add partial resolving to resolver code

License: MIT
Signed-off-by: Jeromy <why@ipfs.io>

core/commands/dag/dag.go

@@ -137,13 +137,23 @@ var DagGetCmd = &cmds.Command{
 			return
 		}
 
-		obj, err := n.Resolver.ResolvePath(req.Context(), p)
+		obj, rem, err := n.Resolver.ResolveToLastNode(req.Context(), p)
 		if err != nil {
 			res.SetError(err, cmds.ErrNormal)
 			return
 		}
 
-		res.SetOutput(obj)
+		var out interface{} = obj
+		if len(rem) > 0 {
+			final, _, err := obj.Resolve(rem)
+			if err != nil {
+				res.SetError(err, cmds.ErrNormal)
+				return
+			}
+			out = final
+		}
+
+		res.SetOutput(out)
 	},
 }
 

path/resolver.go

@@ -73,6 +73,39 @@ func SplitAbsPath(fpath Path) (*cid.Cid, []string, error) {
 	return c, parts[1:], nil
 }
 
+func (r *Resolver) ResolveToLastNode(ctx context.Context, fpath Path) (node.Node, []string, error) {
+	c, p, err := SplitAbsPath(fpath)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	nd, err := r.DAG.Get(ctx, c)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	for len(p) > 0 {
+		val, rest, err := nd.Resolve(p)
+		if err != nil {
+			return nil, nil, err
+		}
+
+		switch val := val.(type) {
+		case *node.Link:
+			next, err := val.GetNode(ctx, r.DAG)
+			if err != nil {
+				return nil, nil, err
+			}
+			nd = next
+			p = rest
+		default:
+			return nd, p, nil
+		}
+	}
+
+	return nd, nil, nil
+}
+
 // ResolvePath fetches the node for given path. It returns the last item
 // returned by ResolvePathComponents.
 func (s *Resolver) ResolvePath(ctx context.Context, fpath Path) (node.Node, error) {