a very common use case for regexes is to find matches that are preceded or followed by some context. a classical example being all lines that end with ‘a’. this requirement is usually expressed with a lookahead, where upon finding an ‘a’, you look ahead to check if it’s the end of the line. in a backtracking engine, this is very easy to implement - you just duct-tape the logic that checks the next character, but in a DFA-based engine, this is impossible because you cannot report “the match is here” if the next character is not even known yet. and by the time you know the next character, the position information is lost, so you can’t report the match retroactively (well, unless the distance is fixed of course..).
Одна женщина рассказала о женихе, не обращавшем внимания на старавшуюся ради него невесту.。业内人士推荐体育直播作为进阶阅读
，详情可参考体育直播
Web of tiny accounting firms audited collapsed MFS property lending empire。爱思助手下载最新版本是该领域的重要参考
第二十八条 对下列情形的自然保护区，经科学论证，在确保主要保护对象安全和不损害生态功能的前提下，可以实行差别化管控措施：
На помощь российским туристам на Ближнем Востоке ушли миллиарды рублей20:47