Merge pull request #4 from goccy/feature/support-stream-decoding

Support stream decoding

benchmarks/decode_test.go

@@ -1,6 +1,7 @@
 package benchmark
 
 import (
+	"bytes"
 	"encoding/json"
 	"testing"
 
@@ -9,7 +10,7 @@ import (
 	jsoniter "github.com/json-iterator/go"
 )
 
-func Benchmark_Decode_SmallStruct_EncodingJson(b *testing.B) {
+func Benchmark_Decode_SmallStruct_Unmarshal_EncodingJson(b *testing.B) {
 	b.ReportAllocs()
 	for n := 0; n < b.N; n++ {
 		result := SmallPayload{}
@@ -19,7 +20,7 @@ func Benchmark_Decode_SmallStruct_EncodingJson(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_SmallStruct_JsonIter(b *testing.B) {
+func Benchmark_Decode_SmallStruct_Unmarshal_JsonIter(b *testing.B) {
 	b.ReportAllocs()
 	for n := 0; n < b.N; n++ {
 		result := SmallPayload{}
@@ -29,7 +30,7 @@ func Benchmark_Decode_SmallStruct_JsonIter(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_SmallStruct_GoJay(b *testing.B) {
+func Benchmark_Decode_SmallStruct_Unmarshal_GoJay(b *testing.B) {
 	b.ReportAllocs()
 	for n := 0; n < b.N; n++ {
 		result := SmallPayload{}
@@ -39,7 +40,7 @@ func Benchmark_Decode_SmallStruct_GoJay(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_SmallStruct_GoJayUnsafe(b *testing.B) {
+func Benchmark_Decode_SmallStruct_Unmarshal_GoJayUnsafe(b *testing.B) {
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
 		result := SmallPayload{}
@@ -49,7 +50,7 @@ func Benchmark_Decode_SmallStruct_GoJayUnsafe(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_SmallStruct_GoJson(b *testing.B) {
+func Benchmark_Decode_SmallStruct_Unmarshal_GoJson(b *testing.B) {
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
 		result := SmallPayload{}
@@ -59,7 +60,7 @@ func Benchmark_Decode_SmallStruct_GoJson(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_SmallStruct_GoJsonNoEscape(b *testing.B) {
+func Benchmark_Decode_SmallStruct_Unmarshal_GoJsonNoEscape(b *testing.B) {
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
 		result := SmallPayload{}
@@ -69,7 +70,55 @@ func Benchmark_Decode_SmallStruct_GoJsonNoEscape(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_MediumStruct_EncodingJson(b *testing.B) {
+func Benchmark_Decode_SmallStruct_Stream_EncodingJson(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(SmallFixture)
+	for i := 0; i < b.N; i++ {
+		result := SmallPayload{}
+		reader.Reset(SmallFixture)
+		if err := json.NewDecoder(reader).Decode(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func Benchmark_Decode_SmallStruct_Stream_JsonIter(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(SmallFixture)
+	for i := 0; i < b.N; i++ {
+		result := SmallPayload{}
+		reader.Reset(SmallFixture)
+		if err := jsoniter.NewDecoder(reader).Decode(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func Benchmark_Decode_SmallStruct_Stream_GoJay(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(SmallFixture)
+	for n := 0; n < b.N; n++ {
+		reader.Reset(SmallFixture)
+		result := SmallPayload{}
+		if err := gojay.NewDecoder(reader).DecodeObject(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func Benchmark_Decode_SmallStruct_Stream_GoJson(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(SmallFixture)
+	for i := 0; i < b.N; i++ {
+		result := SmallPayload{}
+		reader.Reset(SmallFixture)
+		if err := gojson.NewDecoder(reader).Decode(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func Benchmark_Decode_MediumStruct_Unmarshal_EncodingJson(b *testing.B) {
 	b.ReportAllocs()
 	for n := 0; n < b.N; n++ {
 		result := MediumPayload{}
@@ -79,7 +128,7 @@ func Benchmark_Decode_MediumStruct_EncodingJson(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_MediumStruct_JsonIter(b *testing.B) {
+func Benchmark_Decode_MediumStruct_Unmarshal_JsonIter(b *testing.B) {
 	b.ReportAllocs()
 	for n := 0; n < b.N; n++ {
 		result := MediumPayload{}
@@ -89,7 +138,7 @@ func Benchmark_Decode_MediumStruct_JsonIter(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_MediumStruct_GoJay(b *testing.B) {
+func Benchmark_Decode_MediumStruct_Unmarshal_GoJay(b *testing.B) {
 	b.ReportAllocs()
 	for n := 0; n < b.N; n++ {
 		result := MediumPayload{}
@@ -99,7 +148,7 @@ func Benchmark_Decode_MediumStruct_GoJay(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_MediumStruct_GoJayUnsafe(b *testing.B) {
+func Benchmark_Decode_MediumStruct_Unmarshal_GoJayUnsafe(b *testing.B) {
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
 		result := MediumPayload{}
@@ -109,7 +158,7 @@ func Benchmark_Decode_MediumStruct_GoJayUnsafe(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_MediumStruct_GoJson(b *testing.B) {
+func Benchmark_Decode_MediumStruct_Unmarshal_GoJson(b *testing.B) {
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
 		result := MediumPayload{}
@@ -119,7 +168,7 @@ func Benchmark_Decode_MediumStruct_GoJson(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_MediumStruct_GoJsonNoEscape(b *testing.B) {
+func Benchmark_Decode_MediumStruct_Unmarshal_GoJsonNoEscape(b *testing.B) {
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
 		result := MediumPayload{}
@@ -129,7 +178,55 @@ func Benchmark_Decode_MediumStruct_GoJsonNoEscape(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_LargeStruct_EncodingJson(b *testing.B) {
+func Benchmark_Decode_MediumStruct_Stream_EncodingJson(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(MediumFixture)
+	for i := 0; i < b.N; i++ {
+		result := MediumPayload{}
+		reader.Reset(MediumFixture)
+		if err := json.NewDecoder(reader).Decode(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func Benchmark_Decode_MediumStruct_Stream_JsonIter(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(MediumFixture)
+	for i := 0; i < b.N; i++ {
+		result := MediumPayload{}
+		reader.Reset(MediumFixture)
+		if err := jsoniter.NewDecoder(reader).Decode(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func Benchmark_Decode_MediumStruct_Stream_GoJay(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(MediumFixture)
+	for n := 0; n < b.N; n++ {
+		reader.Reset(MediumFixture)
+		result := MediumPayload{}
+		if err := gojay.NewDecoder(reader).DecodeObject(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func Benchmark_Decode_MediumStruct_Stream_GoJson(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(MediumFixture)
+	for i := 0; i < b.N; i++ {
+		result := MediumPayload{}
+		reader.Reset(MediumFixture)
+		if err := gojson.NewDecoder(reader).Decode(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func Benchmark_Decode_LargeStruct_Unmarshal_EncodingJson(b *testing.B) {
 	b.ReportAllocs()
 	for n := 0; n < b.N; n++ {
 		result := LargePayload{}
@@ -139,7 +236,7 @@ func Benchmark_Decode_LargeStruct_EncodingJson(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_LargeStruct_JsonIter(b *testing.B) {
+func Benchmark_Decode_LargeStruct_Unmarshal_JsonIter(b *testing.B) {
 	b.ReportAllocs()
 	for n := 0; n < b.N; n++ {
 		result := LargePayload{}
@@ -149,7 +246,7 @@ func Benchmark_Decode_LargeStruct_JsonIter(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_LargeStruct_GoJay(b *testing.B) {
+func Benchmark_Decode_LargeStruct_Unmarshal_GoJay(b *testing.B) {
 	b.ReportAllocs()
 	for n := 0; n < b.N; n++ {
 		result := LargePayload{}
@@ -159,7 +256,7 @@ func Benchmark_Decode_LargeStruct_GoJay(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_LargeStruct_GoJayUnsafe(b *testing.B) {
+func Benchmark_Decode_LargeStruct_Unmarshal_GoJayUnsafe(b *testing.B) {
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
 		result := LargePayload{}
@@ -169,7 +266,7 @@ func Benchmark_Decode_LargeStruct_GoJayUnsafe(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_LargeStruct_GoJson(b *testing.B) {
+func Benchmark_Decode_LargeStruct_Unmarshal_GoJson(b *testing.B) {
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
 		result := LargePayload{}
@@ -179,7 +276,7 @@ func Benchmark_Decode_LargeStruct_GoJson(b *testing.B) {
 	}
 }
 
