Issue 5063 - [emscripten] Make FilterNotifier calls more efficient

compiled/String.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #pragma once
 
+#include <algorithm>
 #include <cstddef>
 #include <cstring>
-#include <algorithm>
+#include <type_traits>
 
 #include <emscripten.h>
 
 #include "debug.h"
 
 inline void String_assert_readonly(bool readOnly);
 
 class String
 {
   friend class DependentString;
@@ skipping 290 matching lines @@
   }
 
   ~OwnedString()
   {
     if (mBuf)
       delete[] mBuf;
   }
 
   OwnedString& operator=(const String& str)
   {
-    *this = std::move(OwnedString(str));
+    *this = OwnedString(str);
     return *this;
   }
 
   OwnedString& operator=(const OwnedString& str)
   {
-    *this = std::move(OwnedString(str));
+    *this = OwnedString(str);
     return *this;
   }
 
   OwnedString& operator=(OwnedString&& str)
   {
     std::swap(mBuf, str.mBuf);
     std::swap(mLen, str.mLen);
     return *this;
   }
 
@@ skipping 22 matching lines @@
 
   void append(const String& str)
   {
     append(str.mBuf, str.length());
   }
 
   void append(value_type c)
   {
     append(&c, 1);
   }
+
+  template<typename T,
+      typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
+  void append(T num)
+  {
+    bool negative = false;
+    if (num < 0)
+    {
+      negative = true;
+      num = -num;
+    }
+
+    size_type size = 0;
+    for (T i = num; i; i /= 10)
+      size++;
+    size = (size ? size : 1);
+
+    size_type pos = length();
+    grow((negative ? 1 : 0) + size);
+
+    if (negative)
+      mBuf[pos++] = '-';
+
+    for (int i = size - 1; i >= 0; i--)
+    {
+      mBuf[pos + i] = '0' + (num % 10);
+      num /= 10;
+    }
+  }
 };