Promise.hpp

// Copyright (c) 2025 Devexperts LLC.
// SPDX-License-Identifier: MPL-2.0
 
#pragma once
 
#include "../internal/Conf.hpp"
 
DXFCXX_DISABLE_MSC_WARNINGS_PUSH(4251)
 
#include "../exceptions/JavaException.hpp"
 
#include <atomic>
#include <chrono>
#include <memory>
#include <vector>
 
/**
 * \defgroup dxfcpp_promise "Promise" Module
 * \ingroup dxfcpp_modules
 * @{
 */
 
DXFCPP_BEGIN_NAMESPACE
 
struct EventType;
struct JavaException;
struct Promises;
 
struct DXFCPP_EXPORT PromiseImpl {
    protected:
    std::atomic<void *> handle = nullptr;
 
    public:
    explicit PromiseImpl(void *handle);
 
    bool isDone() const;
    bool hasResult() const;
    bool hasException() const;
    bool isCancelled() const;
    JavaException getException() const;
    void await() const;
    void await(std::int32_t timeoutInMilliseconds) const;
    bool awaitWithoutException(std::int32_t timeoutInMilliseconds) const;
    void cancel() const;
};
 
struct DXFCPP_EXPORT VoidPromiseImpl : PromiseImpl {
    std::atomic<void *> handle = nullptr;
    std::atomic<bool> own = true;
 
    explicit VoidPromiseImpl(void *handle, bool own = true);
    ~VoidPromiseImpl();
    void getResult() const;
};
 
struct DXFCPP_EXPORT EventPromiseImpl : PromiseImpl {
    std::atomic<void *> handle = nullptr;
    std::atomic<bool> own = true;
 
    explicit EventPromiseImpl(void *handle, bool own = true);
    ~EventPromiseImpl();
    std::shared_ptr<EventType> getResult() const;
};
 
struct DXFCPP_EXPORT EventsPromiseImpl : PromiseImpl {
    std::atomic<void *> handle = nullptr;
    std::atomic<bool> own = true;
 
    explicit EventsPromiseImpl(void *handle, bool own = true);
    ~EventsPromiseImpl();
    std::vector<std::shared_ptr<EventType>> getResult() const;
};
 
/**
 * Mixin for wrapping calls to common promise methods.
 *
 * @tparam P The promise type
 */
template <typename P> struct CommonPromiseMixin {
    /**
     * Returns `true` when a computation has completed normally, or exceptionally, or was canceled.
     *
     * @return `true` when computation has completed.
     */
    bool isDone() const {
        return static_cast<const P *>(this)->impl.isDone();
    }
 
    /**
     * Returns `true` when computation has completed normally.
     * Use ::getResult() method to get the result of the computation.
     * @return `true` when computation has completed normally.
     * @see ::getResult()
     */
    bool hasResult() const {
        return static_cast<const P *>(this)->impl.hasResult();
    }
 
    /**
     * Returns `true` when a computation has completed exceptionally or was canceled.
     * Use ::getException() method to get the exceptional outcome of the computation.
     * @return `true` when computation has completed exceptionally or was canceled.
     */
    bool hasException() const {
        return static_cast<const P *>(this)->impl.hasException();
    }
 
    /**
     * Returns `true` when computation was cancelled.
     * Use ::getException() method to get the corresponding CancellationException.
     * @return `true` when computation was cancelled.
     * @see ::getException()
     */
    bool isCancelled() const {
        return static_cast<const P *>(this)->impl.isCancelled();
    }
 
    /**
     * Returns exceptional outcome of computation. If the computation has no ::hasException() exception,
     * then this method returns an exception with a message "null". If a computation has completed exceptionally or was
     * cancelled, then the result of this method is not an exception with a message "null". If computation was @ref
     * ::isCancelled() "cancelled", then this method returns "an instance of CancellationException".
     *
     * @return exceptional outcome of computation.
     * @see ::hasException()
     */
    JavaException getException() const {
        return static_cast<const P *>(this)->impl.getException();
    }
 
