Adds a basic Turtle parser

build.rs

@@ -1,5 +1,6 @@
 extern crate peg;
 
 fn main() {
-    peg::cargo_build("src/rio/ntriples/grammar.rustpeg");
+    peg::cargo_build("src/rio/ntriples/ntriples_grammar.rustpeg");
+    peg::cargo_build("src/rio/turtle/turtle_grammar.rustpeg");
 }

src/rio/mod.rs

@@ -2,6 +2,7 @@ use std::error::Error;
 use std::fmt;
 
 pub mod ntriples;
+pub mod turtle;
 
 pub type RioResult<T> = Result<T, RioError>;
 

src/rio/ntriples/mod.rs

@@ -1,7 +1,7 @@
 ///Implements https://www.w3.org/TR/n-triples/
 
 mod grammar {
-    include!(concat!(env!("OUT_DIR"), "/grammar.rs"));
+    include!(concat!(env!("OUT_DIR"), "/ntriples_grammar.rs"));
 }
 
 use model::data::*;
@@ -15,7 +15,7 @@ pub fn read_ntriples<'a, R: Read + 'a>(
     data_factory: &'a DataFactory,
 ) -> impl Iterator<Item = RioResult<Triple>> {
     let factory = data_factory.clone(); //TODO: try to avoid clone here
-    //TODO: use read_lines to avoid allocations
+                                        //TODO: use read_lines to avoid allocations
     BufReader::new(source)
         .lines()
         .flat_map(move |line| match line {

src/rio/ntriples/ntriples_grammar.rustpeg

@@ -35,8 +35,8 @@ literal -> Literal =
 
 
 //[144s]
-LANGTAG -> String = "@" l: $([a-zA-Z]+ ("-" [a-zA-Z0-9]+)*) {
+LANGTAG -> &'input str = "@" l: $([a-zA-Z]+ ("-" [a-zA-Z0-9]+)*) {
-    l.into()
+    l
 }
 
 //[7]
@@ -55,8 +55,8 @@ STRING_LITERAL_QUOTE -> String = "\"" l: ((STRING_LITERAL_QUOTE_simple_char / EC
 STRING_LITERAL_QUOTE_simple_char -> char = c: $([^\u{0022}\u{005c}\u{000a}\u{000d}]) { c.chars().next().unwrap() }
 
 //[141s]
-BLANK_NODE_LABEL -> String = "_:" b: $((PN_CHARS_U / [0-9]) ((PN_CHARS / ".")* PN_CHARS)?) {
+BLANK_NODE_LABEL -> &'input str = "_:" b: $((PN_CHARS_U / [0-9]) ((PN_CHARS / ".")* PN_CHARS)?) {
-    b.into()
+    b
 }
 
 //[10]
@@ -93,6 +93,7 @@ PN_CHARS -> () = PN_CHARS_U / [\-0-9\u{00B7}\u{0300}-\u{036F}\u{203F}-\u{2040}]
 //[162s]
 HEX -> () = ([0-9A-Fa-f])
 
+
 //space
 _ = #quiet<[ \t]*>
 //comment

src/rio/turtle/mod.rs

@@ -0,0 +1,42 @@
+/// Implements https://www.w3.org/TR/turtle/
+
+mod grammar {
+    include!(concat!(env!("OUT_DIR"), "/turtle_grammar.rs"));
+}
+
+use model::data::*;
+use rio::*;
+use std::collections::HashMap;
+use std::io::BufReader;
+use std::io::Read;
+
+//TODO: make private
+pub struct ParserState {
+    pub base_uri: String,
+    pub namespaces: HashMap<String, String>,
+    pub cur_subject: Vec<NamedOrBlankNode>,
+    pub cur_predicate: Vec<NamedNode>,
+}
+
+pub fn read_turtle<'a, R: Read + 'a>(
+    source: R,
+    data_factory: &'a DataFactory,
+) -> RioResult<impl Iterator<Item = Triple>> {
+    let factory = data_factory.clone(); //TODO: try to avoid clone here
+    let mut state = ParserState {
+        base_uri: String::default(),
+        namespaces: HashMap::default(),
+        cur_subject: Vec::default(),
+        cur_predicate: Vec::default(),
+    };
+    let mut string_buffer = String::default();
+    let mut triple_buffer = Vec::default();
+    match BufReader::new(source).read_to_string(&mut string_buffer) {
+        Ok(_) => match grammar::turtleDoc(&string_buffer, &mut state, &mut triple_buffer, &factory)
+        {
+            Ok(_) => Ok(triple_buffer.into_iter()),
+            Err(error) => Err(RioError::new(error)),
+        },
+        Err(error) => Err(RioError::new(error)),
+    }
+}

