Config system v1

Roughly inspired by what I've learned from my work on Space Station 14, without some of the unnecessary cruft and complexity.

Implementation is relatively simple once I figured out all the template order shenanigans.

include/dusk/appname.hpp

@@ -0,0 +1,20 @@
+#ifndef DUSK_APPNAME_HPP
+#define DUSK_APPNAME_HPP
+
+namespace dusk {
+    /**
+     * \brief The internal application name for the game.
+     *
+     * This gets used for file paths and such, and cannot be changed!
+     */
+    constexpr auto AppName = "Dusk";
+
+    /**
+     * \brief The internal organization name for the game.
+     *
+     * This gets used for file paths and such, and cannot be changed!
+     */
+    constexpr auto OrgName = "TwilitRealm";
+}
+
+#endif  // DUSK_APPNAME_HPP

include/dusk/config.hpp

@@ -0,0 +1,114 @@
+#ifndef DUSK_CONFIG_HPP
+#define DUSK_CONFIG_HPP
+
+#include <stdexcept>
+#include "nlohmann/json.hpp"
+#include "config_var.hpp"
+
+namespace dusk::config {
+
+/**
+ * \brief Base class containing virtual functions used for save/load of CVars.
+ */
+class ConfigImplBase {
+protected:
+    virtual ~ConfigImplBase() = default;
+
+public:
+    /**
+     * \brief Load a JSON value into a CVar at the Value layer.
+     */
+    virtual void loadFromJson(ConfigVarBase& cVar, const nlohmann::json& jsonValue) const = 0;
+
+    /**
+     * \brief Load a simple launch argument into the CVar at the Override layer.
+     */
+    virtual void loadFromArg(ConfigVarBase& cVar, std::string_view stringValue) const = 0;
+
+    /**
+     * \brief Dump the value contained in the CVar to JSON.
+     */
+    [[nodiscard]] virtual nlohmann::json dumpToJson(const ConfigVarBase& cVar) const = 0;
+};
+
+template<ConfigValue T>
+class ConfigImpl : public ConfigImplBase {
+    // Just downcasting the references...
+    void loadFromJson(ConfigVarBase& cVar, const nlohmann::json& jsonValue) const final {
+        assert(typeid(cVar) == typeid(ConfigVar<T>));
+        loadFromJson(dynamic_cast<ConfigVar<T>&>(cVar), jsonValue);
+    }
+
+    void loadFromArg(ConfigVarBase& cVar, std::string_view stringValue) const final {
+        assert(typeid(cVar) == typeid(ConfigVar<T>));
+        loadFromArg(dynamic_cast<ConfigVar<T>&>(cVar), stringValue);
+    }
+
+    [[nodiscard]] nlohmann::json dumpToJson(const ConfigVarBase& cVar) const final {
+        assert(typeid(cVar) == typeid(ConfigVar<T>));
+        return dumpToJson(dynamic_cast<const ConfigVar<T>&>(cVar));
+    }
+
+    /**
+     * \brief Load a JSON value into a CVar at the Value layer.
+     */
+    static void loadFromJson(ConfigVar<T>& cVar, const nlohmann::json& jsonValue);
+
+    /**
+     * \brief Load a simple launch argument into the CVar at the Override layer.
+     */
+    static void loadFromArg(ConfigVar<T>& cVar, std::string_view stringValue);
+
+    /**
+     * \brief Dump the value contained in the CVar to JSON.
+     */
+    [[nodiscard]] static nlohmann::json dumpToJson(const ConfigVar<T>& cVar);
+};
+
+/**
+ * \brief Thrown by config loading functions if the value provided is invalid for the CVar.
+ */
+class InvalidConfigError : public std::runtime_error {
+public:
+    explicit InvalidConfigError(const char* what) : runtime_error(what) {}
+};
+
+/**
+ * \brief Register a CVar to make the config system aware of it.
+ *
+ * This must be done on startup *before* config has been loaded.
+ */
+void Register(ConfigVarBase& configVar);
+
+/**
+ * \brief Indicate that all registrations have happened and everything should lock in.
+ */
+void FinishRegistration();
+
+/**
+ * \brief Load config from the standard user preferences location.
+ */
+void LoadFromUserPreferences();
+void LoadFromFileName(const char* path);
+
+/**
+ * \brief Save the config to file.
+ */
+void Save();
+
+/**
+ * \brief Get a registered CVar by name.
+ *
+ * @return null if the CVar does not exist.
+ */
+ConfigVarBase* GetConfigVar(std::string_view name);
+
+template <ConfigValue T>
+const ConfigImplBase* GetConfigImpl() {
+    static ConfigImpl<T> config;
+    return &config;
+}
+
+}  // namespace dusk::config
+
+#endif