    /**
     * Wait for computation to complete or timeout or throw an exception in case of exceptional completion.
     * If the wait is interrupted, then the computation is @ref ::cancel() "canceled",
     * the interruption flag on the current thread is set, and "CancellationException" is thrown.
     *
     * <p>If the wait times are out, then the computation is @ref ::cancel() "canceled" and this method returns `false`.
     * Use this method in the code that shall continue normal execution in case of timeout.
     *
     * @param timeoutInMilliseconds The timeout.
     * @return `true` if the computation has completed normally; `false` when wait timed out.
     * @throws CancellationException if computation was cancelled.
     * @throws PromiseException if computation has completed exceptionally.
     */
    bool awaitWithoutException(std::int32_t timeoutInMilliseconds) const {
        return static_cast<const P *>(this)->impl.awaitWithoutException(timeoutInMilliseconds);
    }
 
    /**
     * Wait for computation to complete or timeout or throw an exception in case of exceptional completion.
     * If the wait is interrupted, then the computation is @ref ::cancel() "canceled",
     * the interruption flag on the current thread is set, and "CancellationException" is thrown.
     *
     * <p>If the wait times are out, then the computation is @ref ::cancel() "canceled" and this method returns `false`.
     * Use this method in the code that shall continue normal execution in case of timeout.
     *
     * @param timeoutInMilliseconds The timeout.
     * @return `true` if the computation has completed normally; `false` when wait timed out.
     * @throws CancellationException if computation was cancelled.
     * @throws PromiseException if computation has completed exceptionally.
     */
    bool awaitWithoutException(const std::chrono::milliseconds &timeoutInMilliseconds) const {
        return static_cast<const P *>(this)->impl.awaitWithoutException(
            dxfcpp::fitToType<std::int32_t>(timeoutInMilliseconds.count()));
    }
 
    /**
     * This method cancels computation. This method does nothing if the computation has already @ref ::isDone() "completed".
     *
     * <p>If cancelled, then ::getException() will return "CancellationException",
     * @ref ::isDone() "isDone", @ref ::isCancelled() "isCancelled", and @ref ::hasException() "hasException" will
     * return `true`, all handlers that were installed with `whenDone` method are notified by invoking their
     * `promiseDone` method, and all waiters on @ref ::await() "join" method throw "CancellationException".
     */
    void cancel() const {
        static_cast<const P *>(this)->impl.cancel();
    }
};
 
/**
 * Mixin for wrapping Promise method calls for a void.
 *
 * @tparam P The promise type.
 */
template <typename P> struct VoidPromiseMixin {
    /**
     * Returns result of computation.
     *
     * @return The result of computation.
     * @see CommonPromiseMixin::hasResult()
     */
    void getResult() const {
        return static_cast<const P *>(this)->impl.getResult();
    }
 
    /**
     * Wait for the computation to complete and return its result or throw an exception in case of exceptional completion.
     * @return result of computation.
     * @throws CancellationException if computation was canceled.
     * @throws PromiseException if computation has completed exceptionally.
     */
    void await() const {
        static_cast<const P *>(this)->impl.await();
 
        return getResult();
    }
 
    /**
     * Wait for the computation to complete or timeout and return its result or throw an exception in case of exceptional
     * completion or timeout.
     *
     * @param timeoutInMilliseconds The timeout.
     * @return The result of computation.
     * @throws CancellationException if computation was canceled or timed out.
     * @throws PromiseException if computation has completed exceptionally.
     */
    void await(std::int32_t timeoutInMilliseconds) const & {
        static_cast<const P *>(this)->impl.await(timeoutInMilliseconds);
 
        return getResult();
    }
 
    /**
     * Wait for the computation to complete or timeout and return its result or throw an exception in case of exceptional
     * completion or timeout.
     *
     * @param timeoutInMilliseconds The timeout.
     * @return The result of computation.
     * @throws CancellationException if computation was cancelled or timed out.
     * @throws PromiseException if computation has completed exceptionally.
     */
    void await(const std::chrono::milliseconds &timeoutInMilliseconds) const & {
        static_cast<const P *>(this)->impl.await(dxfcpp::fitToType<std::int32_t>(timeoutInMilliseconds.count()));
 
        return getResult();
    }
};
 
