golang regexp.MatchString handle url match

Question

I wanna check if a url string match keyword, for example, keyword is google.com, if url string is google.com or https://google.com, then return true, if url is google.com/search or something like that, return true, if url is google.com.id, then return false as it's a different url, I tried one as below but it doesn't work, how to write regular expression? thank u

regexp.MatchString(`^(?:https?://)?([-a-z0-9]+)(?:\.`+keyword+`)*$`, urlstr)

btw, as far as I understood, regular expression will cause some performance issue, anyone can provide other solutions to handle it?

Wiktor Stribiżew · Accepted Answer · 2021-04-19 10:09:59Z

3

You can use

regexp.MatchString(`^(?:https?://)?(?:[^/.\s]+\.)*` + regexp.QuoteMeta(keyword) + `(?:/[^/\s]+)*/?$`)

See the regex demo.

Details:

^ - start of string
(?:https?://)? - an optional http:// or https://
(?:[^/\s]+\.)* - zero or more repetitions of
- [^/.\s]+ - one or more chars other than /, . and whitespace
- \. - a dot
google\.com - an escaped keyword
(?:/[^/\s]+)* - zero or more repetitions of a / and then one or more chars other than / and whitespace chars
/? - an optional /
$ - end of string

Note you need to use regexp.QuoteMeta to escape any special chars in the keyword, like a . that matches any char but line break chars by default.

answered Apr 19, 2021 at 10:09

Wiktor Stribiżew

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5 Comments

Frank Over a year ago

thank u, seems works, if there will be some performance issue on regular expression? any other solutions to handle it?

Wiktor Stribiżew Over a year ago

@Frank I think this regex is efficient enough not to cause any performance problems. Note I assumed there will be no spaces in the URL. If you need to support whitespace, remove all \ss.

Frank Over a year ago

understood, thank u, let me do benchmark for it

Frank Over a year ago

hi got a bug, if keyword is https://google.com which contains https, but urlstr is google.com which not contains https, result will be false, but expected should be true. how to change above expression?

Wiktor Stribiżew Over a year ago

@Frank This is a problem with your data/task definition. If you need to handle URLs with protocol or without in keywords, make sure you only check the parts without protocol, simply remove it with strings.Replace(strings.Replace(urlstr, "https://", "", 1), "http://", "", 1) before checking.

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