Struct ReadOnly 

#[repr(transparent)]
pub struct ReadOnly<T: ?Sized> {
    inner: T,
}

A read-only wrapper.

A ReadOnly<T> disables any interior mutability in T, ensuring that a &ReadOnly<T> is genuinely read-only. Thus, ReadOnly<T> is Immutable regardless of whether T is.

Note that &mut ReadOnly<T> still permits mutation – the read-only property only applies to shared references.

ReadOnly<T> implements Copy and Clone when T: Copy. Cloning copies the value without calling T::clone. Trait implementations that expose or operate on a shared reference to T require T: Immutable. Constructing a wrapper or accessing its contents through AsMut does not require T: Immutable.

Fields

inner: T

Implementations

impl<T> ReadOnly<T>

pub const fn new(t: T) -> ReadOnly<T>

Creates a new ReadOnly.

pub fn into_inner(r: ReadOnly<T>) -> T

Returns the inner value.

impl<T: ?Sized> ReadOnly<T>

pub(crate) fn as_mut(r: &mut ReadOnly<T>) -> &mut T

pub(crate) const unsafe fn as_ref_unchecked(r: &ReadOnly<T>) -> &T

Safety

The caller promises not to mutate the referent (i.e., via interior mutation).

Trait Implementations

impl<T: ?Sized> AsMut<T> for ReadOnly<T>

fn as_mut(&mut self) -> &mut T

Converts this type into a mutable reference of the (usually inferred) input type.

impl<T: ?Sized + Immutable> AsRef<T> for ReadOnly<T>

fn as_ref(&self) -> &T

Converts this type into a shared reference of the (usually inferred) input type.

impl<T: ?Sized + Immutable + Binary> Binary for ReadOnly<T>

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

Formats the value using the given formatter.

impl<T: ?Sized + Immutable> Borrow<T> for ReadOnly<T>

fn borrow(&self) -> &T

Immutably borrows from an owned value.

impl<T: Copy> Clone for ReadOnly<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: ?Sized + Immutable + Debug> Debug for ReadOnly<T>

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

Formats the value using the given formatter.

impl<T: Default> Default for ReadOnly<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T: ?Sized + Immutable> Deref for ReadOnly<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T: ?Sized + Immutable> DerefMut for ReadOnly<T>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<T: ?Sized + Immutable + Display> Display for ReadOnly<T>

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

Formats the value using the given formatter.

impl<'a, T: ?Sized + Immutable> From<&'a T> for &'a ReadOnly<T>

fn from(t: &'a T) -> &'a ReadOnly<T>

Converts to this type from the input type.

impl<T> From<T> for ReadOnly<T>

fn from(t: T) -> Self

Converts to this type from the input type.

impl<T: ?Sized + FromBytes> FromBytes for ReadOnly<T>

fn ref_from_bytes(source: &[u8]) -> Result<&Self, CastError<&[u8], Self>>

where Self: KnownLayout + Immutable,

Interprets the given source as a &Self.

fn ref_from_prefix( source: &[u8], ) -> Result<(&Self, &[u8]), CastError<&[u8], Self>>

where Self: KnownLayout + Immutable,

Interprets the prefix of the given source as a &Self without copying.

fn ref_from_suffix( source: &[u8], ) -> Result<(&[u8], &Self), CastError<&[u8], Self>>

where Self: Immutable + KnownLayout,

Interprets the suffix of the given bytes as a &Self.

fn mut_from_bytes( source: &mut [u8], ) -> Result<&mut Self, CastError<&mut [u8], Self>>

where Self: IntoBytes + KnownLayout,

Interprets the given source as a &mut Self.

fn mut_from_prefix( source: &mut [u8], ) -> Result<(&mut Self, &mut [u8]), CastError<&mut [u8], Self>>

where Self: IntoBytes + KnownLayout,

Interprets the prefix of the given source as a &mut Self without copying.

fn mut_from_suffix( source: &mut [u8], ) -> Result<(&mut [u8], &mut Self), CastError<&mut [u8], Self>>

where Self: IntoBytes + KnownLayout,

Interprets the suffix of the given source as a &mut Self without copying.

fn ref_from_bytes_with_elems( source: &[u8], count: usize, ) -> Result<&Self, CastError<&[u8], Self>>

where Self: KnownLayout<PointerMetadata = usize> + Immutable,

Interprets the given source as a &Self with a DST length equal to count.

fn ref_from_prefix_with_elems( source: &[u8], count: usize, ) -> Result<(&Self, &[u8]), CastError<&[u8], Self>>

where Self: KnownLayout<PointerMetadata = usize> + Immutable,

Interprets the prefix of the given source as a DST &Self with length equal to count.

fn ref_from_suffix_with_elems( source: &[u8], count: usize, ) -> Result<(&[u8], &Self), CastError<&[u8], Self>>

where Self: KnownLayout<PointerMetadata = usize> + Immutable,

Interprets the suffix of the given source as a DST &Self with length equal to count.

fn mut_from_bytes_with_elems( source: &mut [u8], count: usize, ) -> Result<&mut Self, CastError<&mut [u8], Self>>

where Self: IntoBytes + KnownLayout<PointerMetadata = usize> + Immutable,

Interprets the given source as a &mut Self with a DST length equal to count.

fn mut_from_prefix_with_elems( source: &mut [u8], count: usize, ) -> Result<(&mut Self, &mut [u8]), CastError<&mut [u8], Self>>

where Self: IntoBytes + KnownLayout<PointerMetadata = usize>,

Interprets the prefix of the given source as a &mut Self with DST length equal to count.

fn mut_from_suffix_with_elems( source: &mut [u8], count: usize, ) -> Result<(&mut [u8], &mut Self), CastError<&mut [u8], Self>>

where Self: IntoBytes + KnownLayout<PointerMetadata = usize>,

Interprets the suffix of the given source as a &mut Self with DST length equal to count.

fn read_from_bytes(source: &[u8]) -> Result<Self, SizeError<&[u8], Self>>

where Self: Sized,

Reads a copy of Self from the given source.

fn read_from_prefix( source: &[u8], ) -> Result<(Self, &[u8]), SizeError<&[u8], Self>>

where Self: Sized,

Reads a copy of Self from the prefix of the given source.

fn read_from_suffix( source: &[u8], ) -> Result<(&[u8], Self), SizeError<&[u8], Self>>

where Self: Sized,

Reads a copy of Self from the suffix of the given source.

impl<T: ?Sized + FromZeros> FromZeros for ReadOnly<T>

fn zero(&mut self)

Overwrites self with zeros.

fn new_zeroed() -> Self

where Self: Sized,

Creates an instance of Self from zeroed bytes.

impl<T: ?Sized + Immutable + Hash> Hash for ReadOnly<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: ?Sized + IntoBytes> IntoBytes for ReadOnly<T>

fn as_bytes(&self) -> &[u8]

where Self: Immutable,

Gets the bytes of this value.

fn as_mut_bytes(&mut self) -> &mut [u8]

where Self: FromBytes,

Gets the bytes of this value mutably.

fn write_to(&self, dst: &mut [u8]) -> Result<(), SizeError<&Self, &mut [u8]>>

where Self: Immutable,

Writes a copy of self to dst.

fn write_to_prefix( &self, dst: &mut [u8], ) -> Result<(), SizeError<&Self, &mut [u8]>>

where Self: Immutable,

Writes a copy of self to the prefix of dst.

fn write_to_suffix( &self, dst: &mut [u8], ) -> Result<(), SizeError<&Self, &mut [u8]>>

where Self: Immutable,

Writes a copy of self to the suffix of dst.

impl<T: ?Sized + KnownLayout> KnownLayout for ReadOnly<T>

type PointerMetadata = <T as KnownLayout>::PointerMetadata

The type of metadata stored in a pointer to Self.

fn size_for_metadata(meta: Self::PointerMetadata) -> Option<usize>

Computes the size of an object of type Self with the given pointer metadata.

impl<T: ?Sized + Immutable + LowerExp> LowerExp for ReadOnly<T>

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

Formats the value using the given formatter.

impl<T: ?Sized + Immutable + LowerHex> LowerHex for ReadOnly<T>

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

Formats the value using the given formatter.

impl<T: ?Sized + Immutable + Octal> Octal for ReadOnly<T>

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

Formats the value using the given formatter.

impl<T: ?Sized + Immutable + Ord> Ord for ReadOnly<T>

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.

impl<T: ?Sized + Immutable + PartialEq> PartialEq for ReadOnly<T>

fn eq(&self, other: &Self) -> 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<T: ?Sized + Immutable + PartialOrd> PartialOrd for ReadOnly<T>

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<T: ?Sized + TryFromBytes> TryFromBytes for ReadOnly<T>

fn try_ref_from_bytes(source: &[u8]) -> Result<&Self, TryCastError<&[u8], Self>>

where Self: KnownLayout + Immutable,

Attempts to interpret the given source as a &Self.

