Function compact_iri 

pub fn compact_iri<N>(
    vocabulary: &N,
    active_context: &Context<N::Iri, N::BlankId>,
    var: &Term<N::Iri, N::BlankId>,
    vocab: bool,
    reverse: bool,
    options: Options,
) -> Result<Option<Arc<str>>, IriConfusedWithPrefix>
where
    N: Vocabulary,
    N::Iri: Clone + Hash + Eq,
    N::BlankId: Clone + Hash + Eq,

Compacts var into a term, compact IRI or relative IRI reference, without considering any value.

Runs the IRI compaction algorithm with no value, which is how keys, @type values, @id values and the values of @vocab-typed terms are compacted. vocab is true where @vocab applies (keys, @type values, @vocab-typed values) and false for @id values, which may then become IRI references relative to the active context’s base IRI. reverse restricts selection to terms declared with @reverse. Only options.processing_mode is read.

active_context is a processed context, typically the one Process produced for the document’s @context. Returns None when var is Term::Null.

Memoized per active context: a repeated (var, vocab, reverse, processing mode) lookup returns the cached result instead of rerunning the algorithm. The processing mode belongs in the key because term selection depends on it — an @index container term, for instance, is only eligible for an index-less value under JSON-LD 1.1.

Errors

Returns IriConfusedWithPrefix when var can only be written out in full and would then be read back as a compact IRI.