Struct Key

pub struct Key(/* private fields */);

The Key uniquely identifies what “kind” of message this is.

In order to generate it, postcard-schema takes two pieces of data:

• a &str “path” URI, similar to how you would use URIs as part of an HTTP path
• The schema of the message type itself, using the Schema trait

Specifically, we use Fnv1a, and produce a 64-bit digest, by first hashing the path, then hashing the schema. Fnv1a is a non-cryptographic hash function, designed to be reasonably efficient to compute even on small platforms like microcontrollers.

Changing anything about either of the path or the schema will produce a drastically different Key value.

Implementations

impl Key

pub const fn for_path<T>(path: &str) -> Key

where T: Schema + ?Sized,

Create a Key for the given type and path

pub const unsafe fn from_bytes(bytes: [u8; 8]) -> Key

Unsafely create a key from a given 8-byte value

Safety

This MUST only be used with pre-calculated values. Incorrectly created keys could lead to the improper deserialization of messages.

pub const fn to_bytes(&self) -> [u8; 8]

Extract the bytes making up this key

pub const fn const_cmp(&self, other: &Key) -> bool

Compare 2 keys in const context.

impl Key

pub fn for_owned_schema_path(path: &str, nt: &OwnedNamedType) -> Key

Calculate the Key for the given path and OwnedNamedType

Trait Implementations

impl Clone for Key

fn clone(&self) -> Key

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Key

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Key

fn deserialize<__D>( __deserializer: __D, ) -> Result<Key, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<Key> for Key1

fn from(value: Key) -> Self

Converts to this type from the input type.

impl From<Key> for Key2

fn from(value: Key) -> Self

Converts to this type from the input type.

impl From<Key> for Key4

fn from(value: Key) -> Self

Converts to this type from the input type.

impl Hash for Key

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Key

fn cmp(&self, other: &Key) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Key

fn eq(&self, other: &Key) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Key

fn partial_cmp(&self, other: &Key) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Schema for Key

const SCHEMA: &'static NamedType

A recursive data structure that describes the schema of the given type.

impl Serialize for Key

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl TryFrom<&VarKey> for Key

type Error = TooSmall

The type returned in the event of a conversion error.

fn try_from(value: &VarKey) -> Result<Self, Self::Error>

Performs the conversion.

impl Copy for Key

impl Eq for Key

impl StructuralPartialEq for Key