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path: root/ber/marshal.go
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package ber

import (
	"bytes"
	"reflect"
)

type Marshaler interface {
	Marshal() ([]byte, error)
}

type Unarshaler interface {
	Unarshal([]byte) error
}

type ASN1 interface {
	Marshaler
	Unmarshaler
}

type encodeState struct {
	bytes.Buffer
}

func Marshal(v interface{}) ([]byte, error) {
	e := &encodeState{}
	err := e.marshal(v)
	if err != nil {
		return nil, err
	}
	return e.Bytes(), nil
}

func (e *encodeState) marshal(v interface{}) (err error) {
	e.reflectValue(reflect.ValueOf(v))
	return nil
}

func (e *encodeState) reflectValue(v reflect.Value) {
	valueEncoder(v)(e, v)
}

type encoderFunc func(e *encodeState, v reflect.Value)

func valueEncoder(v reflect.Value) encoderFunc {
	if !v.IsValid() {
		return invalidValueEncoder
	}
	return newTypeEncoder(v.Type())
}

func invalidValueEncoder(e *encodeState, v reflect.Value) {
	e.WriteByte(0)
}

func newTypeEncoder(t reflect.Type) encoderFunc {
	switch t.Kind() {
	case reflect.Int:
		return intEncoder
	default:
		return unsupportedTypeEncoder
	}
}

type UnsupportedTypeError struct {
	Type reflect.Type
}

func (e *UnsupportedTypeError) Error() string {
	return "BER: unsupported type: " + e.Type.String()
}

func unsupportedTypeEncoder(e *encodeState, v reflect.Value) {
	e.error(&UnsupportedTypeError{v.Type()})
}

func (e *encodeState) error(err error) {
	panic(err)
}

func intEncoder(e *encodeState, v reflect.Value) {
	b := marshalInt(v.Int())
	e.Write(b)
}

func objEncoder(e *encodeState, v reflect.Value) {
	b := marshalObj(v.Interface().(Obj))
	e.Write(b)
}