From 3bf42c6ff3805a0d42bbc661794a95ff31bedc26 Mon Sep 17 00:00:00 2001 From: untodesu Date: Sat, 15 Mar 2025 16:22:09 +0500 Subject: Add whatever I was working on for the last month --- deps/include/entt/process/process.hpp | 354 ++++++++++++++++++++++++++++++++++ 1 file changed, 354 insertions(+) create mode 100644 deps/include/entt/process/process.hpp (limited to 'deps/include/entt/process/process.hpp') diff --git a/deps/include/entt/process/process.hpp b/deps/include/entt/process/process.hpp new file mode 100644 index 0000000..f2692bd --- /dev/null +++ b/deps/include/entt/process/process.hpp @@ -0,0 +1,354 @@ +#ifndef ENTT_PROCESS_PROCESS_HPP +#define ENTT_PROCESS_PROCESS_HPP + +#include +#include +#include +#include "fwd.hpp" + +namespace entt { + +/** + * @brief Base class for processes. + * + * This class stays true to the CRTP idiom. Derived classes must specify what's + * the intended type for elapsed times.
+ * A process should expose publicly the following member functions whether + * required: + * + * * @code{.cpp} + * void update(Delta, void *); + * @endcode + * + * It's invoked once per tick until a process is explicitly aborted or it + * terminates either with or without errors. Even though it's not mandatory to + * declare this member function, as a rule of thumb each process should at + * least define it to work properly. The `void *` parameter is an opaque + * pointer to user data (if any) forwarded directly to the process during an + * update. + * + * * @code{.cpp} + * void init(); + * @endcode + * + * It's invoked when the process joins the running queue of a scheduler. This + * happens as soon as it's attached to the scheduler if the process is a top + * level one, otherwise when it replaces its parent if the process is a + * continuation. + * + * * @code{.cpp} + * void succeeded(); + * @endcode + * + * It's invoked in case of success, immediately after an update and during the + * same tick. + * + * * @code{.cpp} + * void failed(); + * @endcode + * + * It's invoked in case of errors, immediately after an update and during the + * same tick. + * + * * @code{.cpp} + * void aborted(); + * @endcode + * + * It's invoked only if a process is explicitly aborted. There is no guarantee + * that it executes in the same tick, this depends solely on whether the + * process is aborted immediately or not. + * + * Derived classes can change the internal state of a process by invoking the + * `succeed` and `fail` protected member functions and even pause or unpause the + * process itself. + * + * @sa scheduler + * + * @tparam Derived Actual type of process that extends the class template. + * @tparam Delta Type to use to provide elapsed time. + */ +template +class process { + enum class state : std::uint8_t { + uninitialized = 0, + running, + paused, + succeeded, + failed, + aborted, + finished, + rejected + }; + + template + auto next(std::integral_constant) + -> decltype(std::declval().init(), void()) { + static_cast(this)->init(); + } + + template + auto next(std::integral_constant, Delta delta, void *data) + -> decltype(std::declval().update(delta, data), void()) { + static_cast(this)->update(delta, data); + } + + template + auto next(std::integral_constant) + -> decltype(std::declval().succeeded(), void()) { + static_cast(this)->succeeded(); + } + + template + auto next(std::integral_constant) + -> decltype(std::declval().failed(), void()) { + static_cast(this)->failed(); + } + + template + auto next(std::integral_constant) + -> decltype(std::declval().aborted(), void()) { + static_cast(this)->aborted(); + } + + template + void next(Args &&...) const noexcept {} + +protected: + /** + * @brief Terminates a process with success if it's still alive. + * + * The function is idempotent and it does nothing if the process isn't + * alive. + */ + void succeed() noexcept { + if(alive()) { + current = state::succeeded; + } + } + + /** + * @brief Terminates a process with errors if it's still alive. + * + * The function is idempotent and it does nothing if the process isn't + * alive. + */ + void fail() noexcept { + if(alive()) { + current = state::failed; + } + } + + /** + * @brief Stops a process if it's in a running state. + * + * The function is idempotent and it does nothing if the process isn't + * running. + */ + void pause() noexcept { + if(current == state::running) { + current = state::paused; + } + } + + /** + * @brief Restarts a process if it's paused. + * + * The function is idempotent and it does nothing if the process isn't + * paused. + */ + void unpause() noexcept { + if(current == state::paused) { + current = state::running; + } + } + +public: + /*! @brief Type used to provide elapsed time. */ + using delta_type = Delta; + + /*! @brief Default constructor. */ + constexpr process() = default; + + /*! @brief Default copy constructor. */ + process(const process &) = default; + + /*! @brief Default move constructor. */ + process(process &&) noexcept = default; + + /** + * @brief Default copy assignment operator. + * @return This process. + */ + process &operator=(const process &) = default; + + /** + * @brief Default move assignment operator. + * @return This process. + */ + process &operator=(process &&) noexcept = default; + + /*! @brief Default destructor. */ + virtual ~process() noexcept { + static_assert(std::is_base_of_v, "Incorrect use of the class template"); + } + + /** + * @brief Aborts a process if it's still alive. + * + * The function is idempotent and it does nothing if the process isn't + * alive. + * + * @param immediate Requests an immediate operation. + */ + void abort(const bool immediate = false) { + if(alive()) { + current = state::aborted; + + if(immediate) { + tick({}); + } + } + } + + /** + * @brief Returns true if a process is either running or paused. + * @return True if the process is still alive, false otherwise. + */ + [[nodiscard]] bool alive() const noexcept { + return current == state::running || current == state::paused; + } + + /** + * @brief Returns true if a process is already terminated. + * @return True if the process is terminated, false otherwise. + */ + [[nodiscard]] bool finished() const noexcept { + return current == state::finished; + } + + /** + * @brief Returns true if a process is currently paused. + * @return True if the process is paused, false otherwise. + */ + [[nodiscard]] bool paused() const noexcept { + return current == state::paused; + } + + /** + * @brief Returns true if a process terminated with errors. + * @return True if the process terminated with errors, false otherwise. + */ + [[nodiscard]] bool rejected() const noexcept { + return current == state::rejected; + } + + /** + * @brief Updates a process and its internal state if required. + * @param delta Elapsed time. + * @param data Optional data. + */ + void tick(const Delta delta, void *data = nullptr) { + switch(current) { + case state::uninitialized: + next(std::integral_constant{}); + current = state::running; + break; + case state::running: + next(std::integral_constant{}, delta, data); + break; + default: + // suppress warnings + break; + } + + // if it's dead, it must be notified and removed immediately + switch(current) { + case state::succeeded: + next(std::integral_constant{}); + current = state::finished; + break; + case state::failed: + next(std::integral_constant{}); + current = state::rejected; + break; + case state::aborted: + next(std::integral_constant{}); + current = state::rejected; + break; + default: + // suppress warnings + break; + } + } + +private: + state current{state::uninitialized}; +}; + +/** + * @brief Adaptor for lambdas and functors to turn them into processes. + * + * Lambdas and functors can't be used directly with a scheduler for they are not + * properly defined processes with managed life cycles.
+ * This class helps in filling the gap and turning lambdas and functors into + * full featured processes usable by a scheduler. + * + * The signature of the function call operator should be equivalent to the + * following: + * + * @code{.cpp} + * void(Delta delta, void *data, auto succeed, auto fail); + * @endcode + * + * Where: + * + * * `delta` is the elapsed time. + * * `data` is an opaque pointer to user data if any, `nullptr` otherwise. + * * `succeed` is a function to call when a process terminates with success. + * * `fail` is a function to call when a process terminates with errors. + * + * The signature of the function call operator of both `succeed` and `fail` + * is equivalent to the following: + * + * @code{.cpp} + * void(); + * @endcode + * + * Usually users shouldn't worry about creating adaptors. A scheduler will + * create them internally each and avery time a lambda or a functor is used as + * a process. + * + * @sa process + * @sa scheduler + * + * @tparam Func Actual type of process. + * @tparam Delta Type to use to provide elapsed time. + */ +template +struct process_adaptor: process, Delta>, private Func { + /** + * @brief Constructs a process adaptor from a lambda or a functor. + * @tparam Args Types of arguments to use to initialize the actual process. + * @param args Parameters to use to initialize the actual process. + */ + template + process_adaptor(Args &&...args) + : Func{std::forward(args)...} {} + + /** + * @brief Updates a process and its internal state if required. + * @param delta Elapsed time. + * @param data Optional data. + */ + void update(const Delta delta, void *data) { + Func::operator()( + delta, + data, + [this]() { this->succeed(); }, + [this]() { this->fail(); }); + } +}; + +} // namespace entt + +#endif -- cgit