From b576c1cfe6105a4f392ea9acfd770297d3972888 Mon Sep 17 00:00:00 2001
From: Bob Polis <rpb.polis@avans.nl>
Date: Tue, 5 Oct 2021 14:25:04 +0200
Subject: [PATCH] Added count() and random_choice() functions

---
 plugin.hpp | 166 ++++++++++++++++++++++++++++-------------------------
 1 file changed, 87 insertions(+), 79 deletions(-)

diff --git a/plugin.hpp b/plugin.hpp
index 0c56cf6..e6b4281 100644
--- a/plugin.hpp
+++ b/plugin.hpp
@@ -14,6 +14,7 @@
 #include <map>
 #include <functional>
 #include <iostream>
+#include <random>
 #include <dlfcn.h>
 #include <dirent.h>
 #include <libscerror.hpp>
@@ -22,102 +23,109 @@ namespace sc {
 
 	template <typename T>
 	class plugin {
-	public:
-		static void scan_plugins(const std::string& dir, const std::string& ext) {
-			DIR* plugins_dir = ::opendir(dir.c_str());
-			throw_if_null_msg(plugins_dir, (dir + " could not be opened").c_str());
-			struct dirent* info;
-			while ((info = ::readdir(plugins_dir)) != nullptr) {
-				if (info->d_name[0] != '.') {
-					std::string plugname {info->d_name};
-					std::string::size_type lastdot = plugname.rfind(".");
-					if (plugname.substr(lastdot + 1) == ext) {
-						plugin plugin {dir + '/' + plugname};
-						plugins.emplace(plugname.substr(0, lastdot), std::move(plugin));
+		public:
+			static void scan_plugins(const std::string& dir, const std::string& ext) {
+				DIR* plugins_dir = ::opendir(dir.c_str());
+				throw_if_null_msg(plugins_dir, (dir + " could not be opened").c_str());
+				struct dirent* info;
+				while ((info = ::readdir(plugins_dir)) != nullptr) {
+					if (info->d_name[0] != '.') {
+						std::string plugname {info->d_name};
+						std::string::size_type lastdot = plugname.rfind(".");
+						if (plugname.substr(lastdot + 1) == ext) {
+							plugin plugin {dir + '/' + plugname};
+							plugins.emplace(plugname.substr(0, lastdot), std::move(plugin));
+						}
+					}
+				}
+				throw_if_min1(::closedir(plugins_dir));
+			}
+
+			using processor = std::function<void(const plugin&)>;
+			static void foreach(processor proc) {
+				for (const auto& elem : plugins) {
+					proc(elem.second);
+				}
+			}
+
+			static plugin& get(const std::string& name) {
+				return plugins.at(name);
+			}
+
+			static std::vector<std::string> names() {
+				std::vector<std::string> result;
+				for (const auto& elem : plugins) {
+					result.emplace_back(elem.first);
+				}
+				return result;
+			}
+
+			static size_t count() { return plugins.size(); }
+
+			static plugin& random_choice() {
+				static std::random_device rdev {};
+				static std::default_random_engine reng {rdev()};
+				std::uniform_int_distribution<int> dist {0, count() - 1};
+				return get(names()[dist(reng)]);
+			}
+
+			plugin(const std::string& path) : _path {path} {
+				_plugin = ::dlopen(path.c_str(), RTLD_LAZY);
+
+				const char* err {::dlerror()};
+				if (err) std::cerr << err << '\n';
+				if (_plugin) {
+					_factory = reinterpret_cast<factory>(::dlsym(_plugin, "create_instance"));
+					if (!_factory) {
+						std::cerr << "create_instance() function not found in " << path << '\n';
 					}
 				}
 			}
-			throw_if_min1(::closedir(plugins_dir));
-		}
-		
-		using processor = std::function<void(const plugin&)>;
-		static void foreach(processor proc) {
-			for (const auto& elem : plugins) {
-				proc(elem.second);
-			}
-		}
 
-		static plugin& get(const std::string& name) {
-			return plugins.at(name);
-		}
-
-		static std::vector<std::string> names() {
-			std::vector<std::string> result;
-			for (const auto& elem : plugins) {
-				result.emplace_back(elem.first);
-			}
-			return result;
-		}
-
-		plugin(const std::string& path) : _path {path} {
-			_plugin = ::dlopen(path.c_str(), RTLD_LAZY);
-
-			//std::cerr << path << (_plugin ? "" : " not") << " opened\n";
-			const char* err {::dlerror()};
-			if (err) std::cerr << err << '\n';
-			if (_plugin) {
-				_factory = reinterpret_cast<factory>(::dlsym(_plugin, "create_instance"));
-				if (!_factory) {
-					std::cerr << "create_instance() function not found in " << path << '\n';
+			~plugin() {
+				if (_plugin) {
+					::dlclose(_plugin);
+					_plugin = nullptr;
 				}
 			}
-		}
 
-		~plugin() {
-			if (_plugin) {
-				::dlclose(_plugin);
-				_plugin = nullptr;
-				//std::cerr << _path << " closed\n";
-			}
-		}
+			plugin(const plugin&) = delete;
+			plugin& operator=(const plugin&) = delete;
 
-		plugin(const plugin&) = delete;
-		plugin& operator=(const plugin&) = delete;
-
-		plugin(plugin&& other) {
-			_path = other._path;
-			_plugin = other._plugin;
-			_factory = other._factory;
-			other._plugin = nullptr;
-		}
-
-		plugin& operator=(plugin&& other) {
-			if (this != &other) {
+			plugin(plugin&& other) {
 				_path = other._path;
 				_plugin = other._plugin;
 				_factory = other._factory;
 				other._plugin = nullptr;
 			}
-			return *this;
-		}
 
-		std::string path() const { return _path; }
-
-		std::unique_ptr<T> operator()() const {
-			std::unique_ptr<T> obj;
-			if (_factory) {
-				obj.reset(_factory());
+			plugin& operator=(plugin&& other) {
+				if (this != &other) {
+					_path = other._path;
+					_plugin = other._plugin;
+					_factory = other._factory;
+					other._plugin = nullptr;
+				}
+				return *this;
 			}
-			return obj;
-		}
 
-	private:
-		static std::map<std::string, plugin<T>> plugins;
+			std::string path() const { return _path; }
 
-		std::string _path;
-		void* _plugin {nullptr};
-		using factory = T*(*)();
-		factory _factory {nullptr};
+			std::unique_ptr<T> operator()() const {
+				std::unique_ptr<T> obj;
+				if (_factory) {
+					obj.reset(_factory());
+				}
+				return obj;
+			}
+
+		private:
+			static std::map<std::string, plugin<T>> plugins;
+
+			std::string _path;
+			void* _plugin {nullptr};
+			using factory = T*(*)();
+			factory _factory {nullptr};
 	};
 
 	template <typename T>