Issue 5142 - Convert Element Hiding to C++

compiled/String.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 263 matching lines @@
   void grow(size_type additionalSize)
   {
     OwnedString newValue(length() + additionalSize);
     if (length() > 0)
       std::memcpy(newValue.mBuf, mBuf, sizeof(value_type) * length());
     *this = std::move(newValue);
   }
 
 public:
   explicit OwnedString(size_type len = 0)
-      : String(nullptr, len, READ_WRITE)
+      : String(nullptr, len, len ? READ_WRITE : INVALID)
   {
     if (len)
     {
       mBuf = new value_type[length()];
       annotate_address(mBuf, "String");
     }
     else
       mBuf = nullptr;
   }
 
@@ skipping 22 matching lines @@
     str.mBuf = nullptr;
     str.mLen = READ_WRITE | 0;
   }
 
   ~OwnedString()
   {
     if (mBuf)
       delete[] mBuf;
   }
 
+  void reset(const String& str)
+  {
+    *this = str;
+  }
+
   OwnedString& operator=(const String& str)
   {
     *this = OwnedString(str);
     return *this;
   }
 
   OwnedString& operator=(const OwnedString& str)
   {
     *this = OwnedString(str);
     return *this;
@@ skipping 61 matching lines @@
     if (negative)
       mBuf[pos++] = '-';
 
     for (int i = size - 1; i >= 0; i--)
     {
       mBuf[pos + i] = '0' + (num % 10);
       num /= 10;
     }
   }
 };