emoji.fs

  let (|MessageTextAsEmoji|_|) (text: string) =
    let isEmojiString (str:string) =
      let mutable idx = 0
      let mutable res = true
      while(idx<str.Length) do
        if(Char.IsHighSurrogate(str,idx) || Char.IsLowSurrogate(str,idx)) then
          idx <- idx + 1
        else
          idx <- str.Length
          res <- false
      res

    let symbols = text.Split (char 0x200d,StringSplitOptions.None)
    let mutable failed = false
    if(symbols.Length) <= 3 then
      let mutable res = false
      let mutable idx = 0
      while (idx<symbols.Length) do
        if(isEmojiString symbols.[idx]) then
          idx <- idx + 1
        else
          failed <- true
          idx <- symbols.Length

    if (failed) then None else Some text