Add DecodeOption

decode.go

@@ -24,7 +24,7 @@ type emptyInterface struct {
 	ptr unsafe.Pointer
 }
 
-func unmarshal(data []byte, v interface{}) error {
+func unmarshal(data []byte, v interface{}, optFuncs ...DecodeOptionFunc) error {
 	src := make([]byte, len(data)+1) // append nul byte to the end
 	copy(src, data)
 

internal/decoder/option.go

@@ -0,0 +1,5 @@
+package decoder
+
+type Option struct {
+	FirstWin bool
+}

json.go

@@ -258,6 +258,10 @@ func Unmarshal(data []byte, v interface{}) error {
 	return unmarshal(data, v)
 }
 
+func UnmarshalWithOption(data []byte, v interface{}, optFuncs ...DecodeOptionFunc) error {
+	return unmarshal(data, v, optFuncs...)
+}
+
 func UnmarshalNoEscape(data []byte, v interface{}) error {
 	return unmarshalNoEscape(data, v)
 }

option.go

@@ -1,11 +1,11 @@
 package json
 
 import (
+	"github.com/goccy/go-json/internal/decoder"
 	"github.com/goccy/go-json/internal/encoder"
 )
 
 type EncodeOption = encoder.Option
-
 type EncodeOptionFunc func(*EncodeOption)
 
 func UnorderedMap() EncodeOptionFunc {
@@ -26,3 +26,12 @@ func Colorize(scheme *ColorScheme) EncodeOptionFunc {
 		opt.ColorScheme = scheme
 	}
 }
+
+type DecodeOption = decoder.Option
+type DecodeOptionFunc func(*DecodeOption)
+
+func DecodeFieldPriorityFirstWin() DecodeOptionFunc {
+	return func(opt *DecodeOption) {
+		opt.FirstWin = true
+	}
+}