--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/layout/json_ld_quads.ts	Sun Mar 13 22:00:30 2022 -0700
@@ -0,0 +1,67 @@
+import * as jsonld from "jsonld";
+import { JsonLd, JsonLdArray } from "jsonld/jsonld-spec";
+import { Quad, NamedNode, DataFactory } from "n3";
+const { literal, quad, namedNode } = DataFactory;
+
+// const { rdf } = ns;
+const rdf = { type: "http://www.w3.org/1999/02/22-rdf-syntax-ns#type" };
+
+function parseObjNode(obj: any) {
+  if (obj["@id"]) {
+    return namedNode(obj["@id"]);
+  } else {
+    if (obj["@value"] === undefined) {
+      throw new Error("no @id or @value");
+    }
+    return literal(obj["@value"], obj["@language"] || obj["@type"]);
+  }
+}
+
+function parsePred(
+  onQuad: (q: Quad) => void,
+  graphNode: NamedNode,
+  subjNode: NamedNode,
+  predKey: string,
+  subjGroup: any
+) {
+  let predNode: NamedNode;
+  if (predKey === "@type") {
+    subjGroup["@type"].forEach((aType: string) => {
+      onQuad(quad(subjNode, namedNode(rdf.type), namedNode(aType), graphNode));
+    });
+    return;
+  }
+  predNode = namedNode(predKey);
+  subjGroup[predKey].forEach(function(obj: any) {
+    const objNode = parseObjNode(obj);
+    onQuad(quad(subjNode, predNode, objNode, graphNode));
+  });
+}
+function parseSubj(
+  onQuad: (q: Quad) => void,
+  graphNode: NamedNode,
+  subjGroup: { [predOrId: string]: any }
+) {
+  const subjNode = namedNode(subjGroup["@id"]);
+  for (let predKey in subjGroup) {
+    if (predKey === "@id") {
+      continue;
+    }
+    parsePred(onQuad, graphNode, subjNode, predKey, subjGroup);
+  }
+}
+function parseGraph(onQuad: (q: Quad) => void, g: JsonLd) {
+  var graph = (g as { "@id": string })["@id"];
+  var graphNode = namedNode(graph);
+  (g as { "@graph": JsonLdArray })["@graph"].forEach(subj => {
+    parseSubj(onQuad, graphNode, subj);
+  });
+}
+
+export async function eachJsonLdQuad(
+  jsonLdObj: object,
+  onQuad: (q: Quad) => void
+) {
+  const expanded = await jsonld.expand(jsonLdObj);
+  (expanded as JsonLdArray).forEach((g: JsonLd) => parseGraph(onQuad, g));
+}