From 61c6b8a23ef6381c2d1b1aaa5bfc1e31e35a7ec0 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Wed, 15 Apr 2026 22:55:53 +0200
Subject: Move utf8_strlen() in from DoM.

---
 src/util.cc       | 21 +++++++++++++++++++++
 src/util.h        |  2 ++
 test/util_test.cc |  9 +++++++++
 3 files changed, 32 insertions(+)

diff --git a/src/util.cc b/src/util.cc
index 1984595d..61b9ba66 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -471,3 +471,24 @@ dcp::maybe_throw_from_asdcplib(Kumu::Result_t result, boost::filesystem::path pa
 	}
 }
 
+
+size_t
+dcp::utf8_strlen(string s)
+{
+	size_t const len = s.length();
+	int N = 0;
+	for (size_t i = 0; i < len; ++i) {
+		unsigned char c = s[i];
+		if ((c & 0xe0) == 0xc0) {
+			++i;
+		} else if ((c & 0xf0) == 0xe0) {
+			i += 2;
+		} else if ((c & 0xf8) == 0xf0) {
+			i += 3;
+		}
+		++N;
+	}
+	return N;
+}
+
+
diff --git a/src/util.h b/src/util.h
index cfed9fcb..62c0e295 100644
--- a/src/util.h
+++ b/src/util.h
@@ -171,6 +171,8 @@ void throw_from_asdcplib(Kumu::Result_t result, boost::filesystem::path path, T
 	boost::throw_exception(general);
 }
 
+extern size_t utf8_strlen(std::string s);
+
 }
 
 
diff --git a/test/util_test.cc b/test/util_test.cc
index 5780f898..69f4c891 100644
--- a/test/util_test.cc
+++ b/test/util_test.cc
@@ -276,3 +276,12 @@ BOOST_AUTO_TEST_CASE (unique_string_test)
 		existing.push_back (s);
 	}
 }
+
+
+BOOST_AUTO_TEST_CASE(utf8_strlen_test)
+{
+	BOOST_CHECK_EQUAL(dcp::utf8_strlen("hello world"), 11U);
+	BOOST_CHECK_EQUAL(dcp::utf8_strlen("hëllo world"), 11U);
+	BOOST_CHECK_EQUAL(dcp::utf8_strlen("hëłlo wørld"), 11U);
+}
+
-- 
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