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<?php
//
// NOTICE OF COPYRIGHT
//
// Original code:
//
// Drupal - The copyright of both the Drupal software and the
// "Druplicon" logo belongs to all the original authors,
// though both are licensed under the GPL.
// http://drupal.org
//
// Modifications:
//
// Moodle - Modular Object-Oriented Dynamic Learning Environment
// http://moodle.com
//
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
//
/**
* Based on Drupal's search.module version 1.224
*
* {@link http://cvs.drupal.org/viewcvs/drupal/drupal/modules/search/search.module?view=markup}
*
* Usage: $tokens = tokenise_text($text)
* Returns an array of tokens (key) with their score (value)
* (see function definition for more info)
*
* Major Contributors
* - Martin Dougiamas {@link http://moodle.com}
* - Eloy Lafuente (stronk7) {@link http://contiento.com}
* - Antonio Vicent {@link http://ludens.es}
*
* @package moodlecore
* @copyright (C) 2001-3001 Eloy Lafuente (stronk7) {@link http://contiento.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
/**
* Some constants
*/
define ('MINIMUM_WORD_SIZE', 3); /// Minimum word size to index and search
define ('MAXIMUM_WORD_SIZE', 50); /// Maximum word size to index and search
define ('START_DELIM', "\xce\xa9\xc3\x91\xc3\x91"); // Use these (omega) and (ntilde) utf-8 combinations
define ('CENTER_DELIM', "\xc3\x91\xce\xa9\xc3\x91"); // as safe delimiters (not puncuation nor usual) while
define ('END_DELIM', "\xc3\x91\xc3\x91\xce\xa9"); // processing numbers ($join_numbers = false)
/**
* Matches Unicode character classes to exclude from the search index.
*
* See: http://www.unicode.org/Public/UNIDATA/UCD.html#General_Category_Values
*
* The index only contains the following character classes:
* Lu Letter, Uppercase
* Ll Letter, Lowercase
* Lt Letter, Titlecase
* Lo Letter, Other
* Nd Number, Decimal Digit
* No Number, Other
*/
define('PREG_CLASS_SEARCH_EXCLUDE',
'\x{0}-\x{2f}\x{3a}-\x{40}\x{5b}-\x{60}\x{7b}-\x{bf}\x{d7}\x{f7}\x{2b0}-'.
'\x{385}\x{387}\x{3f6}\x{482}-\x{489}\x{559}-\x{55f}\x{589}-\x{5c7}\x{5f3}-'.
'\x{61f}\x{640}\x{64b}-\x{65e}\x{66a}-\x{66d}\x{670}\x{6d4}\x{6d6}-\x{6ed}'.
'\x{6fd}\x{6fe}\x{700}-\x{70f}\x{711}\x{730}-\x{74a}\x{7a6}-\x{7b0}\x{901}-'.
'\x{903}\x{93c}\x{93e}-\x{94d}\x{951}-\x{954}\x{962}-\x{965}\x{970}\x{981}-'.
'\x{983}\x{9bc}\x{9be}-\x{9cd}\x{9d7}\x{9e2}\x{9e3}\x{9f2}-\x{a03}\x{a3c}-'.
'\x{a4d}\x{a70}\x{a71}\x{a81}-\x{a83}\x{abc}\x{abe}-\x{acd}\x{ae2}\x{ae3}'.
'\x{af1}-\x{b03}\x{b3c}\x{b3e}-\x{b57}\x{b70}\x{b82}\x{bbe}-\x{bd7}\x{bf0}-'.
'\x{c03}\x{c3e}-\x{c56}\x{c82}\x{c83}\x{cbc}\x{cbe}-\x{cd6}\x{d02}\x{d03}'.
'\x{d3e}-\x{d57}\x{d82}\x{d83}\x{dca}-\x{df4}\x{e31}\x{e34}-\x{e3f}\x{e46}-'.
'\x{e4f}\x{e5a}\x{e5b}\x{eb1}\x{eb4}-\x{ebc}\x{ec6}-\x{ecd}\x{f01}-\x{f1f}'.
