Struct Signals 

pub struct Signals {

    pub label_predicate: Option<String>,
    pub default_lang: Option<String>,
    pub base_iri: Option<String>,
    pub time_predicates: Vec<String>,
    pub numeric_predicates: Vec<String>,
    pub link_predicates: Vec<String>,
    pub annotation_predicates: Vec<String>,
    pub quoting_predicates: Vec<String>,
    pub annotated_statement: Option<(String, String)>,
    pub geo_wkt: bool,
    pub geo_latlong: bool,
    pub temporal_extent: Option<(String, String)>,
    pub spatial_bbox: Option<[f64; 4]>,
    pub text_index: Option<TextIndexSignal>,
    pub permutations: Option<PermutationsSignal>,
    pub quoted_triples: Option<QuotedTriplesSignal>,
}

Detected affordances — the index-free hints a newcomer (or the query-library generator) needs to know what the data supports and how to address it. Every field is optional/empty when the corresponding signal is absent, so geo/time query families are emitted only when the data actually has geometry/time.

Fields

label_predicate: Option<String>

Most frequent labelling predicate (rdfs:label/skos:prefLabel/…).

default_lang: Option<String>

Dominant non-empty language tag over literal objects.

base_iri: Option<String>

Dominant subject namespace — the dataset’s own base IRI.

time_predicates: Vec<String>

Temporal predicates, ranked by frequency (most-used first).

numeric_predicates: Vec<String>

Predicates whose objects are numeric (xsd integer/decimal/double/float), ranked by frequency — candidates for MIN/AVG/MAX value-range queries.

link_predicates: Vec<String>

Cross-dataset link predicates present (owl:sameAs/skos:exactMatch/…).

annotation_predicates: Vec<String>

Predicates that make a statement about a statement — the predicate of a statement whose subject is a quoted triple (<< s p o >> :recordedBy :who) — ranked by frequency.

Derived from the triples, and therefore stored, unlike the Signals::quoted_triples presence bit below, which is read off the header at display time. The two answer different questions and neither substitutes for the other: presence says will I meet triple terms in this file, which every already-published file can answer for free; this says which vocabulary annotates statements here, which only a pass over the statements knows and which is what a starter query has to be written in. Empty on the overwhelming majority of datasets, and the whole qt-* query family is gated on it.

quoting_predicates: Vec<String>

Predicates whose object is a quoted triple (:claim :states << s p o >>) — the other place a triple term can stand — ranked by frequency. A dataset can have one shape and not the other, and a query written for the wrong one returns nothing, so they are counted apart.

annotated_statement: Option<(String, String)>

The commonest annotated statement shape: (the predicate inside the quoted triple, the predicate that annotates it), for a statement this graph was seen both to assert (s p o) and to annotate (<< s p o >> :about ?v).

The pair is the witness — the same role class_links plays for LABELED_CLASS. annotation_predicates[0] and the commonest quoted predicate are two independent maxima and need not describe the same statement, so a body that pins both is only safe when the derivation saw them together. Assertedness is part of the witness because RDF-star does not entail it: << s p o >> :about ?v says nothing about whether s p o is in the graph, and a coverage query over a relation the graph never asserts would report 0 / 0.

Matched over a sample of the star layer (ANNOTATION_WITNESS_SAMPLE), so a miss can drop the query that needs it but can never ship a broken one.

geo_wkt: bool

Any geo:asWKT / geo:wktLiteral geometry present.

geo_latlong: bool

Both wgs84:lat and wgs84:long present.

temporal_extent: Option<(String, String)>

MIN/MAX lexical extent over the dominant time predicate (same datatype).

spatial_bbox: Option<[f64; 4]>

[minLon, minLat, maxLon, maxLat] over wgs84 lat/long objects.

text_index: Option<TextIndexSignal>

Whether the file carries a full-text (TEXT_INDEX) section.

Unlike every other signal this one is not derived from the triples and not stored in the card: it is measured from the file’s section directory by whoever reads the card, and DatasetCard::to_json_bytes strips it before the bytes are written. See TextIndexSignal for why.

None therefore means unknown — a card read out of a saved JSON document, with no file to measure — and never “no index”.

permutations: Option<PermutationsSignal>

Which index permutations the file stores. Like Signals::text_index, measured from the file at read time and stripped before the card’s bytes are written; None means unknown (a card document with no file behind it), never “the default”.

quoted_triples: Option<QuotedTriplesSignal>

Whether the file holds any quoted triple, and which export surfaces a consumer can ask for. Like the two signals above, measured from the file at read time and stripped before the card’s bytes are written; None means unknown (a card document with no file behind it), never “no quoted triples”. See QuotedTriplesSignal.

Implementations

impl Signals

pub fn is_empty(&self) -> bool

True when no affordance was detected (lets the whole block be omitted).

Trait Implementations

impl Clone for Signals

fn clone(&self) -> Signals

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Signals

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

Formats the value using the given formatter.

impl Default for Signals

fn default() -> Signals

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Signals

fn deserialize<__D>( __deserializer: __D, ) -> Result<Signals, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Signals

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for Signals

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Signals