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oxigraph/lib/src/sparql/model.rs

517 lines
16 KiB

use crate::error::invalid_input_error;
use crate::io::GraphFormat;
use crate::io::GraphSerializer;
use crate::model::*;
use crate::sparql::csv_results::{read_tsv_results, write_csv_results, write_tsv_results};
use crate::sparql::error::EvaluationError;
use crate::sparql::json_results::write_json_results;
use crate::sparql::xml_results::{read_xml_results, write_xml_results};
use std::error::Error;
use std::io::{BufRead, Write};
use std::rc::Rc;
use std::{fmt, io};
/// Results of a [SPARQL query](https://www.w3.org/TR/sparql11-query/)
pub enum QueryResults {
/// Results of a [SELECT](https://www.w3.org/TR/sparql11-query/#select) query
Solutions(QuerySolutionIter),
/// 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(QueryTripleIter),
}
impl QueryResults {
/// Reads a SPARQL query results serialization
pub fn read(
reader: impl BufRead + 'static,
format: QueryResultsFormat,
) -> Result<Self, io::Error> {
match format {
QueryResultsFormat::Xml => read_xml_results(reader),
QueryResultsFormat::Json => Err(invalid_input_error(
"JSON SPARQL results format parsing has not been implemented yet",
)), //TODO: implement
QueryResultsFormat::Csv => Err(invalid_input_error(
"CSV and TSV SPARQL results format parsing is not implemented",
)),
QueryResultsFormat::Tsv => read_tsv_results(reader),
}
}
/// Writes the query results (solutions or boolean)
///
/// This method fails if it is called on the `Graph` results
///
/// ```
/// use oxigraph::store::Store;
/// use oxigraph::model::*;
/// use oxigraph::sparql::QueryResultsFormat;
///
/// let store = Store::new()?;
/// let ex = NamedNodeRef::new("http://example.com")?;
/// store.insert(QuadRef::new(ex, ex, ex, GraphNameRef::DefaultGraph))?;
///
/// let mut results = Vec::new();
/// store.query("SELECT ?s WHERE { ?s ?p ?o }")?.write(&mut results, QueryResultsFormat::Json)?;
/// assert_eq!(results, "{\"head\":{\"vars\":[\"s\"]},\"results\":{\"bindings\":[{\"s\":{\"type\":\"uri\",\"value\":\"http://example.com\"}}]}}".as_bytes());
/// # Result::<_,Box<dyn std::error::Error>>::Ok(())
/// ```
pub fn write(
self,
writer: impl Write,
format: QueryResultsFormat,
) -> Result<(), EvaluationError> {
match format {
QueryResultsFormat::Xml => write_xml_results(self, writer),
QueryResultsFormat::Json => write_json_results(self, writer),
QueryResultsFormat::Csv => write_csv_results(self, writer),
QueryResultsFormat::Tsv => write_tsv_results(self, writer),
}
}
/// Writes the graph query results
///
/// This method fails if it is called on the `Solution` or `Boolean` results
///
/// ```
/// use oxigraph::store::Store;
/// use oxigraph::io::GraphFormat;
/// use oxigraph::model::*;
/// use std::io::Cursor;
///
/// let graph = "<http://example.com> <http://example.com> <http://example.com> .\n".as_bytes();
///
/// let store = Store::new()?;
/// store.load_graph(Cursor::new(graph), GraphFormat::NTriples, &GraphName::DefaultGraph, None)?;
///
/// let mut results = Vec::new();
/// store.query("CONSTRUCT WHERE { ?s ?p ?o }")?.write_graph(&mut results, GraphFormat::NTriples)?;
/// assert_eq!(results, graph);
/// # Result::<_,Box<dyn std::error::Error>>::Ok(())
/// ```
pub fn write_graph(
self,
write: impl Write,
format: GraphFormat,
) -> Result<(), EvaluationError> {
if let QueryResults::Graph(triples) = self {
let mut writer = GraphSerializer::from_format(format).triple_writer(write)?;
for triple in triples {
writer.write(&triple?)?;
}
writer.finish()?;
Ok(())
} else {
Err(
invalid_input_error("Bindings or booleans could not be formatted as an RDF graph")
.into(),
)
}
}
}
impl From<QuerySolutionIter> for QueryResults {
#[inline]
fn from(value: QuerySolutionIter) -> Self {
QueryResults::Solutions(value)
}
}
/// [SPARQL query](https://www.w3.org/TR/sparql11-query/) results serialization formats
#[derive(Eq, PartialEq, Debug, Clone, Copy, Hash)]
#[non_exhaustive]
pub enum QueryResultsFormat {
/// [SPARQL Query Results XML Format](http://www.w3.org/TR/rdf-sparql-XMLres/)
Xml,
/// [SPARQL Query Results JSON Format](https://www.w3.org/TR/sparql11-results-json/)
Json,
/// [SPARQL Query Results CSV Format](https://www.w3.org/TR/sparql11-results-csv-tsv/)
Csv,
/// [SPARQL Query Results TSV Format](https://www.w3.org/TR/sparql11-results-csv-tsv/)
Tsv,
}
impl QueryResultsFormat {
/// The format canonical IRI according to the [Unique URIs for file formats registry](https://www.w3.org/ns/formats/).
///
/// ```
/// use oxigraph::sparql::QueryResultsFormat;
///
/// assert_eq!(QueryResultsFormat::Json.iri(), "http://www.w3.org/ns/formats/SPARQL_Results_JSON")
/// ```
#[inline]
pub fn iri(self) -> &'static str {
match self {
QueryResultsFormat::Xml => "http://www.w3.org/ns/formats/SPARQL_Results_XML",
QueryResultsFormat::Json => "http://www.w3.org/ns/formats/SPARQL_Results_JSON",
QueryResultsFormat::Csv => "http://www.w3.org/ns/formats/SPARQL_Results_CSV",
QueryResultsFormat::Tsv => "http://www.w3.org/ns/formats/SPARQL_Results_TSV",
}
}
/// The format [IANA media type](https://tools.ietf.org/html/rfc2046).
///
/// ```
/// use oxigraph::sparql::QueryResultsFormat;
///
/// assert_eq!(QueryResultsFormat::Json.media_type(), "application/sparql-results+json")
/// ```
#[inline]
pub fn media_type(self) -> &'static str {
match self {
QueryResultsFormat::Xml => "application/sparql-results+xml",
QueryResultsFormat::Json => "application/sparql-results+json",
QueryResultsFormat::Csv => "text/csv; charset=utf-8",
QueryResultsFormat::Tsv => "text/tab-separated-values; charset=utf-8",
}
}
/// The format [IANA-registered](https://tools.ietf.org/html/rfc2046) file extension.
///
/// ```
/// use oxigraph::sparql::QueryResultsFormat;
///
/// assert_eq!(QueryResultsFormat::Json.file_extension(), "srj")
/// ```
#[inline]
pub fn file_extension(self) -> &'static str {
match self {
QueryResultsFormat::Xml => "srx",
QueryResultsFormat::Json => "srj",
QueryResultsFormat::Csv => "csv",
QueryResultsFormat::Tsv => "tsv",
}
}
/// Looks for a known format from a media type.
///
/// It supports some media type aliases.
/// For example "application/xml" is going to return `Xml` even if it is not its canonical media type.