'\x{f2a}-\x{f3f}\x{f71}-\x{f87}\x{f90}-\x{fd1}\x{102c}-\x{1039}\x{104a}-'.
'\x{104f}\x{1056}-\x{1059}\x{10fb}\x{10fc}\x{135f}-\x{137c}\x{1390}-\x{1399}'.
'\x{166d}\x{166e}\x{1680}\x{169b}\x{169c}\x{16eb}-\x{16f0}\x{1712}-\x{1714}'.
'\x{1732}-\x{1736}\x{1752}\x{1753}\x{1772}\x{1773}\x{17b4}-\x{17db}\x{17dd}'.
'\x{17f0}-\x{180e}\x{1843}\x{18a9}\x{1920}-\x{1945}\x{19b0}-\x{19c0}\x{19c8}'.
'\x{19c9}\x{19de}-\x{19ff}\x{1a17}-\x{1a1f}\x{1d2c}-\x{1d61}\x{1d78}\x{1d9b}-'.
'\x{1dc3}\x{1fbd}\x{1fbf}-\x{1fc1}\x{1fcd}-\x{1fcf}\x{1fdd}-\x{1fdf}\x{1fed}-'.
'\x{1fef}\x{1ffd}-\x{2070}\x{2074}-\x{207e}\x{2080}-\x{2101}\x{2103}-\x{2106}'.
'\x{2108}\x{2109}\x{2114}\x{2116}-\x{2118}\x{211e}-\x{2123}\x{2125}\x{2127}'.
'\x{2129}\x{212e}\x{2132}\x{213a}\x{213b}\x{2140}-\x{2144}\x{214a}-\x{2b13}'.
'\x{2ce5}-\x{2cff}\x{2d6f}\x{2e00}-\x{3005}\x{3007}-\x{303b}\x{303d}-\x{303f}'.
'\x{3099}-\x{309e}\x{30a0}\x{30fb}-\x{30fe}\x{3190}-\x{319f}\x{31c0}-\x{31cf}'.
'\x{3200}-\x{33ff}\x{4dc0}-\x{4dff}\x{a015}\x{a490}-\x{a716}\x{a802}\x{a806}'.
'\x{a80b}\x{a823}-\x{a82b}\x{d800}-\x{f8ff}\x{fb1e}\x{fb29}\x{fd3e}\x{fd3f}'.
'\x{fdfc}-\x{fe6b}\x{feff}-\x{ff0f}\x{ff1a}-\x{ff20}\x{ff3b}-\x{ff40}\x{ff5b}-'.
'\x{ff65}\x{ff70}\x{ff9e}\x{ff9f}\x{ffe0}-\x{fffd}');
/**
* Matches all 'N' Unicode character classes (numbers)
*/
define('PREG_CLASS_NUMBERS',
'\x{30}-\x{39}\x{b2}\x{b3}\x{b9}\x{bc}-\x{be}\x{660}-\x{669}\x{6f0}-\x{6f9}'.
'\x{966}-\x{96f}\x{9e6}-\x{9ef}\x{9f4}-\x{9f9}\x{a66}-\x{a6f}\x{ae6}-\x{aef}'.
'\x{b66}-\x{b6f}\x{be7}-\x{bf2}\x{c66}-\x{c6f}\x{ce6}-\x{cef}\x{d66}-\x{d6f}'.
'\x{e50}-\x{e59}\x{ed0}-\x{ed9}\x{f20}-\x{f33}\x{1040}-\x{1049}\x{1369}-'.
'\x{137c}\x{16ee}-\x{16f0}\x{17e0}-\x{17e9}\x{17f0}-\x{17f9}\x{1810}-\x{1819}'.
'\x{1946}-\x{194f}\x{2070}\x{2074}-\x{2079}\x{2080}-\x{2089}\x{2153}-\x{2183}'.
'\x{2460}-\x{249b}\x{24ea}-\x{24ff}\x{2776}-\x{2793}\x{3007}\x{3021}-\x{3029}'.
'\x{3038}-\x{303a}\x{3192}-\x{3195}\x{3220}-\x{3229}\x{3251}-\x{325f}\x{3280}-'.
'\x{3289}\x{32b1}-\x{32bf}\x{ff10}-\x{ff19}');
/**
* Matches all 'P' Unicode character classes (punctuation)
*/
define('PREG_CLASS_PUNCTUATION',
'\x{21}-\x{23}\x{25}-\x{2a}\x{2c}-\x{2f}\x{3a}\x{3b}\x{3f}\x{40}\x{5b}-\x{5d}'.
'\x{5f}\x{7b}\x{7d}\x{a1}\x{ab}\x{b7}\x{bb}\x{bf}\x{37e}\x{387}\x{55a}-\x{55f}'.
'\x{589}\x{58a}\x{5be}\x{5c0}\x{5c3}\x{5f3}\x{5f4}\x{60c}\x{60d}\x{61b}\x{61f}'.
'\x{66a}-\x{66d}\x{6d4}\x{700}-\x{70d}\x{964}\x{965}\x{970}\x{df4}\x{e4f}'.
'\x{e5a}\x{e5b}\x{f04}-\x{f12}\x{f3a}-\x{f3d}\x{f85}\x{104a}-\x{104f}\x{10fb}'.
'\x{1361}-\x{1368}\x{166d}\x{166e}\x{169b}\x{169c}\x{16eb}-\x{16ed}\x{1735}'.
'\x{1736}\x{17d4}-\x{17d6}\x{17d8}-\x{17da}\x{1800}-\x{180a}\x{1944}\x{1945}'.
'\x{2010}-\x{2027}\x{2030}-\x{2043}\x{2045}-\x{2051}\x{2053}\x{2054}\x{2057}'.
'\x{207d}\x{207e}\x{208d}\x{208e}\x{2329}\x{232a}\x{23b4}-\x{23b6}\x{2768}-'.
'\x{2775}\x{27e6}-\x{27eb}\x{2983}-\x{2998}\x{29d8}-\x{29db}\x{29fc}\x{29fd}'.
'\x{3001}-\x{3003}\x{3008}-\x{3011}\x{3014}-\x{301f}\x{3030}\x{303d}\x{30a0}'.
'\x{30fb}\x{fd3e}\x{fd3f}\x{fe30}-\x{fe52}\x{fe54}-\x{fe61}\x{fe63}\x{fe68}'.
'\x{fe6a}\x{fe6b}\x{ff01}-\x{ff03}\x{ff05}-\x{ff0a}\x{ff0c}-\x{ff0f}\x{ff1a}'.
'\x{ff1b}\x{ff1f}\x{ff20}\x{ff3b}-\x{ff3d}\x{ff3f}\x{ff5b}\x{ff5d}\x{ff5f}-'.
'\x{ff65}');
/**
* Matches all CJK characters that are candidates for auto-splitting
* (Chinese, Japanese, Korean).
* Contains kana and BMP ideographs.
*/
define('PREG_CLASS_CJK', '\x{3041}-\x{30ff}\x{31f0}-\x{31ff}\x{3400}-\x{4db5}'.
'\x{4e00}-\x{9fbb}\x{f900}-\x{fad9}');
/**
* This function process the text passed at input, extracting all the tokens
* and scoring each one based in their number of ocurrences and relation with
* some well-known html tags
*
* @param string $text the text to be tokenised.
* @param array $stop_words array of utf-8 words than can be ignored in
* the text being processed. There are some cool lists of
* stop words at http://snowball.tartarus.org/
* @param boolean $overlap_cjk option to split CJK text into some overlapping
* tokens is order to allow them to be searched. Useful to build
* indexes and search systems.
* @param boolean $join_numbers option to join in one unique token sequences of numbers
* separated by puntuaction chars. Useful to build indexes and
* search systems.
* @return array one sorted array of tokens, with tokens being the keys and scores in the values.