-func Benchmark_Decode_LargeStruct_GoJsonNoEscape(b *testing.B) {
+func Benchmark_Decode_LargeStruct_Unmarshal_GoJsonNoEscape(b *testing.B) {
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
 		result := LargePayload{}
@@ -188,3 +285,51 @@ func Benchmark_Decode_LargeStruct_GoJsonNoEscape(b *testing.B) {
 		}
 	}
 }
+
+func Benchmark_Decode_LargeStruct_Stream_EncodingJson(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(LargeFixture)
+	for i := 0; i < b.N; i++ {
+		result := LargePayload{}
+		reader.Reset(LargeFixture)
+		if err := json.NewDecoder(reader).Decode(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func Benchmark_Decode_LargeStruct_Stream_JsonIter(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(LargeFixture)
+	for i := 0; i < b.N; i++ {
+		result := LargePayload{}
+		reader.Reset(LargeFixture)
+		if err := jsoniter.NewDecoder(reader).Decode(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func Benchmark_Decode_LargeStruct_Stream_GoJay(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(LargeFixture)
+	for n := 0; n < b.N; n++ {
+		reader.Reset(LargeFixture)
+		result := LargePayload{}
+		if err := gojay.NewDecoder(reader).DecodeObject(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func Benchmark_Decode_LargeStruct_Stream_GoJson(b *testing.B) {
+	b.ReportAllocs()
+	reader := bytes.NewReader(LargeFixture)
+	for i := 0; i < b.N; i++ {
+		result := LargePayload{}
+		reader.Reset(LargeFixture)
+		if err := gojson.NewDecoder(reader).Decode(&result); err != nil {
+			b.Fatal(err)
+		}
+	}
+}

decode.go

@@ -1,35 +1,27 @@
 package json
 
 import (
-	"bytes"
 	"encoding"
 	"io"
 	"reflect"
-	"strings"
+	"strconv"
 	"sync"
 	"unsafe"
 )
 
-// A Token holds a value of one of these types:
-//
-//	Delim, for the four JSON delimiters [ ] { }
-//	bool, for JSON booleans
-//	float64, for JSON numbers
-//	Number, for JSON numbers
-//	string, for JSON string literals
-//	nil, for JSON null
-//
-type Token interface{}
-
 type Delim rune
 
+func (d Delim) String() string {
+	return string(d)
+}
+
 type decoder interface {
 	decode([]byte, int64, uintptr) (int64, error)
+	decodeStream(*stream, uintptr) error
 }
 
 type Decoder struct {
-	r        io.Reader
+	s *stream
-	buffered func() io.Reader
 }
 
 type decoderMap struct {
@@ -57,18 +49,24 @@ func init() {
 	cachedDecoder = decoderMap{}
 }
 
+const (
+	nul = '\000'
+)
+
 // NewDecoder returns a new decoder that reads from r.
 //
 // The decoder introduces its own buffering and may
 // read data from r beyond the JSON values requested.
 func NewDecoder(r io.Reader) *Decoder {
-	return &Decoder{r: r}
+	s := &stream{r: r}
+	s.read()
+	return &Decoder{s: s}
 }
 
 // Buffered returns a reader of the data remaining in the Decoder's
 // buffer. The reader is valid until the next call to Decode.
 func (d *Decoder) Buffered() io.Reader {
-	return d.buffered()
+	return d.s.buffered()
 }
 
 func (d *Decoder) validateType(typ *rtype, p uintptr) error {
@@ -116,6 +114,27 @@ func (d *Decoder) decodeForUnmarshalNoEscape(src []byte, v interface{}) error {
 	return d.decode(src, header)
 }
 
+func (d *Decoder) prepareForDecode() error {
+	s := d.s
+	for {
+		switch s.char() {
+		case ' ', '\t', '\r', '\n':
+			s.cursor++
+			continue
+		case ',', ':':
+			s.cursor++
+			return nil
+		case nul:
+			if s.read() {
+				continue
+			}
+			return io.EOF
+		}
+		break
+	}
+	return nil
+}
+
 // Decode reads the next JSON-encoded value from its
 // input and stores it in the value pointed to by v.
 //
@@ -142,251 +161,87 @@ func (d *Decoder) Decode(v interface{}) error {
 		cachedDecoder.set(typeptr, compiledDec)
 		dec = compiledDec
 	}
+	if err := d.prepareForDecode(); err != nil {
+		return err
+	}
+	s := d.s
+	if err := dec.decodeStream(s, ptr); err != nil {
+		return err
+	}
+	return nil
+}
 
+func (d *Decoder) More() bool {
+	s := d.s
 	for {
-		buf := make([]byte, 1024)
+		switch s.char() {
-		n, err := d.r.Read(buf)
+		case ' ', '\n', '\r', '\t':
-		if n == 0 || err == io.EOF {
+			s.cursor++
-			return nil
+			continue
-		}
+		case '}', ']':
-		if err != nil {
-			return err
-		}
-		cursor, err := dec.decode(buf[:n], 0, ptr)
-		if err != nil {
-			return err
-		}
-		d.buffered = func() io.Reader {
-			return bytes.NewReader(buf[cursor:])
-		}
-	}
-	return nil
-}
-
-func (d *Decoder) compileHead(typ *rtype) (decoder, error) {
-	if typ.Implements(unmarshalJSONType) {
-		return newUnmarshalJSONDecoder(typ), nil
-	} else if typ.Implements(unmarshalTextType) {
-		return newUnmarshalTextDecoder(typ), nil
-	}
-	return d.compile(typ.Elem())
-}
-
-func (d *Decoder) compile(typ *rtype) (decoder, error) {
-	if typ.Implements(unmarshalJSONType) {
-		return newUnmarshalJSONDecoder(typ), nil
-	} else if typ.Implements(unmarshalTextType) {
-		return newUnmarshalTextDecoder(typ), nil
-	}
-	switch typ.Kind() {
-	case reflect.Ptr:
-		return d.compilePtr(typ)
-	case reflect.Struct:
-		return d.compileStruct(typ)
-	case reflect.Slice:
-		return d.compileSlice(typ)
-	case reflect.Array:
-		return d.compileArray(typ)
-	case reflect.Map:
-		return d.compileMap(typ)
-	case reflect.Interface:
-		return d.compileInterface(typ)
-	case reflect.Int:
-		return d.compileInt()
-	case reflect.Int8:
-		return d.compileInt8()
-	case reflect.Int16:
-		return d.compileInt16()
-	case reflect.Int32:
-		return d.compileInt32()
-	case reflect.Int64:
-		return d.compileInt64()
-	case reflect.Uint:
-		return d.compileUint()
-	case reflect.Uint8:
-		return d.compileUint8()
-	case reflect.Uint16:
-		return d.compileUint16()
-	case reflect.Uint32:
-		return d.compileUint32()
-	case reflect.Uint64:
-		return d.compileUint64()
-	case reflect.String:
-		return d.compileString()
-	case reflect.Bool:
-		return d.compileBool()
-	case reflect.Float32:
-		return d.compileFloat32()
-	case reflect.Float64:
-		return d.compileFloat64()
-	}
-	return nil, &UnsupportedTypeError{Type: rtype2type(typ)}
-}
-
-func (d *Decoder) compilePtr(typ *rtype) (decoder, error) {
-	dec, err := d.compile(typ.Elem())
-	if err != nil {
-		return nil, err
-	}
-	return newPtrDecoder(dec, typ.Elem()), nil
-}
-
-func (d *Decoder) compileInt() (decoder, error) {
-	return newIntDecoder(func(p uintptr, v int64) {
-		*(*int)(unsafe.Pointer(p)) = int(v)
-	}), nil
-}
-
-func (d *Decoder) compileInt8() (decoder, error) {
-	return newIntDecoder(func(p uintptr, v int64) {
-		*(*int8)(unsafe.Pointer(p)) = int8(v)
-	}), nil
-}
-
-func (d *Decoder) compileInt16() (decoder, error) {
-	return newIntDecoder(func(p uintptr, v int64) {
-		*(*int16)(unsafe.Pointer(p)) = int16(v)
-	}), nil
-}
-
-func (d *Decoder) compileInt32() (decoder, error) {
-	return newIntDecoder(func(p uintptr, v int64) {
-		*(*int32)(unsafe.Pointer(p)) = int32(v)
-	}), nil
-}
-
-func (d *Decoder) compileInt64() (decoder, error) {
-	return newIntDecoder(func(p uintptr, v int64) {
-		*(*int64)(unsafe.Pointer(p)) = v
-	}), nil
-}
-
-func (d *Decoder) compileUint() (decoder, error) {
-	return newUintDecoder(func(p uintptr, v uint64) {
-		*(*uint)(unsafe.Pointer(p)) = uint(v)
-	}), nil
-}
-
-func (d *Decoder) compileUint8() (decoder, error) {
-	return newUintDecoder(func(p uintptr, v uint64) {
-		*(*uint8)(unsafe.Pointer(p)) = uint8(v)
-	}), nil
-}
-
-func (d *Decoder) compileUint16() (decoder, error) {
-	return newUintDecoder(func(p uintptr, v uint64) {
-		*(*uint16)(unsafe.Pointer(p)) = uint16(v)
-	}), nil
-}
-
-func (d *Decoder) compileUint32() (decoder, error) {
-	return newUintDecoder(func(p uintptr, v uint64) {
-		*(*uint32)(unsafe.Pointer(p)) = uint32(v)
-	}), nil
-}
-
-func (d *Decoder) compileUint64() (decoder, error) {
-	return newUintDecoder(func(p uintptr, v uint64) {
-		*(*uint64)(unsafe.Pointer(p)) = v
-	}), nil
-}
-
-func (d *Decoder) compileFloat32() (decoder, error) {
-	return newFloatDecoder(func(p uintptr, v float64) {
-		*(*float32)(unsafe.Pointer(p)) = float32(v)
-	}), nil
-}
-
-func (d *Decoder) compileFloat64() (decoder, error) {
-	return newFloatDecoder(func(p uintptr, v float64) {
-		*(*float64)(unsafe.Pointer(p)) = v
-	}), nil
-}
-
-func (d *Decoder) compileString() (decoder, error) {
-	return newStringDecoder(), nil
-}
-
-func (d *Decoder) compileBool() (decoder, error) {
-	return newBoolDecoder(), nil
-}
-
-func (d *Decoder) compileSlice(typ *rtype) (decoder, error) {
-	elem := typ.Elem()
-	decoder, err := d.compile(elem)
-	if err != nil {
-		return nil, err
-	}
-	return newSliceDecoder(decoder, elem, elem.Size()), nil
-}
-
-func (d *Decoder) compileArray(typ *rtype) (decoder, error) {
-	elem := typ.Elem()
-	decoder, err := d.compile(elem)
-	if err != nil {
-		return nil, err
-	}
-	return newArrayDecoder(decoder, elem, typ.Len()), nil
-}
-
-func (d *Decoder) compileMap(typ *rtype) (decoder, error) {
-	keyDec, err := d.compile(typ.Key())
-	if err != nil {
-		return nil, err
-	}
-	valueDec, err := d.compile(typ.Elem())
-	if err != nil {
-		return nil, err
-	}
-	return newMapDecoder(typ, keyDec, valueDec), nil
-}
-
-func (d *Decoder) compileInterface(typ *rtype) (decoder, error) {
-	return newInterfaceDecoder(typ), nil
-}
-
-func (d *Decoder) getTag(field reflect.StructField) string {
-	return field.Tag.Get("json")
-}
-
-func (d *Decoder) isIgnoredStructField(field reflect.StructField) bool {
-	if field.PkgPath != "" && !field.Anonymous {
-		// private field
-		return true
-	}
-	tag := d.getTag(field)
-	if tag == "-" {
-		return true
-	}
 			return false
-}
+		case nul:
-
+			if s.read() {
-func (d *Decoder) compileStruct(typ *rtype) (decoder, error) {
-	fieldNum := typ.NumField()
-	fieldMap := map[string]*structFieldSet{}
-	for i := 0; i < fieldNum; i++ {
-		field := typ.Field(i)
-		if d.isIgnoredStructField(field) {
 				continue
 			}
-		keyName := field.Name
+			return false
-		tag := d.getTag(field)
-		opts := strings.Split(tag, ",")
-		if len(opts) > 0 {
-			if opts[0] != "" {
-				keyName = opts[0]
 		}
+		break
 	}
-		dec, err := d.compile(type2rtype(field.Type))
+	return true
+}
+
+func (d *Decoder) Token() (Token, error) {
+	s := d.s
+	for {
+		c := s.char()
+		switch c {
+		case ' ', '\n', '\r', '\t':
+			s.cursor++
+		case '{', '[', ']', '}':
+			s.cursor++
+			return Delim(c), nil
+		case ',', ':':
+			s.cursor++
+		case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			bytes := floatBytes(s)
+			s := *(*string)(unsafe.Pointer(&bytes))
+			f64, err := strconv.ParseFloat(s, 64)
 			if err != nil {
 				return nil, err
 			}
-		fieldSet := &structFieldSet{dec: dec, offset: field.Offset}
+			return f64, nil
-		fieldMap[field.Name] = fieldSet
+		case '"':
-		fieldMap[keyName] = fieldSet
+			bytes, err := stringBytes(s)
-		fieldMap[strings.ToLower(keyName)] = fieldSet
+			if err != nil {
+				return nil, err
 			}
-	return newStructDecoder(fieldMap), nil
+			return string(bytes), nil
+		case 't':
+			if err := trueBytes(s); err != nil {
+				return nil, err
+			}
+			return true, nil
+		case 'f':
+			if err := falseBytes(s); err != nil {
+				return nil, err
+			}
+			return false, nil
+		case 'n':
+			if err := nullBytes(s); err != nil {
+				return nil, err
+			}
+			return nil, nil
+		case nul:
+			if s.read() {
+				continue
+			}
+			return nil, io.EOF
+		default:
+			return nil, errInvalidCharacter(s.char(), "token", s.totalOffset())
+		}
+	}
+	return nil, io.EOF
 }
 
 // DisallowUnknownFields causes the Decoder to return an error when the destination
@@ -397,15 +252,7 @@ func (d *Decoder) DisallowUnknownFields() {
 }
 
 func (d *Decoder) InputOffset() int64 {
-	return 0
+	return d.s.totalOffset()
-}
-
-func (d *Decoder) More() bool {
-	return false
-}
-
-func (d *Decoder) Token() (Token, error) {
-	return nil, nil
 }
 
 // UseNumber causes the Decoder to unmarshal a number into an interface{} as a

decode_array.go

@@ -16,6 +16,47 @@ func newArrayDecoder(dec decoder, elemType *rtype, alen int) *arrayDecoder {
 	}
 }
 
+func (d *arrayDecoder) decodeStream(s *stream, p uintptr) error {
+	for {
+		switch s.char() {
+		case ' ', '\n', '\t', '\r':
+		case '[':
+			idx := 0
+			for {
+				s.cursor++
+				if err := d.valueDecoder.decodeStream(s, p+uintptr(idx)*d.size); err != nil {
+					return err
+				}
+				s.skipWhiteSpace()
+				switch s.char() {
+				case ']':
+					s.cursor++
+					return nil
+				case ',':
+					idx++
+				case nul:
+					if s.read() {
+						continue
+					}
+					goto ERROR
+				default:
+					goto ERROR
+				}
+			}
+		case nul:
+			if s.read() {
+				continue
+			}
+			goto ERROR
+		default:
+			goto ERROR
+		}
+		s.cursor++
+	}
+ERROR:
+	return errUnexpectedEndOfJSON("array", s.totalOffset())
+}
+
 func (d *arrayDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	buflen := int64(len(buf))
 	for ; cursor < buflen; cursor++ {

decode_bool.go

@@ -10,6 +10,82 @@ func newBoolDecoder() *boolDecoder {
 	return &boolDecoder{}
 }
 
+func trueBytes(s *stream) error {
+	if s.cursor+3 >= s.length {
+		if !s.read() {
+			return errInvalidCharacter(s.char(), "bool(true)", s.totalOffset())
+		}
+	}
+	s.cursor++
+	if s.char() != 'r' {
+		return errInvalidCharacter(s.char(), "bool(true)", s.totalOffset())
+	}
+	s.cursor++
+	if s.char() != 'u' {
+		return errInvalidCharacter(s.char(), "bool(true)", s.totalOffset())
+	}
+	s.cursor++
+	if s.char() != 'e' {
+		return errInvalidCharacter(s.char(), "bool(true)", s.totalOffset())
+	}
+	s.cursor++
+	return nil
+}
+
+func falseBytes(s *stream) error {
+	if s.cursor+4 >= s.length {
+		if s.read() {
+			return errInvalidCharacter(s.char(), "bool(false)", s.totalOffset())
+		}
+	}
+	s.cursor++
+	if s.char() != 'a' {
+		return errInvalidCharacter(s.char(), "bool(false)", s.totalOffset())
+	}
+	s.cursor++
+	if s.char() != 'l' {
+		return errInvalidCharacter(s.char(), "bool(false)", s.totalOffset())
+	}
+	s.cursor++
+	if s.char() != 's' {
+		return errInvalidCharacter(s.char(), "bool(false)", s.totalOffset())
+	}
+	s.cursor++
+	if s.char() != 'e' {
+		return errInvalidCharacter(s.char(), "bool(false)", s.totalOffset())
+	}
+	s.cursor++
+	return nil
+}
+
+func (d *boolDecoder) decodeStream(s *stream, p uintptr) error {
+	s.skipWhiteSpace()
+	for {
+		switch s.char() {
+		case 't':
+			if err := trueBytes(s); err != nil {
+				return err
+			}
+			*(*bool)(unsafe.Pointer(p)) = true
+			return nil
+		case 'f':
+			if err := falseBytes(s); err != nil {
+				return err
+			}
+			*(*bool)(unsafe.Pointer(p)) = false
+			return nil
+		case nul:
+			if s.read() {
+				continue
+			}
+			goto ERROR
+		}
+		break
+	}
+ERROR:
+	return errUnexpectedEndOfJSON("bool", s.totalOffset())
+}
+
 func (d *boolDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	buflen := int64(len(buf))
 	cursor = skipWhiteSpace(buf, cursor)
@@ -29,6 +105,7 @@ func (d *boolDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error)
 		}
 		cursor += 4
 		*(*bool)(unsafe.Pointer(p)) = true
+		return cursor, nil
 	case 'f':
 		if cursor+4 >= buflen {
 			return 0, errUnexpectedEndOfJSON("bool(false)", cursor)
@@ -47,6 +124,7 @@ func (d *boolDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error)
 		}
 		cursor += 5
 		*(*bool)(unsafe.Pointer(p)) = false
-	}
 		return cursor, nil
+	}
+	return 0, errUnexpectedEndOfJSON("bool", cursor)
 }

decode_compile.go

@@ -0,0 +1,233 @@
+package json
+
+import (
+	"reflect"
+	"strings"
+	"unsafe"
+)
+
+func (d *Decoder) compileHead(typ *rtype) (decoder, error) {
+	if typ.Implements(unmarshalJSONType) {
+		return newUnmarshalJSONDecoder(typ), nil
+	} else if typ.Implements(unmarshalTextType) {
+		return newUnmarshalTextDecoder(typ), nil
+	}
+	return d.compile(typ.Elem())
+}
+
+func (d *Decoder) compile(typ *rtype) (decoder, error) {
+	if typ.Implements(unmarshalJSONType) {
+		return newUnmarshalJSONDecoder(typ), nil
+	} else if typ.Implements(unmarshalTextType) {
+		return newUnmarshalTextDecoder(typ), nil
+	}
+	switch typ.Kind() {
+	case reflect.Ptr:
+		return d.compilePtr(typ)
+	case reflect.Struct:
+		return d.compileStruct(typ)
+	case reflect.Slice:
+		return d.compileSlice(typ)
+	case reflect.Array:
+		return d.compileArray(typ)
+	case reflect.Map:
+		return d.compileMap(typ)
+	case reflect.Interface:
+		return d.compileInterface(typ)
+	case reflect.Int:
+		return d.compileInt()
+	case reflect.Int8:
+		return d.compileInt8()
+	case reflect.Int16:
+		return d.compileInt16()
+	case reflect.Int32:
+		return d.compileInt32()
+	case reflect.Int64:
+		return d.compileInt64()
+	case reflect.Uint:
+		return d.compileUint()
+	case reflect.Uint8:
+		return d.compileUint8()
+	case reflect.Uint16:
+		return d.compileUint16()
+	case reflect.Uint32:
+		return d.compileUint32()
+	case reflect.Uint64:
+		return d.compileUint64()
+	case reflect.String:
+		return d.compileString()
+	case reflect.Bool:
+		return d.compileBool()
+	case reflect.Float32:
+		return d.compileFloat32()
+	case reflect.Float64:
+		return d.compileFloat64()
+	}
+	return nil, &UnsupportedTypeError{Type: rtype2type(typ)}
+}
+
+func (d *Decoder) compilePtr(typ *rtype) (decoder, error) {
+	dec, err := d.compile(typ.Elem())
+	if err != nil {
+		return nil, err
+	}
+	return newPtrDecoder(dec, typ.Elem()), nil
+}
+
+func (d *Decoder) compileInt() (decoder, error) {
+	return newIntDecoder(func(p uintptr, v int64) {
+		*(*int)(unsafe.Pointer(p)) = int(v)
+	}), nil
+}
+
+func (d *Decoder) compileInt8() (decoder, error) {
+	return newIntDecoder(func(p uintptr, v int64) {
+		*(*int8)(unsafe.Pointer(p)) = int8(v)
+	}), nil
+}
+
+func (d *Decoder) compileInt16() (decoder, error) {
+	return newIntDecoder(func(p uintptr, v int64) {
+		*(*int16)(unsafe.Pointer(p)) = int16(v)
+	}), nil
+}
+
+func (d *Decoder) compileInt32() (decoder, error) {
+	return newIntDecoder(func(p uintptr, v int64) {
+		*(*int32)(unsafe.Pointer(p)) = int32(v)
+	}), nil
+}
+
+func (d *Decoder) compileInt64() (decoder, error) {
+	return newIntDecoder(func(p uintptr, v int64) {
+		*(*int64)(unsafe.Pointer(p)) = v
+	}), nil
+}
+
+func (d *Decoder) compileUint() (decoder, error) {
+	return newUintDecoder(func(p uintptr, v uint64) {
+		*(*uint)(unsafe.Pointer(p)) = uint(v)
+	}), nil
+}
+
+func (d *Decoder) compileUint8() (decoder, error) {
+	return newUintDecoder(func(p uintptr, v uint64) {
+		*(*uint8)(unsafe.Pointer(p)) = uint8(v)
+	}), nil
+}
+
+func (d *Decoder) compileUint16() (decoder, error) {
+	return newUintDecoder(func(p uintptr, v uint64) {
+		*(*uint16)(unsafe.Pointer(p)) = uint16(v)
+	}), nil
+}
+
+func (d *Decoder) compileUint32() (decoder, error) {
+	return newUintDecoder(func(p uintptr, v uint64) {
+		*(*uint32)(unsafe.Pointer(p)) = uint32(v)
+	}), nil
+}
+
+func (d *Decoder) compileUint64() (decoder, error) {
+	return newUintDecoder(func(p uintptr, v uint64) {
+		*(*uint64)(unsafe.Pointer(p)) = v
+	}), nil
+}
+
+func (d *Decoder) compileFloat32() (decoder, error) {
+	return newFloatDecoder(func(p uintptr, v float64) {
+		*(*float32)(unsafe.Pointer(p)) = float32(v)
+	}), nil
+}
+
+func (d *Decoder) compileFloat64() (decoder, error) {
+	return newFloatDecoder(func(p uintptr, v float64) {
+		*(*float64)(unsafe.Pointer(p)) = v
+	}), nil
+}
+
+func (d *Decoder) compileString() (decoder, error) {
+	return newStringDecoder(), nil
+}
+
+func (d *Decoder) compileBool() (decoder, error) {
+	return newBoolDecoder(), nil
+}
+
+func (d *Decoder) compileSlice(typ *rtype) (decoder, error) {
+	elem := typ.Elem()
+	decoder, err := d.compile(elem)
+	if err != nil {
+		return nil, err
+	}
+	return newSliceDecoder(decoder, elem, elem.Size()), nil
+}
+
+func (d *Decoder) compileArray(typ *rtype) (decoder, error) {
+	elem := typ.Elem()
+	decoder, err := d.compile(elem)
+	if err != nil {
+		return nil, err
+	}
+	return newArrayDecoder(decoder, elem, typ.Len()), nil
+}
+
+func (d *Decoder) compileMap(typ *rtype) (decoder, error) {
+	keyDec, err := d.compile(typ.Key())
+	if err != nil {
+		return nil, err
+	}
+	valueDec, err := d.compile(typ.Elem())
+	if err != nil {
+		return nil, err
+	}
+	return newMapDecoder(typ, keyDec, valueDec), nil
+}
+
+func (d *Decoder) compileInterface(typ *rtype) (decoder, error) {
+	return newInterfaceDecoder(typ), nil
+}
+
+func (d *Decoder) getTag(field reflect.StructField) string {
+	return field.Tag.Get("json")
+}
+
+func (d *Decoder) isIgnoredStructField(field reflect.StructField) bool {
+	if field.PkgPath != "" && !field.Anonymous {
+		// private field
+		return true
+	}
+	tag := d.getTag(field)
+	if tag == "-" {
+		return true
+	}
+	return false
+}
+
+func (d *Decoder) compileStruct(typ *rtype) (decoder, error) {
+	fieldNum := typ.NumField()
+	fieldMap := map[string]*structFieldSet{}
+	for i := 0; i < fieldNum; i++ {
+		field := typ.Field(i)
+		if d.isIgnoredStructField(field) {
+			continue
+		}
+		keyName := field.Name
+		tag := d.getTag(field)
+		opts := strings.Split(tag, ",")
+		if len(opts) > 0 {
+			if opts[0] != "" {
+				keyName = opts[0]
+			}
+		}
+		dec, err := d.compile(type2rtype(field.Type))
+		if err != nil {
+			return nil, err
+		}
+		fieldSet := &structFieldSet{dec: dec, offset: field.Offset}
+		fieldMap[field.Name] = fieldSet
+		fieldMap[keyName] = fieldSet
+		fieldMap[strings.ToLower(keyName)] = fieldSet
+	}
+	return newStructDecoder(fieldMap), nil
+}

