92 lines
3.8 KiB
C++
92 lines
3.8 KiB
C++
/**
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* Copyright (C) 2015 Topology LP
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* All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to
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* deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#ifndef CPPCODEC_BASE32_CROCKFORD
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#define CPPCODEC_BASE32_CROCKFORD
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#include "detail/codec.hpp"
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#include "detail/base32.hpp"
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namespace cppcodec {
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namespace detail {
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static constexpr const char base32_crockford_alphabet[] = {
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', // at index 10
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // 18 - no I
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'J', 'K', // 20 - no L
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'M', 'N', // 22 - no O
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'P', 'Q', 'R', 'S', 'T', // 27 - no U
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'V', 'W', 'X', 'Y', 'Z' // 32
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};
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class base32_crockford_base
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{
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public:
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static CPPCODEC_ALWAYS_INLINE constexpr size_t alphabet_size() {
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static_assert(sizeof(base32_crockford_alphabet) == 32, "base32 alphabet must have 32 values");
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return sizeof(base32_crockford_alphabet);
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}
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static CPPCODEC_ALWAYS_INLINE constexpr char symbol(alphabet_index_t idx)
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{
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return base32_crockford_alphabet[idx];
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}
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static CPPCODEC_ALWAYS_INLINE constexpr char normalized_symbol(char c)
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{
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// Hex decoding is always case-insensitive (even in RFC 4648), the question
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// is only for encoding whether to use upper-case or lower-case letters.
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return (c == 'O' || c == 'o') ? '0'
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: (c == 'I' || c == 'i' || c == 'L' || c == 'l') ? '1'
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: (c >= 'a' && c <= 'z') ? (c - 'a' + 'A')
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: c;
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}
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static CPPCODEC_ALWAYS_INLINE constexpr bool generates_padding() { return false; }
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static CPPCODEC_ALWAYS_INLINE constexpr bool requires_padding() { return false; }
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static CPPCODEC_ALWAYS_INLINE constexpr bool is_padding_symbol(char) { return false; }
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static CPPCODEC_ALWAYS_INLINE constexpr bool is_eof_symbol(char c) { return c == '\0'; }
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static CPPCODEC_ALWAYS_INLINE constexpr bool should_ignore(char c) {
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return c == '-'; // "Hyphens (-) can be inserted into strings [for readability]."
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}
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};
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// base32_crockford is a concatenative iterative (i.e. streaming) interpretation of Crockford base32.
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// It interprets the statement "zero-extend the number to make its bit-length a multiple of 5"
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// to mean zero-extending it on the right.
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// (The other possible interpretation is base32_crockford_num, a place-based single number encoding system.
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// See http://merrigrove.blogspot.ca/2014/04/what-heck-is-base64-encoding-really.html for more info.)
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class base32_crockford : public base32_crockford_base
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{
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public:
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template <typename Codec> using codec_impl = stream_codec<Codec, base32_crockford>;
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};
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} // namespace detail
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using base32_crockford = detail::codec<detail::base32<detail::base32_crockford>>;
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} // namespace cppcodec
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#endif // CPPCODEC_BASE32_CROCKFORD
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