Support for serializing NaN

package.json

@@ -1,6 +1,6 @@
 {
   "name": "quadstore",
-  "version": "15.2.0",
+  "version": "15.3.0-beta.1",
   "description": "Quadstore is a LevelDB-backed RDF graph database / triplestore for JavaScript runtimes (browsers, Node.js, Deno, Bun, ...) that implements the RDF/JS interfaces and supports SPARQL queries and querying across named graphs.",
   "keywords": [
     "node",

src/serialization/fpstring.ts

@@ -44,6 +44,8 @@
  * +------+------------+-----------------------------------------+--------------------+------------+
  * | 6    | Infinity   |                                         |                    |            |
  * +------+------------+-----------------------------------------+--------------------+------------+
+ * | 7    | NaN        |                                         |                    |            |
+ * +------+------------+-----------------------------------------+--------------------+------------+
  *
  */
 
@@ -64,6 +66,7 @@ const join = (encodingCase: number, exponent: number, mantissa: number): string
 const ZERO = join(3, 0, 0);
 const NEG_INF = join(0, 0, 0);
 const POS_INF = join(6, 0, 0);
+const NAN = join(7, 0, 0);
 
 export const encode = (stringOrNumber: string|number): string => {
 
@@ -72,7 +75,7 @@ export const encode = (stringOrNumber: string|number): string => {
     : stringOrNumber;
 
   if (Number.isNaN(mantissa)) {
-    throw new Error(`Cannot serialize NaN`);
+    return NAN;
   }
 
   if (mantissa === -Infinity) {

src/serialization/terms.ts

@@ -169,6 +169,7 @@ export const termWriter: TermWriter<Term, 'F'> = {
               stringLiteralWriter.write(term, serialized, prefixes);
               break;
             case xsd.integer:
+            case xsd.float:
             case xsd.double:
             case xsd.decimal:
             case xsd.nonPositiveInteger:

src/serialization/xsd.ts

@@ -12,6 +12,7 @@ export const boolean = `${xsd}boolean`;
 
 export const integer = `${xsd}integer`;
 export const decimal = `${xsd}decimal`;
+export const float = `${xsd}float`;
 export const double = `${xsd}double`;
 export const nonPositiveInteger = `${xsd}nonPositiveInteger`;
 export const negativeInteger = `${xsd}negativeInteger`;

test/quadstore/serialization.ts

@@ -103,6 +103,21 @@ export const runSerializationTests = () => {
         toEqualQuad(read, quad);
       });
     });
+
+    it('Should serialize and deserialize a quad having a NaN literal term', async function () {
+      const { store: { dataFactory: factory, indexes }, prefixes } = this;
+      const quad = factory.quad(
+        factory.namedNode('http://ex.com/s'),
+        factory.namedNode('http://ex.com/p'),
+        factory.literal('NaN', factory.namedNode(xsd.double)),
+        factory.namedNode('http://ex.com/g'),
+      );
+      indexes.forEach((index: InternalIndex) => {
+        const key = twoStepsQuadWriter.ingest(quad, prefixes).write(index.prefix, index.terms);
+        const read = quadReader.read(key, index.prefix.length, index.terms, factory, prefixes);
+        toEqualQuad(read, quad);
+      });
+    });
 
   });