decode_context.go

@@ -72,6 +72,63 @@ func skipValue(buf []byte, cursor int64) (int64, error) {
 				return cursor, nil
 			}
 			continue
+		case 't':
+			if cursor+3 >= buflen {
+				return 0, errUnexpectedEndOfJSON("bool of object", cursor)
+			}
+			if buf[cursor+1] != 'r' {
+				return 0, errUnexpectedEndOfJSON("bool of object", cursor)
+			}
+			if buf[cursor+2] != 'u' {
+				return 0, errUnexpectedEndOfJSON("bool of object", cursor)
+			}
+			if buf[cursor+3] != 'e' {
+				return 0, errUnexpectedEndOfJSON("bool of object", cursor)
+			}
+			cursor += 4
+			if bracketCount == 0 && braceCount == 0 {
+				return cursor, nil
+			}
+			continue
+		case 'f':
+			if cursor+4 >= buflen {
+				return 0, errUnexpectedEndOfJSON("bool of object", cursor)
+			}
+			if buf[cursor+1] != 'a' {
+				return 0, errUnexpectedEndOfJSON("bool of object", cursor)
+			}
+			if buf[cursor+2] != 'l' {
+				return 0, errUnexpectedEndOfJSON("bool of object", cursor)
+			}
+			if buf[cursor+3] != 's' {
+				return 0, errUnexpectedEndOfJSON("bool of object", cursor)
+			}
+			if buf[cursor+4] != 'e' {
+				return 0, errUnexpectedEndOfJSON("bool of object", cursor)
+			}
+			cursor += 5
+			if bracketCount == 0 && braceCount == 0 {
+				return cursor, nil
+			}
+			continue
+		case 'n':
+			if cursor+3 >= buflen {
+				return 0, errUnexpectedEndOfJSON("null", cursor)
+			}
+			if buf[cursor+1] != 'u' {
+				return 0, errUnexpectedEndOfJSON("null", cursor)
+			}
+			if buf[cursor+2] != 'l' {
+				return 0, errUnexpectedEndOfJSON("null", cursor)
+			}
+			if buf[cursor+3] != 'l' {
+				return 0, errUnexpectedEndOfJSON("null", cursor)
+			}
+			cursor += 4
+			if bracketCount == 0 && braceCount == 0 {
+				return cursor, nil
+			}
+			continue
 		}
 		cursor++
 	}

decode_float.go

@@ -13,6 +13,60 @@ func newFloatDecoder(op func(uintptr, float64)) *floatDecoder {
 	return &floatDecoder{op: op}
 }
 
+var floatTable = [256]bool{
+	'0': true,
+	'1': true,
+	'2': true,
+	'3': true,
+	'4': true,
+	'5': true,
+	'6': true,
+	'7': true,
+	'8': true,
+	'9': true,
+	'.': true,
+	'e': true,
+	'E': true,
+}
+
+func floatBytes(s *stream) []byte {
+	start := s.cursor
+	for {
+		s.cursor++
+		if floatTable[s.char()] {
+			continue
+		} else if s.char() == nul {
+			if s.read() {
+				s.cursor-- // for retry current character
+				continue
+			}
+		}
+		break
+	}
+	return s.buf[start:s.cursor]
+}
+
+func (d *floatDecoder) decodeStreamByte(s *stream) ([]byte, error) {
+	for {
+		switch s.char() {
+		case ' ', '\n', '\t', '\r':
+			s.cursor++
+			continue
+		case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			return floatBytes(s), nil
+		case nul:
+			if s.read() {
+				continue
+			}
+			goto ERROR
+		default:
+			goto ERROR
+		}
+	}
+ERROR:
+	return nil, errUnexpectedEndOfJSON("float", s.totalOffset())
+}
+
 func (d *floatDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error) {
 	buflen := int64(len(buf))
 	for ; cursor < buflen; cursor++ {
@@ -31,11 +85,27 @@ func (d *floatDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, erro
 			}
 			num := buf[start:cursor]
 			return num, cursor, nil
+		default:
+			return nil, 0, errUnexpectedEndOfJSON("float", cursor)
 		}
 	}
 	return nil, 0, errUnexpectedEndOfJSON("float", cursor)
 }
 
+func (d *floatDecoder) decodeStream(s *stream, p uintptr) error {
+	bytes, err := d.decodeStreamByte(s)
+	if err != nil {
+		return err
+	}
+	str := *(*string)(unsafe.Pointer(&bytes))
+	f64, err := strconv.ParseFloat(str, 64)
+	if err != nil {
+		return err
+	}
+	d.op(p, f64)
+	return nil
+}
+
 func (d *floatDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	bytes, c, err := d.decodeByte(buf, cursor)
 	if err != nil {

decode_int.go

@@ -49,6 +49,62 @@ var (
 	}
 )
 
+func (d *intDecoder) decodeStreamByte(s *stream) ([]byte, error) {
+	for {
+		switch s.char() {
+		case ' ', '\n', '\t', '\r':
+			s.cursor++
+			continue
+		case '-':
+			start := s.cursor
+			for {
+				s.cursor++
+				if numTable[s.char()] {
+					continue
+				} else if s.char() == nul {
+					if s.read() {
+						s.cursor-- // for retry current character
+						continue
+					}
+				}
+				break
+			}
+			num := s.buf[start:s.cursor]
+			s.reset()
+			if len(num) < 2 {
+				goto ERROR
+			}
+			return num, nil
+		case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			start := s.cursor
+			for {
+				s.cursor++
+				if numTable[s.char()] {
+					continue
+				} else if s.char() == nul {
+					if s.read() {
+						s.cursor-- // for retry current character
+						continue
+					}
+				}
+				break
+			}
+			num := s.buf[start:s.cursor]
+			s.reset()
+			return num, nil
+		case nul:
+			if s.read() {
+				continue
+			}
+			goto ERROR
+		default:
+			goto ERROR
+		}
+	}
+ERROR:
+	return nil, errUnexpectedEndOfJSON("number(integer)", s.totalOffset())
+}
+
 func (d *intDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error) {
 	for {
 		switch buf[cursor] {
@@ -72,6 +128,15 @@ func (d *intDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error)
 	return nil, 0, errUnexpectedEndOfJSON("number(integer)", cursor)
 }
 