src/rio/turtle/turtle_grammar.rustpeg

@@ -0,0 +1,275 @@
+//See https://www.w3.org/TR/turtle/#sec-grammar
+
+use std::char;
+use std::iter;
+use model::data::*;
+use rio::turtle::ParserState;
+
+#![arguments(state: &mut ParserState, buffer: &mut Vec<Triple>, data_factory: &DataFactory)]
+
+//[1]
+#[pub]
+turtleDoc -> () = _ (statement _)*
+
+//[2]
+statement -> () = directive / triples "."
+
+//[3]
+directive -> () = prefixID / base / sparqlPrefix / sparqlBase
+
+//[4]
+prefixID -> () = "@prefix" _ ns:PNAME_NS _ i:IRIREF _ "." {
+    state.namespaces.insert(ns.into(), i.into());
+}
+
+//[5]
+base -> () = "@base" _ i:IRIREF _ "." {
+    state.base_uri = i.into();
+}
+
+//[5s]
+sparqlBase -> () = "BASE"i _ i:IRIREF {
+    state.base_uri = i.into();
+}
+
+//[6s]
+sparqlPrefix -> () = "PREFIX"i _ ns:PNAME_NS _ i:IRIREF {
+    state.namespaces.insert(ns.into(), i.into());
+}
+
+//[6]
+triples -> () = subject_push _ predicateObjectList / triples_blankNodePropertyList_push _ predicateObjectList?
+subject_push -> () = s:subject {
+    state.cur_subject.push(s)
+}
+triples_blankNodePropertyList_push -> () = s: blankNodePropertyList {
+    state.cur_subject.push(s)
+}
+
+//[7]
+predicateObjectList -> () = predicate_push _ objectList _ (";" _ (predicate_push _ objectList _)?)*
+predicate_push -> () = v:verb {
+    state.cur_predicate.push(v)
+}
+
+//[8]
+objectList -> () = object _ ("," _ object _)*
+
+//[9]
+verb -> NamedNode = predicate /
+    "a" { data_factory.named_node("http://www.w3.org/1999/02/22-rdf-syntax-ns#type") }
+
+// [10]
+subject -> NamedOrBlankNode =
+    i:iri { i.into() } /
+    b:BlankNode { b.into() } /
+    c:collection { c }
+
+//[11]
+predicate -> NamedNode = iri
+
+// [12]
+object -> () = o:object_value {?
+    match state.cur_subject.last() {
+        Some(s) => match state.cur_predicate.last() {
+            Some(p) => {
+                buffer.push(data_factory.triple(s.clone(), p.clone(), o));
+                Ok(())
+            }
+            None => Err("Predicate not found")
+        },
+        None => Err("Subject not found")
+    }
+}
+
+object_value -> Term =
+    i:iri { i.into() } /
+    b:BlankNode { b.into() } /
+    c:collection { c.into() } /
+    b:blankNodePropertyList { b.into() } /
+    l:literal { l.into() }
+
+//[13]
+literal -> Literal = RDFLiteral / NumericLiteral / BooleanLiteral
+
+//[14]
+blankNodePropertyList -> NamedOrBlankNode = blankNodePropertyList_open _ predicateObjectList _ "]" {?
+    state.cur_subject.pop().ok_or("No subject found in the stack")
+}
+blankNodePropertyList_open -> () = "[" {
+    state.cur_subject.push(data_factory.new_blank_node().into())
+}
+
+//[15]
+collection -> NamedOrBlankNode = '(' _ o:(collection_value*) ')' {
+    let mut current_list_node = NamedOrBlankNode::from(data_factory.named_node("http://www.w3.org/1999/02/22-rdf-syntax-ns#nil"));
