initial commit

encoder.go

@@ -0,0 +1,29 @@
+package ID
+
+import "encoding/base64"
+
+func Decode(input string) (t Type, lastError error) {
+	ret, err := base64.URLEncoding.DecodeString(input)
+
+	if err != nil {
+		lastError = err
+		return
+	}
+
+	for i := 2; i >= 0; i-- {
+		t <<= 8
+		t |= Type(ret[i])
+	}
+
+	return
+}
+
+func (t Type) Encode() string {
+	var buffer [3]byte
+	for i := 0; i < 3; i++ {
+		buffer[i] = byte(t)
+		t >>= 8
+	}
+
+	return base64.URLEncoding.EncodeToString(buffer[:])
+}

encoder_test.go

@@ -0,0 +1,38 @@
+package ID_test
+
+import (
+	"testing"
+
+	"go.dedaa.de/julixau/inftut/ID"
+)
+
+// Verify that the Encoder works
+func TestEncode(t *testing.T) {
+	totest := ID.Type(100)
+	str := totest.Encode()
+
+	if str != "ZAAA" {
+		t.Fail()
+	}
+
+	// encode a number that only fits in 3 bytes
+	totest = ID.Type(100000)
+	if totest.Encode() != "oIYB" {
+		t.Fail()
+	}
+}
+
+// Test the decoder against the Encoder
+func TestDecode(t *testing.T) {
+	id := ID.Type(100000)
+	totest := id.Encode()
+
+	t.Log(id, totest)
+	if res, err := ID.Decode(totest); err != nil {
+		t.Fatal(err)
+	} else if res != id {
+		t.Fatal(res)
+	} else {
+		t.Log(res)
+	}
+}

generator.go

@@ -0,0 +1,25 @@
+package ID
+
+import "math/rand"
+
+const MaxID = 2 << 24
+
+type Type uint
+
+type Generator struct {
+	// IDEA: i hate you
+	step Type
+	Last Type
+}
+
+func (idg Generator) Next() Type {
+	idg.Last = (idg.Last + idg.step) % MaxID
+	return idg.Last
+}
+
+func New(seed uint32) Generator {
+	return Generator{
+		Last: Type(seed % MaxID),
+		step: Type((rand.Uint32() % MaxID) | 1),
+	}
+}