func (ss *Superset) setFromBlobRef(fetcher blobref.SeekFetcher, blobRef *blobref.BlobRef) os.Error {
if blobRef == nil {
return os.NewError("schema/filereader: blobref was nil")
}
ss.BlobRef = blobRef
rsc, _, err := fetcher.Fetch(blobRef)
if err != nil {
return fmt.Errorf("schema/filereader: fetching schema blob %s: %v", blobRef, err)
}
if err = json.NewDecoder(rsc).Decode(ss); err != nil {
return fmt.Errorf("schema/filereader: decoding schema blob %s: %v", blobRef, err)
}
return nil
}
// TODO: make this take a blobref.FetcherAt instead?
func NewFileReader(fetcher blobref.SeekFetcher, fileBlobRef *blobref.BlobRef) (*FileReader, os.Error) {
if fileBlobRef == nil {
return nil, os.NewError("schema/filereader: NewFileReader blobref was nil")
}
ss := new(Superset)
rsc, _, err := fetcher.Fetch(fileBlobRef)
if err != nil {
return nil, fmt.Errorf("schema/filereader: fetching file schema blob: %v", err)
}
if err = json.NewDecoder(rsc).Decode(ss); err != nil {
return nil, fmt.Errorf("schema/filereader: decoding file schema blob: %v", err)
}
if ss.Type != "file" {
return nil, fmt.Errorf("schema/filereader: expected \"file\" schema blob, got %q", ss.Type)
}
return ss.NewFileReader(fetcher), nil
}