qstdweb_p.h

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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#ifndef QSTDWEB_P_H
#define QSTDWEB_P_H
 
//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
 
#include <private/qglobal_p.h>
#include <QtCore/qglobal.h>
#include "QtCore/qhash.h"
#include "QtCore/qiodevice.h"
#include "QtCore/private/qwasmsuspendresumecontrol_p.h"
 
#include <emscripten/val.h>
 
#include <cstdint>
#include <functional>
#include <initializer_list>
#include <memory>
#include <string>
#include <utility>
 
#if QT_CONFIG(thread)
#include <emscripten/proxying.h>
#include <emscripten/threading.h>
#endif  // #if QT_CONFIG(thread)
 
#if QT_CONFIG(wasm_jspi)
# define QT_WASM_EMSCRIPTEN_ASYNC ,emscripten::async()
#else
# define QT_WASM_EMSCRIPTEN_ASYNC
#endif
 
QT_BEGIN_NAMESPACE
 
class QMimeData;
 
namespace qstdweb {
    extern const char makeContextfulPromiseFunctionName[];
 
    // DOM API in C++, implemented using emscripten val.h and bind.h.
    // This is private API and can be extended and changed as needed.
    // The API mirrors that of the native API, with some extensions
    // to ease usage from C++ code.
 
    class ArrayBuffer;
    class Blob;
    class File;
    class FileList;
    class FileReader;
    class Uint8Array;
    class EventCallback;
 
    class Q_CORE_EXPORT ArrayBuffer {
    public:
        explicit ArrayBuffer(uint32_t size);
        explicit ArrayBuffer(const emscripten::val &arrayBuffer);
        uint32_t byteLength() const;
        ArrayBuffer slice(uint32_t begin, uint32_t end) const;
        emscripten::val val() const;
 
    private:
        friend class Uint8Array;
        emscripten::val m_arrayBuffer = emscripten::val::undefined();
    };
 
    class Q_CORE_EXPORT Blob {
    public:
        explicit Blob(const emscripten::val &blob);
        static Blob fromArrayBuffer(const ArrayBuffer &arrayBuffer);
        uint32_t size() const;
        static Blob copyFrom(const char *buffer, uint32_t size, std::string mimeType);
        static Blob copyFrom(const char *buffer, uint32_t size);
        Blob slice(uint32_t begin, uint32_t end) const;
        ArrayBuffer arrayBuffer_sync() const;
        emscripten::val val() const;
        std::string type() const;
 
    private:
        friend class FileReader;
        emscripten::val m_blob = emscripten::val::undefined();
    };
 
    class Q_CORE_EXPORT File {
    public:
        File() = default;
        explicit File(const emscripten::val &file);
        ~File();
 
        File(const File &other);
        File(File &&other);
        File &operator=(const File &other);
        File &operator=(File &&other);
 
        Blob slice(uint64_t begin, uint64_t end) const;
        std::string name() const;
        uint64_t size() const;
        std::string type() const;
        void stream(uint32_t offset, uint32_t length, char *buffer,
                    std::function<void()> completed) const;
        void stream(char *buffer, std::function<void()> completed) const;
        emscripten::val val() const;
        void fileUrlRegistration() const;
        const QString &fileUrlPath() const { return m_urlPath; }
        emscripten::val file() const { return m_file; }
 
    private:
        emscripten::val m_file = emscripten::val::undefined();
        QString m_urlPath;
    };
 
    class Q_CORE_EXPORT FileUrlRegistration
    {
    public:
        explicit FileUrlRegistration(File file);
        ~FileUrlRegistration();
 
        FileUrlRegistration(const FileUrlRegistration &other) = delete;
        FileUrlRegistration(FileUrlRegistration &&other);
        FileUrlRegistration &operator=(const FileUrlRegistration &other) = delete;
        FileUrlRegistration &operator=(FileUrlRegistration &&other);
 
        const QString &path() const { return m_path; }
 
    private:
        QString m_path;
    };
 
    using FileUrlRegistrations = std::vector<std::unique_ptr<FileUrlRegistration>>;
 
    class Q_CORE_EXPORT FileList {
    public:
        FileList() = default;
        explicit FileList(const emscripten::val &fileList);
 
        int length() const;
        File item(int index) const;
        File operator[](int index) const;
        emscripten::val val() const;
 
    private:
        emscripten::val m_fileList = emscripten::val::undefined();
    };
 
    class Q_CORE_EXPORT FileReader {
    public:
        ArrayBuffer result() const;
        void readAsArrayBuffer(const Blob &blob) const;
 
        void onLoad(const std::function<void(emscripten::val)> &onLoad);
        void onError(const std::function<void(emscripten::val)> &onError);
        void onAbort(const std::function<void(emscripten::val)> &onAbort);
        emscripten::val val() const;
 
