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..).
Кардиолог сети клиник «Семейная» Наталья Соловьева назвала четыре категории продуктов, которые полезны для здоровья сердца. Их врач перечислила в разговоре с «Лентой.ру».。业内人士推荐91视频作为进阶阅读
Участник секс-марафона, устроенного порнозвездой Бонни Блю, признался, что напуган известием о ее беременности. Об этом пишет издание The Tab.，详情可参考Line官方版本下载
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