Struct Withheld 

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

Capabilities a context is to be built without, as a bitmask.

A set rather than one capability because a test may want a device short of two things at once, and a bitmask rather than a Vec because ContextConfig is Copy and a heap field would take that away from a published type. Hand-rolled over a u32 like SampleCounts above, for the same reason: this workspace has no bitflags dependency and does not need one.

The name is the type’s only job beyond storage. Nothing here can grant a capability, and a neutral name like CapabilitySet would invite someone to add that direction; Withheld makes it unsayable. Self::apply_to can clear a field and can do nothing else.

Implementations

impl Withheld

pub const fn none() -> Self

Withhold nothing, which is what every ordinary caller wants and what Default gives.

pub const fn of(capability: Capability) -> Self

Withhold exactly one.

pub const fn with(self, capability: Capability) -> Self

The same set with one more withheld.

pub const fn contains(self, capability: Capability) -> bool

Whether this set withholds capability.

pub const fn is_empty(self) -> bool

Whether this set withholds nothing.

pub fn apply_to(self, capabilities: &mut Capabilities)

Clear every withheld capability from capabilities.

Clearing only. A capability already false stays false, so applying this to a device that never had the thing is a no-op rather than a promotion – which is what makes the set safe to apply unconditionally at the end of detection.

A backend that can express a withholding more honestly should do that as well: dropping the extension the capability is backed by means the probe reports false on its own merits and the device is genuinely built without it. This is what covers the fields backed by a format query rather than an extension, and it is the belt to that braces.

Trait Implementations

impl Clone for Withheld

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 Withheld

impl Debug for Withheld

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

Formats the value using the given formatter.

impl Default for Withheld

fn default() -> Self

Returns the “default value” for a type.

impl Eq for Withheld

impl From<Capability> for Withheld

fn from(capability: Capability) -> Self

Converts to this type from the input type.

impl PartialEq for Withheld

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Withheld