%%{

    machine common;

    action comment_begin { fcall comment_tail; }
    action comment_exit { fret; }

    # RFC5322: address_lists, date_time, message_ids, phrase_lists, received

    obs_NO_WS_CTL = 0x01..0x08 | 0x0b | 0x0c | 0x0e..0x1f | 0x7f;
    LF = "\n";
    CR = "\r";
    CRLF = "\r\n";
    WSP = 0x09 | 0x20;
    obs_ctext = obs_NO_WS_CTL;
    VCHAR = 0x21..0x7e;
    obs_qp = "\\" (0x00 | obs_NO_WS_CTL | LF | CR);
    obs_FWS = (CRLF? WSP)+;
    ctext = 0x21..0x27 | 0x2a..0x5b | 0x5d..0x7e | obs_ctext;
    quoted_pair = ("\\" (VCHAR | WSP)) | obs_qp;
    FWS = (WSP* CRLF WSP+) | (CRLF WSP+) | obs_FWS;
    ALPHA = [a-zA-Z];
    DIGIT = [0-9];
    DQUOTE = '"';
    obs_qtext = obs_NO_WS_CTL;
    atext = ALPHA | DIGIT | "!" | "#" | "$" | "%" | "&" |
            "'" | "*" | "+" | "-" | "/" | "=" | "?" | "^" |
            "_" | "`" | "{" | "|" | "}" | "~";
    qtext = 0x21 | 0x23..0x5b | 0x5d..0x7e | obs_qtext;
    obs_dtext = obs_NO_WS_CTL | quoted_pair;
    qcontent = qtext | quoted_pair;

    # Handle recursive comments
    ccontent = ctext | quoted_pair | "(" @comment_begin;
    comment_tail := ((FWS? ccontent)* >comment_s) FWS? ")" @comment_exit;
    comment = "(" @comment_begin %comment_e;
    CFWS = ((FWS? comment)+ FWS?) | FWS;

    quoted_string = CFWS?
                    (DQUOTE
                      (((FWS? qcontent)* FWS?) >qstr_s %qstr_e)
                    DQUOTE)
                    CFWS?;

    atom = CFWS? atext+ CFWS?;
    word = atom | quoted_string;

    # phrase_lists
    obs_phrase = (word | "." | "@")+;
    phrase = (obs_phrase | word+) >phrase_s %phrase_e;
    phrase_lists = phrase ("," FWS* phrase)*;

    # address_lists

    # local_part:
    domain_text = (DQUOTE (FWS? qcontent)+ FWS? DQUOTE) | atext+;
    local_dot_atom_text = ("."* domain_text "."*)+;
    local_dot_atom = CFWS?
                     (local_dot_atom_text >local_dot_atom_s %local_dot_atom_pre_comment_e)
                     CFWS?;
    obs_local_part = word ("." word)*;
    local_part = (local_dot_atom >local_dot_atom_s %local_dot_atom_e |
                  (quoted_string %local_quoted_string_e) |
                  obs_local_part);

    # Treetop parser behavior was to ignore addresses missing '@' inside of angle
    # brackets. This construction preserves that behavior.
    local_part_no_capture = (local_dot_atom | quoted_string | obs_local_part);

    # domain:
    dot_atom_text = "."* domain_text ("."* domain_text)*;
    dtext = 0x21..0x5a | 0x5e..0x7e | obs_dtext;
    dot_atom = CFWS? dot_atom_text (CFWS? >(comment_after_address,1));
    domain_literal = CFWS? "[" (FWS? dtext)* FWS? "]" CFWS?;
    obs_domain = atom ("." atom)*;
    domain = (dot_atom | domain_literal | obs_domain) >domain_s %domain_e;

    # addr_spec:

    # The %(end_addr,N) priority resolves uncertainty when whitespace
    # after an addr_spec could cause it to be interpreted as a
    # display name: "bar@example.com ,..."

    addr_spec_in_angle_brackets =
      (local_part "@" domain) %(end_addr,1) |
      local_part_no_capture   %(end_addr,0);

    addr_spec_no_angle_brackets =
      (local_part "@" domain) %(end_addr,1) |
      local_part              %(end_addr,0);

    # angle_addr:
    obs_domain_list = (CFWS | ",")* "@" domain ("," CFWS? ("@" domain)?)*;
    obs_route = (obs_domain_list ":") >obs_domain_list_s %obs_domain_list_e;
    obs_angle_addr = CFWS? "<" obs_route? addr_spec_in_angle_brackets ">" CFWS?;

    angle_addr = CFWS? ("<" >angle_addr_s) addr_spec_in_angle_brackets ">" CFWS? |
                  obs_angle_addr;

    # Address
    display_name = phrase;
    name_addr = display_name? %(end_addr,2) angle_addr;
    mailbox = (name_addr | addr_spec_no_angle_brackets) >address_s %address_e;
    obs_mbox_list = (CFWS? ",")* mailbox ("," (mailbox | CFWS)?)*;
    mailbox_list = (mailbox (("," | ";") mailbox)*) | obs_mbox_list;
    obs_group_list = (CFWS? ",")+ CFWS?;
    group_list = mailbox_list | CFWS | obs_group_list;
    group = (display_name >group_name_s %group_name_e) ":"
              (group_list?) ";" CFWS?;
    address = group | mailbox;
    #obs_addr_list = (CFWS? ",")* address ("," (address | CFWS)?)*;
    address_lists = address? %(comment_after_address,0)
                    (FWS* ("," | ";") FWS* address?)*;

    # message_ids
    obs_id_left = local_part;
    id_left = dot_atom_text | obs_id_left;
    # id_right modifications to support multiple '@' in msg_id.
    msg_id_atext = ALPHA | DIGIT | "!" | "#" | "$" | "%" | "&" | "'" | "*" |
                   "+" | "-" | "/" | "=" | "?" | "^" | "_" | "`" | "{" | "|" |
                   "}" | "~" | "@";
    msg_id_dot_atom_text = (msg_id_atext+ "."?)+;
    obs_id_right = domain;
    no_fold_literal = "[" (dtext)* "]";
    id_right = msg_id_dot_atom_text | no_fold_literal | obs_id_right;
    msg_id = (CFWS)?
             (("<" id_left "@" id_right ">") >msg_id_s %msg_id_e)
             (CFWS)?;
    message_ids = msg_id (CFWS? msg_id)*;

    include date_time "date_time.rl";
    date_time = (day_of_week ",")?
                (date >date_s %date_e) <: (time >time_s %time_e) CFWS?;

    # Added CFWS? to increase robustness
    # (qmail likes to include a comment style string...?)
    received_token = word | angle_addr | addr_spec_no_angle_brackets | domain;
    received = ((CFWS? received_token*) >received_tokens_s %received_tokens_e)
                ";" date_time;

    # RFC2045: mime_version, content_type, content_transfer_encoding
    mime_version = CFWS?
              (DIGIT+ >major_digits_s %major_digits_e)
              comment? "." comment?
              (DIGIT+ >minor_digits_s %minor_digits_e)
              CFWS?;

    token = 0x21..0x27 | 0x2a..0x2b | 0x2c..0x2e |
            0x30..0x39 | 0x41..0x5a | 0x5e..0x7e;
    value = (quoted_string | (token -- '"' | 0x3d)+) >param_val_s %param_val_e;
    attribute = (token+) >param_attr_s %param_attr_e;
    parameter = CFWS? attribute "=" value CFWS?;

    ietf_token = token+;
    custom_x_token = 'x'i "-" token+;
    extension_token = ietf_token | custom_x_token;
    discrete_type = 'text'i | 'image'i | 'audio'i | 'video'i |
                    'application'i | extension_token;
    composite_type = 'message'i | 'multipart'i | extension_token;
    iana_token = token+;
    main_type = (discrete_type | composite_type) >main_type_s %main_type_e;
    sub_type = (extension_token | iana_token) >sub_type_s %sub_type_e;
    content_type = main_type "/" sub_type (((CFWS? ";"+) | CFWS) parameter CFWS?)*;

    encoding = ('7bits' | '8bits' | '7bit' | '8bit' | 'binary' |
                'quoted-printable' | 'base64' | ietf_token |
                custom_x_token) >encoding_s %encoding_e;
    content_transfer_encoding = CFWS? encoding CFWS? ";"? CFWS?;

    # RFC2183: content_disposition
    # TODO: recognize filename, size, creation date, etc.
    disposition_type = 'inline'i | 'attachment'i | extension_token | '';
    content_disposition = (disposition_type >disp_type_s %disp_type_e)
                          (CFWS? ";" parameter CFWS?)*;

    # Envelope From
    ctime_date = day_name " "+ month " "+ day " " time_of_day " " year;
    null_sender = ('<>' ' '{0,1});
    envelope_from = (addr_spec_no_angle_brackets | null_sender) >address_s %address_e " "
                    (ctime_date >ctime_date_s %ctime_date_e);

    # content_location
    location = quoted_string | ((token | 0x3d)+ >token_string_s %token_string_e);
    content_location = CFWS? location CFWS?;

}%%