Update go-ipld-git to a go-ipld-prime codec (#46)

Codec re-written as an IPLD-prime codec.

CHANGELOG.md

@@ -0,0 +1,9 @@
+# CHANGELOG
+
+## v0.1.0
+
+This release includes BREAKING CHANGES
+
+* go-ipld-git is now a [go-ipld-prime](https://github.com/ipld/go-ipld-prime) IPLD codec. Use `Decode(na ipld.NodeAssembler, r io.Reader) error` and `Encode(n ipld.Node, w io.Writer) error` for direct use if required.
+* There is now only one `Tag` type, `MergeTag` has been removed which had a `text` property. Use `Tag`'s `message` property instead to retrieve the tag message from a commit's `mergetag`. i.e. `<commit>/mergetag/message` instead of `<commit>/mergetag/text`.
+* `PersonInfo` no longer exposes the human-readable RFC3339 format `date` field as a DAG node. The `date` and `timezone` fields are kept as their original string forms (to enable precise round-trips) as they exist in encoded Git data. e.g. `<commit>/author/date` now returns seconds in string form rather than an RFC3339 date string. Use this value and `<commit>/author/timezone` to reconstruct the original if needed.

README.md

@@ -3,17 +3,8 @@ Git ipld format
 
 [![](https://img.shields.io/badge/made%20by-Protocol%20Labs-blue.svg?style=flat-square)](http://ipn.io)
 [![](https://img.shields.io/badge/project-IPFS-blue.svg?style=flat-square)](http://ipfs.io/)
-[![](https://img.shields.io/badge/freenode-%23ipfs-blue.svg?style=flat-square)](http://webchat.freenode.net/?channels=%23ipfs)
-[![Coverage Status](https://codecov.io/gh/ipfs/go-ipld-git/branch/master/graph/badge.svg)](https://codecov.io/gh/ipfs/go-ipld-git/branch/master)
-[![Travis CI](https://travis-ci.org/ipfs/go-ipld-git.svg?branch=master)](https://travis-ci.org/ipfs/go-ipld-git)
 
-> An ipld codec for git objects allowing path traversals across the git graph!
-
-Note: This is WIP and may not be an entirely correct parser.
-
-## Lead Maintainer
-
-[Łukasz Magiera](https://github.com/magik6k)
+> An IPLD codec for git objects allowing path traversals across the git graph.
 
 ## Table of Contents
 
@@ -29,19 +20,49 @@ go get github.com/ipfs/go-ipld-git
 ```
 
 ## About
+
 This is an IPLD codec which handles git objects. Objects are transformed
-into IPLD graph in the following way:
+into IPLD graph as detailed below. Objects are demonstrated here using both
+[IPLD Schemas](https://ipld.io/docs/schemas/) and example JSON forms.
+
+### Commit
+
+```ipldsch
+type GpgSig string
+
+type PersonInfo struct {
+  date String
+  timezone String
+  email String
+  name String
+}
+
+type Commit struct {
+  tree &Tree # see "Tree" section below
+  parents [&Commit]
+  message String
+  author optional PersonInfo
+  committer optional PersonInfo
+  encoding optional String
+  signature optional GpgSig
+  mergetag [Tag]
+  other [String]
+}
+```
+
+As JSON, real data would look something like:
 
-* Commit:
 ```json
 {
   "author": {
-    "date": "1503667703 +0200",
+    "date": "1503667703",
+    "timezone": "+0200",
     "email": "author@mail",
     "name": "Author Name"
   },
   "committer": {
-    "date": "1503667703 +0200",
+    "date": "1503667703",
+    "timezone": "+0200",
     "email": "author@mail",
     "name": "Author Name"
   },
@@ -51,10 +72,22 @@ into IPLD graph in the following way:
   ],
   "tree": <LINK>
 }
+```
 
