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// © 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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