memory_mapped_file.h

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// BSD 3-Clause License
// Copyright (c) 2021-2025, 🍀☀🌕🌥 🌊
// See the LICENSE file in the project root for full license information.
 
#pragma once
 
#include "result.h"
 
#include <cstdint>
#include <filesystem>
#include <span>
 
namespace kcenon::pacs::core {
 
class memory_mapped_file {
public:
    [[nodiscard]] static auto open(const std::filesystem::path& path)
        -> kcenon::pacs::Result<memory_mapped_file>;
 
    [[nodiscard]] auto data() const noexcept -> const std::uint8_t*;
 
    [[nodiscard]] auto size() const noexcept -> std::size_t;
 
    [[nodiscard]] auto as_span() const noexcept -> std::span<const std::uint8_t>;
 
    // Move-only
    memory_mapped_file(const memory_mapped_file&) = delete;
    auto operator=(const memory_mapped_file&) -> memory_mapped_file& = delete;
 
    memory_mapped_file(memory_mapped_file&& other) noexcept;
    auto operator=(memory_mapped_file&& other) noexcept -> memory_mapped_file&;
 
    ~memory_mapped_file();
 
private:
    memory_mapped_file() = default;
 
    void unmap() noexcept;
 
    const std::uint8_t* data_ = nullptr;
    std::size_t size_ = 0;
 
#if defined(_WIN32)
    void* file_handle_ = nullptr;
    void* mapping_handle_ = nullptr;
#else
    int fd_ = -1;
#endif
};
 
}  // namespace kcenon::pacs::core