/**
 * Mixin for wrapping Promise method calls for a single event.
 * @tparam E The event type.
 * @tparam P The promise type.
 */
template <typename E, typename P> struct EventPromiseMixin {
    /**
     * Returns result of computation. If the computation has no @ref CommonPromiseMixin::hasResult() "result", then
     * this method returns `std::shared_ptr<E>(nullptr)`.
     *
     * @return The result of computation.
     * @see CommonPromiseMixin::hasResult()
     */
    std::shared_ptr<E> getResult() const {
        return convertEvent<EventType, E>(static_cast<const P *>(this)->impl.getResult());
    }
 
    /**
     * Wait for the computation to complete and return its result or throw an exception in case of exceptional completion.
     * @return result of computation.
     * @throws CancellationException if computation was canceled.
     * @throws PromiseException if computation has completed exceptionally.
     */
    std::shared_ptr<E> await() const {
        static_cast<const P *>(this)->impl.await();
 
        return getResult();
    }
 
    /**
     * Wait for computation to complete or timeout and return its result or throw an exception in case of exceptional
     * completion or timeout.
     *
     * @param timeoutInMilliseconds The timeout.
     * @return The result of computation.
     * @throws CancellationException if computation was canceled or timed out.
     * @throws PromiseException if computation has completed exceptionally.
     */
    std::shared_ptr<E> await(std::int32_t timeoutInMilliseconds) const & {
        static_cast<const P *>(this)->impl.await(timeoutInMilliseconds);
 
        return getResult();
    }
 
    /**
     * Wait for computation to complete or timeout and return its result or throw an exception in case of exceptional
     * completion or timeout.
     *
     * @param timeoutInMilliseconds The timeout.
     * @return The result of computation.
     * @throws CancellationException if computation was cancelled or timed out.
     * @throws PromiseException if computation has completed exceptionally.
     */
    std::shared_ptr<E> await(const std::chrono::milliseconds &timeoutInMilliseconds) const & {
        static_cast<const P *>(this)->impl.await(dxfcpp::fitToType<std::int32_t>(timeoutInMilliseconds.count()));
 
        return getResult();
    }
};
 
template <typename E, typename P> struct EventsPromiseMixin {
    /**
     * Returns result of computation. If computation has no @ref CommonPromiseMixin::hasResult() "result", then
     * this method returns an empty collection.
     *
     * @return The result of computation.
     * @see CommonPromiseMixin::hasResult()
     */
    std::vector<std::shared_ptr<E>> getResult() const {
        return convertEvents<EventType, E>(static_cast<const P *>(this)->impl.getResult());
    }
 
    /**
     * Wait for computation to complete and return its result or throw an exception in case of exceptional completion.
     * @return result of computation.
     * @throws CancellationException if computation was cancelled.
     * @throws PromiseException if computation has completed exceptionally.
     */
    std::vector<std::shared_ptr<E>> await() const {
        static_cast<const P *>(this)->impl.await();
 
        return getResult();
    }
 
    /**
     * Wait for computation to complete or timeout and return its result or throw an exception in case of exceptional
     * completion or timeout.
     *
     * @param timeoutInMilliseconds The timeout.
     * @return The result of computation.
     * @throws CancellationException if computation was cancelled or timed out.
     * @throws PromiseException if computation has completed exceptionally.
     */
    std::vector<std::shared_ptr<E>> await(std::int32_t timeoutInMilliseconds) const & {
        static_cast<const P *>(this)->impl.await(timeoutInMilliseconds);
 
        return getResult();
    }
 
    /**
     * Wait for computation to complete or timeout and return its result or throw an exception in case of exceptional
     * completion or timeout.
     *
     * @param timeoutInMilliseconds The timeout.
     * @return The result of computation.
     * @throws CancellationException if computation was cancelled or timed out.
     * @throws PromiseException if computation has completed exceptionally.
     */
    std::vector<std::shared_ptr<E>> await(const std::chrono::milliseconds &timeoutInMilliseconds) const & {
        static_cast<const P *>(this)->impl.await(dxfcpp::fitToType<std::int32_t>(timeoutInMilliseconds.count()));
 
        return getResult();
    }
};
 
