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Merged
merged 3 commits into from
Mar 16, 2025
Merged

[libc++][NFC] Simplify string a bit #127135

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43a2800
Simplify string a bit
winner245 Feb 13, 2025
1a640a0
Address philnik777's suggestions
winner245 Feb 20, 2025
5d8cd96
Address reviewer comments
winner245 Feb 26, 2025
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98 changes: 53 additions & 45 deletions libcxx/include/string
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Original file line number Diff line number Diff line change
Expand Up @@ -235,9 +235,9 @@ public:
template <class T>
basic_string& insert(size_type pos1, const T& t); // constexpr since C++20
basic_string& insert(size_type pos1, const basic_string& str,
size_type pos2, size_type n); // constexpr since C++20
size_type pos2, size_type n2=npos); // constexpr since C++20
template <class T>
basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n); // C++17, constexpr since C++20
basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n=npos); // C++17, constexpr since C++20
basic_string& insert(size_type pos, const value_type* s, size_type n=npos); // C++14, constexpr since C++20
basic_string& insert(size_type pos, const value_type* s); // constexpr since C++20
basic_string& insert(size_type pos, size_type n, value_type c); // constexpr since C++20
Expand All @@ -260,7 +260,7 @@ public:
size_type pos2, size_type n2=npos); // C++14, constexpr since C++20
template <class T>
basic_string& replace(size_type pos1, size_type n1, const T& t,
size_type pos2, size_type n); // C++17, constexpr since C++20
size_type pos2, size_type n2=npos); // C++17, constexpr since C++20
basic_string& replace(size_type pos, size_type n1, const value_type* s, size_type n2); // constexpr since C++20
basic_string& replace(size_type pos, size_type n1, const value_type* s); // constexpr since C++20
basic_string& replace(size_type pos, size_type n1, size_type n2, value_type c); // constexpr since C++20
Expand Down Expand Up @@ -2307,7 +2307,7 @@ private:
if (!__str.__is_long()) {
if (__is_long()) {
__annotate_delete();
__alloc_traits::deallocate(__alloc_, __get_long_pointer(), capacity() + 1);
__alloc_traits::deallocate(__alloc_, __get_long_pointer(), __get_long_cap());
__rep_ = __rep();
}
__alloc_ = __str.__alloc_;
Expand All @@ -2322,7 +2322,7 @@ private:
__alloc_ = std::move(__a);
__set_long_pointer(__allocation.ptr);
__set_long_cap(__allocation.count);
__set_long_size(__str.size());
__set_long_size(__str.__get_long_size());
}
}
}
Expand Down Expand Up @@ -2364,8 +2364,14 @@ private:
size_type __old_size = size();
if (__n > __old_size)
__annotate_increase(__n - __old_size);
pointer __p =
__is_long() ? (__set_long_size(__n), __get_long_pointer()) : (__set_short_size(__n), __get_short_pointer());
pointer __p;
if (__is_long()) {
__set_long_size(__n);
__p = __get_long_pointer();
} else {
__set_short_size(__n);
__p = __get_short_pointer();
}
traits_type::move(std::__to_address(__p), __s, __n);
traits_type::assign(__p[__n], value_type());
if (__old_size > __n)
Expand Down Expand Up @@ -2441,8 +2447,8 @@ template <class _CharT,
class _Traits,
class _Allocator = allocator<_CharT>,
class = enable_if_t<__is_allocator<_Allocator>::value> >
explicit basic_string(basic_string_view<_CharT, _Traits>,
const _Allocator& = _Allocator()) -> basic_string<_CharT, _Traits, _Allocator>;
explicit basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
-> basic_string<_CharT, _Traits, _Allocator>;

