Enum DynamicSchema 

#[non_exhaustive]
pub enum DynamicSchema {
    Null,
    Bool,
    U64,
    I64,
    F64,
    String,
    Bytes,
    Seq(Box<DynamicSchema>),
    Map(Vec<(String, DynamicSchema)>),
    Enum(Vec<EnumVariantSchema>),
}

Describes the byte-stream shape of a postcard-encoded payload at one version. See module docs for the variant ↔ wire-format mapping.

DynamicSchema is 'static-friendly: literal schemas can live in const-fn-adjacent contexts (e.g. a LazyLock registry) without borrowing.

Boxing the inner schema in Seq keeps the enum’s size_of reasonable (the alternative — Vec<DynamicSchema> of length 1 — is overkill for the single-element case and reads worse).

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Null

Unit / zero-byte field. Postcard emits no bytes for ().

Bool

Boolean — single byte 0 / 1.

U64

Unsigned 64-bit integer (varint).

I64

Signed 64-bit integer (zigzag varint).

F64

64-bit IEEE-754 float (8 LE bytes).

String

UTF-8 string (varint length + bytes).

Bytes

Raw byte sequence (varint length + bytes).

Seq(Box<DynamicSchema>)

Variable-length sequence of elem-shaped values.

Map(Vec<(String, DynamicSchema)>)

Postcard-encoded struct described as an ordered list of (field_name, field_schema) pairs. Order MUST match the Rust declaration order of the struct that wrote the bytes — postcard reads fields positionally, so a transposed schema will mis-decode the payload as silently as any out-of-order tuple destructure.

Enum(Vec<EnumVariantSchema>)

Postcard-encoded enum: a varint u32 discriminant followed by the matched variant’s payload bytes. variants MUST be sorted strictly ascending by EnumVariantSchema::discriminant; the walker binary-searches the list and a missing discriminant surfaces as Error::SchemaTypeMismatch.

Unit variants set payload = DynamicSchema::Null. Newtype variants set payload to the inner type’s schema. Tuple and struct variants set payload = DynamicSchema::Map(...) with the variant’s fields in declaration order; for tuple variants the field names are the synthetic strings "0", "1", … (postcard writes tuple variants positionally — the same wire shape as a Rust struct’s bytes).

Implementations

impl DynamicSchema

pub fn seq(elem: DynamicSchema) -> Self

Convenience constructor for a Seq schema with elem as the element shape.

pub fn map<I, S>(fields: I) -> Self

where I: IntoIterator<Item = (S, DynamicSchema)>, S: Into<String>,

Convenience constructor for a Map schema. fields is the (name, schema) list in declaration order.

pub fn enumeration<I>(variants: I) -> Self

where I: IntoIterator<Item = EnumVariantSchema>,

Convenience constructor for an Enum schema. variants is the list of variants; the caller is responsible for keeping them sorted ascending by discriminant — the walker debug-asserts the invariant on the first decode of each schema. Use EnumVariantSchema::new for each entry.

Trait Implementations

impl Clone for DynamicSchema

fn clone(&self) -> DynamicSchema

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for DynamicSchema

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

Formats the value using the given formatter.

impl PartialEq for DynamicSchema

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

Tests for self and other values to be equal, and is used by ==.

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

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

impl Eq for DynamicSchema

impl StructuralPartialEq for DynamicSchema