[libc++] Simplify the implementation of string::{append,assign,assign_range} #162254
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philnik777
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@llvm/pr-subscribers-libcxx Author: Nikolas Klauser (philnik777) Changes
Full diff: https://github.com/llvm/llvm-project/pull/162254.diff 1 Files Affected:
diff --git a/libcxx/include/string b/libcxx/include/string
index 363f27a51648c..5e10aa4671621 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -1413,24 +1413,16 @@ public:
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s);
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(size_type __n, value_type __c);
- template <class _InputIterator, __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
- append(_InputIterator __first, _InputIterator __last) {
- const basic_string __temp(__first, __last, __alloc_);
- append(__temp.data(), __temp.size());
- return *this;
- }
-
- template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> = 0>
+ template <class _InputIterator>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
- append(_ForwardIterator __first, _ForwardIterator __last) {
+ append(_InputIterator __first, _InputIterator __last) {
size_type __sz = size();
size_type __cap = capacity();
size_type __n = static_cast<size_type>(std::distance(__first, __last));
if (__n == 0)
return *this;
- if (__string_is_trivial_iterator_v<_ForwardIterator> && !__addr_in_range(*__first)) {
+ if (__string_is_trivial_iterator_v<_InputIterator> && !__addr_in_range(*__first)) {
if (__cap - __sz < __n)
__grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __sz, 0);
__annotate_increase(__n);
@@ -1540,17 +1532,10 @@ public:
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s);
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(size_type __n, value_type __c);
- template <class _InputIterator, __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
+ template <class _InputIterator>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
assign(_InputIterator __first, _InputIterator __last) {
- __assign_with_sentinel(__first, __last);
- return *this;
- }
-
- template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> = 0>
- _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
- assign(_ForwardIterator __first, _ForwardIterator __last) {
- if (__string_is_trivial_iterator_v<_ForwardIterator>) {
+ if _LIBCPP_CONSTEXPR (__string_is_trivial_iterator_v<_InputIterator>) {
size_type __n = static_cast<size_type>(std::distance(__first, __last));
__assign_trivial(__first, __last, __n);
} else {
@@ -1563,8 +1548,7 @@ public:
# if _LIBCPP_STD_VER >= 23
template <_ContainerCompatibleRange<_CharT> _Range>
_LIBCPP_HIDE_FROM_ABI constexpr basic_string& assign_range(_Range&& __range) {
- if constexpr (__string_is_trivial_iterator_v<ranges::iterator_t<_Range>> &&
- (ranges::forward_range<_Range> || ranges::sized_range<_Range>)) {
+ if constexpr (__string_is_trivial_iterator_v<ranges::iterator_t<_Range>>) {
size_type __n = static_cast<size_type>(ranges::distance(__range));
__assign_trivial(ranges::begin(__range), ranges::end(__range), __n);
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ldionne
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Oct 8, 2025
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| __grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __sz, 0); | ||
| __annotate_increase(__n); |
There was a problem hiding this comment.
I guess this could be something like
string __tmp;
__tmp.reserve(__sz + __n);
__tmp.assign(begin(), end());
__tmp.insert(__tmp.end(), __first, __last);
swap(*this, __tmp);
And then we don't have to care about __addr_in_range(*__first) anymore. That's basically the algorithm that we do in vector as well.
This can be done in a follow-up patch.
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__string_is_trivial_iterator_valready implies that the iterator is contiguous. There is no need to specialize for input ranges specifically.