Crate moddef_core 

ModDef runtime for Rust (spec v0.4).

Layering (spec §32):

• codec core (always available, no_std, no alloc): desc::PointDesc descriptors + codec decode/encode + Transport trait + errors.
• alloc: prost schema types (schema), owned value::DecodedValue, the untyped device::Device facade, measurand queries, binary .moddef parsing.
• std (default): protojson YAML/JSON parsing (document), fs helpers, std::error::Error impls.

Embedded targets use generated static descriptor tables (see moddef-codegen) and never parse documents at runtime; servers/gateways parse .moddef files at runtime and use the dynamic facade. Both paths share this codec.

Re-exports

pub use desc::Access;

pub use desc::AddressSpace;

pub use desc::DateTimeEncoding;

pub use desc::FieldDesc;

pub use desc::NaDesc;

pub use desc::PointDesc;

pub use desc::Rational;

pub use desc::ScaleMode;

pub use desc::ScaleRefDesc;

pub use desc::SelectorCaseDesc;

pub use desc::SelectorDesc;

pub use desc::StorageType;

pub use desc::StringPadding;

pub use desc::StringTermination;

pub use desc::ValueKind;

pub use desc::WriteDesc;

pub use error::ConstraintKind;

pub use error::DecodeError;

pub use error::EncodeError;

pub use error::Error;

pub use transport::Transport;

pub use value::Reading;

pub use value::Value;

pub use device::Device;

pub use measurand::MeasurandQuery;

pub use value::DecodedValue;

pub use document::detect_format;

pub use document::load;

pub use document::parse_document;

pub use document::serialize_document;

pub use document::DocumentFormat;

pub use document::ParseError;

Modules

codec

Codec core (spec §8–§15): pure functions over crate::desc::PointDesc, no_std and allocation-free. Kept in behavioral lockstep with go/codec and moddef-ts’s codec (shared vector suite in the conformance tests).

convert

prost schema::Point → PointDesc conversion (alloc). The codec core is heap-free, so descriptors borrow: strings and allowed_values borrow the prost message directly; flag/field/case/na tables need owned side-buffers (DescBufs) because their layout differs from the wire form. Two-step use:

desc

Lightweight, heap-free point descriptors — the codec core’s view of a point (spec §7–§15). Generated code emits static tables of these; the alloc feature converts prost Points into them (see convert).

device

Runtime device facade (spec §32.4): binds a Transport to one parsed device profile for point- and measurand-based reads/writes, with no codegen. Port of moddef-ts Device / go/client/client.go.

document

Document layer (spec §4): parse and serialize the three equivalent encodings — .moddef.yaml, .moddef.json, .moddef (proto binary). YAML and JSON follow proto3 JSON (protojson) semantics via the pbjson-generated serde impls; unknown fields and invalid enum values are rejected, matching the Go implementation and the fixtures under moddef/fixtures/invalid. YAML goes through a YAML→JSON value conversion (numeric keys stringified) — the same round-trip the Go loader uses.

error

Typed errors (spec §26.3/§26.4, §32). Structured variants rather than strings; Display always, std::error::Error under std.

measurand

Measurand queries (spec §22, §26.1). A query selects points by their semantic tuple; unspecified qualifiers are wildcards, base_quantity is required. Mirrors go/client measurandMatches and moddef-ts measurand.ts.

resolve

Import resolution (spec §19). Import URIs follow the package form moddef:<namespace>:<name>:<version> (e.g. moddef:stdlib:measurands:1.0.0), resolved against package roots as <root>/<name>/<version>/<name>.moddef.{yaml,json,binary} — the layout of moddef/stdlib and the Go resolver’s MODDEF_PACKAGE_ROOTS.

rt

Runtime support for generated clients (spec §31). no_std, allocation free: generated code (moddef-codegen) drives the codec core over its static POINTS table and calls into these helpers so the emitted method bodies stay small. Not a stable public API surface — pinned by the generator, may change with it.

schema

Generated protobuf schema types (spec §27), compiled by build.rs from the vendored proto/moddef/v1/*.proto via protox + prost-build. Under std, pbjson-generated serde impls give protojson-semantics JSON (and, via document, YAML) for every message.

transport

Transport abstraction (spec §32.2). Implementations wrap a Modbus client (see moddef-tokio-modbus) or an in-memory register map for tests.

value

Decoded value model (spec §8, §13). The no_std core surfaces Value (no heap: strings decode into caller buffers, flags stay a raw mask with name iteration via the descriptor); the alloc feature adds the owned DecodedValue mirroring the Go/TS union.