template <class _CharT,
class _Traits,
Expand Down Expand Up @@ -2705,38 +2711,42 @@ template <class _CharT, class _Traits, class _Allocator>
template <bool __is_short>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::__assign_no_alias(const value_type* __s, size_type __n) {
size_type __cap = __is_short ? static_cast<size_type>(__min_cap) : __get_long_cap();
const auto __cap = __is_short ? static_cast<size_type>(__min_cap) : __get_long_cap();
const auto __size = __is_short ? __get_short_size() : __get_long_size();
if (__n < __cap) {
size_type __old_size = __is_short ? __get_short_size() : __get_long_size();
if (__n > __old_size)
__annotate_increase(__n - __old_size);
pointer __p = __is_short ? __get_short_pointer() : __get_long_pointer();
__is_short ? __set_short_size(__n) : __set_long_size(__n);
if (__n > __size)
__annotate_increase(__n - __size);
pointer __p;
if (__is_short) {
__p = __get_short_pointer();
__set_short_size(__n);
} else {
__p = __get_long_pointer();
__set_long_size(__n);
}
traits_type::copy(std::__to_address(__p), __s, __n);
traits_type::assign(__p[__n], value_type());
if (__old_size > __n)
__annotate_shrink(__old_size);
if (__size > __n)
__annotate_shrink(__size);
} else {
size_type __sz = __is_short ? __get_short_size() : __get_long_size();
__grow_by_and_replace(__cap - 1, __n - __cap + 1, __sz, 0, __sz, __n, __s);
__grow_by_and_replace(__cap - 1, __n - __cap + 1, __size, 0, __size, __n, __s);
}
return *this;
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::__assign_external(const value_type* __s, size_type __n) {
size_type __cap = capacity();
const auto __cap = capacity();
const auto __size = size();
if (__cap >= __n) {
size_type __old_size = size();
if (__n > __old_size)
__annotate_increase(__n - __old_size);
if (__n > __size)
__annotate_increase(__n - __size);
value_type* __p = std::__to_address(__get_pointer());
traits_type::move(__p, __s, __n);
return __null_terminate_at(__p, __n);
} else {
size_type __sz = size();
__grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s);
__grow_by_and_replace(__cap, __n - __cap, __size, 0, __size, __n, __s);
return *this;
}
}
Expand All @@ -2754,8 +2764,7 @@ basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
size_type __cap = capacity();
size_type __old_size = size();
if (__cap < __n) {
size_type __sz = size();
__grow_by_without_replace(__cap, __n - __cap, __sz, 0, __sz);
__grow_by_without_replace(__cap, __n - __cap, __old_size, 0, __old_size);
__annotate_increase(__n);
} else if (__n > __old_size)
__annotate_increase(__n - __old_size);
Expand All @@ -2767,10 +2776,10 @@ basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::operator=(value_type __c) {
pointer __p;
size_type __old_size = size();
if (__old_size == 0)
__annotate_increase(1);
pointer __p;
if (__is_long()) {
__p = __get_long_pointer();
__set_long_size(1);
Expand All @@ -2793,8 +2802,8 @@ basic_string<_CharT, _Traits, _Allocator>::operator=(const basic_string& __str)
if (!__is_long()) {
if (!__str.__is_long()) {
size_type __old_size = __get_short_size();
if (__get_short_size() < __str.__get_short_size())
__annotate_increase(__str.__get_short_size() - __get_short_size());
if (__old_size < __str.__get_short_size())
__annotate_increase(__str.__get_short_size() - __old_size);
__rep_ = __str.__rep_;
if (__old_size > __get_short_size())
__annotate_shrink(__old_size);
Expand Down Expand Up @@ -2961,10 +2970,9 @@ template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s) {
_LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::assign received nullptr");
return __builtin_constant_p(*__s)
? (__fits_in_sso(traits_type::length(__s)) ? __assign_short(__s, traits_type::length(__s))
: __assign_external(__s, traits_type::length(__s)))
: __assign_external(__s);
if (auto __len = traits_type::length(__s); __builtin_constant_p(__len) && __fits_in_sso(__len))
return __assign_short(__s, __len);
return __assign_external(__s);
}
// append

Expand Down Expand Up @@ -3036,11 +3044,10 @@ _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::pu
}
if (__sz == __cap) {
__grow_by_without_replace(__cap, 1, __sz, __sz, 0);
__annotate_increase(1);
__is_short = false; // the string is always long after __grow_by
} else
__annotate_increase(1);
pointer __p = __get_pointer();
}
__annotate_increase(1);
pointer __p;
if (__is_short) {
__p = __get_short_pointer() + __sz;
__set_short_size(__sz + 1);
Expand Down Expand Up @@ -3424,11 +3431,13 @@ inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocat

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::clear() _NOEXCEPT {
size_type __old_size = size();
size_type __old_size;
if (__is_long()) {
__old_size = __get_long_size();
traits_type::assign(*__get_long_pointer(), value_type());
__set_long_size(0);
} else {
__old_size = __get_short_size();
traits_type::assign(*__get_short_pointer(), value_type());
__set_short_size(0);
}
Expand Down Expand Up @@ -3486,11 +3495,12 @@ inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocat
_LIBCPP_ASSERT_INTERNAL(__is_long(), "Trying to shrink small string");

// We're a long string and we're shrinking into the small buffer.
const auto __ptr = __get_long_pointer();
const auto __size = __get_long_size();
const auto __cap = __get_long_cap();

if (__fits_in_sso(__target_capacity)) {
__annotation_guard __g(*this);
auto __ptr = __get_long_pointer();
auto __size = __get_long_size();
auto __cap = __get_long_cap();
traits_type::copy(std::__to_address(__get_short_pointer()), std::__to_address(__ptr), __size + 1);
__set_short_size(__size);
__alloc_traits::deallocate(__alloc_, __ptr, __cap);
Expand All @@ -3501,7 +3511,6 @@ inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocat
try {
# endif // _LIBCPP_HAS_EXCEPTIONS
__annotation_guard __g(*this);
auto __size = size();
auto __allocation = std::__allocate_at_least(__alloc_, __target_capacity + 1);

// The Standard mandates shrink_to_fit() does not increase the capacity.
Expand All @@ -3513,9 +3522,8 @@ inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocat
}

__begin_lifetime(__allocation.ptr, __allocation.count);
auto __ptr = __get_long_pointer();
traits_type::copy(std::__to_address(__allocation.ptr), std::__to_address(__ptr), __size + 1);
__alloc_traits::deallocate(__alloc_, __ptr, __get_long_cap());
__alloc_traits::deallocate(__alloc_, __ptr, __cap);
__set_long_cap(__allocation.count);
__set_long_pointer(__allocation.ptr);
# if _LIBCPP_HAS_EXCEPTIONS
Expand Down