include/dusk/config_var.hpp

@@ -0,0 +1,228 @@
+#ifndef DUSK_CONFIG_VAR_HPP
+#define DUSK_CONFIG_VAR_HPP
+
+#include "dolphin/types.h"
+#include <type_traits>
+#include <cstdlib>
+#include <string>
+
+/**
+ * The configuration system.
+ *
+ * Configuration works via "configuration variables" aka "CVars". Each stores a single value that
+ * may be individually written to/from a configuration file.
+ *
+ * CVars, like ogres, have layers. Higher layers (e.g. a set value) override lower layers
+ * (e.g. the default value).
+ *
+ * To define a CVar, simply make a global variable of type ConfigVar<T>,
+ * and make sure Register() is called on it during program startup.
+ *
+ * config_var.hpp contains the simplest "just the configuration vars themselves".
+ * This should be safe to include for files that need to *access* configuration,
+ * without blowing up compile times on implementation details.
+ *
+ * config.hpp on the other hand contains far more calls for mutating, loading, and defining CVars.
+ */
+namespace dusk::config {
+
+/**
+ * \brief Layers that a configuration variable can currently be at.
+ *
+ * A configuration variable can be on one of multiple *layers*, which determines where
+ * the current value is coming from.
+ */
+enum class ConfigVarLayer : u8 {
+    /**
+     * The CVar is at the default value defined by the application code.
+     */
+    Default,
+
+    /**
+     * The CVar has been modified by the user and may be saved to config.
+     */
+    Value,
+
+    /**
+     * The CVar is modified by launch argument, overruling the normal config value.
+     * Will not get saved to config.
+     */
+    Override,
+};
+
+class ConfigImplBase;
+
+/**
+ * Base class that all CVars inherit from.
+ * You want the templated ConfigVar instead for actual usage.
+ */
+class ConfigVarBase {
+protected:
+    /**
+     * The name of this CVar, used in the configuration file.
+     */
+    const char* name;
+
+    /**
+     * Whether this CVar has been registered with the global managing logic.
+     * If this is not done, it is not functional.
+     */
+    bool registered;
+
+    /**
+     * The layer this CVar is at.
+     */
+    ConfigVarLayer layer;
+
+    /**
+     * Pointer to an implementation struct for various load/save calls.
+     */
+    const ConfigImplBase* impl;
+
+    ConfigVarBase(const char* name, const ConfigImplBase* impl);
+    virtual ~ConfigVarBase() = default;
+
+    /**
+     * Check that the CVar is registered, aborting if this is not the case.
+     */
+    void checkRegistered() const {
+        if (!registered)
+            abort();
+    }
+
+public:
+    /**
+     * Get the name of this CVar, used in the configuration file.
+     */
+    [[nodiscard]] const char* getName() const noexcept;
+
+    /**
+     * Get the pointer to the implementation struct.
+     */
+    [[nodiscard]] const ConfigImplBase* getImpl() const noexcept;
+
+    /**
+     * Get the layer this CVar is currently at.
+     */
+    [[nodiscard]] constexpr ConfigVarLayer getLayer() const noexcept {
+        return layer;
+    }
+
+    /**
+     * Mark this CVar as being registered with the central save/load logic.
+     * This is necessary to make it legal to access.
+     */
+    void markRegistered();
+};
+
+template <typename T>
+concept ConfigValueInteger =
+    std::is_same_v<T, s8>
+    || std::is_same_v<T, u8>
+    || std::is_same_v<T, s16>
+    || std::is_same_v<T, u16>
+    || std::is_same_v<T, s32>
+    || std::is_same_v<T, u32>
+    || std::is_same_v<T, s64>
+    || std::is_same_v<T, u64>;
+
+/**
+ * \brief Concept that defines the legal set of types that can be used for CVar values.
+ *
+ * Valid types cannot be cv-qualified and must be basic primitive types (int, float, bool),
+ * strings, or enums of the basic primitives.
+ */
+template <typename T>
+concept ConfigValue =
+    !std::is_const_v<T>
+    && !std::is_volatile_v<T>
+    && (std::is_same_v<T, bool>
+        || ConfigValueInteger<T>
+        || std::is_same_v<T, f32>
+        || std::is_same_v<T, f64>
+        || std::is_same_v<T, std::string>
+        || (std::is_enum_v<T> && ConfigValueInteger<std::underlying_type_t<T>>));
+
+template <ConfigValue T>
+const ConfigImplBase* GetConfigImpl();
+
+/**
+ * \brief A CVar storing values.
+ *
+ * @tparam T The type of value stored in the CVar.
+ */
+template <ConfigValue T>
+class ConfigVar : public ConfigVarBase {
+    T defaultValue;
+    T value;
+    T overrideValue;
+
+public:
+    /**
+     * \brief Construct a CVar.
+     *
+     * @param name The name of this CVar. Must be unique.
+     * @param arg Arguments to forward to construct the default value.
+     */
+    template <typename... Args>
+    explicit ConfigVar(const char* name, Args&&... arg)
+        : ConfigVarBase(name, GetConfigImpl<T>()), defaultValue(std::forward<Args>(arg)...),
+        value(), overrideValue() {}
+
+    /**
+     * \brief Get the current value of the CVar.
+     */
+    [[nodiscard]] constexpr const T& getValue() const noexcept {
+        checkRegistered();
+        switch (layer) {
+        case ConfigVarLayer::Default:
+            return defaultValue;
+        case ConfigVarLayer::Value:
+            return value;
+        case ConfigVarLayer::Override:
+            return overrideValue;
+        default:
+            abort();
+        }
+    }
+
+    /**
+     * \brief Change the value of a CVar.
+     *
+     * The new value is always stored at the Value layer.
+     *
+     * @param newValue The new value the CVar will get.
+     * @param replaceOverride If true, clear an existing override layer if there is one.
+     *     If this is false and there is an override layer,
+     *     the result of getValue() will not change immediately.
+     */
+    void setValue(T newValue, bool replaceOverride = true) {
+        checkRegistered();
+        value = std::move(newValue);
+
+        if (replaceOverride) {
+            overrideValue = {};
+            layer = ConfigVarLayer::Value;
+        } else if (layer != ConfigVarLayer::Override) {
+            layer = ConfigVarLayer::Value;
+        }
+    }
+
+    /**
+     * \brief Give a CVar an override value.
+     *
+     * This overrides (but does not replace) the apparent set value of this CVar.
+     * The overriden value will not get saved to config.
+     *
+     * @param newValue The new value the CVar will get.
+     */
+    void setOverrideValue(T newValue) {
+        checkRegistered();
+        overrideValue = std::move(newValue);
+        layer = ConfigVarLayer::Override;
+    }
+};
+
+}
+
+#endif  // DUSK_CONFIG_VAR_HPP

