add file selector with sorting

src/file_selector.hpp

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <filesystem>
+#include <functional>
+
+struct FileSelector {
+	std::filesystem::path _current_file_path = std::filesystem::canonical(".") / ""; // add /
+
+	bool _open_popup {false};
+
+	std::function<bool(const std::filesystem::path& path)> _is_valid = [](auto){ return true; };
+	std::function<void(const std::filesystem::path& path)> _on_choose = [](auto){};
+	std::function<void(void)> _on_cancel = [](){};
+
+	void reset(void);
+
+	public:
+		FileSelector(void);
+
+		// TODO: supply hints
+		void requestFile(
+			std::function<bool(const std::filesystem::path& path)>&& is_valid,
+			std::function<void(const std::filesystem::path& path)>&& on_choose,
+			std::function<void(void)>&& on_cancel
+		);
+
+		// call this each frame
+		void render(void);
+};
+