reflect_extension.go

package jsoniter

import (
	"fmt"
	"github.com/modern-go/reflect2"
	"reflect"
	"sort"
	"strings"
	"unicode"
	"unsafe"
)

var typeDecoders = map[string]ValDecoder{}
var fieldDecoders = map[string]ValDecoder{}
var typeEncoders = map[string]ValEncoder{}
var fieldEncoders = map[string]ValEncoder{}
var extensions = []Extension{}

// StructDescriptor describe how should we encode/decode the struct
type StructDescriptor struct {
	Type   reflect2.Type
	Fields []*Binding
}

// GetField get one field from the descriptor by its name.
// Can not use map here to keep field orders.
func (structDescriptor *StructDescriptor) GetField(fieldName string) *Binding {
	for _, binding := range structDescriptor.Fields {
		if binding.Field.Name() == fieldName {
			return binding
		}
	}
	return nil
}

// Binding describe how should we encode/decode the struct field
type Binding struct {
	levels    []int
	Field     reflect2.StructField
	FromNames []string
	ToNames   []string
	Encoder   ValEncoder
	Decoder   ValDecoder
}

// Extension the one for all SPI. Customize encoding/decoding by specifying alternate encoder/decoder.
// Can also rename fields by UpdateStructDescriptor.
type Extension interface {
	UpdateStructDescriptor(structDescriptor *StructDescriptor)
	StructDecodedHook(ptr unsafe.Pointer, typ reflect2.Type)
	StructFieldDecodedHook(field string, ptr unsafe.Pointer, typ reflect2.Type)
	CreateMapKeyDecoder(typ reflect2.Type) ValDecoder
	CreateMapKeyEncoder(typ reflect2.Type) ValEncoder
	CreateDecoder(typ reflect2.Type) ValDecoder
	CreateEncoder(typ reflect2.Type) ValEncoder
	DecorateDecoder(typ reflect2.Type, decoder ValDecoder) ValDecoder
	DecorateEncoder(typ reflect2.Type, encoder ValEncoder) ValEncoder
}

// DummyExtension embed this type get dummy implementation for all methods of Extension
type DummyExtension struct {
}

// UpdateStructDescriptor No-op
func (extension *DummyExtension) UpdateStructDescriptor(structDescriptor *StructDescriptor) {
}

// StructDecodedHook No-op
func (extension *DummyExtension) StructDecodedHook(ptr unsafe.Pointer, typ reflect2.Type) {
}

// StructFieldDecodedHook No-op
func (extension *DummyExtension) StructFieldDecodedHook(field string, ptr unsafe.Pointer, typ reflect2.Type) {
}

// CreateMapKeyDecoder No-op
func (extension *DummyExtension) CreateMapKeyDecoder(typ reflect2.Type) ValDecoder {
	return nil
}

// CreateMapKeyEncoder No-op
func (extension *DummyExtension) CreateMapKeyEncoder(typ reflect2.Type) ValEncoder {
	return nil
}

// CreateDecoder No-op
func (extension *DummyExtension) CreateDecoder(typ reflect2.Type) ValDecoder {
	return nil
}

// CreateEncoder No-op
func (extension *DummyExtension) CreateEncoder(typ reflect2.Type) ValEncoder {
	return nil
}

// DecorateDecoder No-op
func (extension *DummyExtension) DecorateDecoder(typ reflect2.Type, decoder ValDecoder) ValDecoder {
	return decoder
}

// DecorateEncoder No-op
func (extension *DummyExtension) DecorateEncoder(typ reflect2.Type, encoder ValEncoder) ValEncoder {
	return encoder
}

type EncoderExtension map[reflect2.Type]ValEncoder

// UpdateStructDescriptor No-op
func (extension EncoderExtension) UpdateStructDescriptor(structDescriptor *StructDescriptor) {
}

// StructDecodedHook No-op
func (extension EncoderExtension) StructDecodedHook(ptr unsafe.Pointer, typ reflect2.Type) {
}

// StructFieldDecodedHook No-op
func (extension EncoderExtension) StructFieldDecodedHook(field string, ptr unsafe.Pointer, typ reflect2.Type) {
}

// CreateDecoder No-op
func (extension EncoderExtension) CreateDecoder(typ reflect2.Type) ValDecoder {
	return nil
}

// CreateEncoder get encoder from map
func (extension EncoderExtension) CreateEncoder(typ reflect2.Type) ValEncoder {
	return extension[typ]
}

// CreateMapKeyDecoder No-op
func (extension EncoderExtension) CreateMapKeyDecoder(typ reflect2.Type) ValDecoder {
	return nil
}

