Trait mail_headers::HeaderKind

pub trait HeaderKind: Clone + Default + 'static {
    type Component: EncodableInHeader + Clone;

    const VALIDATOR: Option<HeaderMapValidator>;
    const MAX_ONE: bool;

    fn name() -> HeaderName;

    fn auto_body<H>(body: H) -> Result<Header<Self>, ComponentCreationError>
    where
        H: HeaderTryInto<Self::Component>,
    { ... }
    fn body(body: Self::Component) -> Header<Self> { ... }
}

Trait representing a mail header.

This is not meant to be implemented by hand.* Use the def_headers macro instead.

Required Associated Types

type Component: EncodableInHeader + Clone

the component representing the header-field, e.g. Unstructured for Subject

Required Associated Constants

const VALIDATOR: Option<HeaderMapValidator>

A function which is meant to be called with a reference to the final header map before encoding the headers. It is meant to be used do some of the contextual validations, like e.g. a From header might return a function which checks if the From header has multiple mailboxes and if so checks if there is a Sender header

Calling a contextual validator with a header map not containing a header which it is meant to validate should not cause an error. Only if the header is there and the component is of the expected type and it is invalid in the context an error should be returned.

const MAX_ONE: bool

I true this will assure that the header is at most one time in a header map.

This is similar to VALIDATOR (and can be archived through one) but in difference to any VALIDATOR this is already assured when inserting a header with MAX_ONE set to true in a header map. It exists so that the header map can do, what is most intuitive, replacing insertion for all MAX_ONE headers (like in a normal map) but use adding insertion for all other header (like in a multi map).

Most headers have this set to true.

Required Methods

fn name() -> HeaderName

a method returning the header name

Note:

Once const fn is stable this will be changed to a associated constant.

Provided Methods

fn auto_body<H>(body: H) -> Result<Header<Self>, ComponentCreationError>where
    H: HeaderTryInto<Self::Component>,

Creates a Header instance automatically converting given body to the right type.

Error

The type system assure that you can only use it on conversions which are possible on type level, but they can still fail depending on the actual data. For example creating a Email from a string can fail if the string is not a valid email address. This in turn means that creating a From header from a array of strings can fail if one of them is not a valid email address.

fn body(body: Self::Component) -> Header<Self>

Creates a Header instance for this header kind with given body.

Implementors

impl HeaderKind for Bcc

type Component = MailboxList

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for Cc

type Component = MailboxList

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for Comments

type Component = Unstructured

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for ContentDescription

type Component = Unstructured

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for ContentDisposition

type Component = Disposition

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for ContentId

type Component = MessageId

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for ContentTransferEncoding

type Component = TransferEncoding

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for ContentType

type Component = MediaType

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for Date

type Component = DateTime

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for InReplyTo

type Component = MessageIdList

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for Keywords

type Component = PhraseList

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for MessageId

type Component = MessageId

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for Received

type Component = ReceivedToken

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for References

type Component = MessageIdList

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for ReplyTo

type Component = MailboxList

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for ResentBcc

type Component = OptMailboxList

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = _

impl HeaderKind for ResentCc

type Component = MailboxList

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = _

impl HeaderKind for ResentDate

type Component = DateTime

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = _

impl HeaderKind for ResentFrom

type Component = MailboxList

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = _

impl HeaderKind for ResentMsgId

type Component = MessageId

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = _

impl HeaderKind for ResentSender

type Component = Mailbox

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = _

impl HeaderKind for ResentTo

type Component = MailboxList

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = _

impl HeaderKind for ReturnPath

type Component = Path

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for Sender

type Component = Mailbox

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for Subject

type Component = Unstructured

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

impl HeaderKind for _From

type Component = MailboxList

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = _

impl HeaderKind for _To

type Component = MailboxList

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }