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oxigraph/lib/src/sparql/model.rs

208 lines
5.6 KiB

use crate::model::*;
use crate::sparql::xml_results::{read_xml_results, write_xml_results};
use crate::Result;
use failure::format_err;
use std::fmt;
use std::io::{BufRead, Write};
use uuid::Uuid;
/// Results of a [SPARQL query](https://www.w3.org/TR/sparql11-query/)
pub enum QueryResult<'a> {
/// Results of a [SELECT](https://www.w3.org/TR/sparql11-query/#select) query
Bindings(BindingsIterator<'a>),
/// Result of a [ASK](https://www.w3.org/TR/sparql11-query/#ask) query
Boolean(bool),
/// Results of a [CONSTRUCT](https://www.w3.org/TR/sparql11-query/#construct) or [DESCRIBE](https://www.w3.org/TR/sparql11-query/#describe) query
Graph(Box<dyn Iterator<Item = Result<Triple>> + 'a>),
}
impl<'a> QueryResult<'a> {
pub fn read(reader: impl BufRead + 'a, syntax: QueryResultSyntax) -> Result<Self> {
match syntax {
QueryResultSyntax::Xml => read_xml_results(reader),
}
}
pub fn write<W: Write>(self, writer: W, syntax: QueryResultSyntax) -> Result<W> {
match syntax {
QueryResultSyntax::Xml => write_xml_results(self, writer),
}
}
}
/// [SPARQL query](https://www.w3.org/TR/sparql11-query/) serialization formats
#[derive(Eq, PartialEq, Debug, Clone, Copy, Hash)]
pub enum QueryResultSyntax {
/// [SPARQL Query Results XML Format](http://www.w3.org/TR/rdf-sparql-XMLres/)
Xml,
}
/// An iterator over results bindings
pub struct BindingsIterator<'a> {
variables: Vec<Variable>,
iter: Box<dyn Iterator<Item = Result<Vec<Option<Term>>>> + 'a>,
}
impl<'a> BindingsIterator<'a> {
pub(crate) fn new(
variables: Vec<Variable>,
iter: Box<dyn Iterator<Item = Result<Vec<Option<Term>>>> + 'a>,
) -> Self {
Self { variables, iter }
}
pub fn variables(&self) -> &[Variable] {
&*self.variables
}
pub fn into_values_iter(self) -> Box<dyn Iterator<Item = Result<Vec<Option<Term>>>> + 'a> {
self.iter
}
pub fn destruct(
self,
) -> (
Vec<Variable>,
Box<dyn Iterator<Item = Result<Vec<Option<Term>>>> + 'a>,
) {
(self.variables, self.iter)
}
}
/// A SPARQL query variable
#[derive(Eq, PartialEq, Ord, PartialOrd, Debug, Clone, Hash)]
pub enum Variable {
Variable { name: String },
BlankNode { id: Uuid },
Internal { id: Uuid },
}
impl Variable {
pub fn new(name: impl Into<String>) -> Self {
Variable::Variable { name: name.into() }
}
pub fn has_name(&self) -> bool {
match self {
Variable::Variable { .. } => true,
_ => false,
}
}
pub fn name(&self) -> Result<&str> {
match self {
Variable::Variable { name } => Ok(name),
_ => Err(format_err!("The variable {} has no name", self)),
}
}
}
impl fmt::Display for Variable {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Variable::Variable { name } => write!(f, "?{}", name),
Variable::BlankNode { id } => write!(f, "_:{}", id.to_simple()),
Variable::Internal { id } => write!(f, "?{}", id.to_simple()),
}
}
}
impl Default for Variable {
fn default() -> Self {
Variable::Internal { id: Uuid::new_v4() }
}
}
impl From<BlankNode> for Variable {
fn from(blank_node: BlankNode) -> Self {
Variable::BlankNode {
id: *blank_node.as_uuid(),
}
}
}
#[derive(Eq, PartialEq, Ord, PartialOrd, Debug, Clone, Hash)]
pub enum NamedNodeOrVariable {
NamedNode(NamedNode),
Variable(Variable),
}
impl fmt::Display for NamedNodeOrVariable {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
NamedNodeOrVariable::NamedNode(node) => write!(f, "{}", node),
NamedNodeOrVariable::Variable(var) => write!(f, "{}", var),
}
}
}
impl From<NamedNode> for NamedNodeOrVariable {
fn from(node: NamedNode) -> Self {
NamedNodeOrVariable::NamedNode(node)
}
}
impl From<Variable> for NamedNodeOrVariable {
fn from(var: Variable) -> Self {
NamedNodeOrVariable::Variable(var)
}
}
#[derive(Eq, PartialEq, Ord, PartialOrd, Debug, Clone, Hash)]
pub enum TermOrVariable {
Term(Term),
Variable(Variable),
}
impl fmt::Display for TermOrVariable {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
TermOrVariable::Term(term) => write!(f, "{}", term),
TermOrVariable::Variable(var) => write!(f, "{}", var),
}
}
}
impl From<NamedNode> for TermOrVariable {
fn from(node: NamedNode) -> Self {
TermOrVariable::Term(node.into())
}
}
impl From<BlankNode> for TermOrVariable {
fn from(node: BlankNode) -> Self {
TermOrVariable::Variable(node.into())
}
}
impl From<Literal> for TermOrVariable {
fn from(literal: Literal) -> Self {
TermOrVariable::Term(literal.into())
}
}
impl From<Variable> for TermOrVariable {
fn from(var: Variable) -> Self {
TermOrVariable::Variable(var)
}
}
impl From<Term> for TermOrVariable {
fn from(term: Term) -> Self {
match term {
Term::NamedNode(node) => TermOrVariable::Term(node.into()),
Term::BlankNode(node) => TermOrVariable::Variable(node.into()),
Term::Literal(literal) => TermOrVariable::Term(literal.into()),
}
}
}
impl From<NamedNodeOrVariable> for TermOrVariable {
fn from(element: NamedNodeOrVariable) -> Self {
match element {
NamedNodeOrVariable::NamedNode(node) => TermOrVariable::Term(node.into()),
NamedNodeOrVariable::Variable(var) => TermOrVariable::Variable(var),
}
}
}