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Editing: char16ptr.h
// © 2017 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html // char16ptr.h // created: 2017feb28 Markus W. Scherer #ifndef __CHAR16PTR_H__ #define __CHAR16PTR_H__ #include "unicode/utypes.h" #if U_SHOW_CPLUSPLUS_API || U_SHOW_CPLUSPLUS_HEADER_API #include <cstddef> #include <string_view> #include <type_traits> #endif /** * \file * \brief C++ API: char16_t pointer wrappers with * implicit conversion from bit-compatible raw pointer types. * Also conversion functions from char16_t * to UChar * and OldUChar *. */ /** * \def U_ALIASING_BARRIER * Barrier for pointer anti-aliasing optimizations even across function boundaries. * @internal */ #ifdef U_ALIASING_BARRIER // Use the predefined value. #elif (defined(__clang__) || defined(__GNUC__)) && U_PLATFORM != U_PF_BROWSER_NATIVE_CLIENT # define U_ALIASING_BARRIER(ptr) asm volatile("" : : "rm"(ptr) : "memory") #elif defined(U_IN_DOXYGEN) # define U_ALIASING_BARRIER(ptr) #endif // ICU DLL-exported #if U_SHOW_CPLUSPLUS_API U_NAMESPACE_BEGIN /** * char16_t * wrapper with implicit conversion from distinct but bit-compatible pointer types. * @stable ICU 59 */ class U_COMMON_API Char16Ptr final { public: /** * Copies the pointer. * @param p pointer * @stable ICU 59 */ inline Char16Ptr(char16_t *p); #if !U_CHAR16_IS_TYPEDEF /** * Converts the pointer to char16_t *. * @param p pointer to be converted * @stable ICU 59 */ inline Char16Ptr(uint16_t *p); #endif #if U_SIZEOF_WCHAR_T==2 || defined(U_IN_DOXYGEN) /** * Converts the pointer to char16_t *. * (Only defined if U_SIZEOF_WCHAR_T==2.) * @param p pointer to be converted * @stable ICU 59 */ inline Char16Ptr(wchar_t *p); #endif /** * nullptr constructor. * @param p nullptr * @stable ICU 59 */ inline Char16Ptr(std::nullptr_t p); /** * Destructor. * @stable ICU 59 */ inline ~Char16Ptr(); /** * Pointer access. * @return the wrapped pointer * @stable ICU 59 */ inline char16_t *get() const; /** * char16_t pointer access via type conversion (e.g., static_cast). * @return the wrapped pointer * @stable ICU 59 */ inline operator char16_t *() const { return get(); } private: Char16Ptr() = delete; #ifdef U_ALIASING_BARRIER template<typename T> static char16_t *cast(T *t) { U_ALIASING_BARRIER(t); return reinterpret_cast<char16_t *>(t); } char16_t *p_; #else union { char16_t *cp; uint16_t *up; wchar_t *wp; } u_; #endif }; /// \cond #ifdef U_ALIASING_BARRIER Char16Ptr::Char16Ptr(char16_t *p) : p_(p) {} #if !U_CHAR16_IS_TYPEDEF Char16Ptr::Char16Ptr(uint16_t *p) : p_(cast(p)) {} #endif #if U_SIZEOF_WCHAR_T==2 Char16Ptr::Char16Ptr(wchar_t *p) : p_(cast(p)) {} #endif Char16Ptr::Char16Ptr(std::nullptr_t p) : p_(p) {} Char16Ptr::~Char16Ptr() { U_ALIASING_BARRIER(p_); } char16_t *Char16Ptr::get() const { return p_; } #else Char16Ptr::Char16Ptr(char16_t *p) { u_.cp = p; } #if !U_CHAR16_IS_TYPEDEF Char16Ptr::Char16Ptr(uint16_t *p) { u_.up = p; } #endif #if U_SIZEOF_WCHAR_T==2 Char16Ptr::Char16Ptr(wchar_t *p) { u_.wp = p; } #endif Char16Ptr::Char16Ptr(std::nullptr_t p) { u_.cp = p; } Char16Ptr::~Char16Ptr() {} char16_t *Char16Ptr::get() const { return u_.cp; } #endif /// \endcond /** * const char16_t * wrapper with implicit conversion from distinct but bit-compatible pointer types. * @stable ICU 59 */ class U_COMMON_API ConstChar16Ptr final { public: /** * Copies the pointer. * @param p pointer * @stable ICU 59 */ inline ConstChar16Ptr(const char16_t *p); #if !U_CHAR16_IS_TYPEDEF /** * Converts the pointer to char16_t *. * @param p pointer to be converted * @stable ICU 59 */ inline ConstChar16Ptr(const uint16_t *p); #endif #if U_SIZEOF_WCHAR_T==2 || defined(U_IN_DOXYGEN) /** * Converts the pointer to char16_t *. * (Only defined if U_SIZEOF_WCHAR_T==2.) * @param p pointer to be converted * @stable ICU 59 */ inline ConstChar16Ptr(const wchar_t *p); #endif /** * nullptr constructor. * @param p nullptr * @stable ICU 59 */ inline ConstChar16Ptr(const std::nullptr_t p); /** * Destructor. * @stable ICU 59 */ inline ~ConstChar16Ptr(); /** * Pointer access. * @return the wrapped pointer * @stable ICU 59 */ inline const char16_t *get() const; /** * char16_t pointer access via type conversion (e.g., static_cast). * @return the wrapped pointer * @stable ICU 59 */ inline operator const char16_t *() const { return get(); } private: ConstChar16Ptr() = delete; #ifdef U_ALIASING_BARRIER template<typename T> static const char16_t *cast(const T *t) { U_ALIASING_BARRIER(t); return reinterpret_cast<const char16_t *>(t); } const char16_t *p_; #else union { const char16_t *cp; const uint16_t *up; const wchar_t *wp; } u_; #endif }; /// \cond #ifdef U_ALIASING_BARRIER ConstChar16Ptr::ConstChar16Ptr(const char16_t *p) : p_(p) {} #if !U_CHAR16_IS_TYPEDEF ConstChar16Ptr::ConstChar16Ptr(const uint16_t *p) : p_(cast(p)) {} #endif #if U_SIZEOF_WCHAR_T==2 ConstChar16Ptr::ConstChar16Ptr(const wchar_t *p) : p_(cast(p)) {} #endif ConstChar16Ptr::ConstChar16Ptr(const std::nullptr_t p) : p_(p) {} ConstChar16Ptr::~ConstChar16Ptr() { U_ALIASING_BARRIER(p_); } const char16_t *ConstChar16Ptr::get() const { return p_; } #else ConstChar16Ptr::ConstChar16Ptr(const char16_t *p) { u_.cp = p; } #if !U_CHAR16_IS_TYPEDEF ConstChar16Ptr::ConstChar16Ptr(const uint16_t *p) { u_.up = p; } #endif #if U_SIZEOF_WCHAR_T==2 ConstChar16Ptr::ConstChar16Ptr(const wchar_t *p) { u_.wp = p; } #endif ConstChar16Ptr::ConstChar16Ptr(const std::nullptr_t p) { u_.cp = p; } ConstChar16Ptr::~ConstChar16Ptr() {} const char16_t *ConstChar16Ptr::get() const { return u_.cp; } #endif /// \endcond U_NAMESPACE_END #endif // U_SHOW_CPLUSPLUS_API // Usable in header-only definitions #if U_SHOW_CPLUSPLUS_API || U_SHOW_CPLUSPLUS_HEADER_API namespace U_ICU_NAMESPACE_OR_INTERNAL { #ifndef U_FORCE_HIDE_INTERNAL_API /** @internal */ template<typename T, typename = std::enable_if_t<std::is_same_v<T, UChar>>> inline const char16_t *uprv_char16PtrFromUChar(const T *p) { if constexpr (std::is_same_v<UChar, char16_t>) { return p; } else { #if U_SHOW_CPLUSPLUS_API return ConstChar16Ptr(p).get(); #else #ifdef U_ALIASING_BARRIER U_ALIASING_BARRIER(p); #endif return reinterpret_cast<const char16_t *>(p); #endif } } #if !U_CHAR16_IS_TYPEDEF && (!defined(_LIBCPP_VERSION) || _LIBCPP_VERSION < 180000) /** @internal */ inline const char16_t *uprv_char16PtrFromUint16(const uint16_t *p) { #if U_SHOW_CPLUSPLUS_API return ConstChar16Ptr(p).get(); #else #ifdef U_ALIASING_BARRIER U_ALIASING_BARRIER(p); #endif return reinterpret_cast<const char16_t *>(p); #endif } #endif #if U_SIZEOF_WCHAR_T==2 /** @internal */ inline const char16_t *uprv_char16PtrFromWchar(const wchar_t *p) { #if U_SHOW_CPLUSPLUS_API return ConstChar16Ptr(p).get(); #else #ifdef U_ALIASING_BARRIER U_ALIASING_BARRIER(p); #endif return reinterpret_cast<const char16_t *>(p); #endif } #endif #endif /** * Converts from const char16_t * to const UChar *. * Includes an aliasing barrier if available. * @param p pointer * @return p as const UChar * * @stable ICU 59 */ inline const UChar *toUCharPtr(const char16_t *p) { #ifdef U_ALIASING_BARRIER U_ALIASING_BARRIER(p); #endif return reinterpret_cast<const UChar *>(p); } /** * Converts from char16_t * to UChar *. * Includes an aliasing barrier if available. * @param p pointer * @return p as UChar * * @stable ICU 59 */ inline UChar *toUCharPtr(char16_t *p) { #ifdef U_ALIASING_BARRIER U_ALIASING_BARRIER(p); #endif return reinterpret_cast<UChar *>(p); } /** * Converts from const char16_t * to const OldUChar *. * Includes an aliasing barrier if available. * @param p pointer * @return p as const OldUChar * * @stable ICU 59 */ inline const OldUChar *toOldUCharPtr(const char16_t *p) { #ifdef U_ALIASING_BARRIER U_ALIASING_BARRIER(p); #endif return reinterpret_cast<const OldUChar *>(p); } /** * Converts from char16_t * to OldUChar *. * Includes an aliasing barrier if available. * @param p pointer * @return p as OldUChar * * @stable ICU 59 */ inline OldUChar *toOldUCharPtr(char16_t *p) { #ifdef U_ALIASING_BARRIER U_ALIASING_BARRIER(p); #endif return reinterpret_cast<OldUChar *>(p); } } // U_ICU_NAMESPACE_OR_INTERNAL #endif // U_SHOW_CPLUSPLUS_API || U_SHOW_CPLUSPLUS_HEADER_API // ICU DLL-exported #if U_SHOW_CPLUSPLUS_API U_NAMESPACE_BEGIN #ifndef U_FORCE_HIDE_INTERNAL_API /** * Is T convertible to a std::u16string_view or some other 16-bit string view? * @internal */ template<typename T> constexpr bool ConvertibleToU16StringView = std::is_convertible_v<T, std::u16string_view> #if !U_CHAR16_IS_TYPEDEF && (!defined(_LIBCPP_VERSION) || _LIBCPP_VERSION < 180000) || std::is_convertible_v<T, std::basic_string_view<uint16_t>> #endif #if U_SIZEOF_WCHAR_T==2 || std::is_convertible_v<T, std::wstring_view> #endif ; namespace internal { /** * Pass-through overload. * @internal */ inline std::u16string_view toU16StringView(std::u16string_view sv) { return sv; } #if !U_CHAR16_IS_TYPEDEF && (!defined(_LIBCPP_VERSION) || _LIBCPP_VERSION < 180000) /** * Basically undefined behavior but sometimes necessary conversion * from std::basic_string_view<uint16_t> to std::u16string_view. * @internal */ inline std::u16string_view toU16StringView(std::basic_string_view<uint16_t> sv) { return { ConstChar16Ptr(sv.data()), sv.length() }; } #endif #if U_SIZEOF_WCHAR_T==2 /** * Basically undefined behavior but sometimes necessary conversion * from std::wstring_view to std::u16string_view. * @internal */ inline std::u16string_view toU16StringView(std::wstring_view sv) { return { ConstChar16Ptr(sv.data()), sv.length() }; } #endif /** * Pass-through overload. * @internal */ template <typename T, typename = typename std::enable_if_t<!std::is_pointer_v<std::remove_reference_t<T>>>> inline std::u16string_view toU16StringViewNullable(const T& text) { return toU16StringView(text); } /** * In case of nullptr, return an empty view. * @internal */ template <typename T, typename = typename std::enable_if_t<std::is_pointer_v<std::remove_reference_t<T>>>, typename = void> inline std::u16string_view toU16StringViewNullable(const T& text) { if (text == nullptr) return {}; // For backward compatibility. return toU16StringView(text); } } // internal #endif // U_FORCE_HIDE_INTERNAL_API U_NAMESPACE_END #endif // U_SHOW_CPLUSPLUS_API #endif // __CHAR16PTR_H__
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