Add new resources system in app library

libs/app/include/psemek/app/resource.hpp

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <psemek/io/stream.hpp>
+
+#include <filesystem>
+#include <memory>
+
+namespace psemek::app
+{
+
+	std::filesystem::path resource_root();
+	void set_resource_root(std::filesystem::path const & root);
+
+	// Implemented by a backend library
+	std::unique_ptr<io::istream> open_resource(std::filesystem::path const & relative_path);
+
+}

libs/app/source/resource.cpp

@@ -0,0 +1,24 @@
+#include <psemek/app/resource.hpp>
+#include <psemek/util/executable_path.hpp>
+
+namespace psemek::app
+{
+
+	namespace
+	{
+
+		static std::filesystem::path global_resource_root = util::executable_path().parent_path();
+
+	}
+
+	std::filesystem::path resource_root()
+	{
+		return global_resource_root;
+	}
+
+	void set_resource_root(std::filesystem::path const & root)
+	{
+		global_resource_root = root;
+	}
+
+}

libs/sdl2/source/resource.cpp

@@ -0,0 +1,12 @@
+#include <psemek/app/resource.hpp>
+#include <psemek/io/file_stream.hpp>
+
+namespace psemek::app
+{
+
+	std::unique_ptr<io::istream> open_resource(std::filesystem::path const & relative_path)
+	{
+		return std::make_unique<io::file_istream>(app::resource_root() / relative_path);
+	}
+
+}