file_view.hpp

// Copyright Take Vos 2019, 2021.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
 
#pragma once
 
#include "file_mapping.hpp"
#include "resource_view.hpp"
#include "void_span.hpp"
#include <span>
 
hi_warning_push();
// C26490: Don't use reinterpret_cast (type.1).
// We need to convert bytes to chars to get a string_view from the byte buffer.
hi_warning_ignore_msvc(26490);
 
namespace hi::inline v1 {
 
class file_view : public writable_resource_view {
public:
    file_view(std::shared_ptr<file_mapping> const& mappingObject, std::size_t offset, std::size_t size);
    file_view(
        URL const& location,
        access_mode accessMode = access_mode::open_for_read,
        std::size_t offset = 0,
        std::size_t size = 0);
    ~file_view() = default;
 
    file_view() = delete;
    file_view(file_view const& other) noexcept;
    file_view(file_view&& other) noexcept;
    file_view& operator=(file_view const& other) noexcept;
    file_view& operator=(file_view&& other) noexcept;
 
    [[nodiscard]] access_mode accessMode() const noexcept
    {
        return _file_mapping_object->accessMode();
    }
 
    [[nodiscard]] URL const& location() const noexcept
    {
        return _file_mapping_object->location();
    }
 
    [[nodiscard]] std::size_t offset() const noexcept override
    {
        return _offset;
    }
 
    [[nodiscard]] void_span writable_span() noexcept override
    {
        return *_bytes;
    }
 
    [[nodiscard]] const_void_span span() const noexcept override
    {
        return *_bytes;
    }
 
    void flush(void *base, std::size_t size);
 
    [[nodiscard]] static std::unique_ptr<resource_view> loadView(URL const& location)
    {
        return std::make_unique<file_view>(location);
    }
 
private:
    static void unmap(void_span *bytes) noexcept;
 
    [[nodiscard]] static std::shared_ptr<file_mapping>
    findOrCreateFileMappingObject(URL const& path, access_mode accessMode, std::size_t size);
 
private:
    std::shared_ptr<file_mapping> _file_mapping_object;
 
    std::shared_ptr<void_span> _bytes;
 
    std::size_t _offset;
};
 
} // namespace hi::inline v1
 
hi_warning_pop();