io_utilities.h

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//   OpenNN: Open Neural Networks Library
//   www.opennn.net
//
//   I / O   U T I L I T I E S
//
//   Artificial Intelligence Techniques SL
//   artelnics@artelnics.com
 
#pragma once
 
#include "pch.h"
 
namespace opennn
{

// Thread-safe positional reader. On POSIX uses pread(); on Windows uses
// ReadFile with OVERLAPPED so the offset is per-call and not shared state.
class FileReader
{
public:
    FileReader() = default;
    ~FileReader();
 
    FileReader(const FileReader&)            = delete;
    FileReader& operator=(const FileReader&) = delete;
    FileReader(FileReader&&)                 = delete;
    FileReader& operator=(FileReader&&)      = delete;

    void open(const filesystem::path& path);

    void close();

    [[nodiscard]] bool is_open() const;

    void read_at(void* buffer, size_t bytes, uint64_t offset) const;

    [[nodiscard]] uint64_t file_size() const;
 
private:
#if defined(_WIN32)
    void* handle_ = nullptr;
#else
    int fd_ = -1;
#endif
};
 

// Streaming writer that lands on a .tmp file and renames atomically when
// finish_with_rename() succeeds. Drops the .tmp on destruction otherwise.
class FileWriter
{
public:
    FileWriter() = default;
    ~FileWriter();
 
    FileWriter(const FileWriter&)            = delete;
    FileWriter& operator=(const FileWriter&) = delete;
    FileWriter(FileWriter&&)                 = delete;
    FileWriter& operator=(FileWriter&&)      = delete;

    void open(const filesystem::path& tmp_path);

    [[nodiscard]] bool is_open() const;

    void write(const void* buffer, size_t bytes);

    void finish_with_rename(const filesystem::path& final_path);

    void abort();
 
private:
    filesystem::path tmp_path_;
    ofstream stream_;
    bool finalized_ = false;
};
 

void atomic_rename(const filesystem::path& from, const filesystem::path& to);
 

// CSV reader. Loads a file (or string) into a single buffer and tokenizes
// each non-empty line into a vector of string_views into that buffer.
// The buffer lives in Result, so the views stay valid as long as Result does.
// Handles UTF-8 BOM, quoted fields (the separator inside quotes is ignored),
// and CRLF line endings.
class CsvReader
{
public:

    struct Config
    {
        char separator = ',';
        function<void(string_view)> line_validator;
    };

    struct Result
    {
        string                      buffer;
        vector<vector<string_view>> rows;
    };

    explicit CsvReader(Config c) : config(std::move(c)) {}

    [[nodiscard]] Result read(const filesystem::path& path) const;

    [[nodiscard]] Result read_string(string_view csv_text) const;
 
private:
 
    Config config;
 
    void parse(Result& out) const;
};
 
}
 
// OpenNN: Open Neural Networks Library.
// Copyright(C) 2005-2026 Artificial Intelligence Techniques, SL.
// Licensed under the GNU Lesser General Public License v2.1 or later.