正则表达式特定的重复间隔解析器,大多数工作

Question

我有以下正则表达式:

once|every (?:(?:([1-9][0-9]?[0-9]? )?(hours?|days?))|(?:(?:(?:(1st|2nd|3rd|4th|5th))? ?(monday|tuesday|wednesday|thursday|friday|saturday|sunday)?)|((?:[1-9]|[1-2][0-9]|3[0-1])(?:st|nd|rd|th))) ?(?:(of the month)? ?(?:(?:repeated every )([2-9][0-9]?[0-9]?) (weeks|months))?)?)

这适用于我需要的大部分内容,但不适用于以下字符串...

Every 20th of the month

以下工作很棒......

Once
Every hour
Every day
Every 2 hours
Every 2 days
Every Monday
Every 1st of the month
Every 1st of the month repeated every 3 months
Every 2nd Monday of the month
Every 2nd Monday of the month repeated every 3 months

你能帮我吗？谢谢

Answer 1

问题在于(?:(?:(1st|2nd|3rd|4th|5th))? ?(monday|tuesday|wednesday|thursday|friday|saturday|sunday)?)部分:它可能匹配一个空字符串.因此,它总是"赢".

您可以通过删除?量词sunday)来解决它,使星期几成为强制性模式.看到这个正则表达式演示.

否则,如果使用正则表达式检查的字符串是独立的,则可以使用^(?:和)$模式将整个模式括起来以使它们与整个模式匹配.看到这个正则表达式演示.