Keep only Slice overload of utf8_utf16_substr.

td/telegram/ContactsManager.cpp

@@ -16889,7 +16889,7 @@ tl_object_ptr<td_api::userFullInfo> ContactsManager::get_user_full_info_object(U
           return true;
         }
         if (entity.type == MessageEntity::Type::Url &&
-            !LinkManager::is_internal_link(utf8_utf16_substr(Slice(bio.text), entity.offset, entity.length))) {
+            !LinkManager::is_internal_link(utf8_utf16_substr(bio.text, entity.offset, entity.length))) {
           return true;
         }
         return false;

td/telegram/MessageEntity.cpp

@@ -1793,7 +1793,7 @@ string get_first_url(const FormattedText &text) {
         if (entity.length <= 4) {
           continue;
         }
-        Slice url = utf8_utf16_substr(text.text, entity.offset, entity.length);
+        auto url = utf8_utf16_substr(text.text, entity.offset, entity.length);
         string scheme = to_lower(url.substr(0, 4));
         if (scheme == "ton:" || begins_with(scheme, "tg:") || scheme == "ftp:" || is_plain_domain(url)) {
           continue;

tdutils/td/utils/utf8.cpp

@@ -119,4 +119,41 @@ string utf8_encode(CSlice data) {
   return PSTRING() << "url_decode(" << url_encode(data) << ')';
 }
 
+size_t utf8_utf16_length(Slice str) {
+  size_t result = 0;
+  for (auto c : str) {
+    result += is_utf8_character_first_code_unit(c) + ((c & 0xf8) == 0xf0);
+  }
+  return result;
+}
+
+Slice utf8_utf16_truncate(Slice str, size_t length) {
+  for (size_t i = 0; i < str.size(); i++) {
+    auto c = static_cast<unsigned char>(str[i]);
+    if (is_utf8_character_first_code_unit(c)) {
+      if (length <= 0) {
+        return str.substr(0, i);
+      } else {
+        length--;
+        if (c >= 0xf0) {  // >= 4 bytes in symbol => surrogate pair
+          length--;
+        }
+      }
+    }
+  }
+  return str;
+}
+
+Slice utf8_utf16_substr(Slice str, size_t offset) {
+  if (offset == 0) {
+    return str;
+  }
+  auto offset_pos = utf8_utf16_truncate(str, offset).size();
+  return str.substr(offset_pos);
+}
+
+Slice utf8_utf16_substr(Slice str, size_t offset, size_t length) {
+  return utf8_utf16_truncate(utf8_utf16_substr(str, offset), length);
+}
+
 }  // namespace td

tdutils/td/utils/utf8.h

@@ -29,13 +29,7 @@ inline size_t utf8_length(Slice str) {
 }
 
 /// returns length of UTF-8 string in UTF-16 code units
-inline size_t utf8_utf16_length(Slice str) {
-  size_t result = 0;
-  for (auto c : str) {
-    result += is_utf8_character_first_code_unit(c) + ((c & 0xf8) == 0xf0);
-  }
-  return result;
-}
+size_t utf8_utf16_length(Slice str);
 
 /// appends a Unicode character using UTF-8 encoding
 void append_utf8_character(string &str, uint32 ch);
@@ -69,23 +63,7 @@ T utf8_truncate(T str, size_t length) {
 }
 
 /// truncates UTF-8 string to the given length given in UTF-16 code units
-template <class T>
-T utf8_utf16_truncate(T str, size_t length) {
-  for (size_t i = 0; i < str.size(); i++) {
-    auto c = static_cast<unsigned char>(str[i]);
-    if (is_utf8_character_first_code_unit(c)) {
-      if (length <= 0) {
-        return str.substr(0, i);
-      } else {
-        length--;
-        if (c >= 0xf0) {  // >= 4 bytes in symbol => surrogate pair
-          length--;
-        }
-      }
-    }
-  }
-  return str;
-}
+Slice utf8_utf16_truncate(Slice str, size_t length);
 
 template <class T>
 T utf8_substr(T str, size_t offset) {
@@ -101,19 +79,9 @@ T utf8_substr(T str, size_t offset, size_t length) {
   return utf8_truncate(utf8_substr(str, offset), length);
 }
 
-template <class T>
-T utf8_utf16_substr(T str, size_t offset) {
-  if (offset == 0) {
-    return str;
-  }
-  auto offset_pos = utf8_utf16_truncate(str, offset).size();
-  return str.substr(offset_pos);
-}
+Slice utf8_utf16_substr(Slice str, size_t offset);
 
-template <class T>
-T utf8_utf16_substr(T str, size_t offset, size_t length) {
-  return utf8_utf16_truncate(utf8_utf16_substr(str, offset), length);
-}
+Slice utf8_utf16_substr(Slice str, size_t offset, size_t length);
 
 /// Returns UTF-8 string converted to lower case.
 string utf8_to_lower(Slice str);

test/message_entities.cpp

@@ -959,8 +959,8 @@ TEST(MessageEntities, fix_formatted_text) {
       }
     }
 
-    check_fix_formatted_text(str, entities, td::utf8_utf16_substr(str, 3, 11), fixed_entities, false, false, false,
-                             false);
+    check_fix_formatted_text(str, entities, td::utf8_utf16_substr(str, 3, 11).str(), fixed_entities, false, false,
+                             false, false);
   }
 
   for (td::string text : {"\t", "\r", "\n", "\t ", "\r ", "\n "}) {