From 3b6e27e800975fd98638495608387be9c4b29d90 Mon Sep 17 00:00:00 2001
From: kaetemi <kaetemi@gmail.com>
Date: Wed, 4 Nov 2020 10:00:29 +0800
Subject: [PATCH] Find offset by index

---
 nel/include/nel/misc/utf_string_view.h |  3 ++-
 nel/src/misc/utf_string_view.cpp       | 12 ++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/nel/include/nel/misc/utf_string_view.h b/nel/include/nel/misc/utf_string_view.h
index 8a224cef5..6264f425e 100644
--- a/nel/include/nel/misc/utf_string_view.h
+++ b/nel/include/nel/misc/utf_string_view.h
@@ -131,7 +131,8 @@ public:
 	inline bool empty() const { return !m_Size; }
 	const void *ptr() const { return m_Str; }
 
-	size_t count() const; // Slow count of UTF-32 characters
+	size_t count() const; //< Slow count of UTF-32 codepoints
+	ptrdiff_t offset(ptrdiff_t i); const //< Get byte offset by utf-32 codepoint index
 
 	inline CUtfStringView substr(const iterator &begin, const iterator &end) const
 	{
diff --git a/nel/src/misc/utf_string_view.cpp b/nel/src/misc/utf_string_view.cpp
index 39bf3b92f..283ef9555 100644
--- a/nel/src/misc/utf_string_view.cpp
+++ b/nel/src/misc/utf_string_view.cpp
@@ -230,6 +230,18 @@ size_t CUtfStringView::count() const
 	return res;
 }
 
+ptrdiff_t CUtfStringView::offset(ptrdiff_t i)
+{
+	size_t res = 0;
+	for (iterator it(begin()), end(this->end()); it != end; ++it)
+	{
+		if (res == i)
+			return (ptrdiff_t)it.ptr() - (ptrdiff_t)ptr();
+		++res;
+	}
+	return res;
+}
+
 u32char CUtfStringView::utf8Iterator(const void **addr)
 {
 	// Decode UTF-8