feature: reseed and extraSeed

uuid.d.ts

@@ -64,6 +64,12 @@ export interface UUIDConstructor {
   /*  making construction  */
   new(version: number): UUID;
   new(version: number, ns: string, data: string): UUID;
+
+  /* reseed the internal pseudo random number generator */
+  reseed(seed: string);
+
+  /* provide extra entropy to the internal pseudo random number generator */
+  extraSeed(extraSeed: string);
 }
 
 declare var UUID: UUIDConstructor;

uuid.js

@@ -921,6 +921,26 @@
 
     UUID.PCG = PCG;
 
+    UUID.extraSeed = function (extraSeed) {
+        if (typeof extraSeed !== "string") {
+            throw new Error("UUID: extraSeed: invalid argument (string expected)");
+        }
+        var expanded = sha1_core(
+          s2a(extraSeed, { ibits: 8, obits: 32, obigendian: true }),
+          extraSeed.length * 8)
+        for (var i = 0; i < expanded.length; i++) {
+            ui64_xor(pcg.state, ui64_n2i((expanded[i] >>> 0)));
+        }
+    }
+
+    UUID.reseed = function (seed) {
+        if (typeof seed !== "string") {
+            throw new Error("UUID: reseed: invalid argument (string expected)");
+        }
+        pcg = new PCG(0);
+        UUID.extraSeed(seed);
+    }
+
     /*  export API  */
     return UUID;
 }));

uuid.test.js

@@ -105,5 +105,50 @@ describe("UUID base functionality", function () {
         expect(function () { new UUID().parse("xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"); })
             .to.throw(Error);
     });
+    it("reseed and extraSeed should work reliably", function () {
+        var uuid0, uuid1, uuid2, uuid3, uuid4;
+
+        UUID.reseed("seed0");
+        expect(new UUID(4).format())
+          .to.be.equal(uuid0 = "f8a86041-ca57-4c76-b48a-6dedf4b9acf4");
+        expect(new UUID(4).format())
+          .to.be.equal(uuid1 = "704a0f12-1376-4ef0-b6e1-9d57e5a8a492")
+          .to.not.be.equal(uuid0);
+        UUID.reseed("seed1");
+        expect(new UUID(4).format())
+          .to.be.equal(uuid1 = "31e91c7c-8e7c-4afc-8aa8-c7e42a48b205")
+          .to.not.be.equal(uuid0);
+        UUID.reseed("seed0");
+        expect(new UUID(4).format()).to.be.equal(uuid0);
+
+        UUID.reseed("seed0");
+        expect(new UUID(4).format()).to.be.equal(uuid0);
+        UUID.extraSeed("seed1");
+        expect(new UUID(4).format())
+          .to.be.equal(uuid2 = "dfbf1436-95c6-472a-bc22-ab07219721b4")
+          .to.not.be.equal(uuid1);
+        UUID.extraSeed("seed2");
+        expect(new UUID(4).format())
+          .to.be.equal(uuid3 = "03f775f7-cd94-4896-aefa-edac6b508025")
+          .to.not.be.equal(uuid1)
+          .to.not.be.equal(uuid2);
+        UUID.reseed("seed0");
+        expect(new UUID(4).format()).to.be.equal(uuid0);
+
+        UUID.reseed("seed1");
+        expect(new UUID(4).format()).to.be.equal(uuid1);
+        expect(new UUID(4).format())
+          .to.be.equal("4d01aa6c-0fdd-48d7-b118-38123215d703")
+          .to.not.be.equal(uuid2);
+
+        UUID.reseed("seed2");
+        expect(new UUID(4).format())
+          .to.be.equal(uuid4 = "ec8a811e-8d27-433e-8ba9-b3a4b199cd2e")
+          .to.not.be.equal(uuid3);
+        expect(new UUID(4).format())
+          .to.be.equal("d41053e3-447a-49ca-94f5-240987c0a9c2")
+          .to.not.be.equal(uuid3)
+          .to.not.be.equal(uuid4)
+    })
 });