/**
 * Result of a computation that will be completed normally or exceptionally in the future.
 * @tparam T The result type.
 */
template <typename T> struct Promise {};
 
/**
 * Result of an void receiving that will be completed normally or exceptionally in the future.
 */
template <> struct Promise<void> : CommonPromiseMixin<Promise<void>>, VoidPromiseMixin<Promise<void>> {
    friend struct CommonPromiseMixin<Promise>;
    friend struct VoidPromiseMixin<Promise>;
    friend struct Promises;
 
    private:
    VoidPromiseImpl impl;
 
    public:
    explicit Promise(void *handle, bool own = true) : impl(handle, own) {
    }
 
    Promise(const Promise &) = delete;
    Promise &operator=(const Promise &) = delete;
 
    Promise(Promise && other) noexcept : impl(other.impl.handle, other.impl.own) {
        other.impl.handle = nullptr;
        other.impl.own = false;
    }
 
    Promise &operator=(Promise &&) noexcept = delete;
};
 
/**
 * Result of an event receiving that will be completed normally or exceptionally in the future.
 * @tparam E The event type.
 */
template <typename E>
struct Promise<std::shared_ptr<E>> : CommonPromiseMixin<Promise<std::shared_ptr<E>>>,
                                     EventPromiseMixin<E, Promise<std::shared_ptr<E>>> {
    friend struct CommonPromiseMixin<Promise>;
    friend struct EventPromiseMixin<E, Promise>;
    friend struct Promises;
 
    private:
    EventPromiseImpl impl;
 
    public:
    explicit Promise(void *handle, bool own = true) : impl(handle, own) {
    }
 
    template <Derived<E> D>
    explicit Promise(std::shared_ptr<Promise<std::shared_ptr<D>>> other) : impl(other->impl->handle, false) {
    }
 
    template <BaseOf<E> B> std::shared_ptr<Promise<std::shared_ptr<B>>> sharedAs(bool transferOwnership = false) {
        if (transferOwnership) {
            impl.own = false;
        }
 
        return std::make_shared<Promise<std::shared_ptr<B>>>(impl.handle, transferOwnership);
    }
 
    Promise(const Promise &) = delete;
    Promise &operator=(const Promise &) = delete;
 
    Promise(Promise && other) noexcept : impl(other.impl.handle, other.impl.own) {
        other.impl.handle = nullptr;
        other.impl.own = false;
    }
 
    Promise &operator=(Promise &&) noexcept = delete;
};
 
struct DXFCPP_EXPORT PromiseListImpl {
    std::atomic<void *> handle = nullptr;
 
    explicit PromiseListImpl(void *handle);
    ~PromiseListImpl();
 
    static std::size_t getSize(void *handle);
    static void *getElement(void *handle, std::size_t index);
};
 
/**
 * A list of event receiving results that will be completed normally or exceptionally in the future.
 * It is a std::vector<Promise<std::shared_ptr<E>>> wrapper with Graal semantics.
 * @tparam E The event type.
 */
template <typename E> struct PromiseList {
    friend struct Promises;
 
    using data_type = std::vector<Promise<std::shared_ptr<E>>>;
 
    using iterator_category = std::random_access_iterator_tag;
 
    using value_type = typename data_type::value_type;
    using allocator_type = typename data_type::allocator_type;
    using pointer = typename data_type::pointer;
    using const_pointer = typename data_type::const_pointer;
    using reference = typename data_type::reference;
    using const_reference = typename data_type::const_reference;
    using size_type = typename data_type::size_type;
    using difference_type = typename data_type::difference_type;
 
