Golang reflect.New函数代码示例

func (d *decoder) mapCopy(src reflect.Value, dst reflect.Value) error {
	sv := src.MapKeys()
	dt := dst.Type().Elem()

	for i := range sv {
		ot := reflect.New(dt)

		if dt.Kind() == reflect.Ptr {
			ot = reflect.New(ot.Type().Elem())
		}

		d.pushPath(sv[i].String())
		err := d.decode(src.MapIndex(sv[i]), ot)
		if err != nil && err != ErrIncompatStruct {
			err = errors.New(d.pathString() + err.Error())
			d.path = nil
			return err
		}
		d.popPath()

		if err == nil {
			dst.SetMapIndex(sv[i], ot.Elem())
		}
	}
	return nil
}

// ReadTargets reads targets into map entries.
func (n *MapNode) ReadTargets(c ReadContext, val Val) error {
	list := c.List()
	for _, keyStr := range list {
		keyVal := reflect.New(n.KeyType).Elem()
		if err := n.UnmarshalKey(keyStr, keyVal); err != nil {
			return errors.Wrapf(err, "unmarshaling key")
		}
		elem := *n.ElemNode
		elemContext := c.Push(keyStr)
		elemVal := elem.NewKeyedVal(keyVal)
		err := elem.Read(elemContext, elemVal)
		// Set key field.
		if n.Field != nil && n.Field.KeyField != "" {
			n.Field.SetKeyFunc.Call([]reflect.Value{elemVal.Ptr, elemVal.Key})
		}
		if err != nil {
			return errors.Wrapf(err, "reading child %s", keyStr)
		}
		// TODO: Don't calculate these values every time.
		if reflect.DeepEqual(elemVal.Ptr.Elem().Interface(), reflect.New(elemVal.Ptr.Type().Elem()).Elem().Interface()) {
			nv := reflect.New(elemVal.Ptr.Type()).Elem()
			val.Ptr.Elem().SetMapIndex(elemVal.Key, nv)
		} else {
			val.Ptr.Elem().SetMapIndex(elemVal.Key, elemVal.Final())
		}
	}
	return nil
}

func (s *S) TestUnmarshal(c *C) {
	for i, item := range unmarshalTests {
		t := reflect.ValueOf(item.value).Type()
		var value interface{}
		switch t.Kind() {
		case reflect.Map:
			value = reflect.MakeMap(t).Interface()
		case reflect.String:
			t := reflect.ValueOf(item.value).Type()
			v := reflect.New(t)
			value = v.Interface()
		default:
			pt := reflect.ValueOf(item.value).Type()
			pv := reflect.New(pt.Elem())
			value = pv.Interface()
		}
		err := goyaml.Unmarshal([]byte(item.data), value)
		c.Assert(err, IsNil, Commentf("Item #%d", i))
		if t.Kind() == reflect.String {
			c.Assert(*value.(*string), Equals, item.value, Commentf("Item #%d", i))
		} else {
			c.Assert(value, DeepEquals, item.value, Commentf("Item #%d", i))
		}
	}
}

// Init initializes the container runtime given a JSON configuration that
// conforms to the Config set type.
func (c *CRT) Init(configStr string) error {
	cfg := &Config{}
	err := json.Unmarshal([]byte(configStr), cfg)
	if err != nil {
		return err
	}

	if _, ok := containerIfRegistry[cfg.CRT.Type]; !ok {
		return core.Errorf("unregistered container run time")
	}

	crtConfigType := containerIfRegistry[cfg.CRT.Type].ConfigType
	crtConfig := reflect.New(crtConfigType).Interface()
	err = json.Unmarshal([]byte(configStr), crtConfig)
	if err != nil {
		return err
	}

	crtType := containerIfRegistry[cfg.CRT.Type].CRTType
	crtif := reflect.New(crtType).Interface()
	c.ContainerIf = crtif.(crtclient.ContainerIf)
	err = c.ContainerIf.Init(&core.Config{V: crtConfig})
	if err != nil {
		return err
	}

	return nil
}

// mapEncodeScratch returns a new reflect.Value matching the map's value type,
// and a structPointer suitable for passing to an encoder or sizer.
func mapEncodeScratch(mapType reflect.Type) (keycopy, valcopy reflect.Value, keybase, valbase structPointer) {
	// Prepare addressable doubly-indirect placeholders for the key and value types.
	// This is needed because the element-type encoders expect **T, but the map iteration produces T.