+### Tag
+
+```ipldsch
+type Tag struct {
+  object &Any
+  type String
+  tag String
+  tagger PersonInfo
+  message String
+}
 ```
 
-* Tag:
+As JSON, real data would look something like:
+
 ```json
 {
   "message": "message\n",
@@ -69,10 +102,21 @@ into IPLD graph in the following way:
   },
   "type": "commit"
 }
+```
 
+### Tree
+
+```ipldsch
+type Tree {String:TreeEntry}
+
+type TreeEntry struct {
+  mode String
+  hash &Any
+}
 ```
 
-* Tree:
+As JSON, real data would look something like:
+
 ```json
 {
   "file.name": {
@@ -87,11 +131,23 @@ into IPLD graph in the following way:
 }
 ```
 
+### Blob
+
+```ipldsch
+type Blob bytes
+```
+
+As JSON, real data would look something like:
 
-* Blob:
 ```json
 "<base64 of 'blob <size>\0<data>'>"
 ```
+
+## Lead Maintainers
+
+* [Will Scott](https://github.com/willscott)
+* [Rod Vagg](https://github.com/rvagg)
+
 ## Contribute
 
 PRs are welcome!

blob.go

@@ -1,71 +1,42 @@
 package ipldgit
 
 import (
-	"encoding/json"
-	"errors"
+	"bufio"
+	"fmt"
+	"io"
 
-	cid "github.com/ipfs/go-cid"
-	node "github.com/ipfs/go-ipld-format"
+	"github.com/ipld/go-ipld-prime"
 )
 
-type Blob struct {
-	rawData []byte
-	cid     cid.Cid
-}
-
-func (b *Blob) Cid() cid.Cid {
-	return b.cid
-}
-
-func (b *Blob) Copy() node.Node {
-	nb := *b
-	return &nb
-}
-
-func (b *Blob) Links() []*node.Link {
-	return nil
-}
-
-func (b *Blob) Resolve(_ []string) (interface{}, []string, error) {
-	return nil, nil, errors.New("no such link")
-}
-
-func (b *Blob) ResolveLink(_ []string) (*node.Link, []string, error) {
-	return nil, nil, errors.New("no such link")
-}
-
-func (b *Blob) Loggable() map[string]interface{} {
-	return map[string]interface{}{
-		"type": "git_blob",
+// DecodeBlob fills a NodeAssembler (from `Type.Blob__Repr.NewBuilder()`) from a stream of bytes
+func DecodeBlob(na ipld.NodeAssembler, rd *bufio.Reader) error {
+	sizen, err := readNullTerminatedNumber(rd)
+	if err != nil {
+		return err
 	}
-}
-
-func (b *Blob) MarshalJSON() ([]byte, error) {
-	return json.Marshal(b.rawData)
-}
 
-func (b *Blob) RawData() []byte {
-	return []byte(b.rawData)
-}
+	prefix := fmt.Sprintf("blob %d\x00", sizen)
+	buf := make([]byte, len(prefix)+sizen)
+	copy(buf, prefix)
 
-func (b *Blob) Size() (uint64, error) {
-	return uint64(len(b.rawData)), nil
-}
+	n, err := io.ReadFull(rd, buf[len(prefix):])
+	if err != nil {
+		return err
+	}
 
-func (b *Blob) Stat() (*node.NodeStat, error) {
-	return &node.NodeStat{}, nil
-}
+	if n != sizen {
+		return fmt.Errorf("blob size was not accurate")
+	}
 
-func (b *Blob) String() string {
-	return "[git blob]"
+	return na.AssignBytes(buf)
 }
 
-func (b *Blob) Tree(p string, depth int) []string {
-	return nil
-}
+func encodeBlob(n ipld.Node, w io.Writer) error {
+	b, err := n.AsBytes()
+	if err != nil {
+		return err
+	}
 
-func (b *Blob) GitSha() []byte {
-	return cidToSha(b.Cid())
+	_, err = w.Write(b)
+	return err
 }
-
-var _ node.Node = (*Blob)(nil)