From 960d4b987c9439cd77bbbdee744d224eb8b36824 Mon Sep 17 00:00:00 2001
From: MacRat <m@crat.jp>
Date: Sat, 24 Dec 2022 18:41:23 +0900
Subject: [PATCH] refactor(scheme): simplify text decoder

---
 internal/scheme/textdecode/locale_unix.go    |  6 ++----
 internal/scheme/textdecode/locale_windows.go | 16 +++++++---------
 internal/scheme/textdecode/textdecode.go     |  2 +-
 3 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/internal/scheme/textdecode/locale_unix.go b/internal/scheme/textdecode/locale_unix.go
index 32f3c8d4..34692387 100644
--- a/internal/scheme/textdecode/locale_unix.go
+++ b/internal/scheme/textdecode/locale_unix.go
@@ -7,7 +7,5 @@ import (
 	"golang.org/x/text/encoding/unicode"
 )
 
-// localeDecoder in Unix OS always returns UTF8 decoder.
-func localeDecoder() decoder {
-	return unicode.UTF8.NewDecoder()
-}
+// localeDecoder in Unix OS is an UTF8 decoder.
+var localeDecoder decoder = unicode.UTF8.NewDecoder()
diff --git a/internal/scheme/textdecode/locale_windows.go b/internal/scheme/textdecode/locale_windows.go
index 4b60985e..69dee8ad 100644
--- a/internal/scheme/textdecode/locale_windows.go
+++ b/internal/scheme/textdecode/locale_windows.go
@@ -14,8 +14,11 @@ import (
 	"golang.org/x/text/encoding/unicode"
 )
 
-var (
-	windowsCodePages = map[uint32]encoding.Encoding{
+// localeDecoder in Windows is a decoder for UTF8 or local charset that set by locale settings in OS.
+var localeDecoder decoder
+
+func init() {
+	enc, ok := map[uint32]encoding.Encoding{
 		1200:  unicode.UTF16(unicode.LittleEndian, unicode.IgnoreBOM),
 		1201:  unicode.UTF16(unicode.BigEndian, unicode.IgnoreBOM),
 		65001: unicode.UTF8,
@@ -41,15 +44,10 @@ var (
 
 		950:   traditionalchinese.Big5,
 		54936: simplifiedchinese.GB18030,
-	}
-)
-
-// localeDecoder in Windows returns decoder for UTF8 or local charset that set by locale settings in OS.
-func localeDecoder() decoder {
-	enc, ok := windowsCodePages[windows.GetACP()]
+	}[windows.GetACP()]
 	if !ok {
 		enc = unicode.UTF8
 	}
 
-	return utf8Override{enc.NewDecoder()}
+	localeDecoder = utf8Override{windowsEncoder}
 }
diff --git a/internal/scheme/textdecode/textdecode.go b/internal/scheme/textdecode/textdecode.go
index 1c5cb49a..db083c44 100644
--- a/internal/scheme/textdecode/textdecode.go
+++ b/internal/scheme/textdecode/textdecode.go
@@ -11,7 +11,7 @@ type decoder interface {
 
 // Bytes decodes []byte to string.
 func Bytes(b []byte) (string, error) {
-	dec := localeDecoder()
+	dec := localeDecoder
 	b, dec = bomOverride(b, dec)
 	s, err := dec.Bytes(b)
 	if err != nil {