Crate ifc_schema 

ifc-schema — the IFC schema as data, not as 2,500 generated structs.

The decision

IfcOpenShell generates a class per IFC entity per schema version. That is a very large amount of code, and it must be regenerated for every schema release. This crate instead reads the normative EXPRESS files into tables and answers questions against them.

The evidence that this is the right call: IFC4x3 renames IfcBuildingElement to IfcBuiltElement and drops IfcProxy and the whole *StandardCase family. Generated types would fork the entire API surface; a table just holds different rows.

What this crate is for

Module	Role
version	Which schema a file declares
express	Parser for the official .exp files
entity	Entity descriptors: name, supertype, slots
attribute	Attribute descriptors and declared types
types	Defined types, enumerations, selects
registry	The assembled, queryable schema
inheritance	Supertype-chain walking

Relationship to the model

ifc-model does not depend on this crate. The model stores whatever a file contains, valid or not. The schema is what you consult to interpret what was stored, and it is optional: a file whose schema is unknown still parses, and its entities still round-trip.

use ifc_schema::Schema;

let schema = Schema::from_express(
    "SCHEMA IFC4;\n\
     ENTITY IfcRoot; GlobalId : IfcGloballyUniqueId; END_ENTITY;\n\
     ENTITY IfcWall SUBTYPE OF (IfcRoot); Name : IfcLabel; END_ENTITY;\n\
     END_SCHEMA;",
);

assert!(schema.is_a("IFCWALL", "IfcRoot"));
assert_eq!(schema.attribute_names("IfcWall"), ["GlobalId", "Name"]);

Re-exports

pub use export::write_direct_structural_catalog;

pub use export::write_structural_catalog;

pub use export::StructuralCatalogSummary;

pub use registry::Schema;

pub use version::SchemaVersion;

Modules

attribute

One positional attribute slot on an IFC entity.

completeness

Prove a hand-written entity inventory is complete against the normative EXPRESS schema.

entity

Entity descriptors used by the IFC schema registry.

export

Deterministic, schema-derived structural catalog export.

express

Generic EXPRESS parsing delegated to the canonical STEP workspace.

registry

The assembled, queryable IFC schema.

types

Defined types, enumerations, and selects used by IFC schemas.

version

Which IFC schema version a file declares.

Structs

Attribute

One explicit positional attribute.

EntityDef

One structural entity declaration.

TypeDef

One TYPE declaration.

Enums

TypeKind

Structural shape of a TYPE declaration.

Functions

artifact_decode_schema

Decodes a compiled schema artifact produced by encode_schema (the generation feature).

for_version

The bundled schema for version, or None when none is bundled.

ifc4

The bundled IFC4 ADD2 TC1 schema (776 entities, 397 types).

ifc2x3

The bundled IFC2x3 TC1 schema (653 entities, 327 types).

ifc4x3

The bundled IFC4X3 ADD2 schema (876 entities, 436 types).