From b28cc4f2da1ddd382cbe05e9ee5c5b134f4fca44 Mon Sep 17 00:00:00 2001
From: JunDao <Tnze@Tnze.local>
Date: Sun, 19 May 2019 00:15:14 +0800
Subject: [PATCH] Marshal without test and TagList

---
 nbt/example_test.go |  39 ++++++++++
 nbt/marshal.go      | 184 ++++++++++++++++++++++++++++++++++++++++++++
 nbt/marshal_test.go |  35 +++++++++
 nbt/nbt.go          |   2 +
 4 files changed, 260 insertions(+)
 create mode 100644 nbt/example_test.go
 create mode 100644 nbt/marshal.go
 create mode 100644 nbt/marshal_test.go

diff --git a/nbt/example_test.go b/nbt/example_test.go
new file mode 100644
index 0000000..406954f
--- /dev/null
+++ b/nbt/example_test.go
@@ -0,0 +1,39 @@
+package nbt
+
+import (
+	"bytes"
+	"fmt"
+)
+
+func ExampleUnmarshal() {
+	var data = []byte{
+		0x08, 0x00, 0x04, 0x6e, 0x61, 0x6d, 0x65, 0x00, 0x09,
+		0x42, 0x61, 0x6e, 0x61, 0x6e, 0x72, 0x61, 0x6d, 0x61,
+	}
+
+	var Name string
+
+	if err := Unmarshal(data, &Name); err != nil {
+		panic(err)
+	}
+
+	fmt.Println(Name)
+
+	// Output: Bananrama
+}
+
+func ExampleMarshal() {
+	var value = struct {
+		Name string `nbt:"name"`
+	}{"Tnze"}
+
+	var buf bytes.Buffer
+	if err := Marshal(&buf, value); err != nil {
+		panic(err)
+	}
+
+	fmt.Printf("% 02x ", buf.Bytes())
+
+	// Output:
+	//	0a 00 00 08 00 00 00 04 54 6e 7a 65 00
+}
diff --git a/nbt/marshal.go b/nbt/marshal.go
new file mode 100644
index 0000000..f13f8bf
--- /dev/null
+++ b/nbt/marshal.go
@@ -0,0 +1,184 @@
+package nbt
+
+import (
+	"errors"
+	"io"
+	"math"
+	"reflect"
+)
+
+func Marshal(w io.Writer, v interface{}) error {
+	return NewEncoder(w).Encode(v)
+}
+
+type Encoder struct {
+	w io.Writer
+}
+
+func NewEncoder(w io.Writer) *Encoder {
+	return &Encoder{w: w}
+}
+
+func (e *Encoder) Encode(v interface{}) error {
+	val := reflect.ValueOf(v)
+	return e.marshal(val, "")
+}
+
+func (e *Encoder) marshal(val reflect.Value, tagName string) error {
+	switch vk := val.Kind(); vk {
+	default:
+		return errors.New("unknown type " + vk.String())
+
+	case reflect.Uint8:
+		if err := e.writeTag(TagByte, tagName); err != nil {
+			return err
+		}
+		_, err := e.w.Write([]byte{byte(val.Uint())})
+		return err
+
+	case reflect.Int16, reflect.Uint16:
+		if err := e.writeTag(TagShort, tagName); err != nil {
+			return err
+		}
+		return e.writeInt16(int16(val.Int()))
+
+	case reflect.Int32, reflect.Uint32:
+		if err := e.writeTag(TagInt, tagName); err != nil {
+			return err
+		}
+		return e.writeInt32(int32(val.Int()))
+
+	case reflect.Float32:
+		if err := e.writeTag(TagFloat, tagName); err != nil {
+			return err
+		}
+		return e.writeInt32(int32(math.Float32bits(float32(val.Float()))))
+
+	case reflect.Int64, reflect.Uint64:
+		if err := e.writeTag(TagLong, tagName); err != nil {
+			return err
+		}
+		return e.writeInt64(int64(val.Int()))
+
+	case reflect.Float64:
+		if err := e.writeTag(TagDouble, tagName); err != nil {
+			return err
+		}
+		return e.writeInt64(int64(math.Float64bits(val.Float())))
+
+	case reflect.Array, reflect.Slice:
+		switch val.Type().Elem().Kind() {
+		case reflect.Uint8: // []byte
+			if err := e.writeTag(TagByteArray, tagName); err != nil {
+				return err
+			}
+			if err := e.writeInt32(int32(val.Len())); err != nil {
+				return err
+			}
+			_, err := e.w.Write(val.Bytes())
+			return err
+
+		case reflect.Int32:
+			if err := e.writeTag(TagIntArray, tagName); err != nil {
