func Diff(ctx context.Context, ds dag.DAGService, a, b *dag.ProtoNode) ([]*Change, error) {
if len(a.Links()) == 0 && len(b.Links()) == 0 {
return []*Change{
&Change{
Type: Mod,
Before: a.Cid(),
After: b.Cid(),
},
}, nil
}
var out []*Change
clean_a := a.Copy().(*dag.ProtoNode)
clean_b := b.Copy().(*dag.ProtoNode)
// strip out unchanged stuff
for _, lnk := range a.Links() {
l, err := b.GetNodeLink(lnk.Name)
if err == nil {
if l.Cid.Equals(lnk.Cid) {
// no change... ignore it
} else {
anode, err := lnk.GetNode(ctx, ds)
if err != nil {
return nil, err
}
bnode, err := l.GetNode(ctx, ds)
if err != nil {
return nil, err
}
anodepb, ok := anode.(*dag.ProtoNode)
if !ok {
return nil, dag.ErrNotProtobuf
}
bnodepb, ok := bnode.(*dag.ProtoNode)
if !ok {
return nil, dag.ErrNotProtobuf
}
sub, err := Diff(ctx, ds, anodepb, bnodepb)
if err != nil {
return nil, err
}
for _, subc := range sub {
subc.Path = path.Join(lnk.Name, subc.Path)
out = append(out, subc)
}
}
clean_a.RemoveNodeLink(l.Name)
clean_b.RemoveNodeLink(l.Name)
}
}
for _, lnk := range clean_a.Links() {
out = append(out, &Change{
Type: Remove,
Path: lnk.Name,
Before: lnk.Cid,
})
}
for _, lnk := range clean_b.Links() {
out = append(out, &Change{
Type: Add,
Path: lnk.Name,
After: lnk.Cid,
})
}
return out, nil
}