2 files changed, 36 insertions, 2 deletions
diff --git a/comphelper/qa/string/test_string.cxx b/comphelper/qa/string/test_string.cxx
index 0b2f3ee05479..58f9c3f63c16 100644
--- a/comphelper/qa/string/test_string.cxx
+++ b/comphelper/qa/string/test_string.cxx
@@ -17,6 +17,10 @@
  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  */
 
+#include <sal/config.h>
+
+#include <iterator>
+
 #include <comphelper/string.hxx>
 #include <cppuhelper/implbase.hxx>
 #include <com/sun/star/i18n/CharType.hpp>
@@ -43,6 +47,7 @@ public:
     void testDecimalStringToNumber();
     void testIsdigitAsciiString();
     void testReverseString();
+    void testReverseCodePoints();
     void testSplit();
     void testRemoveAny();
 
@@ -55,6 +60,7 @@ public:
     CPPUNIT_TEST(testDecimalStringToNumber);
     CPPUNIT_TEST(testIsdigitAsciiString);
     CPPUNIT_TEST(testReverseString);
+    CPPUNIT_TEST(testReverseCodePoints);
     CPPUNIT_TEST(testSplit);
     CPPUNIT_TEST(testRemoveAny);
     CPPUNIT_TEST_SUITE_END();
@@ -178,9 +184,28 @@ void TestString::testTokenCount()
 
 void TestString::testReverseString()
 {
-    OUString aOut = ::comphelper::string::reverseString(u"ABC");
+    CPPUNIT_ASSERT_EQUAL(OUString(), comphelper::string::reverseString(u""));
+    CPPUNIT_ASSERT_EQUAL(OUString("cba"), comphelper::string::reverseString(u"abc"));
+    static sal_Unicode const rev[] = {'w', 0xDFFF, 0xDBFF, 'v', 0xDC00, 0xD800, 'u'};
+    CPPUNIT_ASSERT_EQUAL(
+        OUString(rev, std::size(rev)),
+        comphelper::string::reverseString(u"u\U00010000v\U0010FFFFw"));
+    static sal_Unicode const malformed[] = {0xDC00, 0xD800};
+    CPPUNIT_ASSERT_EQUAL(
+        OUString(u"\U00010000"),
+        comphelper::string::reverseString(std::u16string_view(malformed, std::size(malformed))));
+}
 
-    CPPUNIT_ASSERT_EQUAL(OUString("CBA"), aOut);
+void TestString::testReverseCodePoints() {
+    CPPUNIT_ASSERT_EQUAL(OUString(), comphelper::string::reverseCodePoints(""));
+    CPPUNIT_ASSERT_EQUAL(OUString("cba"), comphelper::string::reverseCodePoints("abc"));
+    CPPUNIT_ASSERT_EQUAL(
+        OUString(u"w\U0010FFFFv\U00010000u"),
+        comphelper::string::reverseCodePoints(u"u\U00010000v\U0010FFFFw"));
+    static sal_Unicode const malformed[] = {0xDC00, 0xD800};
+    CPPUNIT_ASSERT_EQUAL(
+        OUString(u"\U00010000"),
+        comphelper::string::reverseCodePoints(OUString(malformed, std::size(malformed))));
 }
 
 void TestString::testSplit()
diff --git a/comphelper/source/misc/string.cxx b/comphelper/source/misc/string.cxx
index 95e936e60142..d0f7cb9ca423 100644
--- a/comphelper/source/misc/string.cxx
+++ b/comphelper/source/misc/string.cxx
@@ -530,6 +530,15 @@ OUString reverseString(std::u16string_view rStr)
     return sBuf.makeStringAndClear();
 }
 
+OUString reverseCodePoints(OUString const & str) {
+    auto const len = str.getLength();
+    OUStringBuffer buf(len);
+    for (auto i = len; i != 0;) {
+        buf.appendUtf32(str.iterateCodePoints(&i, -1));
+    }
+    return buf.makeStringAndClear();
+}
+
 sal_Int32 indexOfAny(std::u16string_view rIn,
         sal_Unicode const*const pChars, sal_Int32 const nPos)
 {