From a87d6cbbb51a19071c5c742ef3c91bbb90a727c6 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Thu, 16 Feb 2023 17:32:17 -0700
Subject: compat/json: Indent: Preserve trailing whitespace

---
 compat/json/compat.go | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

(limited to 'compat/json/compat.go')

diff --git a/compat/json/compat.go b/compat/json/compat.go
index edc6908..d33f278 100644
--- a/compat/json/compat.go
+++ b/compat/json/compat.go
@@ -188,6 +188,15 @@ func Compact(dst *bytes.Buffer, src []byte) error {
 	return err
 }
 
+func isSpace(c byte) bool {
+	switch c {
+	case 0x0020, 0x000A, 0x000D, 0x0009:
+		return true
+	default:
+		return false
+	}
+}
+
 func Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error {
 	start := dst.Len()
 	err := reencode(dst, src, lowmemjson.ReEncoderConfig{
@@ -198,8 +207,18 @@ func Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error {
 	})
 	if err != nil {
 		dst.Truncate(start)
+		return err
 	}
-	return err
+
+	// Preserve trailing whitespace.
+	lastNonWS := len(src) - 1
+	for ; lastNonWS >= 0 && isSpace(src[lastNonWS]); lastNonWS-- {
+	}
+	if _, err := dst.Write(src[lastNonWS+1:]); err != nil {
+		return err
+	}
+
+	return nil
 }
 
 func Valid(data []byte) bool {
-- 
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