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use std::fmt;
/// RDF serialization formats.
///
/// This enumeration is non exhaustive. New formats like JSON-LD might be added in the future.
#[derive(Eq, PartialEq, Debug, Clone, Copy, Hash)]
#[non_exhaustive]
pub enum RdfFormat {
/// [N3](https://w3c.github.io/N3/spec/)
N3,
/// [N-Quads](https://www.w3.org/TR/n-quads/)
NQuads,
/// [N-Triples](https://www.w3.org/TR/n-triples/)
NTriples,
/// [RDF/XML](https://www.w3.org/TR/rdf-syntax-grammar/)
RdfXml,
/// [TriG](https://www.w3.org/TR/trig/)
TriG,
/// [Turtle](https://www.w3.org/TR/turtle/)
Turtle,
}
impl RdfFormat {
/// The format canonical IRI according to the [Unique URIs for file formats registry](https://www.w3.org/ns/formats/).
///
/// ```
/// use oxrdfio::RdfFormat;
///
/// assert_eq!(
/// RdfFormat::NTriples.iri(),
/// "http://www.w3.org/ns/formats/N-Triples"
/// )
/// ```
#[inline]
pub const fn iri(self) -> &'static str {
match self {
Self::N3 => "http://www.w3.org/ns/formats/N3",
Self::NQuads => "http://www.w3.org/ns/formats/N-Quads",
Self::NTriples => "http://www.w3.org/ns/formats/N-Triples",
Self::RdfXml => "http://www.w3.org/ns/formats/RDF_XML",
Self::TriG => "http://www.w3.org/ns/formats/TriG",
Self::Turtle => "http://www.w3.org/ns/formats/Turtle",
}
}
/// The format [IANA media type](https://tools.ietf.org/html/rfc2046).
///
/// ```
/// use oxrdfio::RdfFormat;
///
/// assert_eq!(RdfFormat::NTriples.media_type(), "application/n-triples")
/// ```
#[inline]
pub const fn media_type(self) -> &'static str {
match self {
Self::N3 => "text/n3",
Self::NQuads => "application/n-quads",
Self::NTriples => "application/n-triples",
Self::RdfXml => "application/rdf+xml",
Self::TriG => "application/trig",
Self::Turtle => "text/turtle",
}
}
/// The format [IANA-registered](https://tools.ietf.org/html/rfc2046) file extension.
///
/// ```
/// use oxrdfio::RdfFormat;
///
/// assert_eq!(RdfFormat::NTriples.file_extension(), "nt")
/// ```
#[inline]
pub const fn file_extension(self) -> &'static str {
match self {
Self::N3 => "n3",
Self::NQuads => "nq",
Self::NTriples => "nt",
Self::RdfXml => "rdf",
Self::TriG => "trig",
Self::Turtle => "ttl",
}
}
/// The format name.
///
/// ```
/// use oxrdfio::RdfFormat;
///
/// assert_eq!(RdfFormat::NTriples.name(), "N-Triples")
/// ```
#[inline]
pub const fn name(self) -> &'static str {
match self {
Self::N3 => "N3",
Self::NQuads => "N-Quads",
Self::NTriples => "N-Triples",
Self::RdfXml => "RDF/XML",
Self::TriG => "TriG",
Self::Turtle => "Turtle",
}
}
/// Checks if the formats supports [RDF datasets](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-dataset) and not only [RDF graphs](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-graph).
///
/// ```
/// use oxrdfio::RdfFormat;
///
/// assert_eq!(RdfFormat::NTriples.supports_datasets(), false);
/// assert_eq!(RdfFormat::NQuads.supports_datasets(), true);
/// ```
#[inline]
pub const fn supports_datasets(self) -> bool {
matches!(self, Self::NQuads | Self::TriG)
}
/// Checks if the formats supports [RDF-star quoted triples](https://w3c.github.io/rdf-star/cg-spec/2021-12-17.html#dfn-quoted).
///
/// ```
/// use oxrdfio::RdfFormat;
///
/// assert_eq!(RdfFormat::NTriples.supports_rdf_star(), true);
/// assert_eq!(RdfFormat::RdfXml.supports_rdf_star(), false);
/// ```
#[inline]
#[cfg(feature = "rdf-star")]
pub const fn supports_rdf_star(self) -> bool {
matches!(
self,
Self::NTriples | Self::NQuads | Self::Turtle | Self::TriG
)
}
/// Looks for a known format from a media type.
///
/// It supports some media type aliases.
/// For example, "application/xml" is going to return `RdfFormat::RdfXml` even if it is not its canonical media type.
///
/// Example:
/// ```
/// use oxrdfio::RdfFormat;
///
/// assert_eq!(
/// RdfFormat::from_media_type("text/turtle; charset=utf-8"),
/// Some(RdfFormat::Turtle)
/// )
/// ```
#[inline]
pub fn from_media_type(media_type: &str) -> Option<Self> {
const MEDIA_SUBTYPES: [(&str, RdfFormat); 10] = [
("n-quads", RdfFormat::NQuads),
("n-triples", RdfFormat::NTriples),
("n3", RdfFormat::N3),
("nquads", RdfFormat::NQuads),
("ntriples", RdfFormat::NTriples),
("plain", RdfFormat::NTriples),
("rdf+xml", RdfFormat::RdfXml),
("trig", RdfFormat::TriG),
("turtle", RdfFormat::Turtle),
("xml", RdfFormat::RdfXml),
];
let (r#type, subtype) = media_type
.split_once(';')
.unwrap_or((media_type, ""))
.0
.split_once('/')?;
let r#type = r#type.trim();
if !r#type.eq_ignore_ascii_case("application") && !r#type.eq_ignore_ascii_case("text") {
return None;
}
let subtype = subtype.trim();
let subtype = subtype.strip_prefix("x-").unwrap_or(subtype);
for (candidate_subtype, candidate_id) in MEDIA_SUBTYPES {
if candidate_subtype.eq_ignore_ascii_case(subtype) {
return Some(candidate_id);
}
}
None
}
/// Looks for a known format from an extension.
///
/// It supports some aliases.
///
/// Example:
/// ```
/// use oxrdfio::RdfFormat;
///
/// assert_eq!(RdfFormat::from_extension("nt"), Some(RdfFormat::NTriples))
/// ```
#[inline]
pub fn from_extension(extension: &str) -> Option<Self> {
const MEDIA_TYPES: [(&str, RdfFormat); 8] = [
("n3", RdfFormat::N3),
("nq", RdfFormat::NQuads),
("nt", RdfFormat::NTriples),
("rdf", RdfFormat::RdfXml),
("trig", RdfFormat::TriG),
("ttl", RdfFormat::Turtle),
("txt", RdfFormat::NTriples),
("xml", RdfFormat::RdfXml),
];
for (candidate_extension, candidate_id) in MEDIA_TYPES {
if candidate_extension.eq_ignore_ascii_case(extension) {
return Some(candidate_id);
}
}
None
}
}
impl fmt::Display for RdfFormat {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str(self.name())
}
}