	keycopy = reflect.New(mapType.Key()).Elem()                 // addressable K
	keyptr := reflect.New(reflect.PtrTo(keycopy.Type())).Elem() // addressable *K
	keyptr.Set(keycopy.Addr())                                  //
	keybase = toStructPointer(keyptr.Addr())                    // **K

	// Value types are more varied and require special handling.
	switch mapType.Elem().Kind() {
	case reflect.Slice:
		// []byte
		var dummy []byte
		valcopy = reflect.ValueOf(&dummy).Elem() // addressable []byte
		valbase = toStructPointer(valcopy.Addr())
	case reflect.Ptr:
		// message; the generated field type is map[K]*Msg (so V is *Msg),
		// so we only need one level of indirection.
		valcopy = reflect.New(mapType.Elem()).Elem() // addressable V
		valbase = toStructPointer(valcopy.Addr())
	default:
		// everything else
		valcopy = reflect.New(mapType.Elem()).Elem()                // addressable V
		valptr := reflect.New(reflect.PtrTo(valcopy.Type())).Elem() // addressable *V
		valptr.Set(valcopy.Addr())                                  //
		valbase = toStructPointer(valptr.Addr())                    // **V
	}
	return
}

func decodeMap(v reflect.Value, x interface{}) {
	t := v.Type()
	if v.IsNil() {
		v.Set(reflect.MakeMap(t))
	}
	for k, c := range getNode(x) {
		i := reflect.New(t.Key()).Elem()
		decodeValue(i, k)

		w := v.MapIndex(i)
		if w.IsValid() { // We have an actual element value to decode into.
			if w.Kind() == reflect.Interface {
				w = w.Elem()
			}
			w = reflect.New(w.Type()).Elem()
		} else if t.Elem().Kind() != reflect.Interface { // The map's element type is concrete.
			w = reflect.New(t.Elem()).Elem()
		} else {
			// The best we can do here is to decode as either a string (for scalars) or a map[string]interface {} (for the rest).
			// We could try to guess the type based on the string (e.g. true/false => bool) but that'll get ugly fast,
			// especially if we have to guess the kind (slice vs. array vs. map) and index type (e.g. string, int, etc.)
			switch c.(type) {
			case node:
				w = reflect.MakeMap(stringMapType)
			case string:
				w = reflect.New(stringType).Elem()
			default:
				panic("value is neither node nor string")
			}
		}

		decodeValue(w, c)
		v.SetMapIndex(i, w)
	}
}

func TestUnmarshal(t *testing.T) {
	for i, tt := range unmarshalTests {
		var scan Scanner
		in := []byte(tt.in)
		if err := checkValid(in, &scan); err != nil {
			if !reflect.DeepEqual(err, tt.err) {
				t.Errorf("#%d: checkValid: %#v", i, err)
				continue
			}
		}
		if tt.ptr == nil {
			continue
		}

		// v = new(right-type)
		v := reflect.New(reflect.TypeOf(tt.ptr).Elem())
		dec := NewDecoder(bytes.NewReader(in))
		if tt.useNumber {
			dec.UseNumber()
		}
		if err := dec.Decode(v.Interface()); !reflect.DeepEqual(err, tt.err) {
			t.Errorf("#%d: %v, want %v", i, err, tt.err)
			continue
		} else if err != nil {
			continue
		}
		if !reflect.DeepEqual(v.Elem().Interface(), tt.out) {
			t.Errorf("#%d: mismatch\nhave: %#+v\nwant: %#+v", i, v.Elem().Interface(), tt.out)
			data, _ := Marshal(v.Elem().Interface())
			println(string(data))
			data, _ = Marshal(tt.out)
			println(string(data))
			continue
		}

