func Diff(ctx context.Context, ds dag.DAGService, a, b *dag.Node) []*Change {
if len(a.Links) == 0 && len(b.Links) == 0 {
ak, _ := a.Key()
bk, _ := b.Key()
return []*Change{
&Change{
Type: Mod,
Before: ak,
After: bk,
},
}
}
var out []*Change
clean_a := a.Copy()
clean_b := b.Copy()
// strip out unchanged stuff
for _, lnk := range a.Links {
l, err := b.GetNodeLink(lnk.Name)
if err == nil {
if bytes.Equal(l.Hash, lnk.Hash) {
// no change... ignore it
} else {
anode, _ := lnk.GetNode(ctx, ds)
bnode, _ := l.GetNode(ctx, ds)
sub := Diff(ctx, ds, anode, bnode)
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: key.Key(lnk.Hash),
})
}
for _, lnk := range clean_b.Links {
out = append(out, &Change{
Type: Add,
Path: lnk.Name,
After: key.Key(lnk.Hash),
})
}
return out
}