From f0b407791406c965fc8daf2cd62c133ef2bbc4ca Mon Sep 17 00:00:00 2001
From: Masaaki Goshima <goccy54@gmail.com>
Date: Sat, 5 Jun 2021 00:27:02 +0900
Subject: [PATCH] Add DecodeOption

---
 decode.go                  |  2 +-
 internal/decoder/option.go |  5 +++++
 json.go                    |  4 ++++
 option.go                  | 11 ++++++++++-
 4 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 internal/decoder/option.go

diff --git a/decode.go b/decode.go
index 3d31096..eedbe05 100644
--- a/decode.go
+++ b/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)
 
diff --git a/internal/decoder/option.go b/internal/decoder/option.go
new file mode 100644
index 0000000..a44ca55
--- /dev/null
+++ b/internal/decoder/option.go
@@ -0,0 +1,5 @@
+package decoder
+
+type Option struct {
+	FirstWin bool
+}
diff --git a/json.go b/json.go
index 4ac8536..2517368 100644
--- a/json.go
+++ b/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)
 }
diff --git a/option.go b/option.go
index 444ffd0..d2cd3b1 100644
--- a/option.go
+++ b/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
+	}
+}