*/
function tokenise_text($text, $stop_words = array(), $overlap_cjk = false, $join_numbers = false) {
// Multipliers for scores of words inside certain HTML tags.
// Note: 'a' must be included for link ranking to work.
$tags = array('h1' => 25,
'h2' => 18,
'h3' => 15,
'h4' => 12,
'h5' => 9,
'h6' => 6,
'u' => 3,
'b' => 3,
'i' => 3,
'strong' => 3,
'em' => 3,
'a' => 10);
// Strip off all ignored tags to speed up processing, but insert space before/after
// them to keep word boundaries.
$text = str_replace(array('<', '>'), array(' <', '> '), $text);
$text = strip_tags($text, '<'. implode('><', array_keys($tags)) .'>');
// Split HTML tags from plain text.
$split = preg_split('/\s*<([^>]+?)>\s*/', $text, -1, PREG_SPLIT_DELIM_CAPTURE);
// Note: PHP ensures the array consists of alternating delimiters and literals
// and begins and ends with a literal (inserting $null as required).
$tag = FALSE; // Odd/even counter. Tag or no tag.
$score = 1; // Starting score per word
$accum = ' '; // Accumulator for cleaned up data
$tagstack = array(); // Stack with open tags
$tagwords = 0; // Counter for consecutive words
$focus = 1; // Focus state
$results = array(0 => array()); // Accumulator for words for index
foreach ($split as $value) {
if ($tag) {
// Increase or decrease score per word based on tag
list($tagname) = explode(' ', $value, 2);
$tagname = textlib::strtolower($tagname);
// Closing or opening tag?
if ($tagname[0] == '/') {
$tagname = substr($tagname, 1);
// If we encounter unexpected tags, reset score to avoid incorrect boosting.
if (!count($tagstack) || $tagstack[0] != $tagname) {
$tagstack = array();
$score = 1;
}
else {
// Remove from tag stack and decrement score
$score = max(1, $score - $tags[array_shift($tagstack)]);
}
}
else {
if (isset($tagstack[0]) && $tagstack[0] == $tagname) {
// None of the tags we look for make sense when nested identically.
// If they are, it's probably broken HTML.
$tagstack = array();
$score = 1;
}
else {
// Add to open tag stack and increment score
array_unshift($tagstack, $tagname);
$score += $tags[$tagname];
}
}
// A tag change occurred, reset counter.
$tagwords = 0;
}
else {
// Note: use of PREG_SPLIT_DELIM_CAPTURE above will introduce empty values
if ($value != '') {
$words = tokenise_split($value, $stop_words, $overlap_cjk, $join_numbers);
foreach ($words as $word) {
// Add word to accumulator
$accum .= $word .' ';
$num = is_numeric($word);
// Check word length
if ($num || textlib::strlen($word) >= MINIMUM_WORD_SIZE) {
// Normalize numbers
if ($num && $join_numbers) {
$word = (int)ltrim($word, '-0');
}
if (!isset($results[0][$word])) {
$results[0][$word] = 0;
}
$results[0][$word] += $score * $focus;
// Focus is a decaying value in terms of the amount of unique words up to this point.
// From 100 words and more, it decays, to e.g. 0.5 at 500 words and 0.3 at 1000 words.
$focus = min(1, .01 + 3.5 / (2 + count($results[0]) * .015));
}
$tagwords++;
// Too many words inside a single tag probably mean a tag was accidentally left open.
