grammar.ne

main -> Mailbox | Path

@{%
// from https://github.com/jonathantneal/array-flat-polyfill
if (!Array.prototype.flat) {
	Object.defineProperty(Array.prototype, 'flat', {
		configurable: true,
		value: function flat () {
			var depth = isNaN(arguments[0]) ? 1 : Number(arguments[0]);

			return depth ? Array.prototype.reduce.call(this, function (acc, cur) {
				if (Array.isArray(cur)) {
					acc.push.apply(acc, flat.call(cur, depth - 1));
				} else {
					acc.push(cur);
				}

				return acc;
			}, []) : Array.prototype.slice.call(this);
		},
		writable: true
	});
}

function flat_string(d) {
  if (d) {
    if (Array.isArray(d))
      return d.flat(Infinity).join("");
    return d;
  }
  return "";
}
%}

# Some macros

times_3[X]     -> $X $X $X
times_5[X]     -> $X $X $X $X $X
times_7[X]     -> $X $X $X $X $X $X $X

## https://tools.ietf.org/html/rfc5321#section-4.1.2

Reverse_path   -> Path | "<>"

Forward_path   -> Path

Path           -> "<" ( A_d_l ":" ):? Mailbox ">"
                  {% function(d) { return d[2]; } %}

A_d_l          -> At_domain ( "," At_domain ):*
                # Note that this form, the so-called "source
                # route", MUST BE accepted, SHOULD NOT be
                # generated, and SHOULD be ignored.

At_domain      -> "@" Domain

Domain         -> sub_domain ("." sub_domain):*

#A_label       -> Let_dig (Ldh_str):?

sub_domain     -> U_label

Let_dig        -> ALPHA_DIGIT {% id %}

Ldh_str        -> ALPHA_DIG_DASH:* Let_dig

U_Let_dig      -> ALPHA_DIGIT_U {% id %}

U_Ldh_str      -> ALPHA_DIG_DASH_U:* U_Let_dig

U_label        -> U_Let_dig (U_Ldh_str):?

address_literal  -> "[" ( IPv4_address_literal |
                          IPv6_address_literal |
                          General_address_literal ) "]"
                    # See Section 4.1.3

non_local_part -> Domain | address_literal

Mailbox        -> Local_part "@" non_local_part {%
                    function(d) {
                      return { local_part: flat_string(d[0]), domain: flat_string(d[2]), };
                    }
                  %}

Local_part     -> Dot_string | Quoted_string
                # MAY be case-sensitive

Dot_string     -> Atom ("." Atom):*

# 1*atext

Atom           -> [0-9A-Za-z!#$%&'*+\-/=?^_`{|}~\u0080-\uFFFF/]:+

Quoted_string  -> DQUOTE QcontentSMTP:* DQUOTE

QcontentSMTP   -> qtextSMTP | quoted_pairSMTP

quoted_pairSMTP  -> "\\" [\x20-\x7e]
                    # i.e., backslash followed by any ASCII
                    # graphic (including itself) or SPace

qtextSMTP      -> [\x20-\x21\x23-\x5b\x5d-\x7e\u0080-\uFFFF] {% id %}
                # i.e., within a quoted string, any
                # ASCII graphic or space is permitted
                # without blackslash-quoting except
                # double-quote and the backslash itself.

## https://tools.ietf.org/html/rfc5321#section-4.1.3

IPv4_address_literal  -> Snum times_3["."  Snum]

IPv6_address_literal  -> "IPv6:"i IPv6_addr

General_address_literal  -> Standardized_tag ":" dcontent:+

Standardized_tag  -> Ldh_str
                   # Standardized_tag MUST be specified in a
                   # Standards_Track RFC and registered with IANA

dcontent       -> [\x21-\x5a\x5e-\x7e] {% id %}
                # Printable US_ASCII
                # excl. "[", "\", "]"

Snum           -> DIGIT |
                ( [1-9] DIGIT ) |
                ( "1" DIGIT DIGIT ) |
                ( "2" [0-4] DIGIT ) |
                ( "2" "5" [0-5] )
                # representing a decimal integer
                # value in the range 0 through 255

IPv6_addr      -> IPv6_full | IPv6_comp | IPv6v4_full | IPv6v4_comp

                # HEXDIG:? HEXDIG:? HEXDIG:? HEXDIG
IPv6_hex       -> HEXDIG |
                ( HEXDIG HEXDIG ) |
                ( HEXDIG HEXDIG HEXDIG ) |
                ( HEXDIG HEXDIG HEXDIG HEXDIG )

IPv6_full      -> IPv6_hex times_7[":" IPv6_hex]

IPv6_comp      -> (IPv6_hex times_5[":" IPv6_hex]):? "::"
                  (IPv6_hex times_5[":" IPv6_hex]):?
                # The "::" represents at least 2 16_bit groups of
                # zeros.  No more than 6 groups in addition to the
                # "::" may be present.

IPv6v4_full    -> IPv6_hex times_5[":" IPv6_hex] ":" IPv4_address_literal

IPv6v4_comp    -> (IPv6_hex times_3[":" IPv6_hex]):? "::"
                  (IPv6_hex times_3[":" IPv6_hex] ":"):?
                  IPv4_address_literal
                # The "::" represents at least 2 16_bit groups of
                # zeros.  No more than 4 groups in addition to the
                # "::" and IPv4_address_literal may be present.

DIGIT          -> [0-9] {% id %}

ALPHA_DIGIT_U  -> [0-9A-Za-z\u0080-\uFFFF] {% id %}

ALPHA_DIGIT    -> [0-9A-Za-z] {% id %}

ALPHA_DIG_DASH -> [-0-9A-Za-z] {% id %}

ALPHA_DIG_DASH_U -> [-0-9A-Za-z\u0080-\uFFFF] {% id %}

HEXDIG         -> [0-9A-Fa-f] {% id %}

DQUOTE         -> "\"" {% id %}