typeinfo.go

package msgpack

import (
	"fmt"
	"io/ioutil"
	"reflect"
	"sync"
)

var (
	marshalerType   = reflect.TypeOf(new(Marshaler)).Elem()
	unmarshalerType = reflect.TypeOf(new(Unmarshaler)).Elem()

	encoderType = reflect.TypeOf(new(CustomEncoder)).Elem()
	decoderType = reflect.TypeOf(new(CustomDecoder)).Elem()
)

type (
	encoderFunc func(*Encoder, reflect.Value) error
	decoderFunc func(*Decoder, reflect.Value) error
)

var (
	typEncMap = make(map[reflect.Type]encoderFunc)
	typDecMap = make(map[reflect.Type]decoderFunc)
)

// Register registers encoder and decoder functions for a type.
// In most cases you should prefer implementing CustomEncoder and
// CustomDecoder interfaces.
func Register(typ reflect.Type, enc encoderFunc, dec decoderFunc) {
	typEncMap[typ] = enc
	typDecMap[typ] = dec
}

var structs = newStructCache()

var (
	valueEncoders []encoderFunc
	valueDecoders []decoderFunc
)

func init() {
	valueEncoders = []encoderFunc{
		reflect.Bool:          encodeBoolValue,
		reflect.Int:           encodeInt64Value,
		reflect.Int8:          encodeInt64Value,
		reflect.Int16:         encodeInt64Value,
		reflect.Int32:         encodeInt64Value,
		reflect.Int64:         encodeInt64Value,
		reflect.Uint:          encodeUint64Value,
		reflect.Uint8:         encodeUint64Value,
		reflect.Uint16:        encodeUint64Value,
		reflect.Uint32:        encodeUint64Value,
		reflect.Uint64:        encodeUint64Value,
		reflect.Float32:       encodeFloat32Value,
		reflect.Float64:       encodeFloat64Value,
		reflect.Complex64:     encodeUnsupportedValue,
		reflect.Complex128:    encodeUnsupportedValue,
		reflect.Array:         encodeArrayValue,
		reflect.Chan:          encodeUnsupportedValue,
		reflect.Func:          encodeUnsupportedValue,
		reflect.Interface:     encodeInterfaceValue,
		reflect.Map:           encodeMapValue,
		reflect.Ptr:           encodePtrValue,
		reflect.Slice:         encodeSliceValue,
		reflect.String:        encodeStringValue,
		reflect.Struct:        encodeStructValue,
		reflect.UnsafePointer: encodeUnsupportedValue,
	}
	valueDecoders = []decoderFunc{
		reflect.Bool:          decodeBoolValue,
		reflect.Int:           decodeInt64Value,
		reflect.Int8:          decodeInt64Value,
		reflect.Int16:         decodeInt64Value,
		reflect.Int32:         decodeInt64Value,
		reflect.Int64:         decodeInt64Value,
		reflect.Uint:          decodeUint64Value,
		reflect.Uint8:         decodeUint64Value,
		reflect.Uint16:        decodeUint64Value,
		reflect.Uint32:        decodeUint64Value,
		reflect.Uint64:        decodeUint64Value,
		reflect.Float32:       decodeFloat64Value,
		reflect.Float64:       decodeFloat64Value,
		reflect.Complex64:     decodeUnsupportedValue,
		reflect.Complex128:    decodeUnsupportedValue,
		reflect.Array:         decodeArrayValue,
		reflect.Chan:          decodeUnsupportedValue,
		reflect.Func:          decodeUnsupportedValue,
		reflect.Interface:     decodeInterfaceValue,
		reflect.Map:           decodeMapValue,
		reflect.Ptr:           decodePtrValue,
		reflect.Slice:         decodeSliceValue,
		reflect.String:        decodeStringValue,
		reflect.Struct:        decodeStructValue,
		reflect.UnsafePointer: decodeUnsupportedValue,
	}
}

//------------------------------------------------------------------------------

type field struct {
	name      string
	index     []int
	omitEmpty bool

	encoder encoderFunc
	decoder decoderFunc
}

func (f *field) value(strct reflect.Value) reflect.Value {
	return strct.FieldByIndex(f.index)
}

func (f *field) Omit(strct reflect.Value) bool {
	return f.omitEmpty && isEmptyValue(f.value(strct))
}

func (f *field) EncodeValue(e *Encoder, strct reflect.Value) error {
	return f.encoder(e, f.value(strct))
}

func (f *field) DecodeValue(d *Decoder, strct reflect.Value) error {
	return f.decoder(d, f.value(strct))
}

