================
@@ -319,188 +353,222 @@ struct _LIBCPP_TEMPLATE_VIS
__back_insert_iterator_container<back_insert_iterato
using type = _Container;
};
-/// Write policy for inserting the buffer in a container.
-template <class _Container>
-class _LIBCPP_TEMPLATE_VIS __writer_container {
+// A dynamically growing buffer.
+template <__fmt_char_type _CharT>
+class _LIBCPP_TEMPLATE_VIS __allocating_buffer : public
__output_buffer<_CharT> {
public:
- using _CharT = typename _Container::value_type;
+ __allocating_buffer(const __allocating_buffer&) = delete;
+ __allocating_buffer& operator=(const __allocating_buffer&) = delete;
- _LIBCPP_HIDE_FROM_ABI explicit
__writer_container(back_insert_iterator<_Container> __out_it)
- : __container_{__out_it.__get_container()} {}
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI __allocating_buffer() :
__allocating_buffer{nullptr} {}
- _LIBCPP_HIDE_FROM_ABI auto __out_it() { return
std::back_inserter(*__container_); }
+ [[nodiscard]]
+ _LIBCPP_HIDE_FROM_ABI explicit __allocating_buffer(__max_output_size*
__max_output_size)
+ : __output_buffer<_CharT>{__buffer_, __buffer_size_, __prepare_write,
__max_output_size} {}
- _LIBCPP_HIDE_FROM_ABI void __flush(_CharT* __ptr, size_t __n) {
- __container_->insert(__container_->end(), __ptr, __ptr + __n);
+ _LIBCPP_HIDE_FROM_ABI ~__allocating_buffer() {
+ if (__ptr_ != __buffer_) {
+ ranges::destroy_n(__ptr_, this->__size());
+ allocator_traits<_Alloc>::deallocate(__alloc_, __ptr_,
this->__capacity());
+ }
}
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI basic_string_view<_CharT> __view() {
return {__ptr_, this->__size()}; }
+
private:
- _Container* __container_;
-};
+ // At the moment the allocator is hard-code. There might be reasons to have
+ // an allocator trait in the future. This ensures forward compatibility.
+ using _Alloc = allocator<_CharT>;
+ _LIBCPP_NO_UNIQUE_ADDRESS _Alloc __alloc_;
-/// Selects the type of the writer used for the output iterator.
-template <class _OutIt, class _CharT>
-class _LIBCPP_TEMPLATE_VIS __writer_selector {
- