Struct iffi::MaybeInvalid

#[repr(transparent)]
pub struct MaybeInvalid<T>(_);

Represents a value of the type T that may not be well-defined.

This type guarantees that MaybeInvalid<T> and T have the same, size, alignment and ABI.

Despite that this type uses MaybeUninit internally, the value must always be initialized.

MaybeInvalid<T> is always well-defined if T: Nicheless.

Implementations

impl<T> MaybeInvalid<T>

pub fn new(valid: T) -> Self

Creates a valid value.

pub fn zeroed() -> Self

Creates a potentially invalid value.

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

Gets a shared reference to the value in this container as a byte slice.

pub unsafe fn assume_valid(self) -> T

Extracts the value from this container.

Safety

It is up to the caller to ensure the value in this container is valid. For example, the following code causes UB:

let invalid = MaybeInvalid::<NonZeroU8>::zeroed();
// UB because NonZeroU8 cannot be zero.
let zero = unsafe { invalid.assume_valid() };

pub unsafe fn assume_valid_ref(&self) -> &T

Gets a shared reference to the value in this container.

Safety

See assume_valid.

pub unsafe fn assume_valid_mut(&mut self) -> &mut T

Gets a mutable (unique) reference to the value in this container.

Safety

See assume_valid.

pub fn as_ptr(&self) -> *const T

Gets a pointer to the contained value

impl<T: Nicheless> MaybeInvalid<T>

pub fn into_inner(self) -> T

Extracts the value in this container.

Only implemented for Nicheless types.

If the type is not nicheless, use assume_valid.

Example

let valid = MaybeInvalid::new(5u8);
assert_eq!(valid.into_inner(), 5)

pub fn get(&self) -> &T

Gets a shared reference to the value in this container.

Only implemented for Nicheless types.

If the type is not nicheless, use assume_valid_ref.

pub fn get_mut(&mut self) -> &mut T

Gets a mutable (unique) reference to the value in this container.

Only implemented for Nicheless types.

If the type is not nicheless, use assume_valid_mut.

Trait Implementations

impl<T> Debug for MaybeInvalid<T>

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

Formats the value using the given formatter.

impl Iffi<MaybeInvalid<NonZeroI128>> for NonZeroI128

fn can_transmute(superset: &MaybeInvalid<NonZeroI128>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl Iffi<MaybeInvalid<NonZeroI16>> for NonZeroI16

fn can_transmute(superset: &MaybeInvalid<NonZeroI16>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl Iffi<MaybeInvalid<NonZeroI32>> for NonZeroI32

fn can_transmute(superset: &MaybeInvalid<NonZeroI32>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl Iffi<MaybeInvalid<NonZeroI64>> for NonZeroI64

fn can_transmute(superset: &MaybeInvalid<NonZeroI64>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl Iffi<MaybeInvalid<NonZeroI8>> for NonZeroI8

fn can_transmute(superset: &MaybeInvalid<NonZeroI8>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl Iffi<MaybeInvalid<NonZeroIsize>> for NonZeroIsize

fn can_transmute(superset: &MaybeInvalid<NonZeroIsize>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl Iffi<MaybeInvalid<NonZeroU128>> for NonZeroU128

fn can_transmute(superset: &MaybeInvalid<NonZeroU128>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl Iffi<MaybeInvalid<NonZeroU16>> for NonZeroU16

fn can_transmute(superset: &MaybeInvalid<NonZeroU16>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl Iffi<MaybeInvalid<NonZeroU32>> for NonZeroU32

fn can_transmute(superset: &MaybeInvalid<NonZeroU32>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl Iffi<MaybeInvalid<NonZeroU64>> for NonZeroU64

fn can_transmute(superset: &MaybeInvalid<NonZeroU64>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl Iffi<MaybeInvalid<NonZeroU8>> for NonZeroU8

fn can_transmute(superset: &MaybeInvalid<NonZeroU8>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl Iffi<MaybeInvalid<NonZeroUsize>> for NonZeroUsize

fn can_transmute(superset: &MaybeInvalid<NonZeroUsize>) -> Result<(), Error>

Checks for the safety of transmuting U into Self. Returns Ok(()) if the value is safe, and Err(iffi::Error) otherwise.

impl<T> Nicheless for MaybeInvalid<T>