basic implementation of object diff

License: MIT
Signed-off-by: Jeromy <jeromyj@gmail.com>

core/commands/object/diff.go

@@ -0,0 +1,85 @@
+package objectcmd
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+
+	cmds "github.com/ipfs/go-ipfs/commands"
+	dagutils "github.com/ipfs/go-ipfs/merkledag/utils"
+	path "github.com/ipfs/go-ipfs/path"
+)
+
+var ObjectDiffCmd = &cmds.Command{
+	Helptext: cmds.HelpText{
+		Tagline: "takes a diff of the two given objects",
+		ShortDescription: `
+`,
+	},
+	Arguments: []cmds.Argument{
+		cmds.StringArg("obj_a", true, false, "object to diff against"),
+		cmds.StringArg("obj_b", true, false, "object to diff"),
+	},
+	Run: func(req cmds.Request, res cmds.Response) {
+		node, err := req.InvocContext().GetNode()
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		a := req.Arguments()[0]
+		b := req.Arguments()[1]
+
+		pa, err := path.ParsePath(a)
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		pb, err := path.ParsePath(b)
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		ctx := req.Context()
+
+		obj_a, err := node.Resolver.ResolvePath(ctx, pa)
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		obj_b, err := node.Resolver.ResolvePath(ctx, pb)
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		changes, err := dagutils.Diff(ctx, node.DAG, obj_a, obj_b)
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		res.SetOutput(changes)
+	},
+	Type: []*dagutils.Change{},
+	Marshalers: cmds.MarshalerMap{
+		cmds.Text: func(res cmds.Response) (io.Reader, error) {
+			changes := res.Output().([]*dagutils.Change)
+			buf := new(bytes.Buffer)
+			for _, change := range changes {
+				switch change.Type {
+				case dagutils.Add:
+					fmt.Fprintf(buf, "added new link %q pointing to %s\n", change.Path, change.After)
+				case dagutils.Mod:
+					fmt.Fprintf(buf, "changed %q from %s to %s\n", change.Path, change.Before, change.After)
+				case dagutils.Remove:
+					fmt.Fprintf(buf, "removed link %q (was %s)\n", change.Path, change.Before)
+				}
+			}
+			return buf, nil
+		},
+	},
+}