Adds BNF and text to extend LANGTAG to support base direction and ter…

…m construtors for creating directional language-tagged strings.

Fixes #32.

spec/index.html

@@ -85,7 +85,9 @@
       <a data-cite="RDF12-CONCEPTS#dfn-subject">subject</a> or
       <a data-cite="RDF12-CONCEPTS#dfn-object">object</a> of another
       <a data-cite="RDF12-CONCEPTS#dfn-rdf-triple">triple</a>,
-      making it possible to make statements about other statements.</p>
+      making it possible to make statements about other statements.
+      RDF 1.2 N-Triples also adds support for
+      <a data-cite="RDF12-CONCEPTS#dfn-dir-lang-string">directional language-tagged strings</a>.</p>
   </section>
 
   <section id='sotd'>
@@ -231,7 +233,11 @@ <h3>RDF Literals</h3>
         are used to identify values such as strings, numbers, dates.</p>
 
       <p>Literals (Grammar production <a href="#grammar-production-literal">Literal</a>)
-        have a lexical form followed by a language tag, a datatype IRI, or neither.</p>
+        have a lexical form followed by a
+        <a data-cite="RDF12-CONCEPTS#dfn-language-tag">language tag</a>
+        (possibly including <a data-cite="RDF12-CONCEPTS#dfn-base-direction">base direction</a>),
+        a <a data-cite="RDF12-CONCEPTS#dfn-datatype-iri">datatype IRI</a>,
+        or neither.</p>
 
       <p>The representation of the lexical form consists of an
         initial delimiter <code>&quot;</code> (<span class="codepoint">U+0022</span>),
@@ -252,6 +258,9 @@ <h3>RDF Literals</h3>
         is the characters between the delimiters, after processing any escape sequences.
         If present, the <a data-cite="RDF12-CONCEPTS#dfn-language-tag">language tag</a>
         is preceded by a '<code>@</code>' (<span class="codepoint">U+0040</span>).
+        If present, the <a data-cite="RDF12-CONCEPTS#dfn-base-direction">base direction</a>
+        is included in the <a data-cite="RDF12-CONCEPTS#dfn-language-tag">language tag</a>
+        separated by '<code>--</code>'.
         If there is no language tag, there may be a <a data-cite="RDF12-CONCEPTS#dfn-datatype-iri">datatype IRI</a>,
         preceded by two concatenated <code>^</code> characters,
         each having the code point <span class="codepoint">U+005E</span>.
@@ -267,8 +276,9 @@ <h3>RDF Literals</h3>
         <http://example.org/show/218> <http://www.w3.org/2000/01/rdf-schema#label> "That Seventies Show"^^<http://www.w3.org/2001/XMLSchema#string> . # literal with XML Schema string datatype
         <http://example.org/show/218> <http://www.w3.org/2000/01/rdf-schema#label> "That Seventies Show" . # same as above
         <http://example.org/show/218> <http://example.org/show/localName> "That Seventies Show"@en . # literal with a language tag
+        <http://example.org/show/218> <http://example.org/show/localName> "That Seventies Show"@en-ltr . # literal with a language tag and base direction
         <http://example.org/show/218> <http://example.org/show/localName> "Cette Série des Années Septante"@fr-be .  # literal outside of ASCII range with a region subtag
-        <http://example.org/#spiderman> <http://example.org/text> "This is a multi-linenliteral with many quotes (""""")nand two apostrophes ('')." .
+        <http://example.org/#spiderman> <http://example.org/text> "This is a multi-linenliteral with many quotes (""""") and two apostrophes ('')." .
         <http://en.wikipedia.org/wiki/Helium> <http://example.org/elements/atomicNumber> "2"^^<http://www.w3.org/2001/XMLSchema#integer> . # xsd:integer
         <http://en.wikipedia.org/wiki/Helium> <http://example.org/elements/specificGravity> "1.663E-4"^^<http://www.w3.org/2001/XMLSchema#double> .     # xsd:double
         -->
@@ -325,7 +335,7 @@ <h2>A Canonical form of N-Triples</h2>
         any of which MUST be a single space (<code>U+0020</code>).</li>
       <li><a data-cite="RDF12-CONCEPTS#dfn-literal">Literals</a> with the
         datatype <code>http://www.w3.org/2001/XMLSchema#string</code>
-        MUST NOT use the datatype IRI part of the <a href="#grammar-production-literal">literal</a>,
+        MUST NOT use the <a data-cite="RDF12-CONCEPTS#dfn-datatype-iri">datatype IRI</a> part of the <a href="#grammar-production-literal">literal</a>,
         and are represented using only <a href="#grammar-production-STRING_LITERAL_QUOTE">STRING_LITERAL_QUOTE</a>.
       </li>
       <li><code><a href="#grammar-production-HEX">HEX</a></code> MUST use only uppercase letters (<code>[A-F]</code>).</li>
@@ -498,7 +508,9 @@ <h3>RDF Term Constructors</h3>
               <a data-cite="RDF12-CONCEPTS#dfn-language-tag">language tag</a>
             </td>
             <td>
-              The characters following the <code>@</code> form the unicode string of the language tag.
+              The characters following the <code>@</code> form the unicode string of the <a data-cite="RDF12-CONCEPTS#dfn-language-tag">language tag</a>
+              and optionally the <a data-cite="RDF12-CONCEPTS#dfn-base-direction">base direction</a>,
+              if the matched characters include '<code>--</code>'.
             </td>
           </tr>
           <tr id="handle-STRING_LITERAL_QUOTE">
@@ -523,13 +535,24 @@ <h3>RDF Term Constructors</h3>
             <td>
               The literal has a lexical form of the first rule argument,
               <code>STRING_LITERAL_QUOTE</code>,
-              and either a language tag of <code>LANGTAG</code>
-              or a datatype IRI of <code>iri</code>,
+              and either a <a data-cite="RDF12-CONCEPTS#dfn-language-tag">language tag</a>
+              with optional <a data-cite="RDF12-CONCEPTS#dfn-base-direction">base direction</a>
+              from <code><a href="#grammar-production-LANGTAG" class="type langTag">LANGTAG</a></code>
+              or a <a data-cite="RDF12-CONCEPTS#dfn-datatype-iri">datatype IRI</a> of <code>iri</code>,
               depending on which rule matched the input.
-              If the <code>LANGTAG</code> rule matched,
+              If the <code><a href="#grammar-production-LANGTAG" class="type langTag">LANGTAG</a></code> rule matched,
+              it is split into <a data-cite="RDF12-CONCEPTS#dfn-language-tag">language tag</a>
+              and <a data-cite="RDF12-CONCEPTS#dfn-base-direction">base direction</a>
+              on '<code>--</code>'.
+              If there is no <a data-cite="RDF12-CONCEPTS#dfn-base-direction">base direction</a>,
               the datatype is <code>rdf:langString</code>
-              and the language tag is <code>LANGTAG</code>.
-              If neither a language tag nor a datatype IRI is provided,
+              and the <a data-cite="RDF12-CONCEPTS#dfn-language-tag">language tag</a> is <code><a href="#grammar-production-LANGTAG" class="type langTag">LANGTAG</a></code>.
+              If there is a base direction, the datatype is <code>rdf:dirLangString</code>,
+              the <a data-cite="RDF12-CONCEPTS#dfn-language-tag">language tag</a> is
+              taken from the portion of the matched <code><a href="#grammar-production-LANGTAG" class="type langTag">LANGTAG</a></code> proceding '<code>--</code>'
+              and the <a data-cite="RDF12-CONCEPTS#dfn-base-direction">base direction</a>
+              is taken from the portion of the matched <code><a href="#grammar-production-LANGTAG" class="type langTag">LANGTAG</a></code> following '<code>--</code>'.
+              If neither a language tag nor a <a data-cite="RDF12-CONCEPTS#dfn-datatype-iri">datatype IRI</a> is provided,
               the literal has a datatype of <code>xsd:string</code>.
             </td>
           </tr>
@@ -743,8 +766,10 @@ <h2>Changes between RDF 1.1 and RDF 1.2</h2>
     <li>Separated <a href="#security"></a> from <a href="#sec-mediaReg-n-triples"></a>
       and updated language.</li>
     <li>Changes <a href="#canonical-ntriples"></a> to clarify
-      use of datatype IRIs and expand the use of escapes
+      use of <a data-cite="RDF12-CONCEPTS#dfn-datatype-iri">datatype IRIs</a> and expand the use of escapes
       in literals.</li>
+    <li>Extends <a href="#grammar-production-LANGTAG" class="type langTag">LANGTAG</a> to include
+      an optional <a data-cite="RDF12-CONCEPTS#dfn-base-direction">base direction</a>.</li>
 </ul>
 </section>
 

