Viewing file:  LinkParserHelper.php (4.83 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
<?php
declare(strict_types=1);
/*
* This file is part of the league/commonmark package.
*
* (c) Colin O'Dell <colinodell@gmail.com>
*
* Original code based on the CommonMark JS reference parser (https://bitly.com/commonmark-js)
* - (c) John MacFarlane
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace League\CommonMark\Util;
use League\CommonMark\Parser\Cursor;
/**
* @psalm-immutable
*/
final class LinkParserHelper
{
/**
* Attempt to parse link destination
*
* @return string|null The string, or null if no match
*/
public static function parseLinkDestination(Cursor $cursor): ?string
{
if ($cursor->getCurrentCharacter() === '<') {
return self::parseDestinationBraces($cursor);
}
$destination = self::manuallyParseLinkDestination($cursor);
if ($destination === null) {
return null;
}
return UrlEncoder::unescapeAndEncode(
RegexHelper::unescape($destination)
);
}
public static function parseLinkLabel(Cursor $cursor): int
{
$match = $cursor->match('/^\[(?:[^\\\\\[\]]|\\\\.){0,1000}\]/');
if ($match === null) {
return 0;
}
$length = \mb_strlen($match, 'UTF-8');
if ($length > 1001) {
return 0;
}
return $length;
}
public static function parsePartialLinkLabel(Cursor $cursor): ?string
{
return $cursor->match('/^(?:[^\\\\\[\]]++|\\\\.?)*+/');
}
/**
* Attempt to parse link title (sans quotes)
*
* @return string|null The string, or null if no match
*/
public static function parseLinkTitle(Cursor $cursor): ?string
{
if ($title = $cursor->match('/' . RegexHelper::PARTIAL_LINK_TITLE . '/')) {
// Chop off quotes from title and unescape
return RegexHelper::unescape(\substr($title, 1, -1));
}
return null;
}
public static function parsePartialLinkTitle(Cursor $cursor, string $endDelimiter): ?string
{
$endDelimiter = \preg_quote($endDelimiter, '/');
$regex = \sprintf('/(%s|[^%s\x00])*(?:%s)?/', RegexHelper::PARTIAL_ESCAPED_CHAR, $endDelimiter, $endDelimiter);
if (($partialTitle = $cursor->match($regex)) === null) {
return null;
}
return RegexHelper::unescape($partialTitle);
}
private static function manuallyParseLinkDestination(Cursor $cursor): ?string
{
$remainder = $cursor->getRemainder();
$openParens = 0;
$len = \strlen($remainder);
for ($i = 0; $i < $len; $i++) {
$c = $remainder[$i];
if ($c === '\\' && $i + 1 < $len && RegexHelper::isEscapable($remainder[$i + 1])) {
$i++;
} elseif ($c === '(') {
$openParens++;
// Limit to 32 nested parens for pathological cases
if ($openParens > 32) {
return null;
}
} elseif ($c === ')') {
if ($openParens < 1) {
break;
}
$openParens--;
} elseif (\ord($c) <= 32 && RegexHelper::isWhitespace($c)) {
break;
}
}
if ($openParens !== 0) {
return null;
}
if ($i === 0 && (! isset($c) || $c !== ')')) {
return null;
}
$destination = \substr($remainder, 0, $i);
$cursor->advanceBy(\mb_strlen($destination, 'UTF-8'));
return $destination;
}
/** @var \WeakReference<Cursor>|null */
private static ?\WeakReference $lastCursor = null;
private static bool $lastCursorLacksClosingBrace = false;
private static function parseDestinationBraces(Cursor $cursor): ?string
{
// Optimization: If we've previously parsed this cursor and returned `null`, we know
// that no closing brace exists, so we can skip the regex entirely. This helps avoid
// certain pathological cases where the regex engine can take a very long time to
// determine that no match exists.
if (self::$lastCursor !== null && self::$lastCursor->get() === $cursor) {
if (self::$lastCursorLacksClosingBrace) {
return null;
}
} else {
self::$lastCursor = \WeakReference::create($cursor);
}
if ($res = $cursor->match(RegexHelper::REGEX_LINK_DESTINATION_BRACES)) {
self::$lastCursorLacksClosingBrace = false;
// Chop off surrounding <..>:
return UrlEncoder::unescapeAndEncode(
RegexHelper::unescape(\substr($res, 1, -1))
);
}
self::$lastCursorLacksClosingBrace = true;
return null;
}
}
|