# a comment | ]*>.*? # a canvas tag | ]*>.*? # a script tag | ]*>.*? # a noscript tag | ]*>.*? # a template tag ) | ".*?" # attribute values in double-quotes | \'.*?\' # attribute values in single-quotes | [^\'">\\s]+ # plain attribute values ) )? ) | # OR a single dash (for TYPO3 link tag) (?: \\s+- ) )+\\s* | # OR only spaces \\s* ) /?> # closing the tag with \'>\' or \'/>\' )'; /** * Implements "cropHTML" which is a modified "substr" function allowing to limit a string length to a certain number * of chars (from either start or end of string) and having a pre/postfix applied if the string really was cropped. * * @param string $content The string to perform the operation on * @param int $numberOfChars Max number of chars of the string. Negative value means cropping from end of string. * @param string $replacementForEllipsis The pre/postfix string to apply if cropping occurs. * @param bool $cropToSpace If true then crop will be applied at nearest space. * @return string The processed input value. */ public function crop(string $content, int $numberOfChars, string $replacementForEllipsis, bool $cropToSpace): string { $cropFromRight = $numberOfChars < 0; $sections = $this->splitContentIntoSections($content, $cropFromRight); // Only crop text sections (chars of tag-blocks are not counted). $strLengthOfAllPrevTextSections = 0; // This is the offset of the content item which was cropped. $croppedOffset = null; $amountOfSections = count($sections); // For cropSectionToNextSpace we need a collection of all processed text sections $processedTextSectionsForCropping = []; for ($offset = 0; $offset < $amountOfSections; $offset++) { if ($this->isTextSection($offset)) { $contentOfCurrentSection = $sections[$offset]; $strLengthOfCurrentSection = mb_strlen( html_entity_decode($contentOfCurrentSection, ENT_COMPAT, 'UTF-8'), 'utf-8' ); if ($strLengthOfAllPrevTextSections + $strLengthOfCurrentSection > abs($numberOfChars)) { $croppedOffset = $offset; $cropPosition = $this->getCropPosition( $contentOfCurrentSection, $numberOfChars, $strLengthOfAllPrevTextSections, $cropFromRight ); // Main cropping. Note the +1 and -1. These are there to be able to // check for space characters later on. $contentOfCurrentSection = !$cropFromRight ? mb_substr($contentOfCurrentSection, 0, $cropPosition + 1) : mb_substr($contentOfCurrentSection, -$cropPosition - 1); $contentOfCurrentSection = $this->cropSectionToNextSpace( $contentOfCurrentSection, $processedTextSectionsForCropping, $cropToSpace, $cropFromRight ); $sections[$offset] = $contentOfCurrentSection; break; } $strLengthOfAllPrevTextSections += $strLengthOfCurrentSection; if ($contentOfCurrentSection !== '') { $processedTextSectionsForCropping[] = $contentOfCurrentSection; } } } $sections = $this->closeCroppedTags($sections, $croppedOffset, $numberOfChars, $replacementForEllipsis); // Reverse array once again if we are cropping from the end. if ($numberOfChars < 0) { $sections = array_reverse($sections); } return implode('', $sections); } /** * Split $content into an array(even items in the array are outside the tags, odd numbers are tag-blocks). */ protected function splitContentIntoSections(string $content, bool $cropFromRight): array { $splitPattern = sprintf( self::TAGS_REG_EXP, self::TAGS ); $sections = preg_split( '%' . $splitPattern . '%xs', $content, -1, PREG_SPLIT_DELIM_CAPTURE ); if ($sections === false) { $this->logger->debug('Unable to split "{content}" into tags.', ['content' => $content]); $sections = []; } // Reverse array if we are cropping from right. if ($cropFromRight) { $sections = array_reverse($sections); } return $sections; } protected function getCropPosition( string $contentOfCurrentSection, int $numberOfChars, int $strLengthOfAllPrevTextSections, bool $cropFromRight ): int { $cropPosition = abs($numberOfChars) - $strLengthOfAllPrevTextSections; // The snippet "&[^&\s;]{2,8};" in the RegEx below represents entities. $entityPattern = '/&[^&\\s;]{2,8};/'; preg_match_all($entityPattern, $contentOfCurrentSection, $matches); $entityMatches = $matches[0]; // If we have found any html entities, these should be counted as 1 character. // Strategy is to replace all found entities with an arbitrary character ($) // and use this new string to count offsets. if ($entityMatches !