Add generic QuadToRdfConverter

src/storage/conversion/QuadToRdfConverter.ts

@@ -0,0 +1,31 @@
+import { Readable } from 'stream';
+import rdfSerializer from 'rdf-serialize';
+import { Representation } from '../../ldp/representation/Representation';
+import { RepresentationMetadata } from '../../ldp/representation/RepresentationMetadata';
+import { RepresentationPreferences } from '../../ldp/representation/RepresentationPreferences';
+import { CONTENT_TYPE_QUADS, DATA_TYPE_BINARY } from '../../util/ContentTypes';
+import { checkRequest, matchingTypes } from './ConversionUtil';
+import { RepresentationConverter, RepresentationConverterArgs } from './RepresentationConverter';
+
+/**
+ * Converts `internal/quads` to most major RDF serializations.
+ */
+export class QuadToRdfConverter extends RepresentationConverter {
+  public async canHandle(input: RepresentationConverterArgs): Promise<void> {
+    checkRequest(input, [ CONTENT_TYPE_QUADS ], await rdfSerializer.getContentTypes());
+  }
+
+  public async handle(input: RepresentationConverterArgs): Promise<Representation> {
+    return this.quadsToRdf(input.representation, input.preferences);
+  }
+
+  private async quadsToRdf(quads: Representation, preferences: RepresentationPreferences): Promise<Representation> {
+    const contentType = matchingTypes(preferences, await rdfSerializer.getContentTypes())[0].value;
+    const metadata: RepresentationMetadata = { ...quads.metadata, contentType };
+    return {
+      dataType: DATA_TYPE_BINARY,
+      data: rdfSerializer.serialize(quads.data, { contentType }) as Readable,
+      metadata,
+    };
+  }
+}