fn try_ref_from_prefix( source: &[u8], ) -> Result<(&Self, &[u8]), TryCastError<&[u8], Self>>

where Self: KnownLayout + Immutable,

Attempts to interpret the prefix of the given source as a &Self.

fn try_ref_from_suffix( source: &[u8], ) -> Result<(&[u8], &Self), TryCastError<&[u8], Self>>

where Self: KnownLayout + Immutable,

Attempts to interpret the suffix of the given source as a &Self.

fn try_mut_from_bytes( bytes: &mut [u8], ) -> Result<&mut Self, TryCastError<&mut [u8], Self>>

where Self: KnownLayout + IntoBytes,

Attempts to interpret the given source as a &mut Self without copying.

fn try_mut_from_prefix( source: &mut [u8], ) -> Result<(&mut Self, &mut [u8]), TryCastError<&mut [u8], Self>>

where Self: KnownLayout + IntoBytes,

Attempts to interpret the prefix of the given source as a &mut Self.

fn try_mut_from_suffix( source: &mut [u8], ) -> Result<(&mut [u8], &mut Self), TryCastError<&mut [u8], Self>>

where Self: KnownLayout + IntoBytes,

Attempts to interpret the suffix of the given source as a &mut Self.

fn try_ref_from_bytes_with_elems( source: &[u8], count: usize, ) -> Result<&Self, TryCastError<&[u8], Self>>

where Self: KnownLayout<PointerMetadata = usize> + Immutable,

Attempts to interpret the given source as a &Self with a DST length equal to count.

fn try_ref_from_prefix_with_elems( source: &[u8], count: usize, ) -> Result<(&Self, &[u8]), TryCastError<&[u8], Self>>

where Self: KnownLayout<PointerMetadata = usize> + Immutable,

Attempts to interpret the prefix of the given source as a &Self with a DST length equal to count.

fn try_ref_from_suffix_with_elems( source: &[u8], count: usize, ) -> Result<(&[u8], &Self), TryCastError<&[u8], Self>>

where Self: KnownLayout<PointerMetadata = usize> + Immutable,

Attempts to interpret the suffix of the given source as a &Self with a DST length equal to count.

fn try_mut_from_bytes_with_elems( source: &mut [u8], count: usize, ) -> Result<&mut Self, TryCastError<&mut [u8], Self>>

where Self: KnownLayout<PointerMetadata = usize> + IntoBytes,

Attempts to interpret the given source as a &mut Self with a DST length equal to count.

fn try_mut_from_prefix_with_elems( source: &mut [u8], count: usize, ) -> Result<(&mut Self, &mut [u8]), TryCastError<&mut [u8], Self>>

where Self: KnownLayout<PointerMetadata = usize> + IntoBytes,

Attempts to interpret the prefix of the given source as a &mut Self with a DST length equal to count.

fn try_mut_from_suffix_with_elems( source: &mut [u8], count: usize, ) -> Result<(&mut [u8], &mut Self), TryCastError<&mut [u8], Self>>

where Self: KnownLayout<PointerMetadata = usize> + IntoBytes,

Attempts to interpret the suffix of the given source as a &mut Self with a DST length equal to count.

fn try_read_from_bytes(source: &[u8]) -> Result<Self, TryReadError<&[u8], Self>>

where Self: Sized,

Attempts to read the given source as a Self.

fn try_read_from_prefix( source: &[u8], ) -> Result<(Self, &[u8]), TryReadError<&[u8], Self>>

where Self: Sized,

Attempts to read a Self from the prefix of the given source.

fn try_read_from_suffix( source: &[u8], ) -> Result<(&[u8], Self), TryReadError<&[u8], Self>>

where Self: Sized,

Attempts to read a Self from the suffix of the given source.

impl<T: ?Sized + Immutable + UpperExp> UpperExp for ReadOnly<T>

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

Formats the value using the given formatter.

impl<T: ?Sized + Immutable + UpperHex> UpperHex for ReadOnly<T>

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

Formats the value using the given formatter.

impl<T: Copy + ?Sized> Copy for ReadOnly<T>

impl<T: ?Sized + Immutable + Eq> Eq for ReadOnly<T>

impl<T: ?Sized> Immutable for ReadOnly<T>

impl<T: ?Sized + Unaligned> Unaligned for ReadOnly<T>