///
/// Example:
/// ```
/// use oxigraph::sparql::QueryResultsFormat;
///
/// assert_eq!(QueryResultsFormat::from_media_type("application/sparql-results+json; charset=utf-8"), Some(QueryResultsFormat::Json))
/// ```
pub fn from_media_type(media_type: &str) -> Option<Self> {
if let Some(base_type) = media_type.split(';').next() {
match base_type {
"application/sparql-results+xml" | "application/xml" | "text/xml" => {
Some(QueryResultsFormat::Xml)
}
"application/sparql-results+json" | "application/json" | "text/json" => {
Some(QueryResultsFormat::Json)
}
"text/csv" => Some(QueryResultsFormat::Csv),
"text/tab-separated-values" | "text/tsv" => Some(QueryResultsFormat::Tsv),
_ => None,
}
} else {
None
}
}
}
/// An iterator over [`QuerySolution`]s
///
/// ```
/// use oxigraph::store::Store;
/// use oxigraph::sparql::QueryResults;
///
/// let store = Store::new()?;
/// if let QueryResults::Solutions(solutions) = store.query("SELECT ?s WHERE { ?s ?p ?o }")? {
/// for solution in solutions {
/// println!("{:?}", solution?.get("s"));
/// }
/// }
/// # Result::<_,Box<dyn std::error::Error>>::Ok(())
/// ```
pub struct QuerySolutionIter {
variables: Rc<Vec<Variable>>,
iter: Box<dyn Iterator<Item = Result<Vec<Option<Term>>, EvaluationError>>>,
}
impl QuerySolutionIter {
5 years ago
pub fn new(
variables: Rc<Vec<Variable>>,
iter: Box<dyn Iterator<Item = Result<Vec<Option<Term>>, EvaluationError>>>,
) -> Self {
Self { variables, iter }
}
/// The variables used in the solutions
///
/// ```
/// use oxigraph::store::Store;
/// use oxigraph::sparql::{QueryResults, Variable};
///
/// let store = Store::new()?;
/// if let QueryResults::Solutions(solutions) = store.query("SELECT ?s ?o WHERE { ?s ?p ?o }")? {
/// assert_eq!(solutions.variables(), &[Variable::new("s")?, Variable::new("o")?]);
/// }
/// # Result::<_,Box<dyn std::error::Error>>::Ok(())
/// ```
#[inline]
pub fn variables(&self) -> &[Variable] {
&*self.variables
}
}
impl Iterator for QuerySolutionIter {
type Item = Result<QuerySolution, EvaluationError>;
#[inline]
fn next(&mut self) -> Option<Result<QuerySolution, EvaluationError>> {
Some(self.iter.next()?.map(|values| QuerySolution {
values,
variables: self.variables.clone(),
}))
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
/// Tuple associating variables and terms that are the result of a SPARQL query.
///
/// It is the equivalent of a row in SQL.
pub struct QuerySolution {
values: Vec<Option<Term>>,
variables: Rc<Vec<Variable>>,
}
impl QuerySolution {
/// Returns a value for a given position in the tuple ([`usize`](std::usize)) or a given variable name ([`&str`](std::str) or [`Variable`])
///
/// ```ignore
/// let foo = solution.get("foo"); // Get the value of the variable ?foo if it exists
/// let first = solution.get(1); // Get the value of the second column if it exists
/// ```
#[inline]
pub fn get(&self, index: impl VariableSolutionIndex) -> Option<&Term> {
self.values.get(index.index(self)?).and_then(|e| e.as_ref())
}
/// The number of variables which could be bound
#[inline]
pub fn len(&self) -> usize {
self.values.len()
}
/// Is this binding empty?
#[inline]
pub fn is_empty(&self) -> bool {
self.values.is_empty()
}
/// Returns an iterator over bound variables
#[inline]
pub fn iter(&self) -> impl Iterator<Item = (&Variable, &Term)> {
self.values
.iter()
.enumerate()
.filter_map(move |(i, value)| value.as_ref().map(|value| (&self.variables[i], value)))
}
/// Returns an iterator over all values, bound or not
#[inline]
pub fn values(&self) -> impl Iterator<Item = Option<&Term>> {
self.values.iter().map(|v| v.as_ref())
}
}
/// A utility trait to get values for a given variable or tuple position
pub trait VariableSolutionIndex {
fn index(self, solution: &QuerySolution) -> Option<usize>;
}
impl VariableSolutionIndex for usize {
#[inline]
fn index(self, _: &QuerySolution) -> Option<usize> {
Some(self)
}
}
impl VariableSolutionIndex for &str {
#[inline]
fn index(self, solution: &QuerySolution) -> Option<usize> {
solution.variables.iter().position(|v| v.as_str() == self)
}
}
impl VariableSolutionIndex for &Variable {
#[inline]
fn index(self, solution: &QuerySolution) -> Option<usize> {
solution.variables.iter().position(|v| v == self)
}
}
impl VariableSolutionIndex for Variable {
#[inline]
fn index(self, solution: &QuerySolution) -> Option<usize> {
(&self).index(solution)
}
}
/// An iterator over the triples that compose a graph solution
///
/// ```
/// use oxigraph::store::Store;
/// use oxigraph::sparql::QueryResults;
///
/// let store = Store::new()?;
/// if let QueryResults::Graph(triples) = store.query("CONSTRUCT WHERE { ?s ?p ?o }")? {
/// for triple in triples {
/// println!("{}", triple?);
/// }
/// }
/// # Result::<_,Box<dyn std::error::Error>>::Ok(())
/// ```
pub struct QueryTripleIter {
pub(crate) iter: Box<dyn Iterator<Item = Result<Triple, EvaluationError>>>,
}
impl Iterator for QueryTripleIter {
type Item = Result<Triple, EvaluationError>;
#[inline]
fn next(&mut self) -> Option<Result<Triple, EvaluationError>> {
self.iter.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
#[inline]
fn fold<Acc, G>(self, init: Acc, mut g: G) -> Acc
where
G: FnMut(Acc, Self::Item) -> Acc,
{
self.iter.fold(init, |acc, elt| g(acc, elt))
}
}
/// A SPARQL query variable
///
/// ```
/// use oxigraph::sparql::Variable;
///
/// assert_eq!(
/// "?foo",
/// Variable::new("foo")?.to_string()
/// );
/// # Result::<_,oxigraph::sparql::VariableNameParseError>::Ok(())
/// ```
#[derive(Eq, PartialEq, Ord, PartialOrd, Debug, Clone, Hash)]
pub struct Variable {
name: String,
}
impl Variable {
/// Creates a variable name from a unique identifier.
