samty/codec/base32_rfc4648.hpp

/**
 *  Copyright (C) 2015 Topology LP
 *  All rights reserved.
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a copy
 *  of this software and associated documentation files (the "Software"), to
 *  deal in the Software without restriction, including without limitation the
 *  rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 *  sell copies of the Software, and to permit persons to whom the Software is
 *  furnished to do so, subject to the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included in
 *  all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 *  THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 *  IN THE SOFTWARE.
 */

// Edited by acetone, 2024

#ifndef CPPCODEC_BASE32_RFC4648
#define CPPCODEC_BASE32_RFC4648

#include "detail/codec.hpp"
#include "detail/base32.hpp"

namespace cppcodec_samty {

namespace detail {

// RFC 4648 uses a simple alphabet: A-Z starting at index 0, then 2-7 starting at index 26.
static constexpr const char base32_rfc4648_alphabet[] = {
    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
    'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', // at index 26
    '2', '3', '4', '5', '6', '7'
};

class base32_rfc4648
{
public:
    template <typename Codec> using codec_impl = stream_codec<Codec, base32_rfc4648>;

    static CPPCODEC_ALWAYS_INLINE constexpr size_t alphabet_size() {
        static_assert(sizeof(base32_rfc4648_alphabet) == 32, "base32 alphabet must have 32 values");
        return sizeof(base32_rfc4648_alphabet);
    }
    static CPPCODEC_ALWAYS_INLINE constexpr char symbol(alphabet_index_t idx)
    {
        return base32_rfc4648_alphabet[idx];
    }
    static CPPCODEC_ALWAYS_INLINE constexpr char normalized_symbol(char c)
    {
        // Lower-case letters are accepted, though not generally expected.
        return (c >= 'a' && c <= 'z') ? (c - 'a' + 'A') : c;
    }

    static CPPCODEC_ALWAYS_INLINE constexpr bool generates_padding() { return false; }
    static CPPCODEC_ALWAYS_INLINE constexpr bool requires_padding() { return false; }
    static CPPCODEC_ALWAYS_INLINE constexpr char padding_symbol() { return '='; }
    static CPPCODEC_ALWAYS_INLINE constexpr bool is_padding_symbol(char c) { return c == '='; }
    static CPPCODEC_ALWAYS_INLINE constexpr bool is_eof_symbol(char c) { return c == '\0'; }

    // RFC4648 does not specify any whitespace being allowed in base32 encodings.
    static CPPCODEC_ALWAYS_INLINE constexpr bool should_ignore(char) { return false; }
};

} // namespace detail

using base32_rfc4648 = detail::codec<detail::base32<detail::base32_rfc4648>>;

} // namespace cppcodec

#endif // CPPCODEC_BASE32_RFC4648