neoneo-go/pkg/io/binaryWriter.go
Roman Khimov 5bf00db2c9 io: move BinReader/BinWriter there, redo Serializable with it
The logic here is that we'll have all binary encoding/decoding done via our io
package, which simplifies error handling. This functionality doesn't belong to
util, so it's moved.

This also expands BufBinWriter with Reset() method to fit the needs of core
package.
2019-09-16 23:39:51 +03:00

73 lines
1.8 KiB
Go

package io
import (
"encoding/binary"
"io"
)
//BinWriter is a convenient wrapper around a io.Writer and err object
// Used to simplify error handling when writing into a io.Writer
// from a struct with many fields
type BinWriter struct {
w io.Writer
Err error
}
// NewBinWriterFromIO makes a BinWriter from io.Writer.
func NewBinWriterFromIO(iow io.Writer) *BinWriter {
return &BinWriter{w: iow}
}
// WriteLE writes into the underlying io.Writer from an object v in little-endian format
func (w *BinWriter) WriteLE(v interface{}) {
if w.Err != nil {
return
}
w.Err = binary.Write(w.w, binary.LittleEndian, v)
}
// WriteBE writes into the underlying io.Writer from an object v in big-endian format
func (w *BinWriter) WriteBE(v interface{}) {
if w.Err != nil {
return
}
w.Err = binary.Write(w.w, binary.BigEndian, v)
}
// WriteVarUint writes a uint64 into the underlying writer using variable-length encoding
func (w *BinWriter) WriteVarUint(val uint64) {
if w.Err != nil {
return
}
if val < 0xfd {
w.Err = binary.Write(w.w, binary.LittleEndian, uint8(val))
return
}
if val < 0xFFFF {
w.Err = binary.Write(w.w, binary.LittleEndian, byte(0xfd))
w.Err = binary.Write(w.w, binary.LittleEndian, uint16(val))
return
}
if val < 0xFFFFFFFF {
w.Err = binary.Write(w.w, binary.LittleEndian, byte(0xfe))
w.Err = binary.Write(w.w, binary.LittleEndian, uint32(val))
return
}
w.Err = binary.Write(w.w, binary.LittleEndian, byte(0xff))
w.Err = binary.Write(w.w, binary.LittleEndian, val)
}
// WriteBytes writes a variable length byte array into the underlying io.Writer
func (w *BinWriter) WriteBytes(b []byte) {
w.WriteVarUint(uint64(len(b)))
w.WriteLE(b)
}
// WriteString writes a variable length string into the underlying io.Writer
func (w *BinWriter) WriteString(s string) {
w.WriteBytes([]byte(s))
}