elct9620/mruby-go

package insn

import (
    "encoding/binary"
    "io"
)

var DefaultBinaryOrder = binary.BigEndian

type Reader interface {
    io.Reader
    As(any) error
    Uint16() (uint16, error)
    String() (string, error)
}

type BinaryReader struct {
    io.Reader
    ByteOrder binary.ByteOrder
}

var _ Reader = &BinaryReader{}

func NewBinaryReader(r io.Reader) *BinaryReader {
    return &BinaryReader{r, DefaultBinaryOrder}
}

func (r *BinaryReader) As(data any) error {
    return binary.Read(r, r.ByteOrder, data)
}

func (r *BinaryReader) Uint16() (uint16, error) {
    var v uint16
    err := r.As(&v)
    return v, err
}

func (r *BinaryReader) String() (string, error) {
    sLen, err := r.Uint16()
    if err != nil {
        return "", err
    }

    buf := make([]byte, sLen+1)
    err = r.As(buf)
    if err != nil {
        return "", err
    }

    return string(buf[0:sLen]), nil
}