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use Result;
use reader::rdf_parser::RdfParser;
use graph::Graph;
use error::{Error, ErrorType};
use triple::Triple;
use reader::lexer::n_triples_lexer::NTriplesLexer;
use reader::lexer::rdf_lexer::RdfLexer;
use node::Node;
use reader::lexer::token::Token;
use std::io::Read;
use uri::Uri;
use std::io::Cursor;
pub struct NTriplesParser<R: Read> {
lexer: NTriplesLexer<R>,
}
impl<R: Read> RdfParser for NTriplesParser<R> {
fn decode(&mut self) -> Result<Graph> {
let mut graph = Graph::new(None);
loop {
match self.lexer.peek_next_token()? {
Token::Comment(_) => {
let _ = self.lexer.get_next_token();
continue;
}
Token::EndOfInput => return Ok(graph),
_ => {}
}
match self.read_triple() {
Ok(triple) => graph.add_triple(&triple),
Err(err) => match *err.error_type() {
ErrorType::EndOfInput(_) => return Ok(graph),
_ => {
println!("Error: {}", err.to_string());
return Err(Error::new(
ErrorType::InvalidReaderInput,
"Error while parsing NTriples syntax.",
));
}
},
}
}
}
}
impl NTriplesParser<Cursor<Vec<u8>>> {
pub fn from_string<S>(input: S) -> NTriplesParser<Cursor<Vec<u8>>>
where
S: Into<String>,
{
NTriplesParser::from_reader(Cursor::new(input.into().into_bytes()))
}
}
impl<R: Read> NTriplesParser<R> {
pub fn from_reader(input: R) -> NTriplesParser<R> {
NTriplesParser {
lexer: NTriplesLexer::new(input),
}
}
fn read_triple(&mut self) -> Result<Triple> {
let subject = self.read_subject()?;
let predicate = self.read_predicate()?;
let object = self.read_object()?;
match self.lexer.get_next_token() {
Ok(Token::TripleDelimiter) => {}
_ => {
return Err(Error::new(
ErrorType::InvalidReaderInput,
"Expected triple delimiter.",
))
}
}
Ok(Triple::new(&subject, &predicate, &object))
}
fn read_subject(&mut self) -> Result<Node> {
match self.lexer.get_next_token() {
Ok(Token::BlankNode(id)) => Ok(Node::BlankNode { id }),
Ok(Token::Uri(uri)) => Ok(Node::UriNode { uri: Uri::new(uri) }),
_ => Err(Error::new(
ErrorType::InvalidToken,
"Invalid token for NTriples subject.",
)),
}
}
fn read_predicate(&mut self) -> Result<Node> {
match self.lexer.get_next_token() {
Ok(Token::Uri(uri)) => Ok(Node::UriNode { uri: Uri::new(uri) }),
_ => Err(Error::new(
ErrorType::InvalidToken,
"Invalid token for NTriples predicate.",
)),
}
}
fn read_object(&mut self) -> Result<Node> {
match self.lexer.get_next_token()? {
Token::BlankNode(id) => Ok(Node::BlankNode { id }),
Token::Uri(uri) => Ok(Node::UriNode { uri: Uri::new(uri) }),
Token::LiteralWithLanguageSpecification(literal, lang) => Ok(Node::LiteralNode {
literal,
data_type: None,
language: Some(lang),
}),
Token::LiteralWithUrlDatatype(literal, datatype) => Ok(Node::LiteralNode {
literal,
data_type: Some(Uri::new(datatype)),
language: None,
}),
Token::Literal(literal) => Ok(Node::LiteralNode {
literal,
data_type: None,
language: None,
}),
_ => Err(Error::new(
ErrorType::InvalidToken,
"Invalid token for NTriples object.",
)),
}
}
}
#[cfg(test)]
mod tests {
use reader::n_triples_parser::NTriplesParser;
use reader::rdf_parser::RdfParser;
#[test]
fn test_read_n_triples_from_string() {
let input = "<http://www.w3.org/2001/sw/RDFCore/ntriples/> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://xmlns.com/foaf/0.1/Document> .
<http://www.w3.org/2001/sw/RDFCore/ntriples/> <http://purl.org/dc/terms/title> \"N-Triples\"@en-US .
<http://www.w3.org/2001/sw/RDFCore/ntriples/> <http://xmlns.com/foaf/0.1/maker> _:art .
_:art <http://xmlns.com/foaf/0.1/name> \"Art Barstow\" .";
let mut reader = NTriplesParser::from_string(input.to_string());
match reader.decode() {
Ok(graph) => assert_eq!(graph.count(), 4),
Err(e) => {
println!("Err {}", e.to_string());
assert!(false)
}
}
}
}