New cpp folder structure

Signed-off-by: Alexander Borsuk <me@alex.bio>

libs/shaders/metal_program_pool.hpp

@@ -0,0 +1,45 @@
+#pragma once
+#import <MetalKit/MetalKit.h>
+
+#include "shaders/program_pool.hpp"
+
+#include "drape/pointers.hpp"
+
+#include <map>
+#include <string>
+
+namespace gpu
+{
+enum class SystemProgram
+{
+  ClearColor = 0,
+  ClearDepth,
+  ClearColorAndDepth,
+  
+  SystemProgramsCount
+};
+  
+namespace metal
+{
+class MetalProgramPool : public ProgramPool
+{
+public:
+  explicit MetalProgramPool(id<MTLDevice> device);
+  ~MetalProgramPool() override;
+
+  drape_ptr<dp::GpuProgram> Get(Program program) override;
+  drape_ptr<dp::GpuProgram> GetSystemProgram(SystemProgram program);
+  
+private:
+  drape_ptr<dp::GpuProgram> Get(std::string const & programName,
+                                std::string const & vertexShaderName,
+                                std::string const & fragmentShaderName,
+                                std::map<uint8_t, uint8_t> const & layout);
+  
+  id<MTLFunction> GetFunction(std::string const & name);
+  id<MTLDevice> m_device;
+  id<MTLLibrary> m_library;
+  std::map<std::string, id<MTLFunction>> m_functions;
+};
+}  // namespace metal
+}  // namespace gpu