//------------------------------------------------------------------------------

type fields struct {
	List  []*field
	Table map[string]*field
}

func newFields(numField int) *fields {
	return &fields{
		List:  make([]*field, 0, numField),
		Table: make(map[string]*field, numField),
	}
}

func (fs *fields) Len() int {
	return len(fs.List)
}

func (fs *fields) Add(field *field) {
	fs.List = append(fs.List, field)
	fs.Table[field.name] = field
}

func getFields(typ reflect.Type) *fields {
	numField := typ.NumField()
	fs := newFields(numField)

	for i := 0; i < numField; i++ {
		f := typ.Field(i)
		if f.PkgPath != "" && !f.Anonymous {
			continue
		}

		name, opts := parseTag(f.Tag.Get("msgpack"))
		if name == "-" {
			continue
		}

		if opts.Contains("inline") {
			inlineFields(fs, f)
			continue
		}

		if name == "" {
			name = f.Name
		}
		field := &field{
			name:      name,
			index:     f.Index,
			omitEmpty: opts.Contains("omitempty"),
			encoder:   getEncoder(f.Type),
			decoder:   getDecoder(f.Type),
		}
		fs.Add(field)
	}
	return fs
}

//------------------------------------------------------------------------------

func encodeUnsupportedValue(e *Encoder, v reflect.Value) error {
	return fmt.Errorf("msgpack: Encode(unsupported %T)", v.Interface())
}

func decodeUnsupportedValue(d *Decoder, v reflect.Value) error {
	return fmt.Errorf("msgpack: Decode(unsupported %T)", v.Interface())
}

//------------------------------------------------------------------------------

func encodeBoolValue(e *Encoder, v reflect.Value) error {
	return e.EncodeBool(v.Bool())
}

func decodeBoolValue(d *Decoder, v reflect.Value) error {
	return d.boolValue(v)
}

//------------------------------------------------------------------------------

func encodeFloat32Value(e *Encoder, v reflect.Value) error {
	return e.EncodeFloat32(float32(v.Float()))
}

func encodeFloat64Value(e *Encoder, v reflect.Value) error {
	return e.EncodeFloat64(v.Float())
}

func decodeFloat64Value(d *Decoder, v reflect.Value) error {
	return d.float64Value(v)
}

//------------------------------------------------------------------------------

func encodeStringValue(e *Encoder, v reflect.Value) error {
	return e.EncodeString(v.String())
}

func decodeStringValue(d *Decoder, v reflect.Value) error {
	return d.stringValue(v)
}

//------------------------------------------------------------------------------

func encodeBytesValue(e *Encoder, v reflect.Value) error {
	return e.EncodeBytes(v.Bytes())
}

func decodeBytesValue(d *Decoder, v reflect.Value) error {
	return d.bytesValue(v)
}

//------------------------------------------------------------------------------

func encodeInt64Value(e *Encoder, v reflect.Value) error {
	return e.EncodeInt64(v.Int())
}

func decodeInt64Value(d *Decoder, v reflect.Value) error {
	return d.int64Value(v)
}

//------------------------------------------------------------------------------

func encodeUint64Value(e *Encoder, v reflect.Value) error {
	return e.EncodeUint64(v.Uint())
}

func decodeUint64Value(d *Decoder, v reflect.Value) error {
	return d.uint64Value(v)
}

//------------------------------------------------------------------------------

func encodeSliceValue(e *Encoder, v reflect.Value) error {
	return e.encodeSlice(v)
}

func decodeSliceValue(d *Decoder, v reflect.Value) error {
	return d.sliceValue(v)
}

//------------------------------------------------------------------------------

func encodeArrayValue(e *Encoder, v reflect.Value) error {
	return e.encodeArray(v)
}

func decodeArrayValue(d *Decoder, v reflect.Value) error {
	return d.sliceValue(v)
}

//------------------------------------------------------------------------------

func encodeInterfaceValue(e *Encoder, v reflect.Value) error {
	if v.IsNil() {
		return e.EncodeNil()
	}
	return e.EncodeValue(v.Elem())
}

func decodeInterfaceValue(d *Decoder, v reflect.Value) error {
	if v.IsNil() {
		return d.interfaceValue(v)
	}
	return d.DecodeValue(v.Elem())
}

//------------------------------------------------------------------------------

func encodeMapValue(e *Encoder, v reflect.Value) error {
	return e.encodeMap(v)
}

func decodeMapValue(d *Decoder, v reflect.Value) error {
	return d.mapValue(v)
}

//------------------------------------------------------------------------------

func encodePtrValue(e *Encoder, v reflect.Value) error {
	if v.IsNil() {
		return e.EncodeNil()
	}
	return e.EncodeValue(v.Elem())
}

func decodePtrValue(d *Decoder, v reflect.Value) error {
	if v.IsNil() {
		if !v.CanSet() {
			return fmt.Errorf("msgpack: Decode(nonsettable %T)", v.Interface())
		}
		vv := reflect.New(v.Type().Elem())
		v.Set(vv)
	}
	return d.DecodeValue(v.Elem())
}

//------------------------------------------------------------------------------

func encodeStructValue(e *Encoder, v reflect.Value) error {
	return e.encodeStruct(v)
}

func decodeStructValue(d *Decoder, v reflect.Value) error {
	return d.structValue(v)
}

