first implementation

cid.go

@@ -0,0 +1,48 @@
+package cid
+
+import (
+	"encoding/binary"
+	mh "github.com/jbenet/go-multihash"
+	mbase "github.com/multiformats/go-multibase"
+)
+
+type Cid struct {
+	Version uint64
+	Type    uint64
+	Hash    mh.Multihash
+}
+
+func Decode(v string) (*Cid, error) {
+	_, data, err := mbase.Decode(v)
+	if err != nil {
+		return nil, err
+	}
+
+	return Cast(data)
+}
+
+func Cast(data []byte) (*Cid, error) {
+	vers, n := binary.Uvarint(data)
+	codec, cn := binary.Uvarint(data[n:])
+
+	rest := data[n+cn:]
+	h, err := mh.Cast(rest)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Cid{
+		Version: vers,
+		Type:    codec,
+		Hash:    h,
+	}, nil
+}
+
+func (c *Cid) Bytes() []byte {
+	buf := make([]byte, 8+len(c.Hash))
+	n := binary.PutUvarint(buf, c.Version)
+	n += binary.PutUvarint(buf[n:], c.Type)
+	copy(buf[n:], c.Hash)
+
+	return buf[:n+len(c.Hash)]
+}

cid_test.go

@@ -0,0 +1,40 @@
+package cid
+
+import (
+	"bytes"
+	"testing"
+
+	mh "github.com/jbenet/go-multihash"
+)
+
+func TestBasicMarshaling(t *testing.T) {
+	h, err := mh.Sum([]byte("TEST"), mh.SHA3, 4)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cid := &Cid{
+		Type:    7,
+		Version: 1,
+		Hash:    h,
+	}
+
+	data := cid.Bytes()
+
+	out, err := Cast(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if out.Type != cid.Type {
+		t.Fatal("mismatch on type")
+	}
+
+	if out.Version != cid.Version {
+		t.Fatal("mismatch on version")
+	}
+
+	if !bytes.Equal(out.Hash, cid.Hash) {
+		t.Fatal("multihash mismatch")
+	}
+}

package.json

@@ -0,0 +1,14 @@
+{
+  "author": "whyrusleeping",
+  "bugs": {
+    "url": "https://github.com/multiformats/go-cid"
+  },
+  "gx": {
+    "dvcsimport": "github.com/multiformats/go-cid"
+  },
+  "gxVersion": "0.8.0",
+  "language": "go",
+  "license": "",
+  "name": "go-cid",
+  "version": "0.0.0"
+}