Common: Create Range Projections For std::pair

Source/Core/Common/CMakeLists.txt

@@ -113,6 +113,7 @@ add_library(common
   PcapFile.h
   Profiler.cpp
   Profiler.h
+  Projection.h
   QoSSession.cpp
   QoSSession.h
   Random.cpp

Source/Core/Common/Projection.h

@@ -0,0 +1,30 @@
+// Copyright 2025 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <utility>
+
+namespace Common::Projection
+{
+struct First
+{
+  // TODO C++23: static operator()
+  template <class T>
+  [[nodiscard]] constexpr auto&& operator()(T&& t) const noexcept
+  {
+    return std::forward<T>(t).first;
+  }
+};
+
+struct Second
+{
+  // TODO C++23: static operator()
+  template <class T>
+  [[nodiscard]] constexpr auto&& operator()(T&& t) const noexcept
+  {
+    return std::forward<T>(t).second;
+  }
+};
+
+using Key = First;
+using Value = Second;
+}  // namespace Common::Projection

Source/Core/DolphinLib.props

@@ -143,6 +143,7 @@
     <ClInclude Include="Common\Network.h" />
     <ClInclude Include="Common\PcapFile.h" />
     <ClInclude Include="Common\Profiler.h" />
+    <ClInclude Include="Common\Projection.h" />
     <ClInclude Include="Common\QoSSession.h" />
     <ClInclude Include="Common\Random.h" />
     <ClInclude Include="Common\Result.h" />