include/o3tl/char16_t2wchar_t.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  */
   9
  10 #ifndef INCLUDED_O3TL_CHAR16_T2WCHAR_T_HXX
  11 #define INCLUDED_O3TL_CHAR16_T2WCHAR_T_HXX
  12
  13 #include <sal/config.h>
  14
  15 namespace o3tl {
  16
  17 #if defined _WIN32
  18 // Helpers for safe conversion between wchar_t and char16_t in MSVC
  19
  20 static_assert(sizeof(char16_t) == sizeof(wchar_t),
  21     "These helper functions are only applicable to implementations with 16-bit wchar_t");
  22
  23 // While other implementations define wchar_t as 32-bit integral value, and mostly use
  24 // char-based UTF-8 string APIs, in MSVC wchar_t is (non-conformant) 16-bit, and Unicode
  25 // support is implemented by Unicode-aware WinAPI functions taking UTF-16 LE strings,
  26 // and also stdlib functions taking those strings.
  27 //
  28 // In LibreOffice, internal string representation is also UTF-16 with system endianness
  29 // (sal_Unicode that is typedef for char16_t); so it is an important implementation concept
  30 // to treat internal strings as directly usable by WinAPI/stdlib functions and vice versa.
  31 // Also, it's important to use safe conversion between unrelated underlying C++ types
  32 // used for MSVC and LibreOffice string storage without plain reinterpret_cast that brings
  33 // risks of masking errors like casting char buffers to wchar_t/char16_t.
  34 //
  35 // Use these helpers for wchar_t (WSTR, WCHAR, OLESTR etc) to char16_t (sal_Unicode) string
  36 // conversions instead of reinterpret-cast in Windows-specific code.
  37 inline wchar_t * toW(char16_t * p)
  38 {
  39     return reinterpret_cast<wchar_t *>(p);
  40 }
  41 inline wchar_t const * toW(char16_t const * p)
  42 {
  43     return reinterpret_cast<wchar_t const *>(p);
  44 }
  45 inline char16_t * toU(wchar_t * p)
  46 {
  47     return reinterpret_cast<char16_t *>(p);
  48 }
  49 inline char16_t const * toU(wchar_t const * p)
  50 {
  51     return reinterpret_cast<char16_t const *>(p);
  52 }
  53 #endif
  54
  55 }
  56
  57 #endif
  58
  59 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */