How to generate excerpt with most searched words in PHP?

Question

Here is an excerpt function:

    function excerpt($text, $phrase, $radius = 100, $ending = \"...\") {
270             if (empty($text) or empty($phrase)) {
2         


        

Answer 1

I could not contact erisco, so I am posting his function with multiple fixes (most importantly multibyte support).

/**
 * @param string $text text to be searched
 * @param string $phrase search string
 * @param int $span approximate length of the excerpt
 * @param string $delimiter string to use as a suffix and/or prefix if the excerpt is from the middle of a text
 *
 * @return string
 */
public static function excerpt($text, $phrase, $span = 100, $delimiter = '...')
{
	$phrases = preg_split('/\s+/u', $phrase);
	$regexp = '/\b(?:';
	foreach($phrases as $phrase)
	{
		$regexp.= preg_quote($phrase, '/') . '|';
	}

	$regexp = mb_substr($regexp, 0, -1) .')\b/ui';
	$matches = [];
	preg_match_all($regexp, $text, $matches, PREG_OFFSET_CAPTURE);
	$matches = $matches[0];
	$nodes = [];
	foreach($matches as $match)
	{
		$node = new stdClass;
		$node->phraseLength = mb_strlen($match[0]);
		$node->position = mb_strlen(substr($text, 0, $match[1])); // calculate UTF-8 position (@see https://bugs.php.net/bug.php?id=67487)
		$nodes[] = $node;
	}

	if(count($nodes) > 0)
	{
		$clust = new stdClass;
		$clust->nodes[] = array_shift($nodes);
		$clust->length = $clust->nodes[0]->phraseLength;
		$clust->i = 0;
		$clusters = new stdClass;
		$clusters->data =
		[
			$clust
		];
		$clusters->i = 0;
		foreach($nodes as $node)
		{
			$lastClust = $clusters->data[$clusters->i];
			$lastNode = $lastClust->nodes[$lastClust->i];
			$addedLength = $node->position - $lastNode->position - $lastNode->phraseLength + $node->phraseLength;
			if($lastClust->length + $addedLength <= $span)
			{
				$lastClust->nodes[] = $node;
				$lastClust->length+= $addedLength;
				$lastClust->i++;
			}
			else
			{
				if($addedLength > $span)
				{
					$newClust = new stdClass;
					$newClust->nodes =
					[
						$node
					];
					$newClust->i = 0;
					$newClust->length = $node->phraseLength;
					$clusters->data[] = $newClust;
					$clusters->i++;
				}
				else
				{
					$newClust = clone $lastClust;
					while($newClust->length + $addedLength > $span)
					{
						$shiftedNode = array_shift($newClust->nodes);
						if($shiftedNode === null)
						{
							break;
						}

						$newClust->i--;
						$removedLength = $shiftedNode->phraseLength;
						if(isset($newClust->nodes[0]))
						{
							$removedLength+= $newClust->nodes[0]->position - $shiftedNode->position;
						}

						$newClust->length-= $removedLength;
					}

					if($newClust->i < 0)
					{
						$newClust->i = 0;
					}

					$newClust->nodes[] = $node;
					$newClust->length+= $addedLength;
					$clusters->data[] = $newClust;
					$clusters->i++;
				}
			}
		}

		$bestClust = $clusters->data[0];
		$bestClustSize = count($bestClust->nodes);
		foreach($clusters->data as $clust)
		{
			$newClustSize = count($clust->nodes);
			if($newClustSize > $bestClustSize)
			{
				$bestClust = $clust;
				$bestClustSize = $newClustSize;
			}
		}

		$clustLeft = $bestClust->nodes[0]->position;
		$clustLen = $bestClust->length;
		$padding = intval(round(($span - $clustLen) / 2));
		$clustLeft-= $padding;
		if($clustLeft < 0)
		{
			$clustLen+= $clustLeft * -1 + $padding;
			$clustLeft = 0;
		}
		else
		{
			$clustLen+= $padding * 2;
		}
	}
	else
	{
		$clustLeft = 0;
		$clustLen = $span;
	}

	$textLen = mb_strlen($text);
	$prefix = '';
	$suffix = '';
	if($clustLeft > 0 && !ctype_space(mb_substr($text, $clustLeft, 1))
		&& !ctype_space(mb_substr($text, $clustLeft - 1, 1)))
	{
		$clustLeft++;
		while(!ctype_space(mb_substr($text, $clustLeft, 1)))
		{
			$clustLeft++;
		}

		$prefix = $delimiter;
	}

	$lastChar = $clustLeft + $clustLen;
	if($lastChar < $textLen && !ctype_space(mb_substr($text, $lastChar, 1))
		&& !ctype_space(mb_substr($text, $lastChar + 1, 1)))
	{
		$lastChar--;
		while(!ctype_space(mb_substr($text, $lastChar, 1)))
		{
			$lastChar--;
		}

		$suffix = $delimiter;
		$clustLen = $lastChar - $clustLeft;
	}

	if($clustLeft > 0)
	{
		$prefix = $delimiter;
	}
	if($clustLeft + $clustLen < $textLen)
	{
		$suffix = $delimiter;
	}

	return $prefix . trim(mb_substr($text, $clustLeft, $clustLen + 1)) . $suffix;
}