// CreateMapKeyEncoder No-op
func (extension EncoderExtension) CreateMapKeyEncoder(typ reflect2.Type) ValEncoder {
	return nil
}

// DecorateDecoder No-op
func (extension EncoderExtension) DecorateDecoder(typ reflect2.Type, decoder ValDecoder) ValDecoder {
	return decoder
}

// DecorateEncoder No-op
func (extension EncoderExtension) DecorateEncoder(typ reflect2.Type, encoder ValEncoder) ValEncoder {
	return encoder
}

type DecoderExtension map[reflect2.Type]ValDecoder

// UpdateStructDescriptor No-op
func (extension DecoderExtension) UpdateStructDescriptor(structDescriptor *StructDescriptor) {
}

// StructDecodedHook No-op
func (extension DecoderExtension) StructDecodedHook(ptr unsafe.Pointer, typ reflect2.Type) {
}

// StructFieldDecodedHook No-op
func (extension DecoderExtension) StructFieldDecodedHook(field string, ptr unsafe.Pointer, typ reflect2.Type) {
}

// CreateMapKeyDecoder No-op
func (extension DecoderExtension) CreateMapKeyDecoder(typ reflect2.Type) ValDecoder {
	return nil
}

// CreateMapKeyEncoder No-op
func (extension DecoderExtension) CreateMapKeyEncoder(typ reflect2.Type) ValEncoder {
	return nil
}

// CreateDecoder get decoder from map
func (extension DecoderExtension) CreateDecoder(typ reflect2.Type) ValDecoder {
	return extension[typ]
}

// CreateEncoder No-op
func (extension DecoderExtension) CreateEncoder(typ reflect2.Type) ValEncoder {
	return nil
}

// DecorateDecoder No-op
func (extension DecoderExtension) DecorateDecoder(typ reflect2.Type, decoder ValDecoder) ValDecoder {
	return decoder
}

// DecorateEncoder No-op
func (extension DecoderExtension) DecorateEncoder(typ reflect2.Type, encoder ValEncoder) ValEncoder {
	return encoder
}

type funcDecoder struct {
	fun DecoderFunc
}

func (decoder *funcDecoder) Decode(ptr unsafe.Pointer, iter *Iterator) {
	decoder.fun(ptr, iter)
}

type funcEncoder struct {
	fun         EncoderFunc
	isEmptyFunc func(ptr unsafe.Pointer) bool
}

func (encoder *funcEncoder) Encode(ptr unsafe.Pointer, stream *Stream) {
	encoder.fun(ptr, stream)
}

func (encoder *funcEncoder) IsEmpty(ptr unsafe.Pointer) bool {
	if encoder.isEmptyFunc == nil {
		return false
	}
	return encoder.isEmptyFunc(ptr)
}

// DecoderFunc the function form of TypeDecoder
type DecoderFunc func(ptr unsafe.Pointer, iter *Iterator)

// EncoderFunc the function form of TypeEncoder
type EncoderFunc func(ptr unsafe.Pointer, stream *Stream)

// RegisterTypeDecoderFunc register TypeDecoder for a type with function
func RegisterTypeDecoderFunc(typ string, fun DecoderFunc) {
	typeDecoders[typ] = &funcDecoder{fun}
}

// RegisterTypeDecoder register TypeDecoder for a typ
func RegisterTypeDecoder(typ string, decoder ValDecoder) {
	typeDecoders[typ] = decoder
}

// RegisterFieldDecoderFunc register TypeDecoder for a struct field with function
func RegisterFieldDecoderFunc(typ string, field string, fun DecoderFunc) {
	RegisterFieldDecoder(typ, field, &funcDecoder{fun})
}

// RegisterFieldDecoder register TypeDecoder for a struct field
func RegisterFieldDecoder(typ string, field string, decoder ValDecoder) {
	fieldDecoders[fmt.Sprintf("%s/%s", typ, field)] = decoder
}

// RegisterTypeEncoderFunc register TypeEncoder for a type with encode/isEmpty function
func RegisterTypeEncoderFunc(typ string, fun EncoderFunc, isEmptyFunc func(unsafe.Pointer) bool) {
	typeEncoders[typ] = &funcEncoder{fun, isEmptyFunc}
}

// RegisterTypeEncoder register TypeEncoder for a type
func RegisterTypeEncoder(typ string, encoder ValEncoder) {
	typeEncoders[typ] = encoder
}

// RegisterFieldEncoderFunc register TypeEncoder for a struct field with encode/isEmpty function
func RegisterFieldEncoderFunc(typ string, field string, fun EncoderFunc, isEmptyFunc func(unsafe.Pointer) bool) {
	RegisterFieldEncoder(typ, field, &funcEncoder{fun, isEmptyFunc})
}

