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Highlighter.php
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Highlighter.php
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<?php
namespace TeamTNT\TNTSearch\Support;
class Highlighter
{
protected $options = [
'simple' => false,
'wholeWord' => true,
'caseSensitive' => false,
'stripLinks' => false,
'tagOptions' => [
// 'class' => 'search-term', // Example
// 'title' => 'You searched for this.', // Example
// 'data-toggle' => 'tooltip', // Example
]
];
protected $tokenizer;
public function __construct(TokenizerInterface $tokenizer = null)
{
if (!empty($tokenizer)) {
$this->tokenizer = $tokenizer;
} else {
$this->tokenizer = new Tokenizer;
}
}
/**
* @param $text
* @param $needle
* @param string $tag
* @param array $options
*
* @return string
*/
public function highlight($text, $needle, $tag = 'em', $options = [])
{
$this->options = array_merge($this->options, $options);
$tagAttributes = '';
if (count($this->options['tagOptions'])) {
foreach ($this->options['tagOptions'] as $attr => $value) {
$tagAttributes .= $attr . '="' . $value . '" ';
}
$tagAttributes = ' ' . trim($tagAttributes);
}
$highlight = '<' . $tag . $tagAttributes .'>\1</' . $tag . '>';
$needle = preg_split($this->tokenizer->getPattern(), $needle, -1, PREG_SPLIT_NO_EMPTY);
// Select pattern to use
if ($this->options['simple']) {
$pattern = '#(%s)#';
$sl_pattern = '#(%s)#';
} else {
$pattern = '#(?!<.*?)(%s)(?![^<>]*?>)#';
$sl_pattern = '#<a\s(?:.*?)>(%s)</a>#';
}
// Add Forgotten Unicode
$pattern .= 'u';
// Case sensitivity
if (!($this->options['caseSensitive'])) {
$pattern .= 'i';
$sl_pattern .= 'i';
}
$needle = (array) $needle;
foreach ($needle as $needle_s) {
$needle_s = preg_quote($needle_s);
// Escape needle with optional whole word check
if ($this->options['wholeWord']) {
$needle_s = '\b' . $needle_s . '\b';
}
// Strip links
if ($this->options['stripLinks']) {
$sl_regex = sprintf($sl_pattern, $needle_s);
$text = preg_replace($sl_regex, '\1', $text);
}
$regex = sprintf($pattern, $needle_s);
$text = preg_replace($regex, $highlight, $text);
}
return $text;
}
/**
* find the locations of each of the words
* Nothing exciting here. The array_unique is required
* unless you decide to make the words unique before passing in
*
* @param $words
* @param $fulltext
*
* @return array
*/
public function _extractLocations($words, $fulltext)
{
$locations = array();
foreach ($words as $word) {
$wordlen = mb_strlen($word);
$loc = mb_stripos($fulltext, $word);
while ($loc !== false) {
$locations[] = $loc;
$loc = mb_stripos($fulltext, $word, $loc + $wordlen);
}
}
$locations = array_unique($locations);
sort($locations);
return $locations;
}
/**
* Work out which is the most relevant portion to display
* This is done by looping over each match and finding the smallest distance between two found
* strings. The idea being that the closer the terms are the better match the snippet would be.
* When checking for matches we only change the location if there is a better match.
* The only exception is where we have only two matches in which case we just take the
* first as will be equally distant.
*
* @param $locations
* @param $prevcount
*
* @return int
*/
public function _determineSnipLocation($locations, $prevcount)
{
if (!isset($locations[0])) {
return -1;
}
// If we only have 1 match we dont actually do the for loop so set to the first
$startpos = $locations[0];
$loccount = count($locations);
$smallestdiff = PHP_INT_MAX;
// If we only have 2 skip as its probably equally relevant
if (count($locations) > 2) {
// skip the first as we check 1 behind
for ($i = 1; $i < $loccount; $i++) {
if ($i == $loccount - 1) {
// at the end
$diff = $locations[$i] - $locations[$i - 1];
} else {
$diff = $locations[$i + 1] - $locations[$i];
}
if ($smallestdiff > $diff) {
$smallestdiff = $diff;
$startpos = $locations[$i];
}
}
}
$startpos = $startpos > $prevcount ? $startpos - $prevcount : 0;
return $startpos;
}
/**
* 1/6 ratio on prevcount tends to work pretty well and puts the terms
* in the middle of the extract
*
* @param $words
* @param $fulltext
* @param int $rellength
* @param int $prevcount
* @param string $indicator
*
* @return bool|string
*/
public function extractRelevant($words, $fulltext, $rellength = 300, $prevcount = 50, $indicator = '...')
{
$words = preg_split($this->tokenizer->getPattern(), $words, -1, PREG_SPLIT_NO_EMPTY);
$textlength = mb_strlen($fulltext);
if ($textlength <= $rellength) {
return $fulltext;
}
$locations = $this->_extractLocations($words, $fulltext);
$startpos = $this->_determineSnipLocation($locations, $prevcount);
// if we are going to snip too much...
if ($textlength - $startpos < $rellength) {
$startpos = $startpos - ($textlength - $startpos) / 2;
}
// in case no match is found, reset position for proper math below
if ($startpos == -1) {
$startpos = 0;
}
$reltext = mb_substr($fulltext, $startpos, $rellength);
preg_match_all($this->tokenizer->getPattern(), $reltext, $offset, PREG_OFFSET_CAPTURE);
// since PREG_OFFSET_CAPTURE returns offset in bytes we have to use mb_strlen(substr()) hack here
$last = mb_strlen(substr($reltext, 0, end($offset[0])[1]));
$first = mb_strlen(substr($reltext, 0, $offset[0][0][1]));
// if no match is found, just return first $rellength characters without the last word
if (empty($locations)) {
return mb_substr($reltext, 0, $last) . $indicator;
}
// check to ensure we dont snip the last word if thats the match
if ($startpos + $rellength < $textlength) {
$reltext = mb_substr($reltext, 0, $last) . $indicator; // remove last word
}
// If we trimmed from the front add ...
if ($startpos != 0) {
$reltext = $indicator . mb_substr($reltext, $first + 1); // remove first word
}
return $reltext;
}
}