include/dusk/io.hpp

@@ -0,0 +1,75 @@
+#ifndef DUSK_IO_HPP
+#define DUSK_IO_HPP
+
+#include <vector>
+
+// I can't believe it's 2026 and neither SDL (no error codes) nor
+// C++ (no error codes) have a file system API functional enough for me to use.
+// Here you go, this one's inspired by C#. I only wrote the functions I need.
+
+namespace dusk::io {
+
+/**
+ * \brief A simple file stream wrapping cstdio FILE*.
+ *
+ * Methods on this class throw appropriate C++ exceptions when an error occurs.
+ */
+class FileStream {
+    void* file;
+
+public:
+    FileStream() noexcept;
+
+    /**
+     * \brief Take ownership of a FILE* handle.
+     */
+    explicit FileStream(void* file);
+    FileStream(const FileStream& other) = delete;
+    FileStream(FileStream&& other) noexcept;
+
+    ~FileStream();
+
+    /**
+     * \brief Open a file for reading at the given path.
+     */
+    static FileStream OpenRead(const char* utf8Path);
+
+    /**
+     * \brief Create a file for writing.
+     *
+     * If there is an existing file, its contents are demolished.
+     */
+    static FileStream Create(const char* utf8Path);
+
+    /**
+     * \brief Read the byte contents of a file directly into a vector.
+     */
+    static std::vector<u8> ReadAllBytes(const char* utf8Path);
+
+    /**
+     * \brief Read the byte contents of a file directly into a vector.
+     */
+    static void WriteAllText(const char* utf8Path, std::string_view text);
+
+    /**
+     * \brief Read the remaining contents of the file directly into a vector.
+     */
+    std::vector<u8> ReadFull();
+
+    /**
+     * Get direct access to the underlying FILE* handle.
+     */
+    [[nodiscard]] void* GetFileHandle() const noexcept {
+        return file;
+    }
+
+    /**
+     * Write data to the file.
+     */
+    void Write(const char* data, size_t dataLen);
+};
+
+}
+
+
+#endif  // DUSK_IO_HPP

include/dusk/scope.hpp

@@ -0,0 +1,29 @@
+#ifndef DUSK_SCOPE_HPP
+#define DUSK_SCOPE_HPP
+
+namespace dusk {
+
+/**
+ * A simple value wrapper that will destroy the value at the end of its scope.
+ * @tparam T The type of value contained.
+ * @tparam Destructor The type of function used to destroy the value.
+ */
+template <typename T, typename Destructor>
+    struct ScopeValue {
+        T value;
+        Destructor destructor;
+
+        explicit ScopeValue(T value, Destructor destructor) : value(value), destructor(destructor) {
+        }
+
+        ~ScopeValue() {
+            destructor(value);
+        }
+
+        constexpr operator T&() const noexcept {
+            return value;
+        }
+    };
+}
+
+#endif  // DUSK_SCOPE_HPP

include/dusk/settings.hpp

@@ -0,0 +1,24 @@
+#ifndef DUSK_SETTINGS_HPP
+#define DUSK_SETTINGS_HPP
+
+#include "config_var.hpp"
+
+namespace dusk::settings {
+    using namespace dusk::config;
+
+    namespace enhancements {
+        extern ConfigVar<bool> FastIronBoots;
+        extern ConfigVar<bool> InvertCameraXAxis;
+        extern ConfigVar<bool> QuickTransform;
+        extern ConfigVar<bool> RestoreWiiGlitches;
+        extern ConfigVar<bool> EnableBloom;
+        extern ConfigVar<bool> UseWaterProjectionOffset;
+        extern ConfigVar<bool> MirrorMode;
+
+        void Register();
+    }
+
+    void Register();
+}
+
+#endif  // DUSK_SETTINGS_HPP

include/m_Do/m_Do_controller_pad.h

@@ -3,6 +3,7 @@
 
 #include "JSystem/JUtility/JUTGamePad.h"
 #include "SSystem/SComponent/c_API_controller_pad.h"
+#include "dusk/settings.hpp"
 
 #include "dusk/imgui/ImGuiMenuEnhancements.hpp"
 
@@ -57,7 +58,7 @@ public:
 
     static s16 getStickAngle3D(u32 pad) {
         #if TARGET_PC
-        if (dusk::ImGuiMenuEnhancements::m_enhancements.mirrorMode) {
+        if (dusk::settings::enhancements::MirrorMode.getValue()) {
             return -getCpadInfo(pad).mMainStickAngle;
         } else {
             return getCpadInfo(pad).mMainStickAngle;
@@ -69,7 +70,7 @@ public:
 
     static f32 getSubStickX3D(u32 pad) {
         #if TARGET_PC
-        if (dusk::ImGuiMenuEnhancements::m_enhancements.mirrorMode) {
+        if (dusk::settings::enhancements::MirrorMode.getValue()) {
             return -getCpadInfo(pad).mCStickPosX;
         } else {
             return getCpadInfo(pad).mCStickPosX;