Rust API

The workspace crates are not published on docs.rs yet. Build the generated API reference from the current source and its doc comments:

cargo doc --workspace --all-features --no-deps --open

The verification gate runs the same documentation build with RUSTDOCFLAGS="-D warnings", so a broken intra-doc link fails CI.

Orientation

The generated reference is exhaustive; this page is the map.

ifc-model — start here

Type	Role
Model	The entity graph. Insert, get, iterate, index by type
Entity	Type name plus positional attributes
Value	The encoding-independent value model
EntityId	Stable in-file identity (#42)
Header	File metadata and the declared schema token
Codec	The read/write contract every encoding implements
GlobalId	IFC's base-64 GUID encoding

Value is the type to understand first, because everything in the graph is one:

Variant	STEP form	Note
Null	$	Attribute not set
Derived	*	Derived in a supertype — distinct from Null
Bool	.T. / .F.
LogicalUnknown	.U.	The third boolean state
Integer, Real	42, 2.5
Text	'wall'	Already unescaped to UTF-8
Binary	"0123ABC"
Enum	.ELEMENT.	Unquoted constant
Ref	#42	Reference to another entity
List	(...)	List, set, array, or bag
Typed	IFCLENGTHMEASURE(2.5)	Typed wrapper

Null and Derived are not the same

Collapsing * to $ corrupts files on write. IFC uses * to mean "this attribute is redeclared as derived in a subtype", which is semantically distinct from "not set".

Reading attributes

Entity offers positional accessors with typed convenience:

entity.attribute(0)   // Option<&Value>
entity.text(2)        // Option<&str>
entity.number(3)      // Option<f64>
entity.reference(4)   // Option<EntityId>
entity.references()   // Vec<EntityId> — all outgoing refs
entity.is_type("IFCWALL")

Index constants belong in named *_slot modules, following the pattern in ifc-geometry — bare numeric literals at call sites are how attribute bugs get written.

Querying the model

model.ids_of_type("IFCWALL")     // &[EntityId] — indexed, not a scan
model.of_type("IFCWALL")         // Iterator<(EntityId, &Entity)>
model.type_histogram()           // Vec<(&str, usize)> — great for triage
model.dangling_references()      // Vec<(EntityId, EntityId)>

Build the optional reverse index only when an operation needs incoming references:

use ifc_model::{EntityId, Model, ReverseIndex};

fn print_referrers(model: &Model, target: EntityId) {
    let reverse = ReverseIndex::build(model);
    for hit in reverse.referrers(target) {
        println!("referenced by {:?} in attribute slot {}", hit.from, hit.slot);
    }
}

The index is a deterministic snapshot and records the top-level attribute slot for every referrer. Rebuild it after mutating the model.

Reverse indexes are deliberately on demand

Codecs that only read and rewrite a model do not pay the memory or load-time cost. Traversal-heavy applications build the index once and reuse it.

Codecs

use ifc::{Codec, StepCodec};

let model = StepCodec.read_bytes(bytes)?;
let out   = StepCodec.write_bytes(&model)?;

XmlCodec behaves identically behind the ifcxml feature. Conversion is a read with one and a write with the other.

Python and CLI

Neither exists for this repository today. Sibling repositories (openbim-idm) ship PyO3 bindings and a CLI; the same approach applies here when there is demand.