/
reader.go
60 lines (51 loc) · 987 Bytes
/
reader.go
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package data
import (
"io"
)
type Reader interface {
io.ByteScanner
io.Reader
Len() int
}
type LimitByteReader struct {
R Reader // underlying reader
N int64 // max bytes remaining
}
func LimitedByteReader(r Reader, n int64) *LimitByteReader {
return &LimitByteReader{r, n}
}
func (l *LimitByteReader) Len() int {
return int(l.N)
}
func NewVariableByteReader(r Reader) (Reader, error) {
if length, err := readVariableLength(r); err != nil {
return nil, err
} else {
return LimitedByteReader(r, int64(length)), nil
}
}
func (l *LimitByteReader) Read(p []byte) (n int, err error) {
if l.N <= 0 {
return 0, io.EOF
}
if int64(len(p)) > l.N {
p = p[0:l.N]
}
n, err = l.R.Read(p)
l.N -= int64(n)
return
}
func (l *LimitByteReader) ReadByte() (c byte, err error) {
if l.N <= 0 {
return 0, io.EOF
}
l.N--
return l.R.ReadByte()
}
func (l *LimitByteReader) UnreadByte() error {
if err := l.UnreadByte(); err != nil {
return err
}
l.N++
return nil
}