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use crate::{BlankId, BlankIdBuf, Literal};
use iref::{IriRef, IriRefBuf};

/// gRDF term.
///
/// Either a blank node identifier, IRI reference or literal value.
#[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
pub enum Term {
	/// Blank node identifier.
	Blank(BlankIdBuf),

	/// IRI reference.
	IriRef(IriRefBuf),

	/// Literal value.
	Literal(Literal),
}

impl Term {
	pub fn as_term_ref(&self) -> TermRef {
		match self {
			Self::Blank(id) => TermRef::Blank(id),
			Self::IriRef(iri) => TermRef::IriRef(iri.as_iri_ref()),
			Self::Literal(lit) => TermRef::Literal(lit),
		}
	}

	pub fn as_object_ref(&self) -> TermRef {
		self.as_term_ref()
	}
}

/// gRDF term reference.
///
/// Either a blank node identifier, IRI reference or literal value.
#[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
pub enum TermRef<'a> {
	/// Blank node identifier.
	Blank(&'a BlankId),

	/// IRI reference.
	IriRef(IriRef<'a>),

	/// Literal value.
	Literal(&'a Literal),
}

impl<'a> From<&'a Term> for TermRef<'a> {
	fn from(t: &'a Term) -> Self {
		t.as_term_ref()
	}
}

/// RDF Subject.
///
/// Either a blank node identifier or an IRI reference.
#[derive(Clone, Debug)]
pub enum Subject {
	/// Blank node identifier.
	Blank(BlankIdBuf),

	/// IRI reference.
	IriRef(IriRefBuf),
}

impl Subject {
	pub fn as_subject_ref(&self) -> SubjectRef {
		match self {
			Self::Blank(id) => SubjectRef::Blank(id),
			Self::IriRef(iri) => SubjectRef::IriRef(iri.as_iri_ref()),
		}
	}

	pub fn as_graph_label_ref(&self) -> GraphLabelRef {
		self.as_subject_ref()
	}
}

/// gRDF subject or graph label reference.
///
/// Either a blank node identifier or an IRI reference.
#[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
pub enum SubjectRef<'a> {
	/// Blank node identifier.
	Blank(&'a BlankId),

	/// IRI reference.
	IriRef(IriRef<'a>),
}

impl<'a> From<&'a Subject> for SubjectRef<'a> {
	fn from(t: &'a Subject) -> Self {
		t.as_subject_ref()
	}
}

/// RDF Object.
pub type Object = Term;

/// RDF Object reference.
pub type ObjectRef<'a> = Term;

/// RDF Graph Label.
pub type GraphLabel = Subject;

/// RDF Graph Label reference.
pub type GraphLabelRef<'a> = SubjectRef<'a>;