		// Check round trip.
		if tt.err == nil {
			enc, err := Marshal(v.Interface())
			if err != nil {
				t.Errorf("#%d: error re-marshaling: %v", i, err)
				continue
			}
			vv := reflect.New(reflect.TypeOf(tt.ptr).Elem())
			dec = NewDecoder(bytes.NewReader(enc))
			if tt.useNumber {
				dec.UseNumber()
			}
			if err := dec.Decode(vv.Interface()); err != nil {
				t.Errorf("#%d: error re-unmarshaling %#q: %v", i, enc, err)
				continue
			}
			if !reflect.DeepEqual(v.Elem().Interface(), vv.Elem().Interface()) {
				t.Errorf("#%d: mismatch\nhave: %#+v\nwant: %#+v", i, v.Elem().Interface(), vv.Elem().Interface())
				t.Errorf("     In: %q", strings.Map(noSpace, string(in)))
				t.Errorf("Marshal: %q", strings.Map(noSpace, string(enc)))
				continue
			}
		}
	}
}

func unmarshalMap(value reflect.Value, data interface{}, tag reflect.StructTag) error {
	if data == nil {
		return nil
	}
	mapData, ok := data.(map[string]interface{})
	if !ok {
		return fmt.Errorf("JSON value is not a map (%#v)", data)
	}

	t := value.Type()
	if value.Kind() == reflect.Ptr {
		t = t.Elem()
		if value.IsNil() {
			value.Set(reflect.New(t))
			value.Elem().Set(reflect.MakeMap(t))
		}

		value = value.Elem()
	}

	for k, v := range mapData {
		kvalue := reflect.ValueOf(k)
		vvalue := reflect.New(value.Type().Elem()).Elem()

		unmarshalAny(vvalue, v, "")
		value.SetMapIndex(kvalue, vvalue)
	}

	return nil
}

// callCustom calls 'custom' with sv & dv. custom must be a conversion function.
func (c *Converter) callCustom(sv, dv, custom reflect.Value, scope *scope) error {
	if !sv.CanAddr() {
		sv2 := reflect.New(sv.Type())
		sv2.Elem().Set(sv)
		sv = sv2
	} else {
		sv = sv.Addr()
	}
	if !dv.CanAddr() {
		if !dv.CanSet() {
			return scope.errorf("can't addr or set dest.")
		}
		dvOrig := dv
		dv := reflect.New(dvOrig.Type())
		defer func() { dvOrig.Set(dv) }()
	} else {
		dv = dv.Addr()
	}
	args := []reflect.Value{sv, dv, reflect.ValueOf(scope)}
	ret := custom.Call(args)[0].Interface()
	// This convolution is necessary because nil interfaces won't convert
	// to errors.
	if ret == nil {
		return nil
	}
	return ret.(error)
}

// Internal function to bind receive operations for a channel.
func (c *EncodedConn) bindRecvChan(subject, queue string, channel interface{}) error {
	chVal := reflect.ValueOf(channel)
	if chVal.Kind() != reflect.Chan {
		return ErrChanArg
	}
	argType := chVal.Type().Elem()

	cb := func(m *Msg) {
		var oPtr reflect.Value
		if argType.Kind() != reflect.Ptr {
			oPtr = reflect.New(argType)
		} else {
			oPtr = reflect.New(argType.Elem())
		}
		if err := c.Enc.Decode(m.Subject, m.Data, oPtr.Interface()); err != nil {
			c.Conn.err = errors.New("nats: Got an error trying to unmarshal: " + err.Error())
			if c.Conn.Opts.AsyncErrorCB != nil {
				go c.Conn.Opts.AsyncErrorCB(c.Conn, m.Sub, c.Conn.err)
			}
			return
		}
		if argType.Kind() != reflect.Ptr {
			oPtr = reflect.Indirect(oPtr)
		}
		chVal.Send(oPtr)
	}

	_, err := c.Conn.subscribe(subject, queue, cb)

	return err
}

func RegisterRpcParams(name string, obj interface{}) {
	objType := reflect.TypeOf(obj)
	if name == "" {
		val := reflect.ValueOf(obj)
		name = objType.Name()
		if val.Kind() == reflect.Ptr {
			name = objType.Elem().Name()
		}
	}
	for i := 0; i < objType.NumMethod(); i++ {
		method := objType.Method(i)
		methodType := method.Type
		if methodType.NumIn() == 3 { // if it has three parameters (one is self and two are rpc params)
			out := methodType.In(2)
			if out.Kind() == reflect.Ptr {
				out = out.Elem()
			}
			rpcParamsMap[name+"."+method.Name] = &RpcParams{
				Object:   obj,
				InParam:  reflect.New(methodType.In(1)).Interface(),
				OutParam: reflect.New(out).Interface(),
			}
		}
	}
}