if (count($tagstack) && $tagwords >= 15) {
$tagstack = array();
$score = 1;
}
}
}
}
$tag = !$tag;
}
$res = array();
if (isset($results[0]) && count($results[0]) > 0) {
$res = $results[0];
arsort($res, SORT_NUMERIC);
}
return $res;
}
///
/// Some helper functions (should be considered private)
///
/**
* Splits a string into tokens
*/
function tokenise_split($text, $stop_words, $overlap_cjk, $join_numbers) {
static $last = NULL;
static $lastsplit = NULL;
if ($last == $text) {
return $lastsplit;
}
// Process words
$text = tokenise_simplify($text, $overlap_cjk, $join_numbers);
$words = explode(' ', $text);
// Limit word length to 50
array_walk($words, 'tokenise_truncate_word');
// We have stop words, apply them
if (is_array($stop_words) && !empty($stop_words)) {
// Normalise them
$simp_stop_words = explode(' ', tokenise_simplify(implode(' ', $stop_words), $overlap_cjk, $join_numbers));
// Extract from the list
$words = array_diff($words, $simp_stop_words);
}
// Save last keyword result
$last = $text;
$lastsplit = $words;
return $words;
}
/**
* Simplifies a string according to indexing rules.
*/
function tokenise_simplify($text, $overlap_cjk, $join_numbers) {
// Decode entities to UTF-8
$text = textlib::entities_to_utf8($text, true);
// Lowercase
$text = textlib::strtolower($text);
// Simple CJK handling
if ($overlap_cjk) {
$text = preg_replace_callback('/['. PREG_CLASS_CJK .']+/u', 'tokenise_expand_cjk', $text);
}
// To improve searching for numerical data such as dates, IP addresses
// or version numbers, we consider a group of numerical characters
// separated only by punctuation characters to be one piece.
// This also means that searching for e.g. '20/03/1984' also returns
// results with '20-03-1984' in them.
// Readable regexp: ([number]+)[punctuation]+(?=[number])
if ($join_numbers) {
$text = preg_replace('/(['. PREG_CLASS_NUMBERS .']+)['. PREG_CLASS_PUNCTUATION .']+(?=['. PREG_CLASS_NUMBERS .'])/u', '\1', $text);
} else {
// Keep all the detected numbers+punctuation in a safe place in order to restore them later
preg_match_all('/['. PREG_CLASS_NUMBERS .']+['. PREG_CLASS_PUNCTUATION . PREG_CLASS_NUMBERS .']+/u', $text, $foundseqs);
$storedseqs = array();
foreach (array_unique($foundseqs[0]) as $ntkey => $value) {
$prefix = (string)(count($storedseqs) + 1);
$storedseqs[START_DELIM.$prefix.CENTER_DELIM.$ntkey.END_DELIM] = $value;
}
if (!empty($storedseqs)) {
$text = str_replace($storedseqs, array_keys($storedseqs), $text);
}
}
// The dot, underscore and dash are simply removed. This allows meaningful
// search behaviour with acronyms and URLs.
$text = preg_replace('/[._-]+/', '', $text);
// With the exception of the rules above, we consider all punctuation,
// marks, spacers, etc, to be a word boundary.
$text = preg_replace('/['. PREG_CLASS_SEARCH_EXCLUDE .']+/u', ' ', $text);
// Restore, if not joining numbers, recover the original strings
if (!$join_numbers) {
if (!empty($storedseqs)) {
$text = str_replace(array_keys($storedseqs), $storedseqs, $text);
}
}
return $text;
}
/**
* Basic CJK tokeniser. Simply splits a string into consecutive, overlapping
* sequences of characters (MINIMUM_WORD_SIZE long).
*/
function tokenise_expand_cjk($matches) {
$str = $matches[0];
$l = textlib::strlen($str);
// Passthrough short words
if ($l <= MINIMUM_WORD_SIZE) {
return ' '. $str .' ';
}
$tokens = ' ';
// FIFO queue of characters
$chars = array();
// Begin loop
for ($i = 0; $i < $l; ++$i) {
// Grab next character
$current = textlib::substr($str, 0, 1);
$str = substr($str, strlen($current));
$chars[] = $current;
if ($i >= MINIMUM_WORD_SIZE - 1) {
$tokens .= implode('', $chars) .' ';
array_shift($chars);
}
}
return $tokens;
}
/**
* Helper function for array_walk in search_index_split.
* Truncates one string (token) to MAXIMUM_WORD_SIZE
*/
function tokenise_truncate_word(&$text) {
$text = textlib::substr($text, 0, MAXIMUM_WORD_SIZE);
}
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