///
/// The variable identifier must be valid according to the SPARQL grammar.
pub fn new(name: impl Into<String>) -> Result<Self, VariableNameParseError> {
let name = name.into();
validate_variable_identifier(&name)?;
Ok(Self::new_unchecked(name))
}
/// Creates a variable name from a unique identifier without validation.
///
/// It is the caller's responsibility to ensure that `id` is a valid blank node identifier
/// according to the SPARQL grammar.
///
/// [`Variable::new()`] is a safe version of this constructor and should be used for untrusted data.
#[inline]
pub fn new_unchecked(name: impl Into<String>) -> Self {
Variable { name: name.into() }
}
#[inline]
pub fn as_str(&self) -> &str {
&self.name
}
#[inline]
pub fn into_string(self) -> String {
self.name
}
}
impl fmt::Display for Variable {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "?{}", self.name)
}
}
fn validate_variable_identifier(id: &str) -> Result<(), VariableNameParseError> {
let mut chars = id.chars();
let front = chars.next().ok_or(VariableNameParseError {})?;
match front {
'0'..='9'
| '_'
| ':'
| 'A'..='Z'
| 'a'..='z'
| '\u{00C0}'..='\u{00D6}'
| '\u{00D8}'..='\u{00F6}'
| '\u{00F8}'..='\u{02FF}'
| '\u{0370}'..='\u{037D}'
| '\u{037F}'..='\u{1FFF}'
| '\u{200C}'..='\u{200D}'
| '\u{2070}'..='\u{218F}'
| '\u{2C00}'..='\u{2FEF}'
| '\u{3001}'..='\u{D7FF}'
| '\u{F900}'..='\u{FDCF}'
| '\u{FDF0}'..='\u{FFFD}'
| '\u{10000}'..='\u{EFFFF}' => (),
_ => return Err(VariableNameParseError {}),
}
for c in chars {
match c {
'0'..='9'
| '\u{00B7}'
| '\u{00300}'..='\u{036F}'
| '\u{203F}'..='\u{2040}'
| '_'
| 'A'..='Z'
| 'a'..='z'
| '\u{00C0}'..='\u{00D6}'
| '\u{00D8}'..='\u{00F6}'
| '\u{00F8}'..='\u{02FF}'
| '\u{0370}'..='\u{037D}'
| '\u{037F}'..='\u{1FFF}'
| '\u{200C}'..='\u{200D}'
| '\u{2070}'..='\u{218F}'
| '\u{2C00}'..='\u{2FEF}'
| '\u{3001}'..='\u{D7FF}'
| '\u{F900}'..='\u{FDCF}'
| '\u{FDF0}'..='\u{FFFD}'
| '\u{10000}'..='\u{EFFFF}' => (),
_ => return Err(VariableNameParseError {}),
}
}
Ok(())
}
/// An error raised during [`Variable`] name validation.
#[allow(missing_copy_implementations)]
#[derive(Debug)]
pub struct VariableNameParseError {}
impl fmt::Display for VariableNameParseError {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "The variable name is invalid")
}
}
impl Error for VariableNameParseError {}