зеркало из https://github.com/microsoft/STL.git
214 строки
8.8 KiB
C++
214 строки
8.8 KiB
C++
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// xtwo_byte -- convert one- or two-byte code to 16-bit wide
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// Copyright (c) Microsoft Corporation.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#pragma once
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#ifndef _CVT_XTWO_BYTE_
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#define _CVT_XTWO_BYTE_
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#include <yvals_core.h>
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#if _STL_COMPILER_PREPROCESSOR
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#include <cwchar>
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#include <locale>
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#pragma pack(push, _CRT_PACKING)
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#pragma warning(push, _STL_WARNING_LEVEL)
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#pragma warning(disable : _STL_DISABLED_WARNINGS)
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_STL_DISABLE_CLANG_WARNINGS
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#pragma push_macro("new")
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#undef new
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#if !_HAS_IF_CONSTEXPR
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#pragma warning(disable : 4127) // conditional expression is constant
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#endif // !_HAS_IF_CONSTEXPR
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namespace stdext {
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namespace cvt {
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using _Statype = _CSTD mbstate_t;
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// CLASS TEMPLATE _Cvt_two_byte
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template <class _Elem, class _Table, unsigned long _Maxcode = 0xffff>
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class _Cvt_two_byte
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: public _STD
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codecvt<_Elem, char, _Statype> { // facet for converting between _Elem and one- or two-byte sequences
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public:
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using _Mybase = _STD codecvt<_Elem, char, _Statype>;
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using result = typename _Mybase::result;
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using _Byte = char;
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using intern_type = _Elem;
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using extern_type = _Byte;
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using state_type = _Statype;
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explicit _Cvt_two_byte(size_t _Refs = 0) : _Mybase(_Refs) {}
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virtual ~_Cvt_two_byte() noexcept {}
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protected:
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virtual result do_in(_Statype&, const _Byte* _First1, const _Byte* _Last1, const _Byte*& _Mid1,
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_Elem* _First2, _Elem* _Last2, _Elem*& _Mid2) const override {
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// convert bytes [_First1, _Last1) to [_First2, _Last)
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_Mid1 = _First1;
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_Mid2 = _First2;
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for (; _Mid1 != _Last1 && _Mid2 != _Last2; ++_Mid1) { // get a byte and map it
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unsigned char _Bytecode = static_cast<unsigned char>(*_Mid1);
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unsigned short _Widecode;
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if (_Bytecode < _Table::_Nlow) {
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_Widecode = _Bytecode; // map byte to same wide value
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} else if ((_Widecode = _Table::_Btw[_Bytecode - _Table::_Nlow]) == 0) {
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if
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_CONSTEXPR_IF(_Table::_Nbytes < 2) {
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return _Mybase::error; // no single-byte mapping
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}
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else {
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if (_Mid1 + 1 == _Last1) {
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break; // need another input byte
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}
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// form double-byte code and search for a valid mapping
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_Widecode =
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static_cast<unsigned short>(_Bytecode << 8 | static_cast<unsigned char>(*++_Mid1));
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unsigned long _Lo = 0;
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unsigned long _Hi = sizeof(_Table::_Dbvalid) / sizeof(_Table::_Dbvalid[0]);
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while (_Lo < _Hi) { // test midpoint of remaining interval
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unsigned long _Mid = (_Hi + _Lo) / 2;
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if (_Widecode < _Table::_Dbvalid[_Mid]) {
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_Hi = _Mid;
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} else if (_Widecode == _Table::_Dbvalid[_Mid]) { // found the code, map it
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_Widecode = _Table::_Dbtw[_Mid];
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break;
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} else {
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_Lo = _Mid + 1;
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}
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}
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if (_Hi <= _Lo) {
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return _Mybase::error;
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}
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}
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}
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if (_Maxcode < _Widecode) {
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return _Mybase::error; // value too large
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}
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*_Mid2++ = static_cast<_Elem>(_Widecode);
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}
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return _First1 == _Mid1 ? _Mybase::partial : _Mybase::ok;
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}
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virtual result do_out(_Statype&, const _Elem* _First1, const _Elem* _Last1, const _Elem*& _Mid1,
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_Byte* _First2, _Byte* _Last2, _Byte*& _Mid2) const override {