+    for obj in o.into_iter().rev() {
+        let new_blank_node = NamedOrBlankNode::from(data_factory.new_blank_node());
+        buffer.push(data_factory.triple(new_blank_node.clone(), data_factory.named_node("http://www.w3.org/1999/02/22-rdf-syntax-ns#first"), obj));
+        buffer.push(data_factory.triple(new_blank_node.clone(), data_factory.named_node("http://www.w3.org/1999/02/22-rdf-syntax-ns#rest"), current_list_node));
+        current_list_node = new_blank_node;
+    }
+    current_list_node
+}
+collection_value -> Term = o:object_value _ { o }
+
+//[16]
+NumericLiteral -> Literal =
+    i:$(INTEGER) { data_factory.typed_literal(i, data_factory.named_node("http://www.w3.org/2001/XMLSchema#integer")) } /
+    d:$(DECIMAL) { data_factory.typed_literal(d, data_factory.named_node("http://www.w3.org/2001/XMLSchema#decimal")) } /
+    d:$(DOUBLE) { data_factory.typed_literal(d, data_factory.named_node("http://www.w3.org/2001/XMLSchema#double")) }
+
+//[128s]
+RDFLiteral -> Literal =
+    v:String _ "^^" _ t:iri { data_factory.typed_literal(v, t) } /
+    v:String _ l:LANGTAG { data_factory.language_tagged_literal(v, l) } /
+    v:String { data_factory.simple_literal(v) }
+
+//[133s]
+BooleanLiteral -> Literal =
+    "true" { data_factory.typed_literal("true", data_factory.named_node("http://www.w3.org/2001/XMLSchema#boolean")) } /
+    "false" { data_factory.typed_literal("false", data_factory.named_node("http://www.w3.org/2001/XMLSchema#boolean")) }
+
+//[17]
+String -> String = STRING_LITERAL_QUOTE / STRING_LITERAL_SINGLE_QUOTE / STRING_LITERAL_LONG_SINGLE_QUOTE / STRING_LITERAL_LONG_QUOTE
+
+//[135s]
+iri -> NamedNode = i:(IRIREF / PrefixedName) {
+    data_factory.named_node(i)
+}
+
+//[136s]
+PrefixedName -> String = PNAME_LN /
+    ns:PNAME_NS {? state.namespaces.get(ns).map(|v| v.clone()).ok_or("Prefix not found") }
+
+//[137s]
+BlankNode -> BlankNode =
+    b:BLANK_NODE_LABEL { data_factory.blank_node(b) } /
+    ANON { data_factory.new_blank_node() }
+
+//[18]
+IRIREF -> String = "<" _ i:((_IRIREF_simple_char / UCHAR)*) _ ">" {
+    //TODO: relative URIs resolution
+    i.into_iter().collect()
+}
+_IRIREF_simple_char -> char = c:$([^\u{00}-\u{20}<>"{}|^\u{60}\u{5c}]) { c.chars().next().unwrap() }
+
+//[139s]
+PNAME_NS -> &'input str = ns:$(PN_PREFIX? ":") {
+    ns
+}
+
+//[140s]
+PNAME_LN -> String = ns:$(PNAME_NS) local:$(PN_LOCAL) {?
+    state.namespaces.get(ns).map(|v| v.clone() + local).ok_or("Prefix not found")
+}
+
+//[141s]
+BLANK_NODE_LABEL -> &'input str = "_:" b:$((PN_CHARS_U / [0-9]) ((PN_CHARS / ".")* PN_CHARS)?) {
+    //TODO unescape
+    b
+}
+
+//[144s]
+LANGTAG -> &'input str = "@" l:$([a-zA-Z]+ ("-" [a-zA-Z0-9]+)*) {
+    l
+}
+
+//[19]
+INTEGER -> () = [+-]? [0-9]+
+
+//[20]
