Adds SPARQL XML query results serialization

pull/10/head
Tpt 6 years ago
parent 65ed79742e
commit c30dd409c1
  1. 96
      lib/src/sparql/xml_results.rs

@ -1,15 +1,109 @@
//! Implementation of [SPARQL Query Results XML Format](http://www.w3.org/TR/rdf-sparql-XMLres/)
use model::*; use model::*;
use quick_xml::events::BytesEnd;
use quick_xml::events::BytesStart;
use quick_xml::events::BytesText;
use quick_xml::events::Event; use quick_xml::events::Event;
use quick_xml::Reader; use quick_xml::Reader;
use quick_xml::Writer;
use sparql::algebra::BindingsIterator; use sparql::algebra::BindingsIterator;
use sparql::algebra::QueryResult; use sparql::algebra::QueryResult;
use sparql::algebra::Variable; use sparql::algebra::Variable;
use std::collections::BTreeMap; use std::collections::BTreeMap;
use std::io::BufRead; use std::io::BufRead;
use std::io::Write;
use std::iter::empty; use std::iter::empty;
use std::str::FromStr; use std::str::FromStr;
use Result; use Result;
pub fn write_xml_results<W: Write>(results: QueryResult, sink: W) -> Result<W> {
let mut writer = Writer::new(sink);
match results {
QueryResult::Boolean(value) => {
let mut sparql_open = BytesStart::borrowed_name(b"sparql");
sparql_open.push_attribute(("xmlns", "http://www.w3.org/2005/sparql-results#"));
writer.write_event(Event::Start(sparql_open))?;
writer.write_event(Event::Start(BytesStart::borrowed_name(b"head")))?;
writer.write_event(Event::End(BytesEnd::borrowed(b"head")))?;
writer.write_event(Event::Start(BytesStart::borrowed_name(b"boolean")))?;
writer.write_event(Event::Text(BytesText::from_plain_str(if value {
"true"
} else {
"false"
})))?;
writer.write_event(Event::End(BytesEnd::borrowed(b"boolean")))?;
writer.write_event(Event::End(BytesEnd::borrowed(b"sparql")))?;
}
QueryResult::Bindings(bindings) => {
let (variables, results) = bindings.destruct();
let mut sparql_open = BytesStart::borrowed_name(b"sparql");
sparql_open.push_attribute(("xmlns", "http://www.w3.org/2005/sparql-results#"));
writer.write_event(Event::Start(sparql_open))?;
writer.write_event(Event::Start(BytesStart::borrowed_name(b"head")))?;
for variable in &variables {
let mut variable_tag = BytesStart::borrowed_name(b"variable");
variable_tag.push_attribute(("name", variable.name()?));
writer.write_event(Event::Empty(variable_tag))?;
}
writer.write_event(Event::End(BytesEnd::borrowed(b"head")))?;
writer.write_event(Event::Start(BytesStart::borrowed_name(b"results")))?;
for result in results {
let result = result?;
writer.write_event(Event::Start(BytesStart::borrowed_name(b"result")))?;
for (k, value) in result.into_iter().enumerate() {
if let Some(term) = value {
writer.write_event(Event::Start(BytesStart::borrowed_name(b"binding")))?;
match term {
Term::NamedNode(uri) => {
writer
.write_event(Event::Start(BytesStart::borrowed_name(b"uri")))?;
writer.write_event(Event::Text(BytesText::from_plain_str(
uri.as_str(),
)))?;
writer.write_event(Event::End(BytesEnd::borrowed(b"uri")))?;
}
Term::BlankNode(bnode) => {
writer.write_event(Event::Start(BytesStart::borrowed_name(
b"bnode",
)))?;
writer.write_event(Event::Text(BytesText::from_plain_str(
&bnode.as_uuid().to_simple().to_string(),
)))?;
writer.write_event(Event::End(BytesEnd::borrowed(b"bnode")))?;
}
Term::Literal(literal) => {
let mut literal_tag = BytesStart::borrowed_name(b"literal");
if let Some(language) = literal.language() {
literal_tag.push_attribute(("xml:lang", language));
} else if !literal.is_plain() {
literal_tag
.push_attribute(("datatype", literal.datatype().as_str()));
}
writer.write_event(Event::Start(literal_tag))?;
writer.write_event(Event::Text(BytesText::from_plain_str(
&literal.value(),
)))?;
writer.write_event(Event::End(BytesEnd::borrowed(b"literal")))?;
}
}
writer.write_event(Event::End(BytesEnd::borrowed(b"binding")))?;
}
}
writer.write_event(Event::End(BytesEnd::borrowed(b"result")))?;
}
writer.write_event(Event::End(BytesEnd::borrowed(b"results")))?;
writer.write_event(Event::End(BytesEnd::borrowed(b"sparql")))?;
}
QueryResult::Graph(_) => {
return Err(format_err!(
"Graphs could not be formatted to SPARQL query results XML format"
))
}
}
Ok(writer.into_inner())
}
pub fn read_xml_results(source: impl BufRead + 'static) -> Result<QueryResult<'static>> { pub fn read_xml_results(source: impl BufRead + 'static) -> Result<QueryResult<'static>> {
enum State { enum State {
Start, Start,
@ -130,7 +224,7 @@ pub fn read_xml_results(source: impl BufRead + 'static) -> Result<QueryResult<'s
Event::End(_) => if let State::Head = state { Event::End(_) => if let State::Head = state {
state = State::AfterHead; state = State::AfterHead;
} else { } else {
return Err(format_err!("Unexpected early file end. All results file should have a <head> and a <result> or <boolean> tag")); return Err(format_err!("Unexpected early file end. All results file should have a <head> and a <result> or <boolean> tag"));
}, },
Event::Eof => return Err(format_err!("Unexpected early file end. All results file should have a <head> and a <result> or <boolean> tag")), Event::Eof => return Err(format_err!("Unexpected early file end. All results file should have a <head> and a <result> or <boolean> tag")),
_ => (), _ => (),

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