translating filename wildcards to regex

I need to translate arbitrary good old DOS wildcard strings to regex strings, which then are to be used with System.Text.RegularE开发者_如何学JAVAxpressions.Regex. Unfortunately, my regex knowledge is quite embarrassing.

I'm trying to wrap my head around stuff like *.*, .*, and *.. My current problem is that *. is generally expected to match files that either end with a dot or have no dot at all.

So I translate *. into ^.+[^\.].*$, but this is apparently wrong. It not only matches blah and blah., but also blah.blah.

So what's the correct regex syntax to match blah and blah., but not blah.blah?

I think the following will work for you

^[^.]+\.{0,1}$

from start of string match any character but . and the string may end with 0 or 1 .'s

I can't seem to create a file whose name ends with a dot, but I have observed that the glob *. will match a name that starts with a dot, if the name has no other dots in it. For example, it matches .cvspass, but not .antelope.cfg. It also matches names with no dots at all. The regex for that would be ^\.?[^.]+$.

The "ends with" equivalent would be ^[^.]+\.?$, but I don't think you need that. If you also need to match at start or end (but nowhere else), you can use ^\.?[^.]+\.?$. If the two conditions are mutually exclusive, use ^(?:\.?[^.]+|[^.]+\.)$