Enum style::values::generics::Optional

#[repr(C, u8)]
pub enum Optional<T> {
    None,
    Some(T),
}

An optional value, much like Option<T>, but with a defined struct layout to be able to use it from C++ as well.

Note that this is relatively inefficient, struct-layout-wise, as you have one byte for the tag, but padding to the alignment of T. If you have multiple optional values and care about struct compactness, you might be better off “coalescing” the combinations into a parent enum. But that shouldn’t matter for most use cases.

Variants

None

Some(T)

Implementations

impl<T> Optional<T>

pub fn is_some(&self) -> bool

Returns whether this value is present.

pub fn is_none(&self) -> bool

Returns whether this value is not present.

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

Turns this Optional<> into a regular rust Option<>.

pub fn as_ref(&self) -> Option<&T>

Return a reference to the containing value, if any, as a plain rust Option<>.

Trait Implementations

impl<T> Animate for Optional<T>

where T: Animate,

fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()>

Animate a value towards another one, given an animation procedure.

impl<T: Clone> Clone for Optional<T>

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> ComputeSquaredDistance for Optional<T>

where T: ComputeSquaredDistance,

fn compute_squared_distance(&self, other: &Self) -> Result<SquaredDistance, ()>

Computes the squared distance between two animatable values.

impl<T: Debug> Debug for Optional<T>

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

Formats the value using the given formatter.

impl<'de, T> Deserialize<'de> for Optional<T>

where T: Deserialize<'de>,

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<T> From<Option<T>> for Optional<T>

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

Converts to this type from the input type.

impl<T> MallocSizeOf for Optional<T>

where T: MallocSizeOf,

fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize

Measure the heap usage of all descendant heap-allocated structures, but not the space taken up by the value itself.

impl<T> Parse for Optional<T>

where T: Parse,

fn parse<'i, 't>( context: &ParserContext<'_>, input: &mut Parser<'i, 't>, ) -> Result<Self, ParseError<'i>>

Parse a value of this type.

impl<T: PartialEq> PartialEq for Optional<T>

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

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> Serialize for Optional<T>

where T: Serialize,

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl<T> SpecifiedValueInfo for Optional<T>

where T: SpecifiedValueInfo,

const SUPPORTED_TYPES: u8 = _

Supported CssTypes by the given value type.

fn collect_completion_keywords(_f: &mut dyn FnMut(&[&'static str]))

Collect value starting words for the given specified value type. This includes keyword and function names which can appear at the beginning of a value of this type.

impl<T> ToAnimatedValue for Optional<T>

where T: ToAnimatedValue,

type AnimatedValue = Optional<<T as ToAnimatedValue>::AnimatedValue>

The type of the animated value.

fn from_animated_value(from: Self::AnimatedValue) -> Self

Converts back an animated value into a computed value.

fn to_animated_value(self, context: &Context<'_>) -> Self::AnimatedValue

Converts this value to an animated value.

impl<T> ToAnimatedZero for Optional<T>

where T: ToAnimatedZero,

fn to_animated_zero(&self) -> Result<Self, ()>

Returns a value that, when added with an underlying value, will produce the underlying value. This is used for SMIL animation’s “by-animation” where SMIL first interpolates from the zero value to the ‘by’ value, and then adds the result to the underlying value.

impl<T> ToComputedValue for Optional<T>

where T: ToComputedValue,

type ComputedValue = Optional<<T as ToComputedValue>::ComputedValue>

The computed value type we’re going to be converted to.

fn from_computed_value(from: &Self::ComputedValue) -> Self

Convert a computed value to specified value form.

fn to_computed_value(&self, context: &Context<'_>) -> Self::ComputedValue

Convert a specified value to a computed value, using itself and the data inside the Context.

impl<T> ToCss for Optional<T>

where T: ToCss,

fn to_css<W>(&self, dest: &mut CssWriter<'_, W>) -> Result

where W: Write,

Serialize self in CSS syntax, writing to dest.

fn to_css_string(&self) -> String

Serialize self in CSS syntax and return a string.

impl<T> ToResolvedValue for Optional<T>

where T: ToResolvedValue,

type ResolvedValue = Optional<<T as ToResolvedValue>::ResolvedValue>

The resolved value type we’re going to be converted to.

fn from_resolved_value(from: Self::ResolvedValue) -> Self

Convert a resolved value to resolved value form.

fn to_resolved_value(self, context: &Context<'_>) -> Self::ResolvedValue

Convert a resolved value to a resolved value.

impl<T> ToShmem for Optional<T>

where T: ToShmem,

fn to_shmem(&self, builder: &mut SharedMemoryBuilder) -> Result<Self>

Clones this value into a form suitable for writing into a SharedMemoryBuilder.

impl<T: Copy> Copy for Optional<T>

impl<T> StructuralPartialEq for Optional<T>