// 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
}
func TestReader(t *testing.T) {
switch runtime.GOOS {
case "nacl": // platforms that don't permit direct file system access
t.Skipf("not supported on %q", runtime.GOOS)
}
for _, tc := range sniffTestCases {
content, err := ioutil.ReadFile("testdata/" + tc.filename)
if err != nil {
t.Errorf("%s: error reading file: %v", tc.filename, err)
continue
}
r, err := NewReader(bytes.NewReader(content), tc.declared)
if err != nil {
t.Errorf("%s: error creating reader: %v", tc.filename, err)
continue
}
got, err := ioutil.ReadAll(r)
if err != nil {
t.Errorf("%s: error reading from charset.NewReader: %v", tc.filename, err)
continue
}
e, _ := Lookup(tc.want)
want, err := ioutil.ReadAll(transform.NewReader(bytes.NewReader(content), e.NewDecoder()))
if err != nil {
t.Errorf("%s: error decoding with hard-coded charset name: %v", tc.filename, err)
continue
}
if !bytes.Equal(got, want) {
t.Errorf("%s: got %q, want %q", tc.filename, got, want)
continue
}
}
}
func transformString(t transform.Transformer, s string) (string, error) {
r := transform.NewReader(strings.NewReader(s), t)
b, err := ioutil.ReadAll(r)
return string(b), err
}