    private:
        emscripten::val m_fileReader = emscripten::val::global("FileReader").new_();
        std::unique_ptr<EventCallback> m_onLoad;
        std::unique_ptr<EventCallback> m_onError;
        std::unique_ptr<EventCallback> m_onAbort;
    };
 
    class Q_CORE_EXPORT Uint8Array {
    public:
        explicit Uint8Array(const emscripten::val &uint8Array);
        explicit Uint8Array(const ArrayBuffer &buffer);
        explicit Uint8Array(uint32_t size);
        Uint8Array(const ArrayBuffer &buffer, uint32_t offset, uint32_t length);
        Uint8Array(const char *buffer, uint32_t size);
 
        ArrayBuffer buffer() const;
        uint32_t length() const;
        void set(const Uint8Array &source);
        Uint8Array subarray(uint32_t begin, uint32_t end);
 
        void copyTo(char *destination) const;
        QByteArray copyToQByteArray() const;
 
        static void copy(char *destination, const Uint8Array &source);
        static Uint8Array copyFrom(const char *buffer, uint32_t size);
        static Uint8Array copyFrom(const QByteArray &buffer);
        emscripten::val val() const;
 
    private:
        static emscripten::val constructor_();
        emscripten::val m_uint8Array = emscripten::val::undefined();
    };
 
    class Q_CORE_EXPORT FileSystemWritableFileStream {
    public:
        FileSystemWritableFileStream() = default;
        explicit FileSystemWritableFileStream(const emscripten::val &writableStream);
        emscripten::val val() const;
 
    private:
        emscripten::val m_writableStream = emscripten::val::undefined();
    };
 
    class Q_CORE_EXPORT FileSystemFileHandle {
    public:
        FileSystemFileHandle() = default;
        explicit FileSystemFileHandle(const emscripten::val &fileHandle);
 
        std::string name() const;
        std::string kind() const;
 
        emscripten::val val() const;
 
    private:
        emscripten::val m_fileHandle = emscripten::val::undefined();
    };
 
    // EventCallback here for source compatibility; prefer using QWasmEventHandler directly
    class Q_CORE_EXPORT EventCallback : public QWasmEventHandler
    {
    public:
        EventCallback() = default;
        EventCallback(EventCallback const&) = delete;
        EventCallback& operator=(EventCallback const&) = delete;
        EventCallback(emscripten::val element, const std::string &name,
                      const std::function<void(emscripten::val)> &fn);
    };
 
    struct PromiseCallbacks
    {
        std::function<void(emscripten::val)> thenFunc;
        std::function<void(emscripten::val)> catchFunc;
        std::function<void()> finallyFunc;
    };
 
    // Note: it is ok for the Promise object to go out of scope,
    // the resources will be cleaned up in the finally handler.
    class Q_CORE_EXPORT Promise {
    public:
        template<typename... Args>
        Promise(emscripten::val target, QString methodName, Args... args) {
            m_state = std::make_shared<State>();
            m_state->m_promise = target.call<emscripten::val>(
                methodName.toStdString().c_str(), std::forward<Args>(args)...);
            if (m_state->m_promise.isUndefined() || m_state->m_promise["constructor"]["name"].as<std::string>() != "Promise") {
                 qFatal("This function did not return a promise");
            }
            addFinallyFunction([](){});
        }
 
        Promise(emscripten::val promise) {
            m_state = std::make_shared<State>();
            m_state->m_promise = promise;
            if (m_state->m_promise.isUndefined() || m_state->m_promise["constructor"]["name"].as<std::string>() != "Promise") {
                 qFatal("This function did not return a promise");
            }
            addFinallyFunction([](){});
        }
 
        Promise(const std::vector<Promise> &promises) {
            std::vector<emscripten::val> all;
            all.reserve(promises.size());
            for (const auto &p : promises)
                all.push_back(p.getPromise());
 
            auto arr = emscripten::val::array(all);
            m_state = std::make_shared<State>();
            m_state->m_promise = emscripten::val::global("Promise").call<emscripten::val>("all", arr);
            addFinallyFunction([](){});
        }
 
        Promise& addThenFunction(std::function<void(emscripten::val)> thenFunc);
        Promise& addCatchFunction(std::function<void(emscripten::val)> catchFunc);
        Promise& addFinallyFunction(std::function<void()> finallyFunc);
 
        void suspendExclusive();
 
        emscripten::val getPromise() const;
 
    public:
        class State {
        private:
            friend class Promise;
 
