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 <span>
 
namespace tt {
 
class file_view : public resource_view {
public:
    file_view(std::shared_ptr<file_mapping> const& mappingObject, size_t offset, size_t size);
    file_view(URL const &location, access_mode accessMode=access_mode::open_for_read, size_t offset=0, 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]] size_t offset() const noexcept override { return _offset; }
 
    [[nodiscard]] size_t size() const noexcept override { return _bytes->size(); }
 
    [[nodiscard]] std::byte *data() noexcept { return _bytes->data(); }
 
    [[nodiscard]] std::byte const *data() const noexcept override { return _bytes->data(); }
 
    [[nodiscard]] std::span<std::byte> bytes() noexcept { return *_bytes; }
 
    [[nodiscard]] std::span<std::byte const> bytes() const noexcept override { return *_bytes; }
 
    [[nodiscard]] std::string_view string_view() noexcept {
        return std::string_view{reinterpret_cast<char *>(data()), size()};
    }
 
    [[nodiscard]] std::string_view string_view() const noexcept override {
        return std::string_view{reinterpret_cast<char const *>(data()), size()};
    }
 
    void flush(void* base, 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(std::span<std::byte> *bytes) noexcept;
 
    [[nodiscard]] static std::shared_ptr<file_mapping> findOrCreateFileMappingObject(URL const& path, access_mode accessMode, size_t size);
 
private:
    std::shared_ptr<file_mapping> _file_mapping_object;
 
    std::shared_ptr<std::span<std::byte>> _bytes;
 
    size_t _offset;
 
};
 
}