in src/PatternParser/Parser.php [16:26]
public static function parse(string $pattern): PatternNode {
$tokens = tokenize($pattern);
list($node, $tokens) = self::parseImpl($tokens);
invariant(
C\is_empty($tokens),
'Tokens remaining at end of expression: %s',
\var_export($tokens, true),
);
return $node;
}