// Wrap wraps a given datastore with a key-prefix.
func Wrap(child ds.Datastore, prefix ds.Key) *datastore {
if child == nil {
panic("child (ds.Datastore) is nil")
}
d := ktds.Wrap(child, PrefixTransform(prefix))
return &datastore{Datastore: d, raw: child, prefix: prefix}
}
func (d *Datastore) Query(q query.Query) (query.Results, error) {
if len(q.Filters) > 0 ||
len(q.Orders) > 0 ||
q.Limit > 0 ||
q.Offset > 0 {
// TODO this is overly simplistic, but the only caller is
// `ipfs refs local` for now, and this gets us moving.
return nil, errors.New("mount only supports listing all prefixed keys in random order")
}
key := ds.NewKey(q.Prefix)
cds, mount, k := d.lookup(key)
if cds == nil {
return nil, errors.New("mount only supports listing a mount point")
}
// TODO support listing cross mount points too
// delegate the query to the mounted datastore, while adjusting
// keys in and out
q2 := q
q2.Prefix = k.String()
wrapDS := keytransform.Wrap(cds, &keytransform.Pair{
Convert: func(ds.Key) ds.Key {
panic("this should never be called")
},
Invert: func(k ds.Key) ds.Key {
return mount.Child(k)
},
})
r, err := wrapDS.Query(q2)
if err != nil {
return nil, err
}
r = query.ResultsReplaceQuery(r, q)
return r, nil
}