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[libc++] Simplify the char_traits specializations
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Reviewed By: ldionne, #libc

Spies: mgorny, EricWF, mclow.lists, libcxx-commits

Differential Revision: https://reviews.llvm.org/D127159
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@philnik777
philnik777 committed Jun 13, 2022
1 parent f5b970c commit 993a22e
Showing 1 changed file with 88 additions and 184 deletions.
272 changes: 88 additions & 184 deletions libcxx/include/__string/char_traits.h
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Expand Up @@ -164,40 +164,25 @@ char_traits<_CharT>::assign(char_type* __s, size_t __n, char_type __a)
return __r;
}

// constexpr versions of move/copy/assign.

template <class _CharT>
static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
_CharT* __copy_constexpr(_CharT* __dest, const _CharT* __source, size_t __n) _NOEXCEPT
_CharT* __char_traits_move(_CharT* __dest, const _CharT* __source, size_t __n) _NOEXCEPT
{
_LIBCPP_ASSERT(__libcpp_is_constant_evaluated(), "__copy_constexpr() should always be constant evaluated");
_VSTD::copy_n(__source, __n, __dest);
return __dest;
}

template <class _CharT>
static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
_CharT* __move_constexpr(_CharT* __dest, const _CharT* __source, size_t __n) _NOEXCEPT
{
_LIBCPP_ASSERT(__libcpp_is_constant_evaluated(), "__move_constexpr() should always be constant evaluated");
if (__n == 0)
#ifdef _LIBCPP_COMPILER_GCC
if (__libcpp_is_constant_evaluated()) {
if (__n == 0)
return __dest;
_CharT* __allocation = new _CharT[__n];
std::copy_n(__source, __n, __allocation);
std::copy_n(static_cast<const _CharT*>(__allocation), __n, __dest);
delete[] __allocation;
return __dest;
_CharT* __allocation = new _CharT[__n];
_VSTD::__copy_constexpr(__allocation, __source, __n);
_VSTD::__copy_constexpr(__dest, static_cast<const _CharT*>(__allocation), __n);
delete[] __allocation;
}
#endif
::__builtin_memmove(__dest, __source, __n * sizeof(_CharT));
return __dest;
}

template <class _CharT>
static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
_CharT* __assign_constexpr(_CharT* __s, size_t __n, _CharT __a) _NOEXCEPT
{
_LIBCPP_ASSERT(__libcpp_is_constant_evaluated(), "__assign_constexpr() should always be constant evaluated");
_VSTD::fill_n(__s, __n, __a);
return __s;
}

// char_traits<char>

template <>
Expand Down Expand Up @@ -235,30 +220,25 @@ struct _LIBCPP_TEMPLATE_VIS char_traits<char>

static _LIBCPP_CONSTEXPR_AFTER_CXX14
const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;

static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
{
return __libcpp_is_constant_evaluated()
? _VSTD::__move_constexpr(__s1, __s2, __n)
: __n == 0 ? __s1 : (char_type*)_VSTD::memmove(__s1, __s2, __n);
}
char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT {
return std::__char_traits_move(__s1, __s2, __n);
}

static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
{
if (!__libcpp_is_constant_evaluated()) {
_LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
}
return __libcpp_is_constant_evaluated()
? _VSTD::__copy_constexpr(__s1, __s2, __n)
: __n == 0 ? __s1 : (char_type*)_VSTD::memcpy(__s1, __s2, __n);
}
char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT {
if (!__libcpp_is_constant_evaluated())
_LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
std::copy_n(__s2, __n, __s1);
return __s1;
}

static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
{
return __libcpp_is_constant_evaluated()
? _VSTD::__assign_constexpr(__s, __n, __a)
: __n == 0 ? __s : (char_type*)_VSTD::memset(__s, to_int_type(__a), __n);
}
char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT {
std::fill_n(__s, __n, __a);
return __s;
}

static inline _LIBCPP_CONSTEXPR int_type not_eof(int_type __c) _NOEXCEPT
{return eq_int_type(__c, eof()) ? ~eof() : __c;}
Expand Down Expand Up @@ -341,30 +321,26 @@ struct _LIBCPP_TEMPLATE_VIS char_traits<wchar_t>
size_t length(const char_type* __s) _NOEXCEPT;
static _LIBCPP_CONSTEXPR_AFTER_CXX14
const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;

static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
{
return __libcpp_is_constant_evaluated()
? _VSTD::__move_constexpr(__s1, __s2, __n)
: __n == 0 ? __s1 : _VSTD::wmemmove(__s1, __s2, __n);
}
char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT {
return std::__char_traits_move(__s1, __s2, __n);
}

static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
{
if (!__libcpp_is_constant_evaluated()) {
_LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
}
return __libcpp_is_constant_evaluated()
? _VSTD::__copy_constexpr(__s1, __s2, __n)
: __n == 0 ? __s1 : _VSTD::wmemcpy(__s1, __s2, __n);
}
char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT {
if (!__libcpp_is_constant_evaluated())
_LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
std::copy_n(__s2, __n, __s1);
return __s1;
}

static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
{
return __libcpp_is_constant_evaluated()
? _VSTD::__assign_constexpr(__s, __n, __a)
: __n == 0 ? __s : _VSTD::wmemset(__s, __a, __n);
}
char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT {
std::fill_n(__s, __n, __a);
return __s;
}

