Trait HeaderKind

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

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

    // Required method
    fn name() -> HeaderName;

    // Provided methods
    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 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 Associated Types

type Component: EncodableInHeader + Clone

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

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.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl HeaderKind for Bcc

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = MailboxList

impl HeaderKind for Cc

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = MailboxList

impl HeaderKind for Comments

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = Unstructured

impl HeaderKind for ContentDescription

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = Unstructured

impl HeaderKind for ContentDisposition

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = Disposition

impl HeaderKind for ContentId

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = MessageId

impl HeaderKind for ContentTransferEncoding

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = TransferEncoding

impl HeaderKind for ContentType

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = MediaType

impl HeaderKind for Date

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = DateTime

impl HeaderKind for InReplyTo

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = MessageIdList

impl HeaderKind for Keywords

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = PhraseList

impl HeaderKind for MessageId

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = MessageId

impl HeaderKind for Received

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = ReceivedToken

impl HeaderKind for References

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = MessageIdList

impl HeaderKind for ReplyTo

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = MailboxList

impl HeaderKind for ResentBcc

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator>

type Component = OptMailboxList

impl HeaderKind for ResentCc

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator>

type Component = MailboxList

impl HeaderKind for ResentDate

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator>

type Component = DateTime

impl HeaderKind for ResentFrom

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator>

type Component = MailboxList

impl HeaderKind for ResentMsgId

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator>

type Component = MessageId

impl HeaderKind for ResentSender

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator>

type Component = Mailbox

impl HeaderKind for ResentTo

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator>

type Component = MailboxList

impl HeaderKind for ReturnPath

const MAX_ONE: bool = false

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = Path

impl HeaderKind for Sender

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = Mailbox

impl HeaderKind for Subject

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = Unstructured

impl HeaderKind for _From

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator>

type Component = MailboxList

impl HeaderKind for _To

const MAX_ONE: bool = true

const VALIDATOR: Option<HeaderMapValidator> = { None }

type Component = MailboxList