    using iterator = typename data_type::iterator;
    using const_iterator = typename data_type::const_iterator;
    using reverse_iterator = typename data_type::reverse_iterator;
    using const_reverse_iterator = typename data_type::const_reverse_iterator;
 
    private:
    PromiseListImpl impl;
 
    data_type data_;
 
    public:
    explicit PromiseList(void *handle = nullptr) : impl(handle) {
    }
 
    static std::shared_ptr<PromiseList> create(void *handle) {
        if (!handle) {
            return {};
        }
 
        std::vector<Promise<std::shared_ptr<E>>> result{};
        auto size = PromiseListImpl::getSize(handle);
        auto promiseList = std::make_shared<PromiseList<E>>(handle);
 
        promiseList->data_.reserve(size);
 
        for (std::size_t elementIndex = 0; elementIndex < size; elementIndex++) {
            if (auto element = PromiseListImpl::getElement(handle, elementIndex)) {
                promiseList->data_.emplace_back(element, false);
            }
        }
 
        return promiseList;
    }
 
    pointer data() noexcept {
        return data_.data();
    }
 
    const_pointer data() const noexcept {
        return data_.data();
    }
 
    iterator begin() noexcept {
        return data_.begin();
    }
 
    const_iterator begin() const noexcept {
        return data_.begin();
    }
 
    iterator end() noexcept {
        return data_.end();
    }
 
    const_iterator end() const noexcept {
        return data_.end();
    }
 
    const_iterator cbegin() const noexcept {
        return data_.cbegin();
    }
 
    const_iterator cend() const noexcept {
        return data_.cend();
    }
 
    reverse_iterator rbegin() noexcept {
        return data_.rbegin();
    }
 
    reverse_iterator rend() noexcept {
        return data_.rend();
    }
 
    const_reverse_iterator crbegin() const noexcept {
        return data_.crbegin();
    }
 
    const_reverse_iterator crend() const noexcept {
        return data_.crend();
    }
 
    bool empty() const noexcept {
        return data_.empty();
    }
 
    size_type size() const noexcept {
        return data_.size();
    }
 
    size_type max_size() const noexcept {
        return data_.max_size();
    }
 
    size_type capacity() const noexcept {
        return data_.capacity();
    }
 
    reference operator[](const size_type pos) noexcept {
        return data_[pos];
    }
 
    const_reference operator[](const size_type pos) const noexcept {
        return data_[pos];
    }
 
    reference at(const size_type pos) {
        return data_.at(pos);
    }
 
    const_reference at(const size_type pos) const {
        return data_.at(pos);
    }
 
    reference front() noexcept {
        return data_.front();
    }
 
    const_reference front() const noexcept {
        return data_.front();
    }
 
    reference back() noexcept {
        return data_.back();
    }
 
    const_reference back() const noexcept {
        return data_.back();
    }
};
 
/**
 * Result of an collection of events receiving that will be completed normally or exceptionally in the future.
 * @tparam E The event type.
 */
template <typename E>
struct Promise<std::vector<std::shared_ptr<E>>> : CommonPromiseMixin<Promise<std::vector<std::shared_ptr<E>>>>,
                                                  EventsPromiseMixin<E, Promise<std::vector<std::shared_ptr<E>>>> {
    friend struct CommonPromiseMixin<Promise>;
    friend struct EventsPromiseMixin<E, Promise>;
    friend struct Promises;
 
    private:
    EventsPromiseImpl impl;
 
    public:
    explicit Promise(void *handle, bool own = true) : impl(handle, own) {
    }
 
    Promise(const Promise &) = delete;
    Promise &operator=(const Promise &) = delete;
 
    Promise(Promise && other) noexcept : impl(other.impl.handle, other.impl.own) {
        other.impl.handle = nullptr;
        other.impl.own = false;
    }
 
    Promise &operator=(Promise &&) noexcept = delete;
};
 
DXFCPP_END_NAMESPACE
 
/// @}
 
DXFCXX_DISABLE_MSC_WARNINGS_POP()