// RegisterFieldEncoder register TypeEncoder for a struct field
func RegisterFieldEncoder(typ string, field string, encoder ValEncoder) {
	fieldEncoders[fmt.Sprintf("%s/%s", typ, field)] = encoder
}

// RegisterExtension register extension
func RegisterExtension(extension Extension) {
	extensions = append(extensions, extension)
}

func getTypeDecoderFromExtension(ctx *ctx, typ reflect2.Type) ValDecoder {
	decoder := _getTypeDecoderFromExtension(ctx, typ)
	if decoder != nil {
		for _, extension := range extensions {
			decoder = extension.DecorateDecoder(typ, decoder)
		}
		decoder = ctx.decoderExtension.DecorateDecoder(typ, decoder)
		for _, extension := range ctx.extraExtensions {
			decoder = extension.DecorateDecoder(typ, decoder)
		}
	}
	return decoder
}
func _getTypeDecoderFromExtension(ctx *ctx, typ reflect2.Type) ValDecoder {
	for _, extension := range extensions {
		decoder := extension.CreateDecoder(typ)
		if decoder != nil {
			return decoder
		}
	}
	decoder := ctx.decoderExtension.CreateDecoder(typ)
	if decoder != nil {
		return decoder
	}
	for _, extension := range ctx.extraExtensions {
		decoder := extension.CreateDecoder(typ)
		if decoder != nil {
			return decoder
		}
	}
	typeName := typ.String()
	decoder = typeDecoders[typeName]
	if decoder != nil {
		return decoder
	}
	if typ.Kind() == reflect.Ptr {
		ptrType := typ.(*reflect2.UnsafePtrType)
		decoder := typeDecoders[ptrType.Elem().String()]
		if decoder != nil {
			return &OptionalDecoder{ptrType.Elem(), decoder}
		}
	}
	return nil
}

func getTypeEncoderFromExtension(ctx *ctx, typ reflect2.Type) ValEncoder {
	encoder := _getTypeEncoderFromExtension(ctx, typ)
	if encoder != nil {
		for _, extension := range extensions {
			encoder = extension.DecorateEncoder(typ, encoder)
		}
		encoder = ctx.encoderExtension.DecorateEncoder(typ, encoder)
		for _, extension := range ctx.extraExtensions {
			encoder = extension.DecorateEncoder(typ, encoder)
		}
	}
	return encoder
}

func _getTypeEncoderFromExtension(ctx *ctx, typ reflect2.Type) ValEncoder {
	for _, extension := range extensions {
		encoder := extension.CreateEncoder(typ)
		if encoder != nil {
			return encoder
		}
	}
	encoder := ctx.encoderExtension.CreateEncoder(typ)
	if encoder != nil {
		return encoder
	}
	for _, extension := range ctx.extraExtensions {
		encoder := extension.CreateEncoder(typ)
		if encoder != nil {
			return encoder
		}
	}
	typeName := typ.String()
	encoder = typeEncoders[typeName]
	if encoder != nil {
		return encoder
	}
	if typ.Kind() == reflect.Ptr {
		typePtr := typ.(*reflect2.UnsafePtrType)
		encoder := typeEncoders[typePtr.Elem().String()]
		if encoder != nil {
			return &OptionalEncoder{encoder}
		}
	}
	return nil
}

