Enum QuotedTripleSurface 

pub enum QuotedTripleSurface {
    RdfStar,
    Rdf12,
}

Which surface a << … >> in Turtle/TriG input is read as — the input half of rete export --quoted-triple-syntax, same vocabulary, same two values.

The flag exists because the two standards give one piece of syntax two meanings, and no amount of looking at the bytes can tell them apart:

written	under RdfStar	under Rdf12
<< s p o >>	a quoted triple, one term	a reifier: _:r rdf:reifies <<( s p o )>>, plus a blank node standing where it was
<<( s p o )>>	a syntax error	a triple term, object position only
{| … |}	a syntax error	an annotation on the statement before it

One file, two readings, two different graphs — see the round-trip matrix in crates/rete-cli/tests/quoted_triple_surfaces.rs, which asserts both.

<<( s p o )>> is unambiguous: it is RDF 1.2’s and nothing else’s. That asymmetry is why RdfStar is the default. Reading an RDF-star file as RDF 1.2 silently yields a different graph; reading an RDF 1.2 file as RDF-star is a hard parse error that names the flag. Only one of the two mistakes is survivable, so the default is the one that makes the other mistake loud.

N-Triples and N-Quads ignore this entirely. Their reader is rete’s own (take_term), it has accepted both << s p o >> and <<( s p o )>> since #262, and RDF 1.2 N-Triples has no reifier syntax for << … >> to be — so there is no ambiguity to resolve and nothing to choose. The same goes for RDF/XML.

Whichever surface reads the file, what gets stored is the same canonical token <<s p o>>. rete’s term model is a superset of both: a triple term is a term, and RDF 1.2 reification is ordinary RDF — a blank node, a predicate and a term — which rete already stored before this flag existed.

Variants

RdfStar

<< s p o >> is a quoted triple (RDF-star), in subject or object position — rete’s own storage token. The default, and byte-for-byte the behaviour every rete release before this flag had.

Rdf12

<<( s p o )>> is a triple term and << s p o >> is a reifier (RDF 1.2), with {| … |} annotations read too.

Implementations

impl QuotedTripleSurface

pub fn parse(s: &str) -> Option<QuotedTripleSurface>

Parse the --quoted-triple-syntax value, None for anything else. Shared by rete build, rete validate and rete export so the flag cannot come to mean two things in two directions.

pub const fn as_str(self) -> &'static str

The flag spelling of this surface — the inverse of Self::parse.

Trait Implementations

impl Clone for QuotedTripleSurface

fn clone(&self) -> QuotedTripleSurface

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for QuotedTripleSurface

impl Debug for QuotedTripleSurface

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

Formats the value using the given formatter.

impl Default for QuotedTripleSurface

fn default() -> QuotedTripleSurface

Returns the “default value” for a type.

impl Eq for QuotedTripleSurface

impl Hash for QuotedTripleSurface

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for QuotedTripleSurface

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for QuotedTripleSurface