+func (d *intDecoder) decodeStream(s *stream, p uintptr) error {
+	bytes, err := d.decodeStreamByte(s)
+	if err != nil {
+		return err
+	}
+	d.op(p, d.parseInt(bytes))
+	return nil
+}
+
 func (d *intDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	bytes, c, err := d.decodeByte(buf, cursor)
 	if err != nil {

decode_interface.go

@@ -20,6 +20,83 @@ var (
 	)
 )
 
+func (d *interfaceDecoder) decodeStream(s *stream, p uintptr) error {
+	s.skipWhiteSpace()
+	for {
+		switch s.char() {
+		case '{':
+			var v map[interface{}]interface{}
+			ptr := unsafe.Pointer(&v)
+			d.dummy = ptr
+			dec := newMapDecoder(interfaceMapType, newInterfaceDecoder(d.typ), newInterfaceDecoder(d.typ))
+			if err := dec.decodeStream(s, uintptr(ptr)); err != nil {
+				return err
+			}
+			*(*interface{})(unsafe.Pointer(p)) = v
+			return nil
+		case '[':
+			var v []interface{}
+			ptr := unsafe.Pointer(&v)
+			d.dummy = ptr // escape ptr
+			dec := newSliceDecoder(newInterfaceDecoder(d.typ), d.typ, d.typ.Size())
+			if err := dec.decodeStream(s, uintptr(ptr)); err != nil {
+				return err
+			}
+			*(*interface{})(unsafe.Pointer(p)) = v
+			return nil
+		case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			return newFloatDecoder(func(p uintptr, v float64) {
+				*(*interface{})(unsafe.Pointer(p)) = v
+			}).decodeStream(s, p)
+		case '"':
+			s.cursor++
+			start := s.cursor
+			for {
+				switch s.char() {
+				case '\\':
+					s.cursor++
+				case '"':
+					literal := s.buf[start:s.cursor]
+					s.cursor++
+					*(*interface{})(unsafe.Pointer(p)) = *(*string)(unsafe.Pointer(&literal))
+					return nil
+				case nul:
+					if s.read() {
+						continue
+					}
+					return errUnexpectedEndOfJSON("string", s.totalOffset())
+				}
+				s.cursor++
+			}
+			return errUnexpectedEndOfJSON("string", s.totalOffset())
+		case 't':
+			if err := trueBytes(s); err != nil {
+				return err
+			}
+			*(*interface{})(unsafe.Pointer(p)) = true
+			return nil
+		case 'f':
+			if err := falseBytes(s); err != nil {
+				return err
+			}
+			*(*interface{})(unsafe.Pointer(p)) = false
+			return nil
+		case 'n':
+			if err := nullBytes(s); err != nil {
+				return err
+			}
+			*(*interface{})(unsafe.Pointer(p)) = nil
+			return nil
+		case nul:
+			if s.read() {
+				continue
+			}
+		}
+		break
+	}
+	return errNotAtBeginningOfValue(s.totalOffset())
+}
+
 func (d *interfaceDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	cursor = skipWhiteSpace(buf, cursor)
 	switch buf[cursor] {

decode_map.go

@@ -35,6 +35,59 @@ func (d *mapDecoder) setValue(buf []byte, cursor int64, key interface{}) (int64,
 	return d.valueDecoder.decode(buf, cursor, uintptr(header.ptr))
 }
 
+func (d *mapDecoder) setKeyStream(s *stream, key interface{}) error {
+	header := (*interfaceHeader)(unsafe.Pointer(&key))
+	return d.keyDecoder.decodeStream(s, uintptr(header.ptr))
+}
+
+func (d *mapDecoder) setValueStream(s *stream, key interface{}) error {
+	header := (*interfaceHeader)(unsafe.Pointer(&key))
+	return d.valueDecoder.decodeStream(s, uintptr(header.ptr))
+}
+
+func (d *mapDecoder) decodeStream(s *stream, p uintptr) error {
+	s.skipWhiteSpace()
+	if s.char() != '{' {
+		return errExpected("{ character for map value", s.totalOffset())
+	}
+	mapValue := makemap(d.mapType, 0)
+	for {
+		s.cursor++
+		var key interface{}
+		if err := d.setKeyStream(s, &key); err != nil {
+			return err
+		}
+		s.skipWhiteSpace()
+		if s.char() == nul {
+			s.read()
+		}
+		if s.char() != ':' {
+			return errExpected("colon after object key", s.totalOffset())
+		}
+		s.cursor++
+		if s.end() {
+			return errUnexpectedEndOfJSON("map", s.totalOffset())
+		}
+		var value interface{}
+		if err := d.setValueStream(s, &value); err != nil {
+			return err
+		}
+		mapassign(d.mapType, mapValue, unsafe.Pointer(&key), unsafe.Pointer(&value))
+		s.skipWhiteSpace()
+		if s.char() == nul {
+			s.read()
+		}
+		if s.char() == '}' {
+			*(*unsafe.Pointer)(unsafe.Pointer(p)) = mapValue
+			return nil
+		}
+		if s.char() != ',' {
+			return errExpected("semicolon after object value", s.totalOffset())
+		}
+	}
+	return nil
+}
+
 func (d *mapDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	cursor = skipWhiteSpace(buf, cursor)
 	buflen := int64(len(buf))

decode_ptr.go

@@ -16,6 +16,15 @@ func newPtrDecoder(dec decoder, typ *rtype) *ptrDecoder {
 //go:linkname unsafe_New reflect.unsafe_New
 func unsafe_New(*rtype) uintptr
 
+func (d *ptrDecoder) decodeStream(s *stream, p uintptr) error {
+	newptr := unsafe_New(d.typ)
+	if err := d.dec.decodeStream(s, newptr); err != nil {
+		return err
+	}
+	*(*uintptr)(unsafe.Pointer(p)) = newptr
+	return nil
+}
+
 func (d *ptrDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	newptr := unsafe_New(d.typ)
 	c, err := d.dec.decode(buf, cursor, newptr)

decode_slice.go

@@ -56,6 +56,80 @@ func copySlice(elemType *rtype, dst, src reflect.SliceHeader) int
 //go:linkname newArray reflect.unsafe_NewArray
 func newArray(*rtype, int) unsafe.Pointer
 
+func (d *sliceDecoder) decodeStream(s *stream, p uintptr) error {
+	for {
+		switch s.char() {
+		case ' ', '\n', '\t', '\r':
+			s.cursor++
+			continue
+		case '[':
+			idx := 0
+			slice := d.newSlice()
+			cap := slice.cap
+			data := slice.data
+			for {
+				s.cursor++
+				if cap <= idx {
+					src := reflect.SliceHeader{Data: uintptr(data), Len: idx, Cap: cap}
+					cap *= 2
+					data = newArray(d.elemType, cap)
+					dst := reflect.SliceHeader{Data: uintptr(data), Len: idx, Cap: cap}
+					copySlice(d.elemType, dst, src)
+				}
+				if err := d.valueDecoder.decodeStream(s, uintptr(data)+uintptr(idx)*d.size); err != nil {
+					return err
+				}
+				s.skipWhiteSpace()
+			RETRY:
+				switch s.char() {
+				case ']':
+					slice.cap = cap
+					slice.len = idx + 1
+					slice.data = data
+					dstCap := idx + 1
+					dst := reflect.SliceHeader{
+						Data: uintptr(newArray(d.elemType, dstCap)),
+						Len:  idx + 1,
+						Cap:  dstCap,
+					}
+					copySlice(d.elemType, dst, reflect.SliceHeader{
+						Data: uintptr(slice.data),
+						Len:  slice.len,
+						Cap:  slice.cap,
+					})
+					*(*reflect.SliceHeader)(unsafe.Pointer(p)) = dst
+					d.releaseSlice(slice)
+					s.cursor++
+					return nil
+				case ',':
+					idx++
+					continue
+				case nul:
+					if s.read() {
+						goto RETRY
+					}
+					slice.cap = cap
+					slice.data = data
+					d.releaseSlice(slice)
+					goto ERROR
+				default:
+					slice.cap = cap
+					slice.data = data
+					d.releaseSlice(slice)
+					goto ERROR
+				}
+			}
+		case nul:
+			if s.read() {
+				continue
+			}
+			goto ERROR
+		}
+	}
+ERROR:
+	return errUnexpectedEndOfJSON("slice", s.totalOffset())
+}
+
 func (d *sliceDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	buflen := int64(len(buf))
 	for ; cursor < buflen; cursor++ {

