Expand _string_is_url() protocol-specific patterns.

refs xwmxgh-167

nb

@@ -3005,7 +3005,44 @@ _string_is_email() {
 #   0 (success, true)  If the string is a recognized URL.
 #   1 (error,  false)  if not.
 _string_is_url() {
-  [[ "${1:-}" =~ ^https\:\/\/|^http\:\/\/|^file\:\/\/|^ftp\:\/\/|^sftp\:\/\/ ]]
+  [[ -z "${1:-}" ]] && return 1
+
+  # # https://en.wikipedia.org/wiki/List_of_URI_schemes
+  local _url_patterns=(
+    -e "(afp|attachment|platform):/"
+    -e "(aaas?|acap|adiumxtra|aw|beshare|bolo|chrome|chrome-extension)://"
+    -e "(coaps?|content|crid|cvs|dict|dns|ed2k|facetime|feed|file|finger|fish)://"
+    -e "(ftp|git|gizmoproject|go|gopher|h323|http|https|imap|irc|irc6|ircs)://"
+    -e "(keyparc|lastfm|ldaps?|market|message|mms|ms-help|mumble|ni|nntp)://"
+    -e "(notes|payto|pop|res|resource|rmi|rsync|rtmfp|rtmp|s3|secondlife)://"
+    -e "(sftp|sgn|smb|snmp|soldat|ssh|steam|svn|svn+ssh|teamspeak|telnet)://"
+    -e "(udp|unreal|ut2004|ventrilo|vnc|wais|webcal|wtai|wyciwyg|xri)://"
+    -e "(z39.50r|z39.50s|admin|app|stratum\+tcp|stratum\+udp|web-[a-z]+)://"
+    -e "(zoommtg|zoomus|slack)://"
+    -e "(aim):[^[:space:]]+\?[^[:space:]]+"
+    -e "(dab|fm):[^[:space:]]+\.[^[:space:]]+\.[^[:space:]]+"
+    -e "(data|geo):[^[:space:]]+,[^[:space:]]+"
+    -e "(msnim|things):[^[:space:]]+\?[^[:space:]]+"
+    -e "(feed|mvn|paparazzi|view-source):https?://"
+    -e "gtalk:chat"
+    -e "(im|mailto|reload|sips?|xmpp):[^[:space:]]+\@[^[:space:]]+"
+    -e "jar:[^[:space:]]+\!\/"
+    -e "magnet:\?xt=urn:"
+    -e "maps:q="
+    -e "(sms|tel):\+[0-9]+"
+    -e "(jdbc|spotify|urn):[^[:space:]]+:[^[:space:]]+"
+    -e "tag:[^[:space:]]+,[^[:space:]]+:[^[:space:]]+"
+    -e "ymsgr:sendIM?"
+    -e "doi:10\."
+    # TODO: develop strategy to avoid matching selectors
+    # -e "(apt|amss|barion|bitcoin|callto|cid|dns|drm|fax|gg|go):[^[:space:]]+"
+    # -e "(iax|javascript|message|mid|mvn|news|openpgp4fpr|palm):[^[:space:]]+"
+    # -e "(pres|proxy|psyc|query|session|shc|skype|stuns?):[^[:space:]]+"
+    # -e "(trueconf|turns?|ws|xfire):[^[:space:]]+"
+    # -e "itms:"
+  )
+
+  printf "%s\\n" "${1:-}" | grep -E -q --color=never "${_url_patterns[@]:-}"
 }
 
 # _wrap()