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1038 lines
38 KiB
PHP
1038 lines
38 KiB
PHP
<?php
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register_module([
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"name" => "Library: Search engine",
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"version" => "0.13.1",
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"author" => "Starbeamrainbowlabs",
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"description" => "A library module that provides the backend to the search engine module.",
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"id" => "lib-search-engine",
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"depends" => [ "lib-storage-box" ],
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"code" => function() {
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}
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]);
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/*
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███████ ███████ █████ ██████ ██████ ██ ██
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██ ██ ██ ██ ██ ██ ██ ██ ██
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███████ █████ ███████ ██████ ██ ███████
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██ ██ ██ ██ ██ ██ ██ ██ ██
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███████ ███████ ██ ██ ██ ██ ██████ ██ ██
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*/
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/**
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* Holds a collection to methods to manipulate various types of search index.
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* @package search
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*/
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class search
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{
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/**
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* Words that we should exclude from the inverted index.
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* @source http://xpo6.com/list-of-english-stop-words/
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* @var string[]
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*/
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public static $stop_words = [
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"a", "about", "above", "above", "across", "after", "afterwards", "again",
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"against", "all", "almost", "alone", "along", "already", "also",
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"although", "always", "am", "among", "amongst", "amoungst", "amount",
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"an", "and", "another", "any", "anyhow", "anyone", "anything", "anyway",
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"anywhere", "are", "around", "as", "at", "back", "be", "became",
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"because", "become", "becomes", "becoming", "been", "before",
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"beforehand", "behind", "being", "below", "beside", "besides",
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"between", "beyond", "bill", "both", "bottom", "but", "by", "call",
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"can", "can't", "cannot", "co", "con", "could", "couldnt", "cry", "de",
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"describe", "detail", "do", "done", "down", "due", "during", "each",
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"eg", "eight", "either", "eleven", "else", "elsewhere", "empty",
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"enough", "etc", "even", "ever", "every", "everyone", "everything",
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"everywhere", "except", "few", "fill", "find",
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"fire", "first", "five", "for", "former", "formerly", "found",
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"four", "from", "front", "full", "further", "get", "give", "go", "had",
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"has", "hasnt", "have", "he", "hence", "her", "here", "hereafter",
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"hereby", "herein", "hereupon", "hers", "herself", "him", "himself",
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"his", "how", "however", "ie", "if", "in", "inc", "indeed",
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"interest", "into", "is", "it", "its", "it's", "itself", "keep", "last",
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"latter", "latterly", "least", "less", "ltd", "made", "many", "may",
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"me", "meanwhile", "might", "mine", "more", "moreover", "most",
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"mostly", "move", "much", "must", "my", "myself", "name", "namely",
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"neither", "never", "nevertheless", "next", "nine", "no", "none",
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"nor", "not", "nothing", "now", "nowhere", "of", "off", "often", "on",
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"once", "one", "only", "onto", "or", "other", "others", "otherwise",
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"our", "ours", "ourselves", "out", "over", "own", "part", "per",
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"perhaps", "please", "put", "rather", "re", "same", "see", "seem",
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"seemed", "seeming", "seems", "serious", "several", "she", "should",
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"show", "side", "since", "sincere", "six", "sixty", "so", "some",
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"somehow", "someone", "something", "sometime", "sometimes",
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"somewhere", "still", "such", "system", "take", "ten", "than", "that",
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"the", "their", "them", "themselves", "then", "thence", "there",
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"thereafter", "thereby", "therefore", "therein", "thereupon", "these",
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"they", "thickv", "thin", "third", "this", "those", "though", "three",
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"through", "throughout", "thru", "thus", "to", "together", "too", "top",
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"toward", "towards", "twelve", "twenty", "two", "un", "under", "until",
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"up", "upon", "us", "very", "via", "was", "we", "well", "were", "what",
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"whatever", "when", "whence", "whenever", "where", "whereafter",
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"whereas", "whereby", "wherein", "whereupon", "wherever", "whether",
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"which", "while", "whither", "who", "whoever", "whole", "whom", "whose",
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"why", "will", "with", "within", "without", "would", "yet", "you",
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"your", "yours", "yourself", "yourselves"
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];
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/**
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* The StorageBox that contains the inverted index.
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* @var StorageBox
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*/
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private static $invindex = null;
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/**
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* The 'did you mean?' index for typo correction.
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* Only populated if the feature-search-didyoumean module is present.
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* @var BkTree
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*/
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public static $didyoumeanindex = null;
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/**
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* The transliterator that can be used to transliterate strings.
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* Transliterated strings are more suitable for use with the search index.
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* Note that this is no longer wrapped in a function as of v0.21 for
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* performance reasons.
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* @var Transliterator
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*/
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public static $literator = null;
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/**
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* Sorter for sorting lists of *transliterated* strings.
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* Should work for non-transliterated strings too.
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* @var Collator
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*/
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private static $sorter;
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/**
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* Initialises the search system.
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* Do not call this function! It is called automatically.
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*/
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public static function init() {
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self::$literator = Transliterator::createFromRules(':: Any-Latin; :: Latin-ASCII; :: NFD; :: [:Nonspacing Mark:] Remove; :: Lower(); :: NFC;', Transliterator::FORWARD);
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self::$sorter = new Collator("");
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}
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/**
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* Logs a progress message in the right format depending on the current
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* environment.
