Struct Metadata 

pub struct Metadata {
    pub cardinality: CardinalityClass,
    pub index_addressable: Option<IndexFn>,
    pub natural_order: NaturalOrder,
    pub materialization: Materialization,
}

The metadata bundle carried by every well-formed AST node.

Computed bottom-up; never mutated after propagation. Each field is a closed enum or a closed-form descriptor — no callbacks, no fail-able analyses.

Fields

cardinality: CardinalityClass

Cardinality class (comprehension_forms.md §6.1).

index_addressable: Option<IndexFn>

Closed-form bijection from 0..|c| to the node’s dispensed tuples. None when the node has no addressable index space (raw filter output, dependent cartesian, a truncated Lex order over either). An order other than an untruncated Lex is a one-axis Lattice of its selection: position i is the input’s tuple at the i-th selected position.

natural_order: NaturalOrder

How this node enumerates by default.

materialization: Materialization

Streaming-vs-barrier classification (comprehension_forms.md §6.2).

Trait Implementations

impl Clone for Metadata

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Metadata

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Metadata

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Metadata

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for Metadata

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Metadata