== []) { $escapedContent = str_replace('$', ' ', $contentOfCurrentSection); $replacedContent = preg_replace($entityPattern, '$', $escapedContent, -1); $croppedContent = !$cropFromRight ? mb_substr($replacedContent, 0, $cropPosition) : mb_substr($replacedContent, $numberOfChars, $cropPosition); // In case of negative offsets, we need to reverse everything. // Because the string is cropped from behind, the entities // have to be replaced in reverse, too. if ($cropFromRight) { $croppedContent = strrev($croppedContent); $entityMatches = array_reverse($entityMatches); } foreach ($entityMatches as $entity) { $croppedContent = preg_replace('/\$/', $entity, $croppedContent, 1); } $cropPosition = mb_strlen($croppedContent); } return $cropPosition; } protected function closeCroppedTags( array $sections, ?int $croppedOffset, int $numberOfChars, string $replacementForEllipsis ): array { $closingTags = []; if ($croppedOffset !== null) { $openingTagRegEx = '#^<(\\w+)(?:\\s|>)#'; $closingTagRegEx = '#^)#'; for ($offset = $croppedOffset - 1; $offset >= 0; $offset = $offset - 2) { if (str_ends_with($sections[$offset], '/>')) { // Ignore empty element tags (e.g.
). continue; } preg_match($numberOfChars < 0 ? $closingTagRegEx : $openingTagRegEx, $sections[$offset], $matches); $tagName = $matches[1] ?? null; if ($tagName !== null) { // Seek for the closing (or opening) tag. $amountOfSections = count($sections); for ($seekingOffset = $offset + 2; $seekingOffset < $amountOfSections; $seekingOffset = $seekingOffset + 2) { preg_match($numberOfChars < 0 ? $openingTagRegEx : $closingTagRegEx, $sections[$seekingOffset], $matches); $seekingTagName = $matches[1] ?? null; if ($tagName === $seekingTagName) { // We found a matching tag. // Add closing tag only if it occurs after the cropped content item. if ($seekingOffset > $croppedOffset) { $closingTags[] = $sections[$seekingOffset]; } break; } } } } // Drop the cropped items of the content array. The $closingTags will be added later on again. array_splice($sections, $croppedOffset + 1); } return array_merge($sections, [ $croppedOffset !== null ? trim($replacementForEllipsis) : '', ], $closingTags); } protected function cropSectionToNextSpace( string $contentOfCurrentSection, array $processedTextSectionsForCropping, bool $cropToSpace, bool $cropFromRight ): string { // Crop to space means, we ensure to crop before (or after) a space. // If there are no spaces, this option has no effect. $cropToSpaceApplied = false; if ($cropToSpace) { $exploded = explode(' ', $contentOfCurrentSection); if (!$cropFromRight) { array_unshift( $exploded, ...$processedTextSectionsForCropping ); } else { array_push( $exploded, ...$processedTextSectionsForCropping ); } if (count($exploded) > 1) { if (!$cropFromRight && $exploded[count($exploded) - 1] !== ' ') { array_pop($exploded); $cropToSpaceApplied = true; } elseif ($exploded[0] !== ' ') { array_shift($exploded); $cropToSpaceApplied = true; } } $exploded = array_diff($exploded, $processedTextSectionsForCropping); $contentOfCurrentSection = implode(' ', $exploded); } // Only remove the extra character again, if crop2space did not apply anything. if (!$cropToSpaceApplied) { $contentOfCurrentSection = !$cropFromRight ? mb_substr($contentOfCurrentSection, 0, -1) : mb_substr($contentOfCurrentSection, 1); } return $contentOfCurrentSection; } protected function isTextSection(int $offset): bool { return $offset % 2 === 0; } }