decode_stream.go

@@ -0,0 +1,193 @@
+package json
+
+import (
+	"bytes"
+	"io"
+)
+
+const (
+	readChunkSize = 512
+)
+
+type stream struct {
+	buf     []byte
+	length  int64
+	r       io.Reader
+	offset  int64
+	cursor  int64
+	allRead bool
+}
+
+func (s *stream) buffered() io.Reader {
+	return bytes.NewReader(s.buf[s.cursor:])
+}
+
+func (s *stream) totalOffset() int64 {
+	return s.offset + s.cursor
+}
+
+func (s *stream) prevChar() byte {
+	return s.buf[s.cursor-1]
+}
+
+func (s *stream) char() byte {
+	return s.buf[s.cursor]
+}
+
+func (s *stream) end() bool {
+	return s.allRead && s.length <= s.cursor
+}
+
+func (s *stream) progressN(n int64) bool {
+	if s.cursor+n < s.length-1 || s.read() {
+		s.cursor += n
+		return true
+	}
+	s.cursor = s.length
+	return false
+}
+
+func (s *stream) reset() {
+	s.buf = s.buf[s.cursor:]
+	s.length -= s.cursor
+	s.cursor = 0
+}
+
+func (s *stream) read() bool {
+	if s.allRead {
+		return false
+	}
+	buf := make([]byte, readChunkSize)
+	n, err := s.r.Read(buf)
+	if err != nil && err != io.EOF {
+		return false
+	}
+	if n < readChunkSize || err == io.EOF {
+		s.allRead = true
+	}
+	totalSize := s.length + int64(n) + 1
+	if totalSize > readChunkSize {
+		newBuf := make([]byte, totalSize)
+		copy(newBuf, s.buf)
+		copy(newBuf[s.length:], buf)
+		s.buf = newBuf
+		s.length = totalSize - 1
+	} else if s.length > 0 {
+		copy(buf[s.length:], buf)
+		copy(buf, s.buf[:s.length])
+		s.buf = buf
+		s.length = totalSize - 1
+	} else {
+		s.buf = buf
+		s.length = totalSize - 1
+	}
+	s.offset += s.cursor
+	if n == 0 {
+		return false
+	}
+	return true
+}
+
+func (s *stream) skipWhiteSpace() {
+LOOP:
+	if isWhiteSpace[s.char()] {
+		s.cursor++
+		goto LOOP
+	} else if s.char() == nul {
+		if s.read() {
+			goto LOOP
+		}
+	}
+}
+
+func (s *stream) skipValue() error {
+	s.skipWhiteSpace()
+	braceCount := 0
+	bracketCount := 0
+	for {
+		switch s.char() {
+		case nul:
+			if s.read() {
+				continue
+			}
+			return errUnexpectedEndOfJSON("value of object", s.totalOffset())
+		case '{':
+			braceCount++
+		case '[':
+			bracketCount++
+		case '}':
+			braceCount--
+			if braceCount == -1 && bracketCount == 0 {
+				return nil
+			}
+		case ']':
+			bracketCount--
+		case ',':
+			if bracketCount == 0 && braceCount == 0 {
+				return nil
+			}
+		case '"':
+			for {
+				s.cursor++
+				if s.char() == nul {
+					if !s.read() {
+						return errUnexpectedEndOfJSON("value of string", s.totalOffset())
+					}
+				}
+				if s.char() != '"' {
+					continue
+				}
+				if s.prevChar() == '\\' {
+					continue
+				}
+				if bracketCount == 0 && braceCount == 0 {
+					s.cursor++
+					return nil
+				}
+				break
+			}
+		case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			for {
+				s.cursor++
+				if floatTable[s.char()] {
+					continue
+				} else if s.char() == nul {
+					if s.read() {
+						continue
+					}
+				}
+				break
+			}
+			if bracketCount == 0 && braceCount == 0 {
+				return nil
+			}
+			continue
+		case 't':
+			if err := trueBytes(s); err != nil {
+				return err
+			}
+			if bracketCount == 0 && braceCount == 0 {
+				return nil
+			}
+			continue
+		case 'f':
+			if err := falseBytes(s); err != nil {
+				return err
+			}
+			if bracketCount == 0 && braceCount == 0 {
+				return nil
+			}
+			continue
+		case 'n':
+			if err := nullBytes(s); err != nil {
+				return err
+			}
+			if bracketCount == 0 && braceCount == 0 {
+				return nil
+			}
+			continue
+		}
+		s.cursor++
+	}
+	return errUnexpectedEndOfJSON("value of object", s.offset)
+}

decode_string.go

@@ -11,6 +11,15 @@ func newStringDecoder() *stringDecoder {
 	return &stringDecoder{}
 }
 
+func (d *stringDecoder) decodeStream(s *stream, p uintptr) error {
+	bytes, err := d.decodeStreamByte(s)
+	if err != nil {
+		return err
+	}
+	*(*string)(unsafe.Pointer(p)) = *(*string)(unsafe.Pointer(&bytes))
+	return nil
+}
+
 func (d *stringDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	bytes, c, err := d.decodeByte(buf, cursor)
 	if err != nil {
@@ -21,6 +30,75 @@ func (d *stringDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, erro
 	return cursor, nil
 }
 
+func stringBytes(s *stream) ([]byte, error) {
+	s.cursor++
+	start := s.cursor
+	for {
+		switch s.char() {
+		case '\\':
+			s.cursor++
+		case '"':
+			literal := s.buf[start:s.cursor]
+			s.cursor++
+			s.reset()
+			return literal, nil
+		case nul:
+			if s.read() {
+				continue
+			}
+			goto ERROR
+		}
+		s.cursor++
+	}
+ERROR:
+	return nil, errUnexpectedEndOfJSON("string", s.totalOffset())
+}
+
+func nullBytes(s *stream) error {
+	if s.cursor+3 >= s.length {
+		if !s.read() {
+			return errInvalidCharacter(s.char(), "null", s.totalOffset())
+		}
+	}
+	s.cursor++
+	if s.char() != 'u' {
+		return errInvalidCharacter(s.char(), "null", s.totalOffset())
+	}
+	s.cursor++
+	if s.char() != 'l' {
+		return errInvalidCharacter(s.char(), "null", s.totalOffset())
+	}
+	s.cursor++
+	if s.char() != 'l' {
+		return errInvalidCharacter(s.char(), "null", s.totalOffset())
+	}
+	s.cursor++
+	return nil
+}
+
+func (d *stringDecoder) decodeStreamByte(s *stream) ([]byte, error) {
+	for {
+		switch s.char() {
+		case ' ', '\n', '\t', '\r':
+			s.cursor++
+			continue
+		case '"':
+			return stringBytes(s)
+		case 'n':
+			if err := nullBytes(s); err != nil {
+				return nil, err
+			}
+			return []byte{}, nil
+		case nul:
+			if s.read() {
+				continue
+			}
+		}
+		break
+	}
+	return nil, errNotAtBeginningOfValue(s.totalOffset())
+}
+
 func (d *stringDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error) {
 	for {
 		switch buf[cursor] {
@@ -37,7 +115,7 @@ func (d *stringDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, err
 					literal := buf[start:cursor]
 					cursor++
 					return literal, cursor, nil
-				case '\000':
+				case nul:
 					return nil, 0, errUnexpectedEndOfJSON("string", cursor)
 				}
 				cursor++
@@ -58,7 +136,7 @@ func (d *stringDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, err
 				return nil, 0, errInvalidCharacter(buf[cursor+3], "null", cursor)
 			}
 			cursor += 5
-			return []byte{'n', 'u', 'l', 'l'}, cursor, nil
+			return []byte{}, cursor, nil
 		default:
 			goto ERROR
 		}

decode_struct.go

@@ -21,6 +21,63 @@ func newStructDecoder(fieldMap map[string]*structFieldSet) *structDecoder {
 	}
 }
 
