Struct PrefixedOptional 

#[repr(transparent)]
pub struct PrefixedOptional<T>(pub Optional<T>);

An optional value prefixed by a boolean presence marker.

The wire format is a Boolean followed by T when the boolean is true:

Boolean(is present) + (is present ? T : nothing)

Unlike Optional<T>, this type implements TypeCodec because its wire representation contains its own presence marker. The marker is 0x01 when the wrapped value is Some, and 0x00 when it is None.

Examples

use mcproto_types::{TypeCodec, basic::UnsignedByte};
use mcproto_types::contextual::PrefixedOptional;

let value = PrefixedOptional::some(UnsignedByte(0xab));
let mut encoded = Vec::new();
value.encode(&mut encoded)?;
assert_eq!(encoded, [0x01, 0xab]);

let mut input = encoded.as_slice();
assert_eq!(PrefixedOptional::<UnsignedByte>::decode(&mut input)?, value);
assert!(input.is_empty());

Tuple Fields

0: Optional<T>

The optional value and its context-controlled encoding behavior.

Implementations

impl<T> PrefixedOptional<T>

pub const fn some(value: T) -> Self

Creates a prefixed optional containing value.

pub const fn none() -> Self

Creates a prefixed optional with no value.

pub const fn is_some(&self) -> bool

Returns whether the prefixed optional contains a value.

pub const fn is_none(&self) -> bool

Returns whether the prefixed optional contains no value.

pub const fn as_ref(&self) -> PrefixedOptional<&T>

Returns the contained value by reference, if present.

pub fn into_option(self) -> Option<T>

Extracts the wrapped Option<T>.

Trait Implementations

impl<T: Clone> Clone for PrefixedOptional<T>

fn clone(&self) -> PrefixedOptional<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for PrefixedOptional<T>

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

Formats the value using the given formatter.

impl<T: Default> Default for PrefixedOptional<T>

fn default() -> PrefixedOptional<T>

Returns the “default value” for a type.

impl<T: Eq> Eq for PrefixedOptional<T>

impl<T> From<Option<T>> for PrefixedOptional<T>

fn from(value: Option<T>) -> Self

Converts to this type from the input type.

impl<T> From<Optional<T>> for PrefixedOptional<T>

fn from(value: Optional<T>) -> Self

Converts to this type from the input type.

impl<T> From<PrefixedOptional<T>> for Option<T>

fn from(value: PrefixedOptional<T>) -> Self

Converts to this type from the input type.

impl<T: Hash> Hash for PrefixedOptional<T>

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

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<T: PartialEq> PartialEq for PrefixedOptional<T>

fn eq(&self, other: &PrefixedOptional<T>) -> bool

Equality operator ==.

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

Inequality operator !=.

impl<T: PartialEq> StructuralPartialEq for PrefixedOptional<T>

impl<T> TypeCodec for PrefixedOptional<T>

where T: TypeCodec,

fn encode(&self, writer: &mut impl Write) -> Result<(), CodecError>

Encodes this value to the writer.

fn decode(reader: &mut impl Read) -> Result<Self, CodecError>

Decodes this value from the reader.