1package message

2

3import (

4 "io"

5 "strings"

6

7 "golang.org/x/text/encoding/ianaindex"

8)

9

10// DecodeReader returns a reader that reads from r, decoding as charset. If

11// charset is empty, us-ascii, utf-8 or unknown, the original reader is

12// returned and no decoding takes place.

13func DecodeReader(charset string, r io.Reader) io.Reader {

14 switch strings.ToLower(charset) {

15 case "", "us-ascii", "utf-8":

16 return r

17 }

18 enc, _ := ianaindex.MIME.Encoding(charset)

19 if enc == nil {

20 enc, _ = ianaindex.IANA.Encoding(charset)

21 }

22 // todo: ianaindex doesn't know all encodings, e.g. gb2312. should we transform them, with which code?

23 if enc == nil {

24 return r

25 }

26 return enc.NewDecoder().Reader(r)

27}

28