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* @param string $message The message to log.
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*/
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private static function log_progress(string $message, bool $sameline = false) : void {
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if(is_cli()) {
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if($sameline) $message = "$message\r";
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else $message = "$message\n";
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echo($message);
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}
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else {
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echo("data: $message\n\n");
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flush();
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}
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}
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/**
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* Loads the didyoumean index.
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* Don't forget to call this before making any search queries if didyoumean
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* typo correction is enabled.
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* Note that calling it multiple times has no effect. Returns true if the
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* didyoumean index is already loaded.
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* @param string $filename The filename of the didyoumean index.
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* @param string $seed_word The seed word. If this changes, the index must be rebuilt.
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* @return bool Whether the index was loaded successfully or not. Returns false if the feature-search-didyoumean module is not present.
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*/
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public static function didyoumean_load() : bool {
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global $settings, $paths;
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if(!module_exists("feature-search-didyoumean"))
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return false;
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// Avoid loading twice
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if(is_a(self::$didyoumeanindex, BkTree::class))
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return true;
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self::$didyoumeanindex = new BkTree(
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$paths->didyoumeanindex,
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$settings->search_didyoumean_seed_word
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);
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self::$didyoumeanindex->set_costs(
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$settings->search_didyoumean_cost_insert,
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$settings->search_didyoumean_cost_delete,
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$settings->search_didyoumean_cost_replace
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);
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return true;
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}
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/**
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* Returns a correction for a given word according to the didyoumean index.
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* Note that this is quite an expensive call.
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* Check that the word exists in the regular search index first, and that
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* it's not a stop word before calling this function.
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* @param string $term The term to correct.
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* @return string|null The closest correction found, or null if none could be located.
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*/
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public static function didyoumean_correct(string $term) : ?string {
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global $settings, $paths, $env;
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$start_time = microtime(true);
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// Load the didyoumean index, but only if it's enabled etc
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if(!module_exists("feature-search-didyoumean") || !$settings->search_didyoumean_enabled)
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return null;
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// If it's not loaded already, load the didyoumean index on-demand
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if(self::$didyoumeanindex == null)
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search::didyoumean_load($paths->searchindex);
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$results = self::$didyoumeanindex->lookup(
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$term,
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$settings->search_didyoumean_editdistance
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);
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if(!empty($results)) {
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usort($results, function($a, $b) : int {
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return self::$sorter->compare($a, $b);
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});
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}
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if(!isset($env->perfdata->didyoumean_correction))
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$env->perfdata->didyoumean_correction = 0;
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$env->perfdata->didyoumean_correction += (microtime(true) - $start_time) * 1000;
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return $results[0] ?? null;
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}
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public static function didyoumean_rebuild(bool $output = true) : void {
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global $env;
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if($output && !is_cli()) {
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header("content-type: text/event-stream");
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ob_end_flush();
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}
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$env->perfdata->didyoumean_rebuild = microtime(true);
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if($output) self::log_progress("Beginning didyoumean index rebuild");
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if($output) self::log_progress("Loading indexes");
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self::invindex_load();
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self::didyoumean_load();
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if($output) self::log_progress("Populating index");
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self::$didyoumeanindex->clear();
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$i = 0;
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foreach(self::$invindex->get_keys("|") as $key) {
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$key = $key["key"];
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if(self::$didyoumeanindex->add($key) === null && $output)
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self::log_progress("[$i] Skipping '$key' as it's too long");
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elseif($output && $i % 1500 == 0) self::log_progress("[$i] Added '$key'", true);
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$i++;
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}
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self::log_progress(""); // Blank newline
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if($output) self::log_progress("Syncing to disk...");
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// Closing = saving, but we can't use it afterwards
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self::$didyoumeanindex->close();
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// Just in case it's loaded again later
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self::$didyoumeanindex = null;
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$env->perfdata->didyoumean_rebuild = round(microtime(true) - $env->perfdata->didyoumean_rebuild, 4);
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if($output) self::log_progress("didyoumean index rebuild complete in {$env->perfdata->didyoumean_rebuild}s");
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}
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/**
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* Converts a source string into an index of search terms that can be
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* merged into an inverted index.
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* Automatically transliterates the source string.
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* @param string $source The source string to index.
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* @return array An index represents the specified string.
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*/
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public static function index_generate(string $source) : array {
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// We don't need to normalise or transliterate here because self::tokenize() does this for us
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$source = html_entity_decode($source, ENT_QUOTES);
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$source_length = mb_strlen($source);
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$index = [];
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$terms = self::tokenize($source, true);
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foreach($terms as $term) {
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// Skip over stop words (see https://en.wikipedia.org/wiki/Stop_words)
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if(in_array($term[0], self::$stop_words)) continue;
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if(!isset($index[$term[0]]))
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$index[$term[0]] = [ "freq" => 0, "offsets" => [] ];
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$index[$term[0]]["freq"]++;
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$index[$term[0]]["offsets"][] = $term[1];
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}
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return $index;
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}
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/**
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* Converts a source string into a series of raw tokens.
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* @param string $source The source string to process.
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* @param bool $capture_offsets Whether to capture & return the character offsets of the tokens detected. If true, then each token returned will be an array in the form [ token, char_offset ].
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* @return array An array of raw tokens extracted from the specified source string.
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*/
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public static function tokenize(string $source, bool $capture_offsets = false) : array {
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$flags = PREG_SPLIT_NO_EMPTY; // Don't return empty items
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if($capture_offsets)
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$flags |= PREG_SPLIT_OFFSET_CAPTURE;
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// We don't need to normalise here because the transliterator handles that
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$source = self::$literator->transliterate($source);
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$source = preg_replace('/[\[\]\|\{\}\/]/u', " ", $source);
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return preg_split("/((^\p{P}+)|(\p{P}*\s+\p{P}*)|(\p{P}+$))|\|/u", $source, -1, $flags);
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}
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/**
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* Removes (most) markdown markup from the specified string.
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* Stripped strings are not suitable for indexing!
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* @param string $source The source string to process.
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* @return string The stripped string.
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*/
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public static function strip_markup(string $source) : string {
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return preg_replace('/([\"*_\[\]]| - |`)/u', "", $source);
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}
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/**
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* Rebuilds the master inverted index and clears the page id index.
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* @param bool $output Whether to send progress information to the user's browser.
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*/
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public static function invindex_rebuild(bool $output = true) : void {
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global $pageindex, $env, $paths, $settings;
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$env->perfdata->invindex_rebuild = microtime(true);
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if($output && !is_cli()) {
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header("content-type: text/event-stream");
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ob_end_flush();
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}
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// Clear the id index out
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ids::clear();
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// Clear the existing inverted index out
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if(self::$invindex == null)
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self::invindex_load($paths->searchindex);
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self::$invindex->clear();
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self::$invindex->set("|termlist|", []);
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// Reindex each page in turn
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$i = 0; $max = count(get_object_vars($pageindex));
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$missing_files = 0;
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foreach($pageindex as $pagename => $pagedetails)
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{
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$page_filename = $env->storage_prefix . $pagedetails->filename;
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if(!file_exists($page_filename)) {
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if(!is_cli()) echo("data: ");
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echo("[" . ($i + 1) . " / $max] Error: Can't find $page_filename\n");
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flush();
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$i++; $missing_files++;
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continue;
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}
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// We do not transliterate or normalise here because the indexer will take care of this for us
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$index = self::index_generate(file_get_contents($page_filename));
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$pageid = ids::getid($pagename);
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self::invindex_merge($pageid, $index);
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if($output) {
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$message = "[" . ($i + 1) . " / $max] Added $pagename (id #$pageid) to the new search index.";
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if(!is_cli()) $message = "data: $message\n\n";
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else $message = "$message\r";
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echo($message);
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flush();
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}
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$i++;
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}
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$msg = "Syncing to disk....";
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if(!is_cli()) $msg = "data: $msg\n\n";
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else $msg = "$msg\r";
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echo($msg);
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self::invindex_close();
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$env->perfdata->invindex_rebuild = round(microtime(true) - $env->perfdata->invindex_rebuild, 4);
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if($output && !is_cli()) {
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echo("data: Search index rebuilding complete in {$env->perfdata->invindex_rebuild}s.\n\n");
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echo("data: Couldn't find $missing_files pages on disk. If $settings->sitename couldn't find some pages on disk, then you might need to manually correct $settings->sitename's page index (stored in pageindex.json).\n\n");
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echo("data: Done! Saving new search index to '$paths->searchindex'.\n\n");
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}
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if(is_cli()) echo("\nSearch index rebuilding complete in {$env->perfdata->invindex_rebuild}s.\n");
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}
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/**
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* Sorts an index alphabetically.
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* This allows us to do a binary search instead of a regular
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* sequential search.
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* @param array $index The index to sort.
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*/
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public static function index_sort(&$index) {
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$sorter = self::$sorter;
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uksort($index, function($a, $b) use($sorter) : int {
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return $sorter->compare($a, $b);
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});
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}
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/**
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* Sorts an index by frequency.
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* @param array $index The index to sort.
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*/
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public static function index_sort_freq(&$index) {
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uasort($index, function($a, $b) : int {
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return $b["freq"] > $a["freq"];
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});
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}
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/**
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* Compares two *regular* indexes to find the differences between them.
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* @param array $oldindex The old index.
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* @param array $newindex The new index.
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* @param array $changed An array to be filled with the nterms of all the changed entries.
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* @param array $removed An array to be filled with the nterms of all the removed entries.
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*/
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public static function index_compare($oldindex, $newindex, &$changed, &$removed) {
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foreach($oldindex as $nterm => $entry) {
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if(!isset($newindex[$nterm]))
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$removed[] = $nterm;
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}
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foreach($newindex as $nterm => $entry) {
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if(!isset($oldindex[$nterm]) or // If this word is new
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$newindex[$nterm] !== $oldindex[$nterm]) // If this word has changed
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$changed[$nterm] = $newindex[$nterm];
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}
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}
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/**
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* Loads a connection to an inverted index.
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*/
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public static function invindex_load() {
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global $env, $paths;
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// If the inverted index is alreayd loaded, it doesn't need loading again
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if(self::$invindex !== null) return;
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$start_time = microtime(true);
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self::$invindex = new StorageBox($paths->searchindex);
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$env->perfdata->searchindex_load_time = round((microtime(true) - $start_time)*1000, 3);
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}
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/**
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* Closes the currently open inverted index.
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*/
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public static function invindex_close() {
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global $env;
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$start_time = microtime(true);
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self::$invindex->close();
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self::$invindex = null;
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$env->perfdata->searchindex_close_time = round((microtime(true) - $start_time)*1000, 3);
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}
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/**
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* Merge an index into an inverted index.
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* @param int $pageid The id of the page to assign to the index that's being merged.
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* @param array $index The regular index to merge.
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* @param array $removals An array of index entries to remove from the inverted index. Useful for applying changes to an inverted index instead of deleting and remerging an entire page's index.
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*/
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public static function invindex_merge($pageid, &$index, &$removals = []) : void {
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if(self::$invindex == null)
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throw new Exception("Error: Can't merge into an inverted index that isn't loaded.");
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if(!self::$invindex->has("|termlist|"))
|
|
self::$invindex->set("|termlist|", []);
|
|
$termlist = self::$invindex->get("|termlist|");
|
|
|
|
// Remove all the subentries that were removed since last time
|
|
foreach($removals as $nterm) {
|
|
// Delete the offsets
|
|
self::$invindex->delete("$nterm|$pageid");
|
|
// Delete the item from the list of pageids containing this term
|
|
$nterm_pageids = self::$invindex->get_arr_simple($nterm);
|
|
array_splice($nterm_pageids, array_search($pageid, $nterm_pageids), 1);
|
|
if(empty($nterm_pageids)) { // No need to keep the pageid list if there's nothing in it
|
|
self::$invindex->delete($nterm);
|
|
// Update the termlist if we're deleting the term completely
|
|
$termlist_loc = array_search($nterm, $termlist);
|
|
if($termlist_loc !== false) array_splice($termlist, $termlist_loc, 1);
|
|
}
|
|
else
|
|
self::$invindex->set_arr_simple($nterm, $nterm_pageids);
|
|
}
|
|
|
|
// Merge all the new / changed index entries into the inverted index
|
|
foreach($index as $nterm => $newentry) {
|
|
// if(!is_string($nterm)) $nterm = strval($nterm);
|
|
if(!self::$invindex->has($nterm)) {
|
|
self::$invindex->set_arr_simple($nterm, []);
|
|
$termlist[] = $nterm;
|
|
}
|
|
|
|
// Update the nterm pageid list
|
|
$nterm_pageids = self::$invindex->get_arr_simple($nterm);
|
|
if(array_search($pageid, $nterm_pageids) === false) {
|
|
$nterm_pageids[] = $pageid;
|
|
self::$invindex->set_arr_simple($nterm, $nterm_pageids);
|
|
}
|
|
|
|
// Store the offset list
|
|
self::$invindex->set("$nterm|$pageid", $newentry);
|
|
}
|
|
|
|
self::$invindex->set("|termlist|", $termlist);
|
|
}
|
|
|
|
/**
|
|
* Deletes the given pageid from the given pageindex.
|
|
* @param int $pageid The pageid to remove.
|
|
*/
|
|
public static function invindex_delete(int $pageid) {
|
|
$termlist = self::$invindex->get("|termlist|");
|
|
foreach($termlist as $nterm) {
|
|
$nterm_pageids = self::$invindex->get_arr_simple($nterm);
|
|
$nterm_loc = array_search($pageid, $nterm_pageids);
|
|
// If this nterm doesn't appear in the list, we're not interested
|
|
if($nterm_loc === false)
|
|
continue;
|
|
|
|
// Delete it from the ntemr list
|
|
array_splice($nterm_pageids, $nterm_loc, 1);
|
|
|
|
// Delete the offset list
|
|
self::$invindex->delete("$nterm|$pageid");
|
|
|
|
// If this term doesn't appear in any other documents, delete it
|
|
if(count($nterm_pageids) === 0) {
|
|
self::$invindex->delete($nterm);
|
|
array_splice($termlist, array_search($nterm, $termlist), 1);
|
|
}
|
|
else // Save the document id list back, since it still contains other pageids
|
|
self::$invindex->set_arr_simple($nterm, $nterm_pageids);
|
|
}
|
|
// Save the termlist back to the store
|
|
self::$invindex->set("|termlist|", $termlist);
|
|
}
|
|
|
|
|
|
/*
|
|
* ███████ ████████ █████ ███████
|
|
* ██ ██ ██ ██ ██
|
|
* ███████ ██ ███████ ███████
|
|
* ██ ██ ██ ██ ██
|
|
* ███████ ██ ██ ██ ███████
|
|
*/
|
|
|
|
/**
|
|
* Splits a query string into tokens. Does not require that the input string be transliterated.
|
|
* Was based on my earlier explode_adv: https://starbeamrainbowlabs.com/blog/article.php?article=posts/081-PHP-String-Splitting.html
|
|
* Now improved to be strtok-based, since it's much faster.
|
|
* Example I used when writing this: https://www.php.net/manual/en/function.strtok.php#94463
|
|
* @param string $query The query string to split.
|
|
*/
|
|
public function stas_split($query) {
|
|
$query = self::$literator->transliterate($query);
|
|
|
|
$terms = [];
|
|
$next_token = strtok($query, " \r\n\t");
|
|
while(true) {
|
|
if(strpos($next_token, '"') !== false)
|
|
$next_token .= " " . strtok('"') . '"';
|
|
if(strpos($next_token, "'") !== false)
|
|
$next_token .= " " . strtok("'") . "'";
|
|
|
|
$terms[] = $next_token;
|
|
|
|
$next_token = strtok(" \r\n\t");
|
|
if($next_token === false) break;
|
|
}
|
|
|
|
return $terms;
|
|
}
|
|
|
|
/**
|
|
* Parses an array of query tokens into an associative array of search directives.
|
|
* Supported syntax derived from these sources:
|
|
* https://help.duckduckgo.com/duckduckgo-help-pages/results/syntax/
|
|
* https://docs.microsoft.com/en-us/windows/win32/lwef/-search-2x-wds-aqsreference
|
|
|
|
* @param string[] $tokens The array of query tokens to parse.
|
|
*/
|
|
public function stas_parse($tokens) {
|
|
global $settings;
|
|
|
|
/* Supported Syntax *
|
|
*
|
|
* -term exclude a term
|
|
* +term double the weighting of a term
|
|
* terms !dest terms redirect entire query (minus the !bang) to interwiki with registered shortcut dest
|
|
* prefix:term apply prefix operator to term
|
|
* "term" exactly this term (don't try and correct)
|
|
*/
|
|
$result = [
|
|
"terms" => [],
|
|
"exclude" => [],
|
|
"interwiki" => null
|
|
];
|
|
|
|
|
|
$count = count($tokens);
|
|
for($i = count($tokens) - 1; $i >= 0; $i--) {
|
|
// Look for excludes
|
|
if($tokens[$i][0] == "-") {
|
|
if(in_array(substr($tokens[$i], 1), self::$stop_words)) {
|
|
$result["tokens"][] = [
|
|
"term" => substr($tokens[$i], 1),
|
|
"weight" => -1,
|
|
"location" => "all",
|
|
"exact" => false
|
|
];
|
|
}
|
|
else // FUTURE: Correct excludes too
|
|
$result["exclude"][] = substr($tokens[$i], 1);
|
|
|
|
continue;
|
|
}
|
|
|
|
// Look for weighted terms
|
|
if($tokens[$i][0] == "+") {
|
|
if(in_array(substr($tokens[$i], 1), self::$stop_words)) {
|
|
$result["tokens"] = [ "term" => substr($tokens[$i], 1), "weight" => -1, "location" => "all" ];
|
|
}
|
|
else {
|
|
$term = trim(substr($tokens[$i], 1), '"');
|
|
$result["terms"][] = [
|
|
"term" => $term,
|
|
"weight" => 2,
|
|
"location" => "all",
|
|
// if it's different, then there were quotes
|
|
"exact" => substr($tokens[$i], 1) != $term
|
|
];
|
|
}
|
|
continue;
|
|
}
|
|
|
|
// Look for interwiki searches
|
|
// You can only go to 1 interwiki destination at once, so we replace any previous finding with this one
|
|
if($tokens[$i][0] == "!" || substr($tokens[$i], -1) == "!")
|
|
$result["interwiki"] = trim($tokens[$i], "!");
|
|
|
|
// Look for colon directives in the form directive:term
|
|
// Also supports prefix:"quoted term with spaces", quotes stripped automatically
|
|
/*** Example directives *** (. = implemented, * = not implemented)
|
|
. intitle search only page titles for term
|
|
. intags search only tags for term
|
|
. inbody search page body only for term
|
|
* before search only pages that were last modified before term
|
|
* after search only pages that were last modified after term
|
|
* size search only pages that match the size spec term (e.g. 1k+ -> more than 1k bytes, 2k- -> less than 2k bytes, >5k -> more than 5k bytes, <10k -> less than 10k bytes)
|
|
**************************/
|
|
if(strpos($tokens[$i], ":") !== false) {
|
|
$parts = explode(":", $tokens[$i], 2);
|
|
|
|
$exact = false;
|
|
$term = trim($parts[1], '"');
|
|
// If we trim off quotes, then it must be because it should be exact
|
|
if($parts[1] != $term) $exact = true;
|
|
|
|
switch($parts[0]) {
|
|
case "intitle": // BUG: What if a normal word is found in a title?
|
|
$result["terms"][] = [
|
|
"term" => $term,
|
|
"weight" => $settings->search_title_matches_weighting * mb_strlen($parts[1]),
|
|
"location" => "title",
|
|
"exact" => $exact
|
|
];
|
|
break;
|
|
case "intags":
|
|
$result["terms"][] = [
|
|
"term" => $term,
|
|
"weight" => $settings->search_tags_matches_weighting * mb_strlen($parts[1]),
|
|
"location" => "tags",
|
|
"exact" => $exact
|
|
];
|
|
break;
|
|
case "inbody":
|
|
$result["terms"][] = [
|
|
"term" => $term,
|
|
"weight" => 1,
|
|
"location" => "body",
|
|
"exact" => $exact
|
|
];
|
|
break;
|
|
default:
|
|
if(!isset($result[$parts[0]]))
|
|
$result[$parts[0]] = [];
|
|
$result[$parts[0]][] = $term;
|
|
break;
|
|
}
|
|
continue;
|
|
}
|
|
|
|
$exact = false;
|
|
$term = trim($tokens[$i], '"');
|
|
// If we trim off quotes, then it must be because it should be exact
|
|
if($tokens[$i] != $term) $exact = true;
|
|
|
|
// Doesn't appear to be particularly special *shrugs*
|
|
// Set the weight to -1 if it's a stop word
|
|
$result["terms"][] = [
|
|
"term" => $term,
|
|
"weight" => in_array($tokens[$i], self::$stop_words) ? -1 : 1,
|
|
"location" => "all",
|
|
"exact" => $exact // If true then we shouldn't try to autocorrect it
|
|
];
|
|
}
|
|
|
|
|
|
// Correct typos, but only if that's enabled
|
|
if(module_exists("feature-search-didyoumean") && $settings->search_didyoumean_enabled) {
|
|
$terms_count = count($result["terms"]);
|
|
for($i = 0; $i < $terms_count; $i++) {
|
|
// error_log("[stas_parse/didyoumean] Now looking at #$i: ".var_export($result["terms"][$i], true)."(total count: $terms_count)");
|
|
if($result["terms"][$i]["exact"] || // Skip exact-only
|
|
$result["terms"][$i]["weight"] < 1 || // Skip stop & irrelevant words
|
|
self::invindex_term_exists($result["terms"][$i]["term"]))
|
|
continue;
|
|
|
|
// It's not a stop word or in the index, try and correct it
|
|
// self::didyoumean_correct auto-loads the didyoumean index on-demand
|
|
$correction = self::didyoumean_correct($result["terms"][$i]["term"]);
|
|
// Make a note if we fail to correct a term
|
|
if(!is_string($correction)) {
|
|
$result["terms"][$i]["corrected"] = false;
|
|
continue;
|
|
}
|
|
|
|
$result["terms"][$i]["term_before"] = $result["terms"][$i]["term"];
|
|
$result["terms"][$i]["term"] = $correction;
|
|
$result["terms"][$i]["corrected"] = true;
|
|
}
|
|
}
|
|
|
|
return $result;
|
|
}
|
|
|
|
/**
|
|
* Determines whether a term exists in the currently loaded inverted search
|
|
* index.
|
|
* Note that this only checked for precisely $term. See
|
|
* search::didyoumean_correct() for typo correction.
|
|
* @param string $term The term to search for.
|
|
* @return bool Whether term exists in the inverted index or not.
|
|
*/
|
|
public static function invindex_term_exists(string $term) {
|
|
// In the inverted index $term should have a list of page names in it
|
|
// if the temr exists in the index, and won't exists if not
|
|
return self::$invindex->has($term);
|
|
}
|
|
|
|
/**
|
|
* Returns the page ids that contain the given (transliterated) search term.
|
|
* @param string $term The search term to look for.
|
|
* @return string[] The list of page ids that contain the given term.
|
|
*/
|
|
public static function invindex_term_getpageids(string $term) {
|
|
return self::$invindex->get_arr_simple($term);
|
|
}
|
|
|
|
/**
|
|
* Gets the offsets object for a given term on a given page.
|
|
* The return object is in the form { freq: 4, offsets: [2,3,4] }
|
|
* @param string $term The term to search for.
|
|
* @param int $pageid The id of the page to retrieve the offsets list for.
|
|
* @return object The offsets object as described above.
|
|
*/
|
|
public static function invindex_term_getoffsets(string $term, int $pageid) {
|
|
return self::$invindex->get("$term|$pageid");
|
|
}
|
|
|
|
/**
|
|
* Searches the given inverted index for the specified search terms.
|
|
* Note that this automatically pushes the query string through STAS which
|
|
* can be a fairly expensive operation, so use 2nd argument if you need
|
|
* to debug the STAS parsing result if possible.
|
|
* @param string $query The search query. If an array is passed, it is assumed it has already been pre-parsed with search::stas_parse().
|
|
* @param &stdClass $query_stas An object to fill with the result of the STAS parsing.
|
|
* @return array An array of matching pages.
|
|
*/
|
|
public static function invindex_query($query, &$query_stas = null)
|
|
{
|
|
global $settings, $pageindex;
|
|
|
|
$query_stas = self::stas_parse(
|
|
self::stas_split(self::$literator->transliterate($query))
|
|
);
|
|
|
|
/* Sub-array format:
|
|
* [
|
|
* nterms : [ nterm => frequency, nterm => frequency, .... ],
|
|
* offsets_body : int[],
|
|
* matches_title : int,
|
|
* matches_tags : int
|
|
* ]
|
|
*/
|
|
$matching_pages = [];
|
|
$match_template = [
|
|
"nterms" => [],
|
|
"offsets_body" => [],
|
|
"rank_title" => 0,
|
|
"rank_tags" => 0
|
|
];
|
|
|
|
// Query the inverted index
|
|
foreach($query_stas["terms"] as $term_def) {
|
|
if($term_def["weight"] == -1)
|
|
continue; // Skip stop words
|
|
|
|
if(!in_array($term_def["location"], ["all", "inbody"]))
|
|
continue; // Skip terms we shouldn't search the page body for
|
|
|
|
if(!self::$invindex->has($term_def["term"]))
|
|
continue; // Skip if it's not in the index
|
|
|
|
// For each page that contains this term.....
|
|
$term_pageids = self::$invindex->get_arr_simple($term_def["term"]);
|
|
foreach($term_pageids as $pageid) {
|
|
// Check to see if it contains any words we should exclude
|
|
$skip = false;
|
|
foreach($query_stas["exclude"] as $excl_term) {
|
|
if(self::$invindex->has("$excl_term|$pageid")) {
|
|
$skip = true;
|
|
break;
|
|
}
|
|
}
|
|
if($skip) continue;
|
|
|
|
// Get the list of offsets
|
|
$page_offsets = self::$invindex->get("{$term_def["term"]}|$pageid");
|
|
|
|
if(!isset($matching_pages[$pageid]))
|
|
$matching_pages[$pageid] = $match_template; // Arrays are assigned by copy in php
|
|
|
|
// Add it to the appropriate $matching_pages entry, not forgetting to apply the weighting
|
|
$matching_pages[$pageid]["offsets_body"] = array_merge(
|
|
$matching_pages[$pageid]["offsets_body"],
|
|
$page_offsets->offsets
|
|
);
|
|
$matching_pages[$pageid]["nterms"][$term_def["term"]] = $page_offsets->freq * $term_def["weight"];
|
|
}
|
|
|
|
}
|
|
|
|
// Query page titles & tags
|
|
foreach($query_stas["terms"] as $term_def) {
|
|
// No need to skip stop words here, since we're doing a normal
|
|
// sequential search anyway
|
|
if(!in_array($term_def["location"], ["all", "title", "tags"]))
|
|
continue; // Skip terms we shouldn't search the page body for
|
|
|
|
// Loop over the pageindex and search the titles / tags
|
|
reset($pageindex); // Reset array/object pointer
|
|
foreach($pageindex as $pagename => $pagedata) {
|
|
// Setup a variable to hold the current page's id
|
|
$pageid = null; // Cache the page id
|
|
|
|
$lit_title = self::$literator->transliterate($pagename);
|
|
$lit_tags = isset($pagedata->tags) ? self::$literator->transliterate(implode(" ", $pagedata->tags)) : null;
|
|
$pageid = null; // populated on-demand
|
|
|
|
// Make sure that the title & tags don't contain a term we should exclude
|
|
$skip = false;
|
|
foreach($query_stas["exclude"] as $excl_term) {
|
|
if(mb_strpos($lit_title, $excl_term) !== false) {
|
|
$skip = true;
|
|
if($pageid === null) $pageid = ids::getid($pagename);
|
|
// Delete it from the candidate matches (it might be present in the tags / title but not the body)
|
|
if(isset($matching_pages[$pageid]))
|
|
unset($matching_pages[$pageid]);
|
|
break;
|
|
}
|
|
}
|
|
if($skip) continue;
|
|
|
|
// Consider matches in the page title
|
|
if(in_array($term_def["location"], ["all", "title"])) {
|
|
// FUTURE: We may be able to optimise this further by using preg_match_all + preg_quote instead of mb_stripos_all. Experimentation / benchmarking is required to figure out which one is faster
|
|
$title_matches = mb_stripos_all($lit_title, $term_def["term"]);
|
|
$title_matches_count = $title_matches !== false ? count($title_matches) : 0;
|
|
if($title_matches_count > 0) {
|
|
if($pageid === null) $pageid = ids::getid($pagename);
|
|
// We found the qterm in the title
|
|
if(!isset($matching_pages[$pageid]))
|
|
$matching_pages[$pageid] = $match_template; // Assign by copy
|
|
|
|
$matching_pages[$pageid]["rank_title"] += $title_matches_count * $term_def["weight"];
|
|
}
|
|
}
|
|
|
|
// If this page doesn't have any tags, skip it
|
|
if($lit_tags == null)
|
|
continue;
|
|
|
|
if(!in_array($term_def["location"], ["all", "tags"]))
|
|
continue; // If we shouldn't search the tags, no point in continuing
|
|
|
|
// Consider matches in the page's tags
|
|
$tag_matches = isset($pagedata->tags) ? mb_stripos_all($lit_tags, $term_def["term"]) : false;
|
|
$tag_matches_count = $tag_matches !== false ? count($tag_matches) : 0;
|
|
|
|
if($tag_matches_count > 0) {// And we found the qterm in the tags
|
|
if($pageid === null) $pageid = ids::getid($pagename);
|
|
|
|
if(!isset($matching_pages[$pageid]))
|
|
$matching_pages[$pageid] = $match_template; // Assign by copy
|
|
|
|
$matching_pages[$pageid]["rank_tags"] += $tag_matches_count * $term_def["weight"];
|
|
}
|
|
}
|
|
}
|
|
|
|
// TODO: Implement the rest of STAS here
|
|
|
|
reset($matching_pages);
|
|
foreach($matching_pages as $pageid => &$pagedata) {
|
|
$pagedata["pagename"] = ids::getpagename($pageid);
|
|
$pagedata["rank"] = 0;
|
|
|
|
$pageOffsets = [];
|
|
|
|
// Loop over each search term found on this page
|
|
reset($pagedata["nterms"]);
|
|
foreach($pagedata["nterms"] as $pterm => $frequency) {
|
|
// Add the number of occurrences of this search term to the ranking
|
|
// Multiply it by the length of the word
|
|
$pagedata["rank"] += $frequency * strlen($pterm);
|
|
}
|
|
|
|
// Consider matches in the title / tags
|
|
$pagedata["rank"] += $pagedata["rank_title"] + $pagedata["rank_tags"];
|
|
|
|
// TODO: Consider implementing kernel density estimation here.
|
|
// https://en.wikipedia.org/wiki/Kernel_density_estimation
|
|
// We want it to have more of an effect the more words that are present in the query. Maybe a logarithmic function would be worth investigating here?
