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oxigraph/lib/sparesults/src/csv.rs

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//! Implementation of [SPARQL 1.1 Query Results CSV and TSV Formats](https://www.w3.org/TR/sparql11-results-csv-tsv/)
use crate::error::{ParseError, SyntaxError, SyntaxErrorKind};
use oxrdf::Variable;
use oxrdf::{vocab::xsd, *};
use std::io::{self, BufRead, Write};
use std::str::FromStr;
pub fn write_boolean_csv_result<W: Write>(mut sink: W, value: bool) -> io::Result<W> {
sink.write_all(if value { b"true" } else { b"false" })?;
Ok(sink)
}
pub struct CsvSolutionsWriter<W: Write> {
sink: W,
variables: Vec<Variable>,
}
impl<W: Write> CsvSolutionsWriter<W> {
pub fn start(mut sink: W, variables: Vec<Variable>) -> io::Result<Self> {
let mut start_vars = true;
for variable in &variables {
if start_vars {
start_vars = false;
} else {
sink.write_all(b",")?;
}
sink.write_all(variable.as_str().as_bytes())?;
}
Ok(Self { sink, variables })
}
pub fn write<'a>(
&mut self,
solution: impl IntoIterator<Item = (VariableRef<'a>, TermRef<'a>)>,
) -> io::Result<()> {
let mut values = vec![None; self.variables.len()];
for (variable, value) in solution {
if let Some(position) = self.variables.iter().position(|v| *v == variable) {
values[position] = Some(value);
}
}
self.sink.write_all(b"\r\n")?;
let mut start_binding = true;
for value in values {
if start_binding {
start_binding = false;
} else {
self.sink.write_all(b",")?;
}
if let Some(value) = value {
write_csv_term(value, &mut self.sink)?;
}
}
Ok(())
}
pub fn finish(mut self) -> io::Result<W> {
self.sink.flush()?;
Ok(self.sink)
}
}
fn write_csv_term<'a>(term: impl Into<TermRef<'a>>, sink: &mut impl Write) -> io::Result<()> {
match term.into() {
TermRef::NamedNode(uri) => sink.write_all(uri.as_str().as_bytes()),
TermRef::BlankNode(bnode) => {
sink.write_all(b"_:")?;
sink.write_all(bnode.as_str().as_bytes())
}
TermRef::Literal(literal) => write_escaped_csv_string(literal.value(), sink),
#[cfg(feature = "rdf-star")]
TermRef::Triple(triple) => {
write_csv_term(&triple.subject, sink)?;
sink.write_all(b" ")?;
write_csv_term(&triple.predicate, sink)?;
sink.write_all(b" ")?;
write_csv_term(&triple.object, sink)
}
}
}
fn write_escaped_csv_string(s: &str, sink: &mut impl Write) -> io::Result<()> {
if s.bytes().any(|c| matches!(c, b'"' | b',' | b'\n' | b'\r')) {
sink.write_all(b"\"")?;
for c in s.bytes() {
if c == b'\"' {
sink.write_all(b"\"\"")
} else {
sink.write_all(&[c])
}?;
}
sink.write_all(b"\"")
} else {
sink.write_all(s.as_bytes())
}
}
pub fn write_boolean_tsv_result<W: Write>(mut sink: W, value: bool) -> io::Result<W> {
sink.write_all(if value { b"true" } else { b"false" })?;
Ok(sink)
}
pub struct TsvSolutionsWriter<W: Write> {
sink: W,
variables: Vec<Variable>,
}
impl<W: Write> TsvSolutionsWriter<W> {
pub fn start(mut sink: W, variables: Vec<Variable>) -> io::Result<Self> {
let mut start_vars = true;
for variable in &variables {
if start_vars {
start_vars = false;
} else {
sink.write_all(b"\t")?;
}
sink.write_all(b"?")?;
sink.write_all(variable.as_str().as_bytes())?;
}
Ok(Self { sink, variables })
}
pub fn write<'a>(
&mut self,
solution: impl IntoIterator<Item = (VariableRef<'a>, TermRef<'a>)>,
) -> io::Result<()> {
let mut values = vec![None; self.variables.len()];
for (variable, value) in solution {
if let Some(position) = self.variables.iter().position(|v| *v == variable) {
values[position] = Some(value);
}
}
self.sink.write_all(b"\n")?;
let mut start_binding = true;
for value in values {
if start_binding {
start_binding = false;
} else {
self.sink.write_all(b"\t")?;
}
if let Some(value) = value {
write_tsv_term(value, &mut self.sink)?;
}
}
Ok(())
}
pub fn finish(mut self) -> io::Result<W> {
self.sink.flush()?;
Ok(self.sink)
}
}
fn write_tsv_term<'a>(term: impl Into<TermRef<'a>>, sink: &mut impl Write) -> io::Result<()> {
//TODO: full Turtle serialization
match term.into() {
TermRef::NamedNode(node) => write!(sink, "<{}>", node.as_str()),
TermRef::BlankNode(node) => write!(sink, "_:{}", node.as_str()),
TermRef::Literal(literal) => match literal.datatype() {
xsd::BOOLEAN => match literal.value() {
"true" | "1" => sink.write_all(b"true"),
"false" | "0" => sink.write_all(b"false"),
_ => sink.write_all(literal.to_string().as_bytes()),
},
xsd::INTEGER => {
if literal.value().bytes().all(|c| matches!(c, b'0'..=b'9')) {
sink.write_all(literal.value().as_bytes())
} else {
sink.write_all(literal.to_string().as_bytes())
}
}
_ => sink.write_all(literal.to_string().as_bytes()),