//------------------------------------------------------------------------------

func encodeCustomValuePtr(e *Encoder, v reflect.Value) error {
	if !v.CanAddr() {
		return fmt.Errorf("msgpack: Encode(non-addressable %T)", v.Interface())
	}
	switch v.Kind() {
	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
		if v.IsNil() {
			return e.EncodeNil()
		}
	}
	encoder := v.Addr().Interface().(CustomEncoder)
	return encoder.EncodeMsgpack(e)
}

func encodeCustomValue(e *Encoder, v reflect.Value) error {
	switch v.Kind() {
	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
		if v.IsNil() {
			return e.EncodeNil()
		}
	}
	encoder := v.Interface().(CustomEncoder)
	return encoder.EncodeMsgpack(e)
}

func decodeCustomValuePtr(d *Decoder, v reflect.Value) error {
	if !v.CanAddr() {
		return fmt.Errorf("msgpack: Decode(nonsettable %T)", v.Interface())
	}
	if d.gotNilCode() {
		return d.DecodeNil()
	}
	decoder := v.Addr().Interface().(CustomDecoder)
	return decoder.DecodeMsgpack(d)
}

func decodeCustomValue(d *Decoder, v reflect.Value) error {
	if d.gotNilCode() {
		return d.DecodeNil()
	}
	if v.IsNil() {
		v.Set(reflect.New(v.Type().Elem()))
	}
	decoder := v.Interface().(CustomDecoder)
	return decoder.DecodeMsgpack(d)
}

func marshalValue(e *Encoder, v reflect.Value) error {
	marshaler := v.Interface().(Marshaler)
	b, err := marshaler.MarshalMsgpack()
	if err != nil {
		return err
	}
	_, err = e.w.Write(b)
	return err
}

func unmarshalValue(d *Decoder, v reflect.Value) error {
	if v.IsNil() {
		v.Set(reflect.New(v.Type().Elem()))
	}
	b, err := ioutil.ReadAll(d.r)
	if err != nil {
		return err
	}
	unmarshaler := v.Interface().(Unmarshaler)
	return unmarshaler.UnmarshalMsgpack(b)
}

//------------------------------------------------------------------------------

type structCache struct {
	l sync.RWMutex
	m map[reflect.Type]*fields
}

func newStructCache() *structCache {
	return &structCache{
		m: make(map[reflect.Type]*fields),
	}
}

func (m *structCache) Fields(typ reflect.Type) *fields {
	m.l.RLock()
	fs, ok := m.m[typ]
	m.l.RUnlock()
	if !ok {
		m.l.Lock()
		fs, ok = m.m[typ]
		if !ok {
			fs = getFields(typ)
			m.m[typ] = fs
		}
		m.l.Unlock()
	}

	return fs
}

func inlineFields(fs *fields, f reflect.StructField) {
	typ := f.Type
	for typ.Kind() == reflect.Ptr {
		typ = typ.Elem()
	}
	inlinedFields := getFields(typ).List
	if len(inlinedFields) == 0 {
		panic("no fields to inline")
	}
	for _, field := range inlinedFields {
		if _, ok := fs.Table[field.name]; ok {
			// Don't overwrite shadowed fields.
			continue
		}
		field.index = append(f.Index, field.index...)
		fs.Add(field)
	}
}

func getEncoder(typ reflect.Type) encoderFunc {
	enc := getTypeEncoder(typ)
	if id := extTypeId(typ); id != -1 {
		return makeExtEncoder(id, enc)
	}
	return enc
}

func getTypeEncoder(typ reflect.Type) encoderFunc {
	kind := typ.Kind()

	if typ.Implements(encoderType) {
		return encodeCustomValue
	}

	// Addressable struct field value.
	if reflect.PtrTo(typ).Implements(encoderType) {
		return encodeCustomValuePtr
	}

	if typ.Implements(marshalerType) {
		return marshalValue
	}
	if encoder, ok := typEncMap[typ]; ok {
		return encoder
	}

	if kind == reflect.Slice && typ.Elem().Kind() == reflect.Uint8 {
		return encodeBytesValue
	}

	return valueEncoders[kind]
}

func getDecoder(typ reflect.Type) decoderFunc {
	kind := typ.Kind()

	// Addressable struct field value.
	if kind != reflect.Ptr && reflect.PtrTo(typ).Implements(decoderType) {
		return decodeCustomValuePtr
	}

	if typ.Implements(decoderType) {
		return decodeCustomValue
	}

	if typ.Implements(unmarshalerType) {
		return unmarshalValue
	}

	if decoder, ok := typDecMap[typ]; ok {
		return decoder
	}

	if kind == reflect.Slice && typ.Elem().Kind() == reflect.Uint8 {
		return decodeBytesValue
	}

	return valueDecoders[kind]
}

func isEmptyValue(v reflect.Value) bool {
	switch v.Kind() {
	case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
		return v.Len() == 0
	case reflect.Bool:
		return !v.Bool()
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return v.Int() == 0
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		return v.Uint() == 0
	case reflect.Float32, reflect.Float64:
		return v.Float() == 0
	case reflect.Interface, reflect.Ptr:
		return v.IsNil()
	}
	return false
}