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57 lines
1.3 KiB
57 lines
1.3 KiB
4 years ago
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#pragma once
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#include <cstdint>
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#include <string>
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#include <utility>
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#include "utils/stdcompat/string_view.hpp"
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namespace devilution {
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constexpr char32_t Utf8DecodeError = 0xD83F;
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/**
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* Decodes the first code point from UTF8-encoded input.
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*
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* Sets `len` to the length of the code point in bytes.
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* Returns `Utf8DecodeError` on error.
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*/
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char32_t DecodeFirstUtf8CodePoint(string_view input, uint8_t *len);
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/**
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* Decodes and removes the first code point from UTF8-encoded input.
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*/
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inline char32_t ConsumeFirstUtf8CodePoint(string_view *input)
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{
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uint8_t len;
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const char32_t result = DecodeFirstUtf8CodePoint(*input, &len);
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input->remove_prefix(len);
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return result;
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}
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/**
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* Returns true if this is a trailing byte in a UTF-8 code point encoding.
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*
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* A trailing byte is any byte that is not the heading byte.
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*/
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inline bool IsTrailUtf8CodeUnit(char x)
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{
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return static_cast<signed char>(x) < -0x40;
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}
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/**
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* Returns the start byte index of the last code point in a UTF-8 string.
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*/
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inline std::size_t FindLastUtf8Symbols(string_view input)
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{
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if (input.empty())
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return 0;
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std::size_t pos = input.size() - 1;
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while (pos > 0 && IsTrailUtf8CodeUnit(input[pos]))
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--pos;
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return pos;
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}
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} // namespace devilution
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