func (d *Decoder) decodeSlice(s *decodStatus, v reflect.Value, t reflect.Type, tg tag) error {
	if _, isInline := tg.Modifiers["inline"]; isInline {
		val, ok := s.GetValue(d.env)
		if !ok {
			return nil
		}
		elements := d.arrSep.Split(val, -1)
		slice := reflect.MakeSlice(t, 0, len(elements))
		for _, s := range elements {
			mv := reflect.New(t.Elem())
			err := d.decodeField(mv.Elem(), s)
			if err != nil {
				return err
			}
			slice = reflect.Append(slice, mv.Elem())
		}
		v.Set(slice)
		return nil
	}
	index := s.GetIndex()
	slice := reflect.MakeSlice(t, 0, len(index))
	for _, i := range index {
		mv := reflect.New(t.Elem())
		err := d.decodeElement(s, mv.Elem(), mv.Elem().Type(), tag{Name: strconv.Itoa(i), Modifiers: tg.Modifiers})
		if err != nil {
			return err
		}
		slice = reflect.Append(slice, mv.Elem())
	}
	v.Set(slice)
	return nil
}

func (d *decoder) mapping(n *node, out reflect.Value) (good bool) {
	if set := d.setter("!!map", &out, &good); set != nil {
		defer set()
	}
	if out.Kind() == reflect.Struct {
		return d.mappingStruct(n, out)
	}

	if out.Kind() == reflect.Interface {
		// No type hints. Will have to use a generic map.
		iface := out
		out = settableValueOf(make(map[interface{}]interface{}))
		iface.Set(out)
	}

	if out.Kind() != reflect.Map {
		return false
	}
	outt := out.Type()
	kt := outt.Key()
	et := outt.Elem()

	l := len(n.children)
	for i := 0; i < l; i += 2 {
		k := reflect.New(kt).Elem()
		if d.unmarshal(n.children[i], k) {
			e := reflect.New(et).Elem()
			if d.unmarshal(n.children[i+1], e) {
				out.SetMapIndex(k, e)
			}
		}
	}
	return true
}

func (d *mapAsMapDecoder) decode(dv, sv reflect.Value) {
	dt := dv.Type()
	dv.Set(reflect.MakeMap(reflect.MapOf(dt.Key(), dt.Elem())))

	var mapKey reflect.Value
	var mapElem reflect.Value

	keyType := dv.Type().Key()
	elemType := dv.Type().Elem()

	for _, sElemKey := range sv.MapKeys() {
		var dElemKey reflect.Value
		var dElemVal reflect.Value

		if !mapKey.IsValid() {
			mapKey = reflect.New(keyType).Elem()
		} else {
			mapKey.Set(reflect.Zero(keyType))
		}
		dElemKey = mapKey

		if !mapElem.IsValid() {
			mapElem = reflect.New(elemType).Elem()
		} else {
			mapElem.Set(reflect.Zero(elemType))
		}
		dElemVal = mapElem

		d.keyDec(dElemKey, sElemKey)
		d.elemDec(dElemVal, sv.MapIndex(sElemKey))

		dv.SetMapIndex(dElemKey, dElemVal)
	}
}

// decodeMap treats the next bytes as an XDR encoded variable array of 2-element
// structures whose fields are of the same type as the map keys and elements
// represented by the passed reflection value.  Pointers are automatically
// indirected and allocated as necessary.  It returns the  the number of bytes
// actually read.
//
// An UnmarshalError is returned if any issues are encountered while decoding
// the elements.
func (d *Decoder) decodeMap(v reflect.Value) (int, error) {
	dataLen, n, err := d.DecodeUint()
	if err != nil {
		return n, err
	}

	// Allocate storage for the underlying map if needed.
	vt := v.Type()
	if v.IsNil() {
		v.Set(reflect.MakeMap(vt))
	}

	// Decode each key and value according to their type.
	keyType := vt.Key()
	elemType := vt.Elem()
	for i := uint32(0); i < dataLen; i++ {
		key := reflect.New(keyType).Elem()
		n2, err := d.decode(key)
		n += n2
		if err != nil {
			return n, err
		}

		val := reflect.New(elemType).Elem()
		n2, err = d.decode(val)
		n += n2
		if err != nil {
			return n, err
		}
		v.SetMapIndex(key, val)
	}
	return n, nil
}