Enum Computed 

pub enum Computed<T> {
    Literal(T),
    Expr(String),
}

A scenario value that is either a plain literal or, prefixed with =, an expression to evaluate.

#[serde(untagged)]: deserialization tries Literal(T) first, falling back to Expr(String) only when the JSON value doesn’t fit T. That ordering is why this works cleanly for the numbers and strictly-typed colours this issue targets — a JSON string can never satisfy a numeric T, so "= $W/2" always falls through to Expr — but is a deliberate non-goal for Computed<String>: there, every JSON string ("= ..." included) already satisfies Literal(String) first and Expr is never reached. Schema fields that want expression support are expected to use a strictly-typed T (a number, or a colour type with its own validating Deserialize), not a bare String.

This type carries no evaluation logic of its own — resolving an Expr(String) variant means calling Expr::parse on its contents and then Expr::eval (or folding it statically, see the crate::expr module doc) — deliberately, so this crate does not have to hand back an opinion on when that happens; that is a decision for whatever owns the field (the static-folding pass, or the per-frame engine context).

Variants

Literal(T)

Expr(String)

Trait Implementations

impl<T: Clone> Clone for Computed<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: Debug> Debug for Computed<T>

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

Formats the value using the given formatter.

impl<'de, T> Deserialize<'de> for Computed<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: JsonSchema> JsonSchema for Computed<T>

fn schema_name() -> String

The name of the generated JSON Schema.

fn schema_id() -> Cow<'static, str>

Returns a string that uniquely identifies the schema produced by this type.

fn json_schema(generator: &mut SchemaGenerator) -> Schema

Generates a JSON Schema for this type.

fn is_referenceable() -> bool

Whether JSON Schemas generated for this type should be re-used where possible using the $ref keyword.

impl<T: PartialEq> PartialEq for Computed<T>

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

Equality operator ==.

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

Inequality operator !=.

impl<T> Serialize for Computed<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: PartialEq> StructuralPartialEq for Computed<T>