Struct Expr 

pub struct Expr<T: FromValue = OwnedDataValue> { /* private fields */ }

Compiled JSONLogic resolving to a T, made by ExprEngine::compile.

An expression that reads nothing folds at compile into a constant, and every evaluation lends that constant from the expression, never cloning it.

Implementations

impl<T: FromValue> Expr<T>

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

The folded constant, if the expression reads nothing.

pub fn raw(&self) -> &Value

The authored JSON.

Trait Implementations

impl<T: FromValue> ConfigField for Expr<T>

const NULL_IS_VALUE: bool = true

null is a constant expression.

fn compile(raw: &Value, cx: &mut CompileCx<'_>) -> Option<Self>

Compiles raw; None after recording at least one issue.

fn visit(&self, v: &mut Visit<'_>)

Reports the field’s expressions.

fn resolve(&self, r: &mut dyn Resolver) -> Result<Option<OwnedDataValue>>

The field’s value for this call, resolved through r, or None when it has none (an Option the input left unset, with no default). The value sits where Self::visit reports the field’s expressions: a list’s elements at their indices, a map’s values at their keys, and an element left unset is null, keeping its place.

fn kind() -> FieldKind

What the field is.

const IS_OUTPUT: bool = false

Whether the field is an output: a destination its call writes to. false unless the type is Output or an Option of one. The derive reads a field typed Output or marked #[output] as an output and asserts that this is true, so a type that merely shares the name is refused at compile time.

fn absent() -> Option<Self>

The value when the key is absent and no default is declared. None makes the field required.

impl<T: FromValue> Debug for Expr<T>

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

Formats the value using the given formatter.

impl<T: FromValue> ResolveExpr for Expr<T>

fn raw(&self) -> &Value

The authored JSON.