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<?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\Extension\CommonMark\Parser\Inline;
use League\CommonMark\Extension\CommonMark\Node\Inline\Code;
use League\CommonMark\Node\Inline\Text;
use League\CommonMark\Parser\Cursor;
use League\CommonMark\Parser\Inline\InlineParserInterface;
use League\CommonMark\Parser\Inline\InlineParserMatch;
use League\CommonMark\Parser\InlineParserContext;
final class BacktickParser implements InlineParserInterface
{
/**
* Max bound for backtick code span delimiters.
*
* @see https://github.com/commonmark/cmark/commit/8ed5c9d
*/
private const MAX_BACKTICKS = 1000;
/** @var \WeakReference<Cursor>|null */
private ?\WeakReference $lastCursor = null;
private bool $lastCursorScanned = false;
/** @var array<int, int> backtick count => position of known ender */
private array $seenBackticks = [];
public function getMatchDefinition(): InlineParserMatch
{
return InlineParserMatch::regex('`+');
}
public function parse(InlineParserContext $inlineContext): bool
{
$ticks = $inlineContext->getFullMatch();
$cursor = $inlineContext->getCursor();
$cursor->advanceBy($inlineContext->getFullMatchLength());
$currentPosition = $cursor->getPosition();
$previousState = $cursor->saveState();
if ($this->findMatchingTicks(\strlen($ticks), $cursor)) {
$code = $cursor->getSubstring($currentPosition, $cursor->getPosition() - $currentPosition - \strlen($ticks));
$c = \preg_replace('/\n/m', ' ', $code) ?? '';
if (
$c !== '' &&
$c[0] === ' ' &&
\substr($c, -1, 1) === ' ' &&
\preg_match('/[^ ]/', $c)
) {
$c = \substr($c, 1, -1);
}
$inlineContext->getContainer()->appendChild(new Code($c));
return true;
}
// If we got here, we didn't match a closing backtick sequence
$cursor->restoreState($previousState);
$inlineContext->getContainer()->appendChild(new Text($ticks));
return true;
}
/**
* Locates the matching closer for a backtick code span.
*
* Leverages some caching to avoid traversing the same cursor multiple times when
* we've already seen all the potential backtick closers.
*
* @see https://github.com/commonmark/cmark/commit/8ed5c9d
*
* @param int $openTickLength Number of backticks in the opening sequence
* @param Cursor $cursor Cursor to scan
*
* @return bool True if a matching closer was found, false otherwise
*/
private function findMatchingTicks(int $openTickLength, Cursor $cursor): bool
{
// Reset the seenBackticks cache if this is a new cursor
if ($this->lastCursor === null || $this->lastCursor->get() !== $cursor) {
$this->seenBackticks = [];
$this->lastCursor = \WeakReference::create($cursor);
$this->lastCursorScanned = false;
}
if ($openTickLength > self::MAX_BACKTICKS) {
return false;
}
// Return if we already know there's no closer
if ($this->lastCursorScanned && isset($this->seenBackticks[$openTickLength]) && $this->seenBackticks[$openTickLength] <= $cursor->getPosition()) {
return false;
}
while ($ticks = $cursor->match('/`{1,' . self::MAX_BACKTICKS . '}/m')) {
$numTicks = \strlen($ticks);
// Did we find the closer?
if ($numTicks === $openTickLength) {
return true;
}
// Store position of closer
if ($numTicks <= self::MAX_BACKTICKS) {
$this->seenBackticks[$numTicks] = $cursor->getPosition() - $numTicks;
}
}
// Got through whole input without finding closer
$this->lastCursorScanned = true;
return false;
}
}
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