Issue 119 - Switch to injecting CSS for element hiding

src/shared/EventWithSetter.h

+#pragma once
+/*
+* This file is part of Adblock Plus <https://adblockplus.org/>,
+* Copyright (C) 2006-2016 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/>.
+*/
+#include "AutoHandle.h"
+#include <cstdint>
+#include <memory>
+
+/// Wrapper around unnamed manual event windows object.
+class Event {
+public:
+  enum {
+    InfiniteTimeout = 0xFFFFFFFF
+  };
+  /// Creates manual event with nonsignaled initial state.
+  Event();
+  ~Event();
+  void Set();
+  void Reset();
+  bool operator!() const {
+    return m_handle == nullptr;
+  }
+  bool Wait(int32_t timeoutMsec = InfiniteTimeout);
+private:
+  Event(const Event&);
+  void operator=(const Event&);
+private:
+  HANDLE m_handle;
+};
+
+/// This class is a temporary replacement of std::promise/std::future.
+///
+/// Before scheduling a task to a worker thread, the caller creates
+/// `EventWithSetter` and obtains `EventWithSetter::Setter`. The task at the
+/// end should call `EventWithSetter::Setter::Set` to notify the caller about
+/// finishing.
+/// If the the task is not finished because it has been canceled or it has
+/// thrown an exception then the `EventWithSetter::Wait` returns `false`.
+/// Example:
+/// EventWithSetter event;
+/// { // this scope is important because without it if `doWork()` throws
+///   // `setter` won't be destroyed and the caller will wait forever.
+///   auto setter = event.CreateSetter();
+///   dispatchTask([setter]{
+///     doWork();
+///     setter->Set();
+///   });
+/// }
+/// if (event.Wait()) onSuccess();
+/// else onFail();
+class EventWithSetter
+{
+public:
+  class Setter;
+private:
+  struct Data
+  {
+    Data() : isSetCalled(false), isSetterCreated(false)
+    {}
+    Event event;
+    std::weak_ptr<Setter> eventSetter;
+    bool isSetCalled;
+    bool isSetterCreated;
+  };
+  typedef std::shared_ptr<Data> DataPtr;
+public:
+  class Setter
+  {
+  public:
+    Setter(const DataPtr& data);
+    ~Setter();
+    void Set();
+  private:
+    Setter(const Setter&);
+    void operator=(const Setter&);
+  private:
+    DataPtr m_data;
+  };
+  EventWithSetter();
+  std::shared_ptr<Setter> CreateSetter();
+  bool Wait(int32_t timeoutMsec = Event::InfiniteTimeout);
+private:
+  EventWithSetter(const EventWithSetter&);
+  void operator=(const EventWithSetter&);
+private:
+  DataPtr m_data;
+};