func()

in internal/apijson/decoder.go [344:519]
152 lines of code
42 McCabe index (conditional complexity)

func (d *decoderBuilder) newStructTypeDecoder(t reflect.Type) decoderFunc {
	// map of json field name to struct field decoders
	decoderFields := map[string]decoderField{}
	anonymousDecoders := []decoderField{}
	extraDecoder := (*decoderField)(nil)
	var inlineDecoders []decoderField

	for i := 0; i < t.NumField(); i++ {
		idx := []int{i}
		field := t.FieldByIndex(idx)
		if !field.IsExported() {
			continue
		}
		// If this is an embedded struct, traverse one level deeper to extract
		// the fields and get their encoders as well.
		if field.Anonymous {
			anonymousDecoders = append(anonymousDecoders, decoderField{
				fn:  d.typeDecoder(field.Type),
				idx: idx[:],
			})
			continue
		}
		// If json tag is not present, then we skip, which is intentionally
		// different behavior from the stdlib.
		ptag, ok := parseJSONStructTag(field)
		if !ok {
			continue
		}
		// We only want to support unexported fields if they're tagged with
		// `extras` because that field shouldn't be part of the public API.
		if ptag.extras {
			extraDecoder = &decoderField{ptag, d.typeDecoder(field.Type.Elem()), idx, field.Name}
			continue
		}
		if ptag.inline {
			df := decoderField{ptag, d.typeDecoder(field.Type), idx, field.Name}
			inlineDecoders = append(inlineDecoders, df)
			continue
		}
		if ptag.metadata {
			continue
		}

		oldFormat := d.dateFormat
		dateFormat, ok := parseFormatStructTag(field)
		if ok {
			switch dateFormat {
			case "date-time":
				d.dateFormat = time.RFC3339
			case "date":
				d.dateFormat = "2006-01-02"
			}
		}
		decoderFields[ptag.name] = decoderField{ptag, d.typeDecoder(field.Type), idx, field.Name}
		d.dateFormat = oldFormat
	}

	return func(node gjson.Result, value reflect.Value, state *decoderState) (err error) {
		if field := value.FieldByName("JSON"); field.IsValid() {
			if raw := field.FieldByName("raw"); raw.IsValid() {
				setUnexportedField(raw, node.Raw)
			}
		}

		for _, decoder := range anonymousDecoders {
			// ignore errors
			decoder.fn(node, value.FieldByIndex(decoder.idx), state)
		}

		for _, inlineDecoder := range inlineDecoders {
			var meta Field
			dest := value.FieldByIndex(inlineDecoder.idx)
			isValid := false
			if dest.IsValid() && node.Type != gjson.Null {
				inlineState := decoderState{exactness: state.exactness, strict: true}
				err = inlineDecoder.fn(node, dest, &inlineState)
				if err == nil {
					isValid = true
				}
			}

			if node.Type == gjson.Null {
				meta = Field{
					raw:    node.Raw,
					status: null,
				}
			} else if !isValid {
				// If an inline decoder fails, unset the field and move on.
				if dest.IsValid() {
					dest.SetZero()
				}
				continue
			} else if isValid {
				meta = Field{
					raw:    node.Raw,
					status: valid,
				}
			}
			setMetadataSubField(value, inlineDecoder.idx, inlineDecoder.goname, meta)
		}

		typedExtraType := reflect.Type(nil)
		typedExtraFields := reflect.Value{}
		if extraDecoder != nil {
			typedExtraType = value.FieldByIndex(extraDecoder.idx).Type()
			typedExtraFields = reflect.MakeMap(typedExtraType)
		}
		untypedExtraFields := map[string]Field{}

		for fieldName, itemNode := range node.Map() {
			df, explicit := decoderFields[fieldName]
			var (
				dest reflect.Value
				fn   decoderFunc
				meta Field
			)
			if explicit {
				fn = df.fn
				dest = value.FieldByIndex(df.idx)
			}
			if !explicit && extraDecoder != nil {
				dest = reflect.New(typedExtraType.Elem()).Elem()
				fn = extraDecoder.fn
			}

			isValid := false
			if dest.IsValid() && itemNode.Type != gjson.Null {
				err = fn(itemNode, dest, state)
				if err == nil {
					isValid = true
				}
			}

			if itemNode.Type == gjson.Null {
				meta = Field{
					raw:    itemNode.Raw,
					status: null,
				}
			} else if !isValid {
				meta = Field{
					raw:    itemNode.Raw,
					status: invalid,
				}
			} else if isValid {
				meta = Field{
					raw:    itemNode.Raw,
					status: valid,
				}
			}

			if explicit {
				setMetadataSubField(value, df.idx, df.goname, meta)
			}
			if !explicit {
				untypedExtraFields[fieldName] = meta
			}
			if !explicit && extraDecoder != nil {
				typedExtraFields.SetMapIndex(reflect.ValueOf(fieldName), dest)
			}
		}

		if extraDecoder != nil && typedExtraFields.Len() > 0 {
			value.FieldByIndex(extraDecoder.idx).Set(typedExtraFields)
		}

		// Set exactness to 'extras' if there are untyped, extra fields.
		if len(untypedExtraFields) > 0 && state.exactness > extras {
			state.exactness = extras
		}

		if len(untypedExtraFields) > 0 {
			setMetadataExtraFields(value, []int{-1}, "ExtraFields", untypedExtraFields)
		}
		return nil
	}
}