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// convert [_First1, _Last1) to bytes [_First2, _Last)
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_Mid1 = _First1;
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_Mid2 = _First2;
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for (; _Mid1 != _Last1 && _Mid2 != _Last2; ++_Mid1) { // get an element and map it
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unsigned long _Hugecode = static_cast<unsigned long>(*_Mid1);
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unsigned short _Widecode = static_cast<unsigned short>(_Hugecode);
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if (_Maxcode < _Widecode) {
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return _Mybase::error; // value too large
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}
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if (_Widecode >= _Table::_Nlow
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&& (_Widecode >= 0x100
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|| _Table::_Btw[_Widecode - _Table::_Nlow] != _Widecode)) { // search for a valid mapping
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unsigned long _Lo = 0;
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unsigned long _Hi = sizeof(_Table::_Wvalid) / sizeof(_Table::_Wvalid[0]);
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while (_Lo < _Hi) { // test midpoint of remaining interval
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unsigned long _Mid = (_Hi + _Lo) / 2;
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if (_Widecode < _Table::_Wvalid[_Mid]) {
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_Hi = _Mid;
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} else if (_Widecode == _Table::_Wvalid[_Mid]) { // found the code, map it
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_Widecode = _Table::_Wtb[_Mid];
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break;
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} else {
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_Lo = _Mid + 1;
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}
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}
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if (_Hi <= _Lo) {
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return _Mybase::error;
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}
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}
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if (_Widecode >= 0x100) {
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if (_Mid2 + 1 == _Last2) {
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return _Mybase::partial; // need room for another byte
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}
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*_Mid2++ = static_cast<_Byte>(_Widecode >> 8); // put ms byte
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}
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*_Mid2++ = static_cast<_Byte>(_Widecode);
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}
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return _First1 == _Mid1 ? _Mybase::partial : _Mybase::ok;
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}
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virtual result do_unshift(_Statype&, _Byte* _First2, _Byte*, _Byte*& _Mid2) const override {
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// generate bytes to return to default shift state
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_Mid2 = _First2;
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return _Mybase::ok;
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}
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virtual int do_length(_Statype& _State, const _Byte* _First1, const _Byte* _Last1, size_t _Count) const
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noexcept override {
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// return min(_Count, converted length of bytes [_First1, _Last1))
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size_t _Wchars = 0;
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_Statype _Mystate = _State;
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while (_Wchars < _Count && _First1 != _Last1) { // convert another wide character
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const _Byte* _Mid1;
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_Elem* _Mid2;
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_Elem _Ch;
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switch (do_in(_Mystate, _First1, _Last1, _Mid1, &_Ch, &_Ch + 1,
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_Mid2)) { // test result of single wide-char conversion
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case _Mybase::noconv:
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return static_cast<int>(_Wchars + (_Last1 - _First1));
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case _Mybase::ok:
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if (_Mid2 == &_Ch + 1) {
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++_Wchars; // replacement do_in might not convert one
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}
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_First1 = _Mid1;
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break;
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default:
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return static_cast<int>(_Wchars); // error or partial
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}
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}
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return static_cast<int>(_Wchars);
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}
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virtual bool do_always_noconv() const noexcept override { // return true if conversions never change input
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return false;
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}
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virtual int do_max_length() const noexcept override { // return maximum length required for a conversion
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return _Table::_Nbytes; // length of sequence
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}
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virtual int do_encoding() const noexcept override { // return length of code sequence (from codecvt)
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return 0; // 0 => varying length
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}
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};
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} // namespace cvt
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} // namespace stdext
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#pragma pop_macro("new")
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_STL_RESTORE_CLANG_WARNINGS
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#pragma warning(pop)
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#pragma pack(pop)
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#endif // _STL_COMPILER_PREPROCESSOR
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#endif // _CVT_XTWO_BYTE_
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