Struct Len 

pub struct Len(pub usize);

Length context.

Used for providing an already read or in-memory length value to a type that would otherwise read it from a Reader.

Sequence implementations of SchemaReadContext, such as Vec, trust caller-provided lengths. They do not validate the length or check whether allocating capacity for that length is within reasonable limits. Callers should perform any validation of the length they require before passing it to these implementations.

Examples

struct Header {
    data_len: u8,
}

struct Data {
    header: Header,
    data: Vec<u8>,
}

unsafe impl<C: Config> SchemaWrite<C> for Data {
    type Src = Self;

    fn size_of(src: &Self::Src) -> WriteResult<usize> {
        Ok(1 + src.data.len())
    }

    fn write(mut writer: impl Writer, src: &Self::Src) -> WriteResult<()> {
        writer.write(&[src.header.data_len])?;
        writer.write(&src.data)?;
        Ok(())
    }
}

unsafe impl<'de, C: Config> SchemaRead<'de, C> for Data {
    type Dst = Self;

    fn read(
        mut reader: impl Reader<'de>,
        dst: &mut MaybeUninit<Self::Dst>,
    ) -> ReadResult<()> {
        let len = reader.take_byte()?;

        let data = <Vec<u8> as SchemaReadContext<C, _>>::get_with_context(
            context::Len(len as usize),
            reader
        )?;

        dst.write(Self {
            header: Header { data_len: len },
            data,
        });

        Ok(())
    }
}

let data = Data {
    header: Header { data_len: 8},
    data: vec![0u8; 8],
};
let bytes = wincode::serialize(&data).unwrap();
let deserialized = wincode::deserialize(&bytes).unwrap();
assert_eq!(data, deserialized);

Tuple Fields

0: usize

Trait Implementations

impl Clone for Len

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Len

impl Debug for Len

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

Formats the value using the given formatter.

impl Eq for Len

impl Ord for Len

fn cmp(&self, other: &Self) -> 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.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for Len

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

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for Len

fn partial_cmp(&self, other: &Self) -> 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<'de, T, C: ConfigCore> SchemaReadContext<'de, C, Len> for Vec<T>

where T: SchemaRead<'de, C>,

Available on crate feature alloc only.

type Dst = Vec<<T as SchemaRead<'de, C>>::Dst>

fn read_with_context( ctx: Len, reader: impl Reader<'de>, dst: &mut MaybeUninit<Self::Dst>, ) -> ReadResult<()>

Read into dst from reader with context.

const TYPE_META: TypeMeta = TypeMeta::Dynamic

Metadata about the type’s serialization.

fn get_with_context(ctx: Ctx, reader: impl Reader<'de>) -> ReadResult<Self::Dst>

Read Self::Dst from reader into a new Self::Dst with context.

impl<'de, C: ConfigCore> SchemaReadContext<'de, C, Len> for &'de str

type Dst = &'de str

fn read_with_context( context::Len: Len, reader: impl Reader<'de>, dst: &mut MaybeUninit<Self::Dst>, ) -> ReadResult<()>

Read into dst from reader with context.

const TYPE_META: TypeMeta = TypeMeta::Dynamic

Metadata about the type’s serialization.

fn get_with_context(ctx: Ctx, reader: impl Reader<'de>) -> ReadResult<Self::Dst>

Read Self::Dst from reader into a new Self::Dst with context.

impl<'de, C: Config> SchemaReadContext<'de, C, Len> for String

Available on crate feature alloc only.

type Dst = String

fn read_with_context( ctx: Len, reader: impl Reader<'de>, dst: &mut MaybeUninit<Self::Dst>, ) -> ReadResult<()>

Read into dst from reader with context.

const TYPE_META: TypeMeta = TypeMeta::Dynamic

Metadata about the type’s serialization.

fn get_with_context(ctx: Ctx, reader: impl Reader<'de>) -> ReadResult<Self::Dst>

Read Self::Dst from reader into a new Self::Dst with context.

impl<'de, T, C: ConfigCore> SchemaReadContext<'de, C, Len> for &'de [T]

where T: SchemaRead<'de, C> + ZeroCopy<C>,

const TYPE_META: TypeMeta

Metadata about the type’s serialization.

type Dst = &'de [<T as SchemaRead<'de, C>>::Dst]

fn read_with_context( context::Len: Len, reader: impl Reader<'de>, dst: &mut MaybeUninit<Self::Dst>, ) -> ReadResult<()>

Read into dst from reader with context.

fn get_with_context(ctx: Ctx, reader: impl Reader<'de>) -> ReadResult<Self::Dst>

Read Self::Dst from reader into a new Self::Dst with context.

impl<'de, T, C: ConfigCore> SchemaReadContext<'de, C, Len> for Cow<'de, [T]>

where [T]: ToOwned, &'de [T]: SchemaReadContext<'de, C, Len, Dst = &'de [T]>, <[T] as ToOwned>::Owned: SchemaReadContext<'de, C, Len, Dst = <[T] as ToOwned>::Owned>,

Available on crate feature alloc only.

type Dst = Cow<'de, [T]>

fn read_with_context( ctx: Len, reader: impl Reader<'de>, dst: &mut MaybeUninit<Self::Dst>, ) -> ReadResult<()>

Read into dst from reader with context.

const TYPE_META: TypeMeta = TypeMeta::Dynamic

Metadata about the type’s serialization.

fn get_with_context(ctx: Ctx, reader: impl Reader<'de>) -> ReadResult<Self::Dst>

Read Self::Dst from reader into a new Self::Dst with context.

impl StructuralPartialEq for Len