Optimises Turtle URI and string literals decoding

Avoids copies when possible

src/rio/turtle/mod.rs

@@ -5,18 +5,21 @@ mod grammar {
     #![allow(clippy)]
 
     use model::*;
+    use rio::utils::unescape_characters;
+    use std::borrow::Cow;
     use std::collections::BTreeMap;
     use std::collections::HashMap;
     use std::io::BufReader;
     use std::io::Read;
     use url::ParseOptions;
     use url::Url;
+    use utils::StaticSliceMap;
 
     include!(concat!(env!("OUT_DIR"), "/turtle_grammar.rs"));
 
     pub struct ParserState {
         base_uri: Option<Url>,
-        namespaces: HashMap<String, String>,
+        namespaces: HashMap<String, Url>,
         cur_subject: Vec<NamedOrBlankNode>,
         cur_predicate: Vec<NamedNode>,
         bnodes_map: BTreeMap<String, BlankNode>,
@@ -47,6 +50,21 @@ mod grammar {
         turtleDoc(&string_buffer, &mut state, &mut triple_buffer)?;
         Ok(triple_buffer.into_iter())
     }
+
+    const UNESCAPE_CHARACTERS: [u8; 8] = [b't', b'b', b'n', b'r', b'f', b'"', b'\'', b'\\'];
+    lazy_static! {
+        static ref UNESCAPE_REPLACEMENT: StaticSliceMap<char, char> = StaticSliceMap::new(
+            &['t', 'b', 'n', 'r', 'f', '"', '\'', '\\'],
+            &[
+                '\u{0009}', '\u{0008}', '\u{000A}', '\u{000D}', '\u{000C}', '\u{0022}', '\u{0027}',
+                '\u{005C}'
+            ]
+        );
+    }
+
+    pub fn unescape_echars(input: &str) -> Cow<str> {
+        unescape_characters(input, &UNESCAPE_CHARACTERS, &UNESCAPE_REPLACEMENT)
+    }
 }
 
 pub(crate) type ParseError = self::grammar::ParseError;

src/rio/turtle/turtle_grammar.rustpeg

@@ -4,6 +4,7 @@ use std::char;
 use model::vocab::rdf;
 use model::vocab::xsd;
 use std::iter;
+use rio::utils::unescape_unicode_codepoints;
 
 #![arguments(state: &mut ParserState, buffer: &mut Vec<Triple>)]
 
@@ -22,25 +23,13 @@ prefixID -> () = "@prefix" _ ns:PNAME_NS _ i:IRIREF _ "." {
 }
 
 //[5]
-base -> () = "@base" _ i:IRIREF _ "." {?
-    match state.url_parser().parse(&i) {
-        Ok(url) => {
+base -> () = "@base" _ url:IRIREF _ "." {
     state.base_uri = Some(url);
-            Ok(())
-        },
-        Err(error) => Err("IRI parsing failed")
-    }
 }
 
 //[5s]
-sparqlBase -> () = "BASE"i _ i:IRIREF {?
-    match state.url_parser().parse(&i) {
-        Ok(url) => {
+sparqlBase -> () = "BASE"i _ url:IRIREF {
     state.base_uri = Some(url);
-            Ok(())
-        },
-        Err(error) => Err("IRI parsing failed")
-    }
 }
 
 //[6s]
@@ -149,15 +138,12 @@ BooleanLiteral -> Literal =
 String -> String = STRING_LITERAL_LONG_SINGLE_QUOTE / STRING_LITERAL_LONG_QUOTE / STRING_LITERAL_QUOTE / STRING_LITERAL_SINGLE_QUOTE
 
 //[135s]
-iri -> NamedNode = i:(IRIREF / PrefixedName) {?
-    match state.url_parser().parse(&i) {
-       Ok(url) => Ok(NamedNode::new(url)),
-       Err(error) => Err("IRI parsing failed")
-    }
+iri -> NamedNode = i:(IRIREF / PrefixedName) {
+    i.into()
 }
 
