i.type = d.type');
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$inner->condition($this->conditions);
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// Remove existing fields and expressions, they are not needed for a count
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// query.
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$fields =& $inner->getFields();
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$fields = array();
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$expressions =& $inner->getExpressions();
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$expressions = array();
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// Add the sid as the only field and count them as a subquery.
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$count = db_select($inner->fields('i', array('sid')), NULL, array('target' => 'slave'));
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// Add the COUNT() expression.
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$count->addExpression('COUNT(*)');
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return $count;
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}
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}
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