static inline _LIBCPP_CONSTEXPR int_type not_eof(int_type __c) _NOEXCEPT
{return eq_int_type(__c, eof()) ? ~eof() : __c;}
static inline _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT
Expand Down Expand Up @@ -465,31 +441,23 @@ struct _LIBCPP_TEMPLATE_VIS char_traits<char8_t>
const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;

static _LIBCPP_CONSTEXPR_AFTER_CXX17
char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
{
return __libcpp_is_constant_evaluated()
? _VSTD::__move_constexpr(__s1, __s2, __n)
: __n == 0 ? __s1 : (char_type*)_VSTD::memmove(__s1, __s2, __n);
}
char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT {
return std::__char_traits_move(__s1, __s2, __n);
}

static _LIBCPP_CONSTEXPR_AFTER_CXX17
char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
{
if (!__libcpp_is_constant_evaluated()) {
_LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
}
return __libcpp_is_constant_evaluated()
? _VSTD::__copy_constexpr(__s1, __s2, __n)
: __n == 0 ? __s1 : (char_type*)_VSTD::memcpy(__s1, __s2, __n);
}
char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT {
if (!__libcpp_is_constant_evaluated())
_LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
std::copy_n(__s2, __n, __s1);
return __s1;
}

static _LIBCPP_CONSTEXPR_AFTER_CXX17
char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
{
return __libcpp_is_constant_evaluated()
? _VSTD::__assign_constexpr(__s, __n, __a)
: __n == 0 ? __s : (char_type*)_VSTD::memset(__s, to_int_type(__a), __n);
}
char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT {
std::fill_n(__s, __n, __a);
return __s;
}

static inline constexpr int_type not_eof(int_type __c) noexcept
{return eq_int_type(__c, eof()) ? ~eof() : __c;}
Expand Down Expand Up @@ -572,12 +540,25 @@ struct _LIBCPP_TEMPLATE_VIS char_traits<char16_t>
size_t length(const char_type* __s) _NOEXCEPT;
_LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;

_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
static char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
static char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT {
return std::__char_traits_move(__s1, __s2, __n);
}

_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
static char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
static char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT {
if (!__libcpp_is_constant_evaluated())
_LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
std::copy_n(__s2, __n, __s1);
return __s1;
}

_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
static char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT;
static char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT {
std::fill_n(__s, __n, __a);
return __s;
}

static inline _LIBCPP_CONSTEXPR int_type not_eof(int_type __c) _NOEXCEPT
{return eq_int_type(__c, eof()) ? ~eof() : __c;}
Expand Down Expand Up @@ -628,50 +609,6 @@ char_traits<char16_t>::find(const char_type* __s, size_t __n, const char_type& _
return nullptr;
}

inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char16_t*
char_traits<char16_t>::move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
{
if (__n == 0) return __s1;
char_type* __r = __s1;
if (__s1 < __s2)
{
for (; __n; --__n, ++__s1, ++__s2)
assign(*__s1, *__s2);
}
else if (__s2 < __s1)
{
__s1 += __n;
__s2 += __n;
for (; __n; --__n)
assign(*--__s1, *--__s2);
}
return __r;
}

inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char16_t*
char_traits<char16_t>::copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
{
if (!__libcpp_is_constant_evaluated()) {
_LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
}
char_type* __r = __s1;
for (; __n; --__n, ++__s1, ++__s2)
assign(*__s1, *__s2);
return __r;
}

inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char16_t*
char_traits<char16_t>::assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
{
char_type* __r = __s;
for (; __n; --__n, ++__s)
assign(*__s, __a);
return __r;
}

template <>
struct _LIBCPP_TEMPLATE_VIS char_traits<char32_t>
{
Expand All @@ -694,12 +631,23 @@ struct _LIBCPP_TEMPLATE_VIS char_traits<char32_t>
size_t length(const char_type* __s) _NOEXCEPT;
_LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;

_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
static char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
static char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT {
return std::__char_traits_move(__s1, __s2, __n);
}

_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
static char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
static char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT {
std::copy_n(__s2, __n, __s1);
return __s1;
}

_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
static char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT;
static char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT {
std::fill_n(__s, __n, __a);
return __s;
}

static inline _LIBCPP_CONSTEXPR int_type not_eof(int_type __c) _NOEXCEPT
{return eq_int_type(__c, eof()) ? ~eof() : __c;}
Expand Down Expand Up @@ -750,50 +698,6 @@ char_traits<char32_t>::find(const char_type* __s, size_t __n, const char_type& _
return nullptr;
}

inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char32_t*
char_traits<char32_t>::move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
{
if (__n == 0) return __s1;
char_type* __r = __s1;
if (__s1 < __s2)
{
for (; __n; --__n, ++__s1, ++__s2)
assign(*__s1, *__s2);
}
else if (__s2 < __s1)
{
__s1 += __n;
__s2 += __n;
for (; __n; --__n)
assign(*--__s1, *--__s2);
}
return __r;
}

inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char32_t*
char_traits<char32_t>::copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
{
if (!__libcpp_is_constant_evaluated()) {
_LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
}
char_type* __r = __s1;
for (; __n; --__n, ++__s1, ++__s2)
assign(*__s1, *__s2);
return __r;
}

inline _LIBCPP_CONSTEXPR_AFTER_CXX17
char32_t*
char_traits<char32_t>::assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
{
char_type* __r = __s;
for (; __n; --__n, ++__s)
assign(*__s, __a);
return __r;
}

#endif // _LIBCPP_HAS_NO_UNICODE_CHARS

// helper fns for basic_string and string_view
Expand Down

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