 //[136s]
-PrefixedName -> String = PNAME_LN /
+PrefixedName -> Url = PNAME_LN /
     ns:PNAME_NS {? state.namespaces.get(ns).map(|v| v.clone()).ok_or("Prefix not found") }
 
 //[137s]
@@ -166,10 +152,12 @@ BlankNode -> BlankNode =
     ANON { BlankNode::default() }
 
 //[18]
-IRIREF -> String = "<" i:((_IRIREF_simple_char / UCHAR)*) ">" {
-    i.into_iter().collect()
+IRIREF -> Url = "<" i:$(([^\u{00}-\u{20}<>"{}|^\u{60}\u{5c}] / UCHAR)*) ">" {?
+    match state.url_parser().parse(&unescape_unicode_codepoints(i)) {
+       Ok(url) => Ok(url),
+       Err(error) => Err("IRI parsing failed")
+    }
 }
-_IRIREF_simple_char -> char = c:$([^\u{00}-\u{20}<>"{}|^\u{60}\u{5c}]) { c.chars().next().unwrap() }
 
 //[139s]
 PNAME_NS -> &'input str = ns:$(PN_PREFIX? ":") {
@@ -177,8 +165,14 @@ PNAME_NS -> &'input str = ns:$(PN_PREFIX? ":") {
 }
 
 //[140s]
-PNAME_LN -> String = ns:$(PNAME_NS) local:PN_LOCAL {?
-    state.namespaces.get(ns).map(|v| v.clone() + &local).ok_or("Prefix not found")
+PNAME_LN -> Url = ns:$(PNAME_NS) local:PN_LOCAL {?
+    match state.namespaces.get(ns) {
+        Some(ns) => match ns.join(&local) {
+            Ok(url) => Ok(url),
+            Err(error) => Err("IRI parsing failed")
+        },
+        None => Err("Prefix not found")
+    }
 }
 
 //[141s]
@@ -204,60 +198,32 @@ DOUBLE -> () = [+-]? ([0-9]+ "." [0-9]* / "."? [0-9]+) EXPONENT
 EXPONENT -> () = [eE] [+-]? [0-9]+
 
 //[22]
-STRING_LITERAL_QUOTE -> String = "\"" l:((STRING_LITERAL_QUOTE_simple_char / ECHAR / UCHAR)*) "\"" {
-    l.into_iter().collect()
+STRING_LITERAL_QUOTE -> String = "\"" l: $(([^"\u{005c}\u{000a}\u{000d}] / ECHAR / UCHAR)*) "\"" {
+    unescape_unicode_codepoints(&unescape_echars(l)).into_owned()
 }
-STRING_LITERAL_QUOTE_simple_char -> char = c:$([^"\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 -> String = "'" l:$(([^'\u{005c}\u{000a}\u{000d}] / ECHAR / UCHAR)*) "'" {
+    unescape_unicode_codepoints(&unescape_echars(l)).into_owned()
 }
-STRING_LITERAL_SINGLE_QUOTE_simple_char -> char = c:$([^'\u{005c}\u{000a}\u{000d}]) { c.chars().next().unwrap() }
 
 //[24]
-STRING_LITERAL_LONG_SINGLE_QUOTE -> String = "'''" l:(STRING_LITERAL_LONG_SINGLE_QUOTE_inner*) "'''" {
-    l.into_iter().collect()
+STRING_LITERAL_LONG_SINGLE_QUOTE -> String = "'''" l:$(STRING_LITERAL_LONG_SINGLE_QUOTE_inner*) "'''" {
+    unescape_unicode_codepoints(&unescape_echars(l)).into_owned()
 }
-STRING_LITERAL_LONG_SINGLE_QUOTE_inner -> String = a:$(("''" / "'")?) b:(STRING_LITERAL_LONG_SINGLE_QUOTE_simple_char / ECHAR / UCHAR) {
-    let mut s = a.to_string();
-    s.push(b);
-    s
-}
-STRING_LITERAL_LONG_SINGLE_QUOTE_simple_char -> char = c:$([^'\u{005c}]) { c.chars().next().unwrap() }
+STRING_LITERAL_LONG_SINGLE_QUOTE_inner -> () = ("''" / "'")? ([^'\u{005c}] / ECHAR / UCHAR)
 