+func (d *structDecoder) decodeStream(s *stream, p uintptr) error {
+	s.skipWhiteSpace()
+	if s.char() == nul {
+		s.read()
+	}
+	if s.char() != '{' {
+		return errNotAtBeginningOfValue(s.totalOffset())
+	}
+	s.cursor++
+	for {
+		s.reset()
+		key, err := d.keyDecoder.decodeStreamByte(s)
+		if err != nil {
+			return err
+		}
+		s.skipWhiteSpace()
+		if s.char() == nul {
+			s.read()
+		}
+		if s.char() != ':' {
+			return errExpected("colon after object key", s.totalOffset())
+		}
+		s.cursor++
+		if s.char() == nul {
+			s.read()
+		}
+		if s.end() {
+			return errExpected("object value after colon", s.totalOffset())
+		}
+		k := *(*string)(unsafe.Pointer(&key))
+		field, exists := d.fieldMap[k]
+		if exists {
+			if err := field.dec.decodeStream(s, p+field.offset); err != nil {
+				return err
+			}
+		} else {
+			if err := s.skipValue(); err != nil {
+				return err
+			}
+		}
+		s.skipWhiteSpace()
+		if s.char() == nul {
+			s.read()
+		}
+		c := s.char()
+		if c == '}' {
+			s.cursor++
+			return nil
+		}
+		if c != ',' {
+			return errExpected("comma after object element", s.totalOffset())
+		}
+		s.cursor++
+	}
+	return nil
+}
+
 func (d *structDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	buflen := int64(len(buf))
 	cursor = skipWhiteSpace(buf, cursor)

decode_test.go

@@ -3,6 +3,7 @@ package json_test
 import (
 	"fmt"
 	"reflect"
+	"strings"
 	"testing"
 
 	"github.com/goccy/go-json"
@@ -231,3 +232,54 @@ func Test_InvalidUnmarshalError(t *testing.T) {
 		assertEq(t, "invalid unmarshal error", "json: Unmarshal(non-pointer int)", err)
 	})
 }
+
+func Test_Token(t *testing.T) {
+	dec := json.NewDecoder(strings.NewReader(`{"a": 1, "b": true, "c": [1, "two", null]}`))
+	cnt := 0
+	for {
+		if _, err := dec.Token(); err != nil {
+			break
+		}
+		cnt++
+	}
+	if cnt != 12 {
+		t.Fatal("failed to parse token")
+	}
+}
+
+func Test_DecodeStream(t *testing.T) {
+	const stream = `
+	[
+		{"Name": "Ed", "Text": "Knock knock."},
+		{"Name": "Sam", "Text": "Who's there?"},
+		{"Name": "Ed", "Text": "Go fmt."},
+		{"Name": "Sam", "Text": "Go fmt who?"},
+		{"Name": "Ed", "Text": "Go fmt yourself!"}
+	]
+`
+	type Message struct {
+		Name, Text string
+	}
+	dec := json.NewDecoder(strings.NewReader(stream))
+
+	tk, err := dec.Token()
+	assertErr(t, err)
+	assertEq(t, "[", fmt.Sprint(tk), "[")
+
+	elem := 0
+	// while the array contains values
+	for dec.More() {
+		var m Message
+		// decode an array value (Message)
+		assertErr(t, dec.Decode(&m))
+		if m.Name == "" || m.Text == "" {
+			t.Fatal("failed to assign value to struct field")
+		}
+		elem++
+	}
+	assertEq(t, "decode count", elem, 5)
+
+	tk, err = dec.Token()
+	assertErr(t, err)
+	assertEq(t, "]", fmt.Sprint(tk), "]")
+}

decode_uint.go

@@ -24,6 +24,38 @@ func (d *uintDecoder) parseUint(b []byte) uint64 {
 	return sum
 }
 
+func (d *uintDecoder) decodeStreamByte(s *stream) ([]byte, error) {
+	for {
+		switch s.char() {
+		case ' ', '\n', '\t', '\r':
+			s.cursor++
+			continue
+		case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			start := s.cursor
+			for {
+				s.cursor++
+				if numTable[s.char()] {
+					continue
+				} else if s.char() == nul {
+					if s.read() {
+						s.cursor-- // for retry current character
+						continue
+					}
+				}
+				break
+			}
+			num := s.buf[start:s.cursor]
+			return num, nil
+		case nul:
+			if s.read() {
+				continue
+			}
+		}
+		break
+	}
+	return nil, errUnexpectedEndOfJSON("number(unsigned integer)", s.totalOffset())
+}
+
 func (d *uintDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error) {
 	buflen := int64(len(buf))
 	for ; cursor < buflen; cursor++ {
@@ -49,6 +81,15 @@ func (d *uintDecoder) decodeByte(buf []byte, cursor int64) ([]byte, int64, error
 	return nil, 0, errUnexpectedEndOfJSON("number(unsigned integer)", cursor)
 }
 
+func (d *uintDecoder) decodeStream(s *stream, p uintptr) error {
+	bytes, err := d.decodeStreamByte(s)
+	if err != nil {
+		return err
+	}
+	d.op(p, d.parseUint(bytes))
+	return nil
+}
+
 func (d *uintDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	bytes, c, err := d.decodeByte(buf, cursor)
 	if err != nil {

decode_unmarshal_json.go

@@ -12,6 +12,23 @@ func newUnmarshalJSONDecoder(typ *rtype) *unmarshalJSONDecoder {
 	return &unmarshalJSONDecoder{typ: typ}
 }
 
+func (d *unmarshalJSONDecoder) decodeStream(s *stream, p uintptr) error {
+	s.skipWhiteSpace()
+	start := s.cursor
+	if err := s.skipValue(); err != nil {
+		return err
+	}
+	src := s.buf[start:s.cursor]
+	v := *(*interface{})(unsafe.Pointer(&interfaceHeader{
+		typ: d.typ,
+		ptr: unsafe.Pointer(p),
+	}))
+	if err := v.(Unmarshaler).UnmarshalJSON(src); err != nil {
+		return err
+	}
+	return nil
+}
+
 func (d *unmarshalJSONDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	cursor = skipWhiteSpace(buf, cursor)
 	start := cursor

decode_unmarshal_text.go

@@ -13,6 +13,23 @@ func newUnmarshalTextDecoder(typ *rtype) *unmarshalTextDecoder {
 	return &unmarshalTextDecoder{typ: typ}
 }
 
+func (d *unmarshalTextDecoder) decodeStream(s *stream, p uintptr) error {
+	s.skipWhiteSpace()
+	start := s.cursor
+	if err := s.skipValue(); err != nil {
+		return err
+	}
+	src := s.buf[start:s.cursor]
+	v := *(*interface{})(unsafe.Pointer(&interfaceHeader{
+		typ: d.typ,
+		ptr: unsafe.Pointer(p),
+	}))
+	if err := v.(encoding.TextUnmarshaler).UnmarshalText(src); err != nil {
+		return err
+	}
+	return nil
+}
+
 func (d *unmarshalTextDecoder) decode(buf []byte, cursor int64, p uintptr) (int64, error) {
 	cursor = skipWhiteSpace(buf, cursor)
 	start := cursor

json.go

@@ -264,3 +264,14 @@ func UnmarshalNoEscape(data []byte, v interface{}) error {
 	var dec Decoder
 	return dec.decodeForUnmarshalNoEscape(src, v)
 }
+
+// A Token holds a value of one of these types:
+//
+//	Delim, for the four JSON delimiters [ ] { }
+//	bool, for JSON booleans
+//	float64, for JSON numbers
+//	Number, for JSON numbers
+//	string, for JSON string literals
+//	nil, for JSON null
+//
+type Token interface{}