|
|
|
|
// TODO: Remove items if the computed rank is below a threshold
|
|
}
|
|
|
|
uasort($matching_pages, function($a, $b) {
|
|
if($a["rank"] == $b["rank"]) return 0;
|
|
return ($a["rank"] < $b["rank"]) ? +1 : -1;
|
|
});
|
|
|
|
return $matching_pages;
|
|
}
|
|
|
|
/**
|
|
* Extracts a context string (in HTML) given a search query that could be displayed
|
|
* in a list of search results.
|
|
* @param string $pagename The name of the paget that this source belongs to. Used when consulting the inverted index.
|
|
* @param string $query_parsed The *parsed* search query to generate the context for (basically the output of search::stas_parse()).
|
|
* @param string $source The page source to extract the context from.
|
|
* @return string The generated context string.
|
|
*/
|
|
public static function extract_context($pagename, $query_parsed, $source)
|
|
{
|
|
global $settings;
|
|
|
|
$pageid = ids::getid($pagename);
|
|
$nterms = $query_parsed["terms"];
|
|
|
|
// Query the inverted index for offsets
|
|
$matches = [];
|
|
foreach($nterms as $nterm) {
|
|
// Skip if the page isn't found in the inverted index for this word
|
|
if(!self::$invindex->has("{$nterm["term"]}|$pageid"))
|
|
continue;
|
|
|
|
$nterm_offsets = self::$invindex->get("{$nterm["term"]}|$pageid")->offsets;
|
|
|
|
foreach($nterm_offsets as $next_offset)
|
|
$matches[] = [ $nterm["term"], $next_offset ];
|
|
}
|
|
|
|
// Sort the matches by offset
|
|
usort($matches, function($a, $b) {
|
|
if($a[1] == $b[1]) return 0;
|
|
return ($a[1] > $b[1]) ? +1 : -1;
|
|
});
|
|
|
|
$sourceLength = mb_strlen($source);
|
|
|
|
$contexts = [];
|
|
|
|
$matches_count = count($matches);
|
|
$total_context_length = 0;
|
|
for($i = 0; $i < $matches_count; $i++) {
|
|
$next_context = [
|
|
"from" => max(0, $matches[$i][1] - $settings->search_characters_context),
|
|
"to" => min($sourceLength, $matches[$i][1] + mb_strlen($matches[$i][0]) + $settings->search_characters_context)
|
|
];
|
|
|
|
if(end($contexts) !== false && end($contexts)["to"] > $next_context["from"]) {
|
|
// This next context overlaps with the previous one
|
|
// Extend the last one instead of adding a new one
|
|
|
|
// The array pointer is pointing at the last element now because we called end() above
|
|
|
|
// Update the total context length counter appropriately
|
|
$total_context_length += $next_context["to"] - $contexts[key($contexts)]["to"];
|
|
$contexts[key($contexts)]["to"] = $next_context["to"];
|
|
}
|
|
else { // No overlap here! Business as usual.
|
|
$contexts[] = $next_context;
|
|
// Update the total context length counter as normal
|
|
$total_context_length += $next_context["to"] - $next_context["from"];
|
|
}
|
|
|
|
|
|
end($contexts);
|
|
$last_context = &$contexts[key($contexts)];
|
|
if($total_context_length > $settings->search_characters_context_total) {
|
|
// We've reached the limit on the number of characters this context should contain. Trim off the context to fit and break out
|
|
$last_context["to"] -= $total_context_length - $settings->search_characters_context_total;
|
|
break;
|
|
}
|
|
}
|
|
|
|
$contexts_text = [];
|
|
foreach($contexts as $context) {
|
|
$contexts_text[] = substr($source, $context["from"], $context["to"] - $context["from"]);
|
|
}
|
|
|
|
// BUG: Make sure that a snippet is centred on the word in question if we have to cut it short
|
|
|
|
$result = implode(" … ", $contexts_text);
|
|
end($contexts); // If there's at least one item in the list and were not at the very end of the page, add an extra ellipsis
|
|
if(isset($contexts[0]) && $contexts[key($contexts)]["to"] < $sourceLength) $result .= "… ";
|
|
// Prepend an ellipsis if the context doesn't start at the beginning of a page
|
|
if(isset($contexts[0]) && $contexts[0]["from"] > 0) $result = " …$result";
|
|
|
|
return $result;
|
|
}
|
|
|
|
/**
|
|
* Highlights the keywords of a context string.
|
|
* @param array $query_parsed The *parsed* query to use when highlighting (the output of search::stas_parse())
|
|
* @param string $context The context string to highlight.
|
|
* @return string The highlighted (HTML) string.
|
|
*/
|
|
public static function highlight_context($query_parsed, $context)
|
|
{
|
|
$qterms = $query_parsed["terms"];
|
|
|
|
foreach($qterms as $qterm) {
|
|
// Stop words are marked by STAS
|
|
if($qterm["weight"] == -1)
|
|
continue;
|
|
|
|
// From http://stackoverflow.com/a/2483859/1460422
|
|
$context = preg_replace("/" . preg_replace('/\\//u', "\/", preg_quote($qterm["term"])) . "/iu", "<strong class='search-term-highlight'>$0</strong>", $context);
|
|
}
|
|
|
|
return $context;
|
|
}
|
|
}
|
|
// Run the init function
|
|
search::init();
|
|
|
|
?>
|