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..).
«Они сами заварили эту кашу». Китай начал давить на Иран из-за конфликта с США. Что требует Пекин от партнера?19:31。爱思助手下载最新版本对此有专业解读
。关于这个话题，体育直播提供了深入分析
至於伊朗最高領袖及其高階軍事顧問被殺，這是一記重擊，但不代表政權必然崩潰。。业内人士推荐体育直播作为进阶阅读
居民代表由居民小组一般按每二十户至五十户推选一人产生，也可以根据实际需要在适当范围内推选产生。居民小组组长由居民小组从居民代表中推选。居民小组组长和居民代表的任期与居民委员会的任期相同，可以连选连任。