/
ztext.go
137 lines (119 loc) · 2.59 KB
/
ztext.go
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package ztext
import (
"bufio"
"bytes"
"fmt"
"io"
"github.com/gogs/chardet"
"golang.org/x/text/encoding/ianaindex"
"golang.org/x/text/transform"
)
var boms = map[string][]byte{
"UTF-8": {0xef, 0xbb, 0xbf},
"UTF-16LE": {0xff, 0xfe},
"UTF-16BE": {0xfe, 0xff},
"UTF-32BE": {0x00, 0x00, 0xfe, 0xff},
"UTF-32LE": {0xff, 0xfe, 0x00, 0x00},
}
func NewCharsetReader(source io.Reader, charset string) *CharsetReader {
return &CharsetReader{
source: source,
charset: charset,
reader: bufio.NewReader(source),
}
}
func NewAutoReader(source io.Reader) *CharsetReader {
return &CharsetReader{
source: source,
reader: bufio.NewReader(source),
}
}
type CharsetReader struct {
source io.Reader
reader *bufio.Reader
charset string
decodingReader io.Reader
}
func (r *CharsetReader) deleteBom(head []byte, charset string) {
bom, ok := boms[charset]
if !ok {
return
}
if bytes.Equal(bom, head[:len(bom)]) {
r.reader.Discard(len(bom))
}
}
func (r *CharsetReader) init() (err error) {
if r.decodingReader != nil {
return
}
head, err := r.reader.Peek(2048)
// Try to autodetect the encoding
if r.charset == "" {
if err == io.EOF {
err = nil
} else if err != nil {
return err
}
encResult, err := chardet.NewTextDetector().DetectBest(head)
if err != nil {
return err
}
r.charset = encResult.Charset
}
r.deleteBom(head, r.charset)
if r.charset == "UTF-8" {
r.decodingReader = r.reader
return
}
e, err := ianaindex.MIME.Encoding(r.charset)
if err != nil {
return err
} else if e == nil {
return fmt.Errorf("unsupported charset: %s", r.charset)
}
r.decodingReader = transform.NewReader(r.reader, e.NewDecoder())
return
}
func (r *CharsetReader) Read(d []byte) (n int, err error) {
if err = r.init(); err != nil {
return
}
n, err = r.decodingReader.Read(d)
return
}
func (r *CharsetReader) Close() (err error) {
if c, ok := r.source.(io.Closer); ok {
return c.Close()
}
return
}
func NewCharsetWriter(source io.Writer, charset string) (w *CharsetWriter, err error) {
e, err := ianaindex.MIME.Encoding(charset)
if err != nil {
return
} else if e == nil {
err = fmt.Errorf("no encoder found for charset: %s", charset)
return
}
t := transform.NewWriter(source, e.NewEncoder())
return &CharsetWriter{
charset: charset,
source: source,
WriteCloser: t,
}, nil
}
type CharsetWriter struct {
charset string
source io.Writer
io.WriteCloser
}
func (w *CharsetWriter) Close() (err error) {
if err = w.WriteCloser.Close(); err != nil {
return
}
if c, ok := w.source.(io.Closer); ok {
return c.Close()
}
return
}