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/*
* Copyright © 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
*
* 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.
*/
#pragma once
#include <cstdint>
namespace vte {
namespace base {
/* See https://bjoern.hoehrmann.de/utf-8/decoder/dfa/ for more
* information on this branchless UTF-8 decoder.
*/
class UTF8Decoder {
public:
enum {
ACCEPT = 0,
REJECT = 12,
REJECT_REWIND = 108
};
UTF8Decoder() noexcept = default;
UTF8Decoder(UTF8Decoder const&) noexcept = default;
UTF8Decoder(UTF8Decoder&&) noexcept = default;
~UTF8Decoder() noexcept = default;
UTF8Decoder& operator= (UTF8Decoder const&) = delete;
UTF8Decoder& operator= (UTF8Decoder&&) = delete;
inline constexpr uint32_t codepoint() const noexcept { return m_codepoint; }
inline uint32_t decode(uint32_t byte) noexcept {
uint32_t type = kTable[byte];
m_codepoint = (m_state != ACCEPT) ?
(byte & 0x3fu) | (m_codepoint << 6) :
(0xff >> type) & (byte);
m_state = kTable[256 + m_state + type];
return m_state;
}
inline void reset() noexcept {
m_state = ACCEPT;
m_codepoint = 0xfffdU;
}
inline bool flush() noexcept {
auto state = m_state;
if (m_state != ACCEPT)
reset();
return state != m_state;
}
private:
uint32_t m_state{ACCEPT};
uint32_t m_codepoint{0};
static uint8_t const kTable[];
}; // class UTF8Decoder
} // namespace base
} // namespace vte
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