            State(const State&) = delete;
            State(State&&) = delete;
            State& operator=(const State&) = delete;
            State& operator=(State&&) = delete;
 
        public:
            State() { ++s_numInstances; }
            ~State() { --s_numInstances; }
            static size_t numInstances() { return s_numInstances; }
 
        private:
            emscripten::val m_promise = emscripten::val::undefined();
            QList<uint32_t> m_handlers;
            static size_t s_numInstances;
        };
 
    private:
        std::shared_ptr<State> m_state;
 
    public:
        // Deprecated: To be backwards compatible
        static uint32_t Q_CORE_EXPORT adoptPromise(emscripten::val promise, PromiseCallbacks callbacks, QList<uint32_t> *handlers = nullptr);
 
        template<typename... Args>
        static uint32_t make(emscripten::val target,
                      QString methodName,
                      PromiseCallbacks callbacks,
                      Args... args)
        {
            emscripten::val promiseObject = target.call<emscripten::val>(
                methodName.toStdString().c_str(), std::forward<Args>(args)...);
            if (promiseObject.isUndefined() || promiseObject["constructor"]["name"].as<std::string>() != "Promise") {
                 qFatal("This function did not return a promise");
            }
 
            return adoptPromise(std::move(promiseObject), std::move(callbacks));
        }
 
        template<typename... Args>
        static void make(
            QList<uint32_t> &handlers,
            emscripten::val target,
                      QString methodName,
                      PromiseCallbacks callbacks,
                      Args... args)
        {
            emscripten::val promiseObject = target.call<emscripten::val>(
                methodName.toStdString().c_str(), std::forward<Args>(args)...);
            if (promiseObject.isUndefined() || promiseObject["constructor"]["name"].as<std::string>() != "Promise") {
                 qFatal("This function did not return a promise");
            }
 
            adoptPromise(std::move(promiseObject), std::move(callbacks), &handlers);
        }
 
        static void Q_CORE_EXPORT suspendExclusive(QList<uint32_t> handlerIndices);
        static void Q_CORE_EXPORT all(std::vector<emscripten::val> promises, PromiseCallbacks callbacks);
    };
 
    template<class F>
    decltype(auto) bindForever(F wrappedCallback)
    {
        return wrappedCallback;
    }
 
    class Q_CORE_EXPORT BlobIODevice: public QIODevice
    {
    public:
        BlobIODevice(Blob blob);
        bool open(QIODeviceBase::OpenMode mode) override;
        bool isSequential() const override;
        qint64 size() const override;
        bool seek(qint64 pos) override;
 
    protected:
        qint64 readData(char *data, qint64 maxSize) override;
        qint64 writeData(const char *, qint64) override;
 
    private:
        Blob m_blob;
    };
 
    class Uint8ArrayIODevice: public QIODevice
    {
    public:
        Uint8ArrayIODevice(Uint8Array array);
        bool open(QIODevice::OpenMode mode) override;
        bool isSequential() const override;
        qint64 size() const override;
        bool seek(qint64 pos) override;
 
    protected:
        qint64 readData(char *data, qint64 maxSize) override;
        qint64 writeData(const char *data, qint64 size) override;
 
    private:
        Uint8Array m_array;
    };
 
    class Q_CORE_EXPORT FileSystemWritableFileStreamIODevice: public QIODevice
    {
    public:
        FileSystemWritableFileStreamIODevice(FileSystemWritableFileStream stream);
        bool open(QIODevice::OpenMode mode) override;
        void close() override;
        bool isSequential() const override;
        qint64 size() const override;
        bool seek(qint64 pos) override;
 
    protected:
        qint64 readData(char *data, qint64 maxSize) override;
        qint64 writeData(const char *data, qint64 size) override;
 
    private:
        FileSystemWritableFileStream m_stream;
        qint64 m_size = 0;
    };
 
    class Q_CORE_EXPORT FileSystemFileIODevice: public QIODevice
    {
    public:
        FileSystemFileIODevice(FileSystemFileHandle fileHandle);
        bool open(QIODevice::OpenMode mode) override;
        void close() override;
        bool isSequential() const override;
        qint64 size() const override;
        bool seek(qint64 pos) override;
 
    protected:
        qint64 readData(char *data, qint64 maxSize) override;
        qint64 writeData(const char *data, qint64 size) override;
 
    private:
        FileSystemFileHandle m_fileHandle;
        std::unique_ptr<BlobIODevice> m_blobDevice;
        std::unique_ptr<FileSystemWritableFileStreamIODevice> m_writableDevice;
        qint64 m_size = 0;
    };
 
    inline emscripten::val window()
    {
        static emscripten::val savedWindow = emscripten::val::global("window");
        return savedWindow;
    }
 
    bool Q_CORE_EXPORT haveAsyncify();
    bool Q_CORE_EXPORT haveJspi();
    bool canBlockCallingThread();
}
 
QT_END_NAMESPACE
 
#endif