Fix relative IRIs containing a forward slash and a colon

Co-authored-by: rubensworks <440384+rubensworks@users.noreply.github.com>

Author: Copilot

lib/RdfXmlParser.ts

@@ -141,6 +141,20 @@ export class RdfXmlParser extends Transform implements RDF.Sink<EventEmitter, RD
    * @return {NamedNode} an IRI.
    */
   public valueToUri(value: string, activeTag: IActiveTag): RDF.NamedNode {
+    // Per RFC 3986, a URI scheme must be: ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
+    // A forward slash is not allowed in a URI scheme, so a value like 'x/y:z' where a slash
+    // appears before the colon is unambiguously a relative IRI (not an absolute one).
+    // The relative-to-absolute-iri library incorrectly treats any value with a colon as absolute,
+    // so we must pre-process such relative IRIs containing a slash before the colon.
+    // We temporarily replace all colons with the null character U+0000 (which is illegal in XML
+    // and therefore can never legitimately appear in a parsed IRI value), resolve against the base
+    // IRI treating the whole value as a relative path, then restore the colons.
+    const colonPos = value.indexOf(':');
+    const firstSlashPos = value.indexOf('/');
+    if (colonPos > 0 && firstSlashPos >= 0 && firstSlashPos < colonPos) {
+      const encoded = value.split(':').join('\u0000');
+      return this.uriToNamedNode(resolve(encoded, activeTag.baseIRI).split('\u0000').join(':'));
+    }
     return this.uriToNamedNode(resolve(value, activeTag.baseIRI));
   }
 

test/RdfXmlParser-test.ts

@@ -211,6 +211,21 @@ abc`)).rejects.toBeTruthy();
         expect(parser.valueToUri('xyz', { baseIRI: 'http://aa/././a' }))
           .toEqual(DF.namedNode('http://aa/xyz'));
       });
+
+      it('create a named node from a relative IRI with a slash before the colon', () => {
+        expect(parser.valueToUri('x/y:z', { baseIRI: 'http://base.org/path/' }))
+          .toEqual(DF.namedNode('http://base.org/path/x/y:z'));
+      });
+
+      it('create a named node from a relative IRI with a slash before the colon and no trailing slash on base', () => {
+        expect(parser.valueToUri('x/y:z', { baseIRI: 'http://base.org/path' }))
+          .toEqual(DF.namedNode('http://base.org/x/y:z'));
+      });
+
+      it('create a named node from a relative IRI with multiple colons after a slash', () => {
+        expect(parser.valueToUri('x/y:z:w', { baseIRI: 'http://base.org/path/' }))
+          .toEqual(DF.namedNode('http://base.org/path/x/y:z:w'));
+      });
     });
 
     describe('should error with line numbers', () => {
@@ -2100,6 +2115,21 @@ abc`)).rejects.toBeTruthy();
           ]);
       });
 
+      // 2.14 - relative IRI with a colon after a slash
+      it('relative IRI containing a slash before a colon should be resolved against the base IRI', async () => {
+        const parserThis = new RdfXmlParser({ baseIRI: 'https://example.com/base/' });
+        const array = await parse(parserThis, `<?xml version="1.0" encoding="UTF-8"?>
+<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+         xmlns:default="https://example.com/default/">
+  <default:C rdf:about="x/y:z"/>
+</rdf:RDF>`);
+        return expect(array)
+          .toBeRdfIsomorphic([
+            quad('https://example.com/base/x/y:z', 'http://www.w3.org/1999/02/22-rdf-syntax-ns#type',
+              'https://example.com/default/C'),
+          ]);
+      });
+
       // 2.15
       it('rdf:li properties', async () => {
         const array = await parse(parser, `<?xml version="1.0"?>