refactor: extract readToSlice and readToStruct method

Signed-off-by: ZhangJian He <shoothzj@gmail.com>

go.mod

@@ -4,8 +4,8 @@ go 1.20
 
 require (
 	github.com/libgox/addr v0.2.0
-	github.com/libgox/buffer v0.0.0-20241015042438-2a8f016fc865
-	github.com/libgox/gocollections v0.0.0-20241015042445-f5331b9e5556
+	github.com/libgox/buffer v0.0.0-20241024142853-0102c7922ab2
+	github.com/libgox/gocollections v0.0.0-20241024144716-59fe0afe6953
 	github.com/stretchr/testify v1.9.0
 	golang.org/x/exp v0.0.0-20240823005443-9b4947da3948
 )

go.sum

@@ -2,10 +2,10 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/libgox/addr v0.2.0 h1:he4Vv7lzcGy/1qNpjJufEWRql0S23Ki/j0XpTDMDu3s=
 github.com/libgox/addr v0.2.0/go.mod h1:j0hEfpRqTZy4BsstS9Egsn1U0JmNdj/VkbF2VBmJlFw=
-github.com/libgox/buffer v0.0.0-20241015042438-2a8f016fc865 h1:Qk14CPqIuf6+geOE6NmItHg9gtgmP91ir9tWS5d1b2E=
-github.com/libgox/buffer v0.0.0-20241015042438-2a8f016fc865/go.mod h1:VAuNNs9Mp5NttnP8etLB4FI4ZZ67sRUnk/jTb/BnSqo=
-github.com/libgox/gocollections v0.0.0-20241015042445-f5331b9e5556 h1:NbndOXKVReG/ex7tV6p/CMNNC+QWOtjrkzH3w89u/EI=
-github.com/libgox/gocollections v0.0.0-20241015042445-f5331b9e5556/go.mod h1:Y4udpR8lStv1f67hVWbMCrcTyTvf98bFFsu/ZXvAvZ0=
+github.com/libgox/buffer v0.0.0-20241024142853-0102c7922ab2 h1:L12VlOPRQ5qMkD8H2swxYhUir+MBkbo9CKZdNfY5QdQ=
+github.com/libgox/buffer v0.0.0-20241024142853-0102c7922ab2/go.mod h1:VAuNNs9Mp5NttnP8etLB4FI4ZZ67sRUnk/jTb/BnSqo=
+github.com/libgox/gocollections v0.0.0-20241024144716-59fe0afe6953 h1:qnlK5i5xCbMjQLqFa6JfNn3r7mtRMwMtuqJjyhgAYK8=
+github.com/libgox/gocollections v0.0.0-20241024144716-59fe0afe6953/go.mod h1:Y4udpR8lStv1f67hVWbMCrcTyTvf98bFFsu/ZXvAvZ0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=

opcua/client.go

@@ -12,7 +12,6 @@ import (
 
 	"github.com/libgox/addr"
 	"github.com/libgox/buffer"
-
 	"github.com/protocol-laboratory/opcua-go/opcua/ua"
 )
 

opcua/enc/decoder.go

@@ -187,7 +187,7 @@ func (d *bufferedDecoder) fillMessageBody(msg *uamsg.Message) error {
 				return err
 			}
 			messageBody.Service = service
-		case uamsg.ObjectCreateSessionResponse_Encoding_DefaultBinary:
+		case uamsg.ObjectCreateSessionResponse_Encoding_DefaultBinary.Identifier:
 			service := &uamsg.CreateSessionResponse{}
 			err = d.readTo(reflect.ValueOf(service).Elem())
 			if err != nil {
@@ -214,6 +214,12 @@ func (d *bufferedDecoder) readTo(value reflect.Value) error {
 			return err
 		}
 		value.SetUint(uint64(dataByte))
+	case reflect.Uint16:
+		b, err := d.r.readN(2)
+		if err != nil {
+			return err
+		}
+		value.SetUint(uint64(binary.LittleEndian.Uint16(b)))
 	case reflect.Uint32:
 		b, err := d.r.readN(4)
 		if err != nil {
@@ -265,75 +271,87 @@ func (d *bufferedDecoder) readTo(value reflect.Value) error {
 		}
 		value.SetString(string(b))
 	case reflect.Slice:
-		b, err := d.r.readN(4)
+		err, done := d.readToSlice(value, valueType)
+		if done {
+			return err
+		}
+	case reflect.Ptr, reflect.Interface:
+		if value.IsNil() {
+			return errors.New("ptr or interface{} variant can not be nil")
+		}
+		err := d.readTo(value.Elem())
+		if err != nil {
+			return err
+		}
+	case reflect.Struct:
+		err := readToStruct(value, valueType, d)
 		if err != nil {
 			return err
 		}
-		sliceLen := int32(binary.LittleEndian.Uint32(b))
+	default:
+		return errors.New("unsupported type")
+	}
 
-		if sliceLen == -1 {
-			return nil
+	return nil
+}
+
+func (d *bufferedDecoder) readToSlice(value reflect.Value, valueType reflect.Type) (error, bool) {
+	b, err := d.r.readN(4)
+	if err != nil {
+		return err, true
+	}
+	sliceLen := int32(binary.LittleEndian.Uint32(b))
+
+	if sliceLen == -1 {
+		return nil, true
+	}
+
+	sliceValue := reflect.MakeSlice(valueType, int(sliceLen), int(sliceLen))
+	for i := 0; i < sliceValue.Len(); i++ {
+		if valueType.Elem().Kind() == reflect.Ptr {
+			structPtr := reflect.New(valueType.Elem().Elem())
+			err = d.readTo(structPtr.Elem())
+			if err != nil {
+				return err, true
+			}
+			sliceValue.Index(i).Set(structPtr)
+		} else {
+			// simple slice, like []uint32
+			err = d.readTo(sliceValue.Index(i))
+			if err != nil {
+				return err, true
+			}
 		}
+	}
+	value.Set(sliceValue)
+	return nil, false
+}
 
-		sliceValue := reflect.MakeSlice(valueType, int(sliceLen), int(sliceLen))
-		for i := 0; i < sliceValue.Len(); i++ {
-			if valueType.Elem().Kind() == reflect.Ptr {
-				// valueType = []*MyStruct
-				// valueType.Elem() = *MyStruct
-				// valueType.Elem().Elem() = MyStruct,
-				structPtr := reflect.New(valueType.Elem().Elem())
-				err = d.readTo(structPtr.Elem())
+func readToStruct(value reflect.Value, valueType reflect.Type, d *bufferedDecoder) error {
+	decoder, ok := SpecialStructDecoderMap[value.Type().Name()]
+	if !ok {
+		// recursively construct all members
+		for i := 0; i < value.NumField(); i++ {
+			if value.Field(i).Kind() == reflect.Ptr && value.Field(i).IsNil() {
+				structPtr := reflect.New(valueType.Field(i).Type.Elem())
+				err := d.readTo(structPtr.Elem())
 				if err != nil {
 					return err
 				}
-				sliceValue.Index(i).Set(structPtr)
+				value.Field(i).Set(structPtr)
 			} else {
-				// simple slice, like []uint32
-				err = d.readTo(sliceValue.Index(i))
+				err := d.readTo(value.Field(i))
 				if err != nil {
 					return err
 				}
 			}
 		}
-		value.Set(sliceValue)
-	case reflect.Ptr, reflect.Interface:
-		if value.IsNil() {
-			return errors.New("ptr or interface{} variant can not be nil")
-		}
-		err := d.readTo(value.Elem())
+	} else {
+		err := decoder(d.r, value)
 		if err != nil {
 			return err
 		}
-	case reflect.Struct:
-		decoder, ok := SpecialStructDecoderMap[value.Type().Name()]
-		if !ok {
-			// recursively construct all members
-			for i := 0; i < value.NumField(); i++ {
-				if value.Field(i).Kind() == reflect.Ptr && value.Field(i).IsNil() {
-					structPtr := reflect.New(valueType.Field(i).Type.Elem())
-					err := d.readTo(structPtr.Elem())
-					if err != nil {
-						return err
-					}
-					value.Field(i).Set(structPtr)
-				} else {
-					err := d.readTo(value.Field(i))
-					if err != nil {
-						return err
-					}
-				}
-			}
-		} else {
-			err := decoder(d.r, value)
-			if err != nil {
-				return err
-			}
-		}
-
-	default:
-		return errors.New("unsupported type")
 	}
-
 	return nil
 }