},
#[cfg(feature = "rdf-star")]
TermRef::Triple(triple) => {
sink.write_all(b"<<")?;
write_tsv_term(&triple.subject, sink)?;
sink.write_all(b" ")?;
write_tsv_term(&triple.predicate, sink)?;
sink.write_all(b" ")?;
write_tsv_term(&triple.object, sink)?;
sink.write_all(b">>")?;
Ok(())
}
}
}
pub enum TsvQueryResultsReader<R: BufRead> {
Solutions {
variables: Vec<Variable>,
solutions: TsvSolutionsReader<R>,
},
Boolean(bool),
}
impl<R: BufRead> TsvQueryResultsReader<R> {
pub fn read(mut source: R) -> Result<Self, ParseError> {
let mut buffer = String::new();
// We read the header
source.read_line(&mut buffer)?;
if buffer.trim().eq_ignore_ascii_case("true") {
return Ok(Self::Boolean(true));
}
if buffer.trim().eq_ignore_ascii_case("false") {
return Ok(Self::Boolean(false));
}
let mut variables = Vec::new();
for v in buffer.split('\t') {
let v = v.trim();
let variable = Variable::from_str(v).map_err(|e| {
SyntaxError::msg(format!("Invalid variable declaration '{}': {}", v, e))
})?;
if variables.contains(&variable) {
return Err(SyntaxError::msg(format!(
"The variable {} is declared twice",
variable
))
.into());
}
variables.push(variable);
}
Ok(Self::Solutions {
variables,
solutions: TsvSolutionsReader { source, buffer },
})
}
}
pub struct TsvSolutionsReader<R: BufRead> {
source: R,
buffer: String,
}
impl<R: BufRead> TsvSolutionsReader<R> {
pub fn read_next(&mut self) -> Result<Option<Vec<Option<Term>>>, ParseError> {
self.buffer.clear();
if self.source.read_line(&mut self.buffer)? == 0 {
return Ok(None);
}
Ok(Some(
self.buffer
.split('\t')
.map(|v| {
let v = v.trim();
if v.is_empty() {
Ok(None)
} else {
Ok(Some(Term::from_str(v).map_err(|e| SyntaxError {
inner: SyntaxErrorKind::Term(e),
})?))
}
})
.collect::<Result<_, ParseError>>()?,
))
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::io::Cursor;
use std::rc::Rc;
use std::str;
fn build_example() -> (Vec<Variable>, Vec<Vec<Option<Term>>>) {
(
vec![
Variable::new_unchecked("x"),
Variable::new_unchecked("literal"),
],
vec![
vec![
Some(NamedNode::new_unchecked("http://example/x").into()),
Some(Literal::new_simple_literal("String").into()),
],
vec![
Some(NamedNode::new_unchecked("http://example/x").into()),
Some(Literal::new_simple_literal("String-with-dquote\"").into()),
],
vec![
Some(BlankNode::new_unchecked("b0").into()),
Some(Literal::new_simple_literal("Blank node").into()),
],
vec![
None,
Some(Literal::new_simple_literal("Missing 'x'").into()),
],
vec![None, None],
vec![
Some(NamedNode::new_unchecked("http://example/x").into()),
None,
],
vec![
Some(BlankNode::new_unchecked("b1").into()),
Some(
Literal::new_language_tagged_literal_unchecked("String-with-lang", "en")
.into(),
),
],
vec![
Some(BlankNode::new_unchecked("b1").into()),
Some(Literal::new_typed_literal("123", xsd::INTEGER).into()),
],
],
)
}
#[test]
fn test_csv_serialization() -> io::Result<()> {
let (variables, solutions) = build_example();
let mut writer = CsvSolutionsWriter::start(Vec::new(), variables.clone())?;
let variables = Rc::new(variables);
for solution in solutions {
writer.write(
variables
.iter()
.zip(&solution)
.filter_map(|(v, s)| s.as_ref().map(|s| (v.as_ref(), s.as_ref()))),
)?;
}
let result = writer.finish()?;
assert_eq!(str::from_utf8(&result).unwrap(), "x,literal\r\nhttp://example/x,String\r\nhttp://example/x,\"String-with-dquote\"\"\"\r\n_:b0,Blank node\r\n,Missing 'x'\r\n,\r\nhttp://example/x,\r\n_:b1,String-with-lang\r\n_:b1,123");
Ok(())
}
#[test]
fn test_tsv_serialization() -> io::Result<()> {
let (variables, solutions) = build_example();
let mut writer = TsvSolutionsWriter::start(Vec::new(), variables.clone())?;
let variables = Rc::new(variables);
for solution in solutions {
writer.write(
variables
.iter()
.zip(&solution)
.filter_map(|(v, s)| s.as_ref().map(|s| (v.as_ref(), s.as_ref()))),
)?;
}
let result = writer.finish()?;
assert_eq!(str::from_utf8(&result).unwrap(), "?x\t?literal\n<http://example/x>\t\"String\"\n<http://example/x>\t\"String-with-dquote\\\"\"\n_:b0\t\"Blank node\"\n\t\"Missing 'x'\"\n\t\n<http://example/x>\t\n_:b1\t\"String-with-lang\"@en\n_:b1\t123");
Ok(())
}
#[test]
fn test_bad_tsv() {
let mut bad_tsvs = vec![
"?", "?p", "?p?o", "?p\n<", "?p\n_", "?p\n_:", "?p\n\"", "?p\n<<",
];
let a_lot_of_strings = format!("?p\n{}\n", "<".repeat(100_000));
bad_tsvs.push(&a_lot_of_strings);
for bad_tsv in bad_tsvs {
if let Ok(TsvQueryResultsReader::Solutions { mut solutions, .. }) =
TsvQueryResultsReader::read(Cursor::new(bad_tsv))
{
while let Ok(Some(_)) = solutions.read_next() {}
}
}
}
}