func describeStruct(ctx *ctx, typ reflect2.Type) *StructDescriptor {
	structType := typ.(*reflect2.UnsafeStructType)
	embeddedBindings := []*Binding{}
	bindings := []*Binding{}
	for i := 0; i < structType.NumField(); i++ {
		field := structType.Field(i)
		tag, hastag := field.Tag().Lookup(ctx.getTagKey())
		if ctx.onlyTaggedField && !hastag {
			continue
		}
		tagParts := strings.Split(tag, ",")
		if tag == "-" {
			continue
		}
		if field.Anonymous() && (tag == "" || tagParts[0] == "") {
			if field.Type().Kind() == reflect.Struct {
				structDescriptor := describeStruct(ctx, field.Type())
				for _, binding := range structDescriptor.Fields {
					binding.levels = append([]int{i}, binding.levels...)
					omitempty := binding.Encoder.(*structFieldEncoder).omitempty
					binding.Encoder = &structFieldEncoder{field, binding.Encoder, omitempty}
					binding.Decoder = &structFieldDecoder{field, binding.Decoder}
					embeddedBindings = append(embeddedBindings, binding)
				}
				continue
			} else if field.Type().Kind() == reflect.Ptr {
				ptrType := field.Type().(*reflect2.UnsafePtrType)
				if ptrType.Elem().Kind() == reflect.Struct {
					structDescriptor := describeStruct(ctx, ptrType.Elem())
					for _, binding := range structDescriptor.Fields {
						binding.levels = append([]int{i}, binding.levels...)
						omitempty := binding.Encoder.(*structFieldEncoder).omitempty
						binding.Encoder = &dereferenceEncoder{binding.Encoder}
						binding.Encoder = &structFieldEncoder{field, binding.Encoder, omitempty}
						binding.Decoder = &dereferenceDecoder{ptrType.Elem(), binding.Decoder}
						binding.Decoder = &structFieldDecoder{field, binding.Decoder}
						embeddedBindings = append(embeddedBindings, binding)
					}
					continue
				}
			}
		}
		fieldNames := calcFieldNames(field.Name(), tagParts[0], tag)
		fieldCacheKey := fmt.Sprintf("%s/%s", typ.String(), field.Name())
		decoder := fieldDecoders[fieldCacheKey]
		if decoder == nil {
			decoder = decoderOfType(ctx.append(field.Name()), field.Type())
		}
		encoder := fieldEncoders[fieldCacheKey]
		if encoder == nil {
			encoder = encoderOfType(ctx.append(field.Name()), field.Type())
		}
		binding := &Binding{
			Field:     field,
			FromNames: fieldNames,
			ToNames:   fieldNames,
			Decoder:   decoder,
			Encoder:   encoder,
		}
		binding.levels = []int{i}
		bindings = append(bindings, binding)
	}
	return createStructDescriptor(ctx, typ, bindings, embeddedBindings)
}
func createStructDescriptor(ctx *ctx, typ reflect2.Type, bindings []*Binding, embeddedBindings []*Binding) *StructDescriptor {
	structDescriptor := &StructDescriptor{
		Type:   typ,
		Fields: bindings,
	}
	for _, extension := range extensions {
		extension.UpdateStructDescriptor(structDescriptor)
	}
	ctx.encoderExtension.UpdateStructDescriptor(structDescriptor)
	ctx.decoderExtension.UpdateStructDescriptor(structDescriptor)
	for _, extension := range ctx.extraExtensions {
		extension.UpdateStructDescriptor(structDescriptor)
	}
	processTags(structDescriptor, ctx.frozenConfig)
	// merge normal & embedded bindings & sort with original order
	allBindings := sortableBindings(append(embeddedBindings, structDescriptor.Fields...))
	sort.Sort(allBindings)
	structDescriptor.Fields = allBindings
	return structDescriptor
}

type sortableBindings []*Binding

func (bindings sortableBindings) Len() int {
	return len(bindings)
}

func (bindings sortableBindings) Less(i, j int) bool {
	left := bindings[i].levels
	right := bindings[j].levels
	k := 0
	for {
		if left[k] < right[k] {
			return true
		} else if left[k] > right[k] {
			return false
		}
		k++
	}
}

func (bindings sortableBindings) Swap(i, j int) {
	bindings[i], bindings[j] = bindings[j], bindings[i]
}

func processTags(structDescriptor *StructDescriptor, cfg *frozenConfig) {
	for _, binding := range structDescriptor.Fields {
		shouldOmitEmpty := false
		tagParts := strings.Split(binding.Field.Tag().Get(cfg.getTagKey()), ",")
		for _, tagPart := range tagParts[1:] {
			if tagPart == "omitempty" {
				shouldOmitEmpty = true
			} else if tagPart == "string" {
				if binding.Field.Type().Kind() == reflect.String {
					binding.Decoder = &stringModeStringDecoder{binding.Decoder, cfg}
					binding.Encoder = &stringModeStringEncoder{binding.Encoder, cfg}
				} else {
					binding.Decoder = &stringModeNumberDecoder{binding.Decoder}
					binding.Encoder = &stringModeNumberEncoder{binding.Encoder}
				}
			}
		}
		binding.Decoder = &structFieldDecoder{binding.Field, binding.Decoder}
		binding.Encoder = &structFieldEncoder{binding.Field, binding.Encoder, shouldOmitEmpty}
	}
}

func calcFieldNames(originalFieldName string, tagProvidedFieldName string, wholeTag string) []string {
	// ignore?
	if wholeTag == "-" {
		return []string{}
	}
	// rename?
	var fieldNames []string
	if tagProvidedFieldName == "" {
		fieldNames = []string{originalFieldName}
	} else {
		fieldNames = []string{tagProvidedFieldName}
	}
	// private?
	isNotExported := unicode.IsLower(rune(originalFieldName[0]))
	if isNotExported {
		fieldNames = []string{}
	}
	return fieldNames
}