Rewritten replace char algorithm

source/main.cpp

@@ -27,21 +27,40 @@
 
 int main()
 {
+    std::string str{ };
+    str.reserve(1'000);
 
-#if 1
-    utf8::ustring str{ "привет" };
+    std::string a{ "s" };
+    std::string b{ "п" };
+    std::string c{ "\xf0\x92\x8d\x87" };
 
-    str.replace_char("s", 0);
-    str.replace_char("g", 0);
-    str.replace_char("п", 0);
-    str.replace_char("s", 3);
-    str.replace_char("g", 4);
-    str.replace_char("п", 3);
-    str.replace_char("\xf0\x92\x8d\x87", 2);
-    str.replace_char("g", 2);
-    str.replace_char("مرحبا", 2);
+    for (std::size_t i{}; i < 5'000; ++i)
+    {
+        str += a;
+        str += b;
+        str += c;
+    }
 
-    std::cout << str << '\n';
+    std::chrono::duration<double> res{ };
+
+#if 0
+    auto start = std::chrono::high_resolution_clock::now();
+
+    utf8::ustring tmp{ str };
+    for (std::size_t i{}; i < 1'000'000'000; ++i)
+    {
+        tmp.replace_char("s", 0);
+        tmp.replace_char("ы", 300);
+        tmp.replace_char("\xf0\x92\x8d\x87", 1234);
+        tmp.replace_char("ы", 789);
+        tmp.replace_char("\xf0\x92\x8d\x87", 1900);
+    }
+
+    auto end = std::chrono::high_resolution_clock::now();
+    res = end - start;
+
+    std::cout << res.count() << "s\n";
+    std::cout << tmp << '\n';
 #endif
 
     return 0;

utf8-string-lib/utf8_string.cpp

@@ -170,9 +170,19 @@ namespace utf8
             std::basic_string<char> new_string{ };
             new_string.resize(old_string_size + new_symbol_size - old_symbol_info.Symbol_Size); // calculate & resize new string size
 
-            std::memcpy(new_string.data(), String.c_str(), replace_position); // copy bytes to a new string before idx
-            std::memcpy((new_string.data() + replace_position), new_symbol.data(), new_symbol_size); // insert a new symbol by idx
-            std::memcpy((new_string.data() + replace_position + new_symbol_size), (String.c_str() + replace_position + old_symbol_info.Symbol_Size), old_string_size - replace_position); // copy bytes after inserted symbol
+            for (std::size_t i{}, counter{}; i < old_string_size;)
+            {
+                if (i == replace_position)
+                {
+                    std::memcpy(new_string.data() + i, new_symbol.data(), new_symbol_size);
+                    counter += new_symbol_size;
+                    i += old_symbol_info.Symbol_Size;
+
+                    continue;
+                }
+
+                new_string[counter++] = String[i++];
+            }
 
             auto new_offset{ static_cast<std::ptrdiff_t>(new_symbol_size) - static_cast<std::ptrdiff_t>(old_symbol_info.Symbol_Size) };
             Recalculate_Symbols_Offset(idx + 1, new_offset);