Program Listing for File random_string.cpp

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/*
  Copyright 2018-2024, Barcelona Supercomputing Center (BSC), Spain
  Copyright 2015-2024, Johannes Gutenberg Universitaet Mainz, Germany

  This software was partially supported by the
  EC H2020 funded project NEXTGenIO (Project ID: 671951, www.nextgenio.eu).

  This software was partially supported by the
  ADA-FS project under the SPPEXA project funded by the DFG.

  This file is part of GekkoFS.

  GekkoFS is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  GekkoFS is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with GekkoFS.  If not, see <https://www.gnu.org/licenses/>.

  SPDX-License-Identifier: GPL-3.0-or-later
*/

#include <string>
#include <random>
#include <array>
#include <algorithm>

namespace helpers {

std::string
random_string(std::size_t length) {
    constexpr std::array<char, 63> charset{"0123456789"
                                           "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                                           "abcdefghijklmnopqrstuvwxyz"};

    thread_local static std::mt19937 rng{std::random_device{}()};
    thread_local static std::uniform_int_distribution<std::string::size_type>
            pick(0, std::size(charset) - 2);

    std::string s(length, '\0');

    std::generate_n(std::begin(s), length,
                    [&]() { return charset[pick(rng)]; });

    return s;
}

} // namespace helpers