From 294f826364b1b4e01e73d0c473bb48918fe8adc4 Mon Sep 17 00:00:00 2001
From: frosch <frosch@openttd.org>
Date: Fri, 4 Apr 2025 21:43:46 +0200
Subject: [PATCH] Codechange: Replace last usage of Utf8CharLen with Utf8View.

---
 src/string_func.h | 17 -----------------
 src/textbuf.cpp   | 32 +++++++++++++++++++-------------
 2 files changed, 19 insertions(+), 30 deletions(-)

diff --git a/src/string_func.h b/src/string_func.h
index f692ff7b1a..0952993855 100644
--- a/src/string_func.h
+++ b/src/string_func.h
@@ -106,23 +106,6 @@ inline char32_t Utf8Consume(Titr &s)
 	return c;
 }
 
-/**
- * Return the length of a UTF-8 encoded character.
- * @param c Unicode character.
- * @return Length of UTF-8 encoding for character.
- */
-inline int8_t Utf8CharLen(char32_t c)
-{
-	if (c < 0x80)       return 1;
-	if (c < 0x800)      return 2;
-	if (c < 0x10000)    return 3;
-	if (c < 0x110000)   return 4;
-
-	/* Invalid valid, we encode as a '?' */
-	return 1;
-}
-
-
 /**
  * Return the length of an UTF-8 encoded value based on a single char. This
  * char should be the first byte of the UTF-8 encoding. If not, or encoding
diff --git a/src/textbuf.cpp b/src/textbuf.cpp
index 111be15df0..25d2481b60 100644
--- a/src/textbuf.cpp
+++ b/src/textbuf.cpp
@@ -170,24 +170,30 @@ bool Textbuf::InsertString(const char *str, bool marked, const char *caret, cons
 
 	if (str == nullptr) return false;
 
-	uint16_t bytes = 0, chars = 0;
-	char32_t c;
-	for (const char *ptr = str; (c = Utf8Consume(&ptr)) != '\0';) {
-		if (!IsValidChar(c, this->afilter)) break;
+	uint16_t chars = 0;
+	uint16_t bytes;
+	{
+		Utf8View view(str);
+		auto cur = view.begin();
+		const auto end = view.end();
+		while (cur != end) {
+			if (!IsValidChar(*cur, this->afilter)) break;
 
-		uint8_t len = Utf8CharLen(c);
-		if (this->buf.size() + bytes + len >= this->max_bytes) break;
-		if (this->chars + chars + 1   > this->max_chars) break;
+			auto next = cur;
+			++next;
+			if (this->buf.size() + next.GetByteOffset() >= this->max_bytes) break;
+			if (this->chars + chars + 1 > this->max_chars) break;
 
-		bytes += len;
-		chars++;
-
-		/* Move caret if needed. */
-		if (ptr == caret) this->caretpos = insertpos + bytes;
+			cur = next;
+			chars++;
+		}
+		bytes = static_cast<uint16_t>(cur.GetByteOffset());
 	}
-
 	if (bytes == 0) return false;
 
+	/* Move caret if needed. */
+	if (str <= caret && caret <= str + bytes) this->caretpos = insertpos + (caret - str);
+
 	if (marked) {
 		this->markpos = insertpos;
 		this->markend = insertpos + bytes;