// NewReaderLabel returns a reader that converts from the specified charset to
// UTF-8. It uses Lookup to find the encoding that corresponds to label, and
// returns an error if Lookup returns nil. It is suitable for use as
// encoding/xml.Decoder's CharsetReader function.
func NewReaderLabel(label string, input io.Reader) (io.Reader, error) {
e, _ := Lookup(label)
if e == nil {
return nil, fmt.Errorf("unsupported charset: %q", label)
}
return transform.NewReader(input, e.NewDecoder()), nil
}
// NewReader returns an io.Reader that converts the content of r to UTF-8.
// It calls DetermineEncoding to find out what r's encoding is.
func NewReader(r io.Reader, contentType string) (io.Reader, error) {
preview := make([]byte, 1024)
n, err := io.ReadFull(r, preview)
switch {
case err == io.ErrUnexpectedEOF:
preview = preview[:n]
r = bytes.NewReader(preview)
case err != nil:
return nil, err
default:
r = io.MultiReader(bytes.NewReader(preview), r)
}
if e, _, _ := DetermineEncoding(preview, contentType); e != encoding.Nop {
r = transform.NewReader(r, e.NewDecoder())
}
return r, nil
}