+				return err
+			}
+			n := val.Len()
+			if err := e.writeInt32(int32(n)); err != nil {
+				return err
+			}
+			for i := 0; i < n; i++ {
+				if err := e.writeInt32(int32(val.Index(i).Int())); err != nil {
+					return err
+				}
+			}
+
+		case reflect.Int64:
+			if err := e.writeTag(TagLongArray, tagName); err != nil {
+				return err
+			}
+			n := val.Len()
+			if err := e.writeInt32(int32(n)); err != nil {
+				return err
+			}
+			for i := 0; i < n; i++ {
+				if err := e.writeInt64(val.Index(i).Int()); err != nil {
+					return err
+				}
+			}
+
+		default:
+			return errors.New("unknow type " + val.Type().String() + " slice")
+		}
+
+	case reflect.String:
+		if err := e.writeTag(TagString, tagName); err != nil {
+			return err
+		}
+		if err := e.writeInt16(int16(val.Len())); err != nil {
+			return err
+		}
+		_, err := e.w.Write([]byte(val.String()))
+		return err
+
+	case reflect.Struct:
+		if err := e.writeTag(TagCompound, ""); err != nil {
+			return err
+		}
+
+		n := val.NumField()
+		for i := 0; i < n; i++ {
+			f := val.Type().Field(i)
+			tag := f.Tag.Get("nbt")
+			if (f.PkgPath != "" && !f.Anonymous) || tag == "-" {
+				continue // Private field
+			}
+
+			tagName := f.Name
+			if tag != "" {
+				tagName = tag
+			}
+
+			err := e.marshal(val.Field(i), tagName)
+			if err != nil {
+				return err
+			}
+		}
+		_, err := e.w.Write([]byte{TagEnd})
+		return err
+	}
+	return nil
+}
+
+func (e *Encoder) writeTag(tagType byte, tagName string) error {
+	if _, err := e.w.Write([]byte{tagType}); err != nil {
+		return err
+	}
+	bName := []byte(tagName)
+	if err := e.writeInt16(int16(len(bName))); err != nil {
+		return err
+	}
+	_, err := e.w.Write(bName)
+	return err
+}
+
+func (e *Encoder) writeNamelessTag(tagType byte, tagName string) error {
+	_, err := e.w.Write([]byte{tagType})
+	return err
+}
+
+func (e *Encoder) writeInt16(n int16) error {
+	e.w.Write([]byte{byte(n >> 8), byte(n)})
+	return nil
+}
+
+func (e *Encoder) writeInt32(n int32) error {
+	e.w.Write([]byte{byte(n >> 24), byte(n >> 16), byte(n >> 8), byte(n)})
+	return nil
+}
+
+func (e *Encoder) writeInt64(n int64) error {
+	e.w.Write([]byte{
+		byte(n >> 56), byte(n >> 48), byte(n >> 40), byte(n >> 32),
+		byte(n >> 24), byte(n >> 16), byte(n >> 8), byte(n)})
+	return nil
+}
diff --git a/nbt/marshal_test.go b/nbt/marshal_test.go
new file mode 100644
index 0000000..0bc0bd8
--- /dev/null
+++ b/nbt/marshal_test.go
@@ -0,0 +1,35 @@
+package nbt
+
+import (
+	"bytes"
+	"reflect"
+	"testing"
+)
+
+func TestMarshal(t *testing.T) {
+	var (
+		want = []byte{
+			0x0A, 0, 0,
+			0x08, 0, 4, 0x4e, 0x61, 0x6d, 0x65, 0, 4, 0x54, 0x6e, 0x7a, 0x65,
+			0x01, 0x00, 0x08, 0x42, 0x79, 0x74, 0x65, 0x54, 0x65, 0x73, 0x74, 0xFF,
+
+			0,
+		}
+		value struct {
+			Name     string
+			ByteTest byte
+		}
+	)
+	value.Name = "Tnze"
+	value.ByteTest = 0xFF
+
+	var buf bytes.Buffer
+	if err := Marshal(&buf, value); err != nil {
+		t.Fatal(err)
+	}
+
+	gets := buf.Bytes()
+	if !reflect.DeepEqual(gets, want) {
+		t.Errorf("marshal wrong: get [% 02x], want [% 02x]", gets, want)
+	}
+}
diff --git a/nbt/nbt.go b/nbt/nbt.go
index 6f2c643..bf21959 100644
--- a/nbt/nbt.go
+++ b/nbt/nbt.go
@@ -1,3 +1,5 @@
+// Package nbt implement the Named Binary Tag format of Minecraft.
+// It provides api like encoding/xml package.
 package nbt
 
 import (