 //[25]
-STRING_LITERAL_LONG_QUOTE -> String = "\"\"\"" l:(STRING_LITERAL_LONG_QUOTE_inner*) "\"\"\"" {
-    l.into_iter().collect()
-}
-STRING_LITERAL_LONG_QUOTE_inner -> String = a:$(("\"\"" / "\"")?) b:(STRING_LITERAL_LONG_QUOTE_simple_char / ECHAR / UCHAR) {
-    let mut s = a.to_string();
-    s.push(b);
-    s
+STRING_LITERAL_LONG_QUOTE -> String = "\"\"\"" l:$(STRING_LITERAL_LONG_QUOTE_inner*) "\"\"\"" {
+    unescape_unicode_codepoints(&unescape_echars(l)).into_owned()
 }
-STRING_LITERAL_LONG_QUOTE_simple_char -> char = c:$([^"\u{005c}]) { c.chars().next().unwrap() }
+STRING_LITERAL_LONG_QUOTE_inner -> () = ("\"\"" / "\"")? ([^"\u{005c}] / ECHAR / UCHAR)
 
 //[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()
-}
+UCHAR -> () = "\\u" HEX HEX HEX HEX / "\\U" HEX HEX HEX HEX HEX HEX HEX HEX
 
 //[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
-    }
-}
+ECHAR -> () = "\\" [tbnrf"'\\]
 
 //[161s]
 WS -> () = #quiet<[\u{20}\u{9}\u{D}\u{A}]>

src/rio/utils.rs

@@ -14,7 +14,7 @@ pub fn unescape_unicode_codepoints(input: &str) -> Cow<str> {
 fn needs_unescape_unicode_codepoints(input: &str) -> bool {
     let bytes = input.as_bytes();
     for i in 1..bytes.len() {
-        if (bytes[i] == b'u' || bytes[i] == b'U') && bytes[i - 1] == b'/' {
+        if (bytes[i] == b'u' || bytes[i] == b'U') && bytes[i - 1] == b'\\' {
             return true;
         }
     }
@@ -108,7 +108,7 @@ pub fn unescape_characters<'a>(
 fn needs_unescape_characters(input: &str, characters: &[u8]) -> bool {
     let bytes = input.as_bytes();
     for i in 1..bytes.len() {
-        if bytes[i - 1] == b'/' && characters.contains(&bytes[i]) {
+        if bytes[i - 1] == b'\\' && characters.contains(&bytes[i]) {
             return true;
         }
     }

src/utils.rs

@@ -78,6 +78,19 @@ impl ExactSizeIterator for EscapeRDF {
     }
 }
 
+#[test]
+fn test_escaper() {
+    assert_eq!("foo", "foo".escape());
+    assert_eq!(
+        "John said: \\\"Hello World!\\\"",
+        "John said: \"Hello World!\"".escape()
+    );
+    assert_eq!(
+        "John said: \\\"Hello World!\\\\\\\"",
+        "John said: \"Hello World!\\\"".escape()
+    );
+}
+
 pub struct StaticSliceMap<K: 'static + Copy + Eq, V: 'static + Copy> {
     keys: &'static [K],
     values: &'static [V],

tests/rdf_test_cases.rs

@@ -73,8 +73,8 @@ fn turtle_w3c_testsuite() {
                         action_graph.is_isomorphic(&result_graph).unwrap(),
                         "Failure on {}. Expected file:\n{}\nParsed file:\n{}\n",
                         test,
-                        action_graph,
-                        result_graph
+                        result_graph,
+                        action_graph
                     ),
                     Err(error) => assert!(
                         false,