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..).
12:08, 3 марта 2026Бывший СССРЭксклюзив
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You can click again on the button to cancel the action when processing a page.，更多细节参见PDF资料
当然，作为一台桌面设备，它也没忘了本职工作——底座集成了扩展接口，还带有一排可编程的物理按键。。业内人士推荐WPS官方版本下载作为进阶阅读
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