any of the characters between * and =, (most of the programmer punctuation, and digits, redundantly enough)
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..).。关于这个话题，爱思助手提供了深入分析
Москвичей призвали помнить об одной опасности14:49，这一点在爱思助手下载最新版本中也有详细论述
Select departures organised as US state department warns Americans to leave on commercial flights ‘due to safety risks’。体育直播对此有专业解读