Consider not recompiling regex expressions every time

[linkdata]

E.g. at parser.go:245:

func searchDomain(text string) (name, extension string) {
  r := regexp.MustCompile(`(?i)\[?domain\:?(\s*\_?name)?\]?[\s\.]*\:?\s*([^\s\,\;\(\)]+)\.([^\s\,\;\(\)\.]{2,})`)
  m := r.FindStringSubmatch(text)
  // ....
}

Instead place them in a private global variable:

var searchDomainRx = regexp.MustCompile(`(?i)\[?domain\:?(\s*\_?name)?\]?[\s\.]*\:?\s*([^\s\,\;\(\)]+)\.([^\s\,\;\(\)\.]{2,})`)
func searchDomain(text string) (name, extension string) {
  m := searchDomainRx.FindStringSubmatch(text)
  // ....
}

[likexian]

Hello @linkdata Thanks for your feedback and PRs #58.