spec/ntriples-bnf.html

@@ -64,7 +64,7 @@ <h3 id="terminals">Productions for terminals</h3>
       <td>[11]</td>
       <td><code>LANGTAG</code></td>
       <td>::=</td>
-      <td>"<code class="grammar-literal">@</code>" <code class="grammar-brac">[</code><code class="grammar-literal">a-zA-Z</code><code class="grammar-brac">]</code><code class="grammar-plus">+</code> <code class="grammar-paren">(</code>"<code class="grammar-literal">-</code>" <code class="grammar-brac">[</code><code class="grammar-literal">a-zA-Z0-9</code><code class="grammar-brac">]</code><code class="grammar-plus">+</code><code class="grammar-paren">)</code><code class="grammar-star">*</code></td>
+      <td>"<code class="grammar-literal">@</code>" <code class="grammar-brac">[</code><code class="grammar-literal">a-zA-Z</code><code class="grammar-brac">]</code><code class="grammar-plus">+</code> <code class="grammar-paren">(</code>"<code class="grammar-literal">-</code>" <code class="grammar-brac">[</code><code class="grammar-literal">a-zA-Z0-9</code><code class="grammar-brac">]</code><code class="grammar-plus">+</code><code class="grammar-paren">)</code><code class="grammar-star">*</code> <code class="grammar-paren">(</code>"<code class="grammar-literal">--</code>" <code class="grammar-brac">[</code><code class="grammar-literal">a-zA-Z0-9</code><code class="grammar-brac">]</code><code class="grammar-plus">+</code><code class="grammar-paren">)</code><code class="grammar-opt">?</code></td>
     </tr>
     <tr id="grammar-production-STRING_LITERAL_QUOTE">
       <td>[12]</td>

spec/ntriples.bnf

@@ -10,7 +10,7 @@ quotedTriple      ::= '<<' subject predicate object '>>'
 
 IRIREF            ::=  '<' ([^#x00-#x20<>"{}|^`\] | UCHAR)* '>'
 BLANK_NODE_LABEL  ::= '_:' ( PN_CHARS_U | [0-9] ) ((PN_CHARS|'.')* PN_CHARS)?
-LANGTAG           ::= "@" [a-zA-Z]+ ( "-" [a-zA-Z0-9]+ )*
+LANGTAG           ::= "@" [a-zA-Z]+ ( "-" [a-zA-Z0-9]+ )* ( "--" [a-zA-Z0-9]+ )?
 STRING_LITERAL_QUOTE ::= '"' ( [^#x22#x5C#xA#xD] | ECHAR | UCHAR )* '"'
 UCHAR             ::= ( "\u" HEX HEX HEX HEX )
                     | ( "\U" HEX HEX HEX HEX HEX HEX HEX HEX )