+DECIMAL -> () = [+-]? [0-9]* "." [0-9]+
+
+//[21]
+DOUBLE -> () = [+-]? ([0-9]+ "." [0-9]* EXPONENT / "." [0-9]+ EXPONENT / [0-9]+ EXPONENT)
+
+//[154s]
+EXPONENT -> () = [eE] [+-]? [0-9]+
+
+//[22]
+STRING_LITERAL_QUOTE -> String = "\"" l:((STRING_LITERAL_QUOTE_simple_char / ECHAR / UCHAR)*) "\"" {
+    l.into_iter().collect()
+}
+STRING_LITERAL_QUOTE_simple_char -> char = c:$([^\u{0022}\u{005c}\u{000a}\u{000d}]) { c.chars().next().unwrap() }
+
+//[23]
+STRING_LITERAL_SINGLE_QUOTE -> String = "'" l:((STRING_LITERAL_SINGLE_QUOTE_simple_char / ECHAR / UCHAR)*) "'" {
+    l.into_iter().collect()
+}
+STRING_LITERAL_SINGLE_QUOTE_simple_char -> char = c:$([^\u{0027}\u{005c}\u{000a}\u{000d}]) { c.chars().next().unwrap() }
+
+//[24]
+STRING_LITERAL_LONG_SINGLE_QUOTE -> String = "'''" ("'" / "''")? l:((STRING_LITERAL_LONG_SINGLE_QUOTE_simple_char / ECHAR / UCHAR)*) "'''" {
+    l.into_iter().collect()
+}
+STRING_LITERAL_LONG_SINGLE_QUOTE_simple_char -> char = c:$([^\u{0027}\u{005c}]) { c.chars().next().unwrap() }
+
+//[25]
+STRING_LITERAL_LONG_QUOTE -> String = "\"\"\"" ("\"" / "\"\"")? l:((STRING_LITERAL_LONG_QUOTE_simple_char / ECHAR / UCHAR)*) "\"\"\"" {
+l.into_iter().collect()
+}
+STRING_LITERAL_LONG_QUOTE_simple_char -> char = c:$([^\u{0022}\u{005c}]) { c.chars().next().unwrap() }
+
+//[26]
+UCHAR -> char = "\\u" h:$(HEX HEX HEX HEX) {
+    u32::from_str_radix(h, 16).ok().and_then(char::from_u32).unwrap()
+} / "\\U" h:$(HEX HEX HEX HEX HEX HEX HEX HEX) {
+    u32::from_str_radix(h, 16).ok().and_then(char::from_u32).unwrap()
+}
+
+//[159s]
+ECHAR -> char = "\\" c:$([tbnrf"'\\]) {
+    match c {
+        "t" => '\u{0009}',
+        "b" => '\u{0008}',
+        "n" => '\u{000A}',
+        "r" => '\u{000D}',
+        "f" => '\u{000C}',
+        "\"" => '\u{0022}',
+        "'" => '\u{0027}',
+        "\\" => '\u{005C}',
+        _ => panic!("unexpected escaped char") // not possible
+    }
+}
+
+//[161s]
+WS -> () = #quiet<[\u{20}\u{9}\u{D}\u{A}]>
+
+//[162s]
+ANON -> () = "[" WS* "]"
+
+//[163s]
+PN_CHARS_BASE -> () = [A-Za-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}]
+
+//[164s]
+PN_CHARS_U -> () = PN_CHARS_BASE / "_"
+
+//[166s]
+PN_CHARS -> () = PN_CHARS_U / [\-0-9\u{00B7}\u{0300}-\u{036F}\u{203F}-\u{2040}]
+
+//[167s]
+PN_PREFIX -> () = PN_CHARS_BASE PN_CHARS* ("." PN_CHARS+)*
+
+//[168s]
+PN_LOCAL -> () = (PN_CHARS_U / ":" / [0-9] / PLX) (PN_CHARS / ":" / PLX)* ("." (PN_CHARS / ":" / PLX)+)*
+
+//[169s]
+PLX -> String =
+    p:$(PERCENT) { p.into() } /
+    e:PN_LOCAL_ESC { iter::once(e).collect() }
+
+//[170s]
+PERCENT -> () = "%" HEX HEX
+
+//[171s]
+HEX -> () = ([0-9A-Fa-f])
+
+//[172s]
+PN_LOCAL_ESC -> char = "\\" c:$([_~\.\-!$&'()*+,;=/?#@%]) { c.chars().next().unwrap() }
+
+
+//space
+_ = #quiet<([ \t\n\r] / comment)*>
+//comment
+comment = #quiet<"#" [^\r\n]*>