Add tests and examples for pk.Opt and pk.Tuple.

net/packet/packet_test.go

@@ -99,27 +99,6 @@ func TestVarLong_ReadFrom(t *testing.T) {
 	}
 }
 
-func TestAry_ReadFrom(t *testing.T) {
-	var num pk.Int = 2
-	var ary []pk.String
-	var bin = []byte{
-		4, 'T', 'n', 'z', 'e',
-		0,
-	}
-	var data = pk.Ary{Len: &num, Ary: &ary}
-	if _, err := data.ReadFrom(bytes.NewReader(bin)); err != nil {
-		t.Fatal(err)
-	}
-	if len(ary) != int(num) {
-		t.Fatalf("length not match: %d != %d", len(ary), num)
-	}
-	for i, v := range []string{"Tnze", ""} {
-		if string(ary[i]) != v {
-			t.Errorf("want %q, get %q", v, ary[i])
-		}
-	}
-}
-
 //go:embed joingame_test.bin
 var testJoinGameData []byte
 

net/packet/util.go

@@ -70,22 +70,25 @@ func (a Ary) ReadFrom(r io.Reader) (n int64, err error) {
 }
 
 type Opt struct {
-	Has   interface{} // Boolean, *Boolean or func() bool
+	Has   interface{} // Pointer of bool, or `func() bool`
 	Field interface{} // FieldEncoder, FieldDecoder or both (Field)
 }
 
 func (o Opt) has() bool {
-	switch o.Has.(type) {
-	case Boolean:
-		return bool(o.Has.(Boolean))
-	case *Boolean:
-		return bool(*o.Has.(*Boolean))
-	case func() bool:
-		return o.Has.(func() bool)()
+	v := reflect.ValueOf(o.Has)
+	for {
+		switch v.Kind() {
+		case reflect.Ptr:
+			v = v.Elem()
+		case reflect.Bool:
+			return v.Bool()
+		case reflect.Func:
+			return v.Interface().(func() bool)()
 		default:
 			panic(errors.New("unsupported Has value"))
 		}
 	}
+}
 
 func (o Opt) WriteTo(w io.Writer) (int64, error) {
 	if o.has() {

net/packet/util_test.go

@@ -2,9 +2,9 @@ package packet_test
 
 import (
 	"bytes"
-	"testing"
-
+	"fmt"
 	pk "github.com/Tnze/go-mc/net/packet"
+	"testing"
 )
 
 func ExampleAry_WriteTo() {
@@ -42,6 +42,27 @@ func ExampleAry_ReadFrom() {
 	}
 }
 
+func TestAry_ReadFrom(t *testing.T) {
+	var num pk.Int = 2
+	var ary []pk.String
+	var bin = []byte{
+		4, 'T', 'n', 'z', 'e',
+		0,
+	}
+	var data = pk.Ary{Len: &num, Ary: &ary}
+	if _, err := data.ReadFrom(bytes.NewReader(bin)); err != nil {
+		t.Fatal(err)
+	}
+	if len(ary) != int(num) {
+		t.Fatalf("length not match: %d != %d", len(ary), num)
+	}
+	for i, v := range []string{"Tnze", ""} {
+		if string(ary[i]) != v {
+			t.Errorf("want %q, get %q", v, ary[i])
+		}
+	}
+}
+
 func TestAry_WriteTo(t *testing.T) {
 	var buf bytes.Buffer
 	want := []byte{
@@ -51,6 +72,7 @@ func TestAry_WriteTo(t *testing.T) {
 	}
 	int3, long3, varint3, varlong3 := pk.Int(3), pk.Long(3), pk.VarInt(3), pk.VarLong(3)
 	for _, item := range [...]pk.Ary{
+		{Len: 3, Ary: []pk.Int{1, 2, 3}},
 		{Len: int3, Ary: []pk.Int{1, 2, 3}},
 		{Len: long3, Ary: []pk.Int{1, 2, 3}},
 		{Len: varint3, Ary: []pk.Int{1, 2, 3}},
@@ -70,3 +92,97 @@ func TestAry_WriteTo(t *testing.T) {
 		buf.Reset()
 	}
 }
+
+func ExampleOpt_ReadFrom() {
+	var has pk.Boolean
+
+	var data pk.String
+	p1 := pk.Packet{Data: []byte{
+		0x01,                  // pk.Boolean(true)
+		4, 'T', 'n', 'z', 'e', // pk.String
+	}}
+	if err := p1.Scan(
+		&has,
+		pk.Opt{
+			Has: &has, Field: &data,
+		},
+	); err != nil {
+		panic(err)
+	}
+	fmt.Println(data)
+
+	var data2 pk.String = "WILL NOT BE READ, WILL NOT BE COVERED"
+	p2 := pk.Packet{Data: []byte{
+		0x00, // pk.Boolean(false)
+		// empty
+	}}
+	if err := p2.Scan(
+		&has,
+		pk.Opt{
+			Has: &has, Field: &data2,
+		},
+	); err != nil {
+		panic(err)
+	}
+	fmt.Println(data2)
+
+	// Output:
+	// Tnze
+	// WILL NOT BE READ, WILL NOT BE COVERED
+}
+
+func ExampleOpt_ReadFrom_func() {
+	// As an example, we define this packet as this:
+	// +------+-----------------+----------------------------------+
+	// | Name | Type            | Notes                            |
+	// +------+-----------------+----------------------------------+
+	// | Flag | Unsigned Byte   | Odd if the following is present. |
+	// +------+-----------------+----------------------------------+
+	// | User | Optional String | The player's name.               |
+	// +------+-----------------+----------------------------------+
+	// So we need a function to decide if the User field is present.
+	var flag pk.Byte
+	var data pk.String
+	p := pk.Packet{Data: []byte{
+		0b_0010_0011,          // pk.Byte(flag)
+		4, 'T', 'n', 'z', 'e', // pk.String
+	}}
+	if err := p.Scan(
+		&flag,
+		pk.Opt{
+			Has: func() bool {
+				return flag&1 != 0
+			},
+			Field: &data,
+		},
+	); err != nil {
+		panic(err)
+	}
+	fmt.Println(data)
+
+	// Output: Tnze
+}
+
+func ExampleTuple_ReadFrom() {
+	// When you need to read an "Optional Array of X":
+	var has pk.Boolean
+	var arylen pk.Int
+	var ary []pk.String
+
+	var p pk.Packet // = conn.ReadPacket()
+	if err := p.Scan(
+		&has,
+		pk.Opt{
+			Has: &has,
+			Field: pk.Tuple{
+				&arylen,
+				pk.Ary{
+					Len: &arylen,
+					Ary: &ary,
+				},
+			},
+		},
+	); err != nil {
+		panic(err)
+	}
+}