When I try this regex in golang I'm getting regex parsing error.
error parsing regexp: invalid or unsupported Perl syntax:
(?!
regexp.MustCompile("^(?!On.*On\\s.+?wrote:)(On\\s(.+?)wrote:)$"),
Can someone tell me why its not working and help me to fix this issue?
Thanks
Go regex does not support lookarounds.
As a workaround, you may use
regexp.MustCompile("^On\\s(.+?)wrote:$")
and
regexp.MustCompile("^On.*On\\s.+?wrote:")
and check if the first one matches the string and the second does not.
You could also add an optional capturing group (.*On)?
regexp.MustCompile("^On(.*On)?\\s.+?wrote:")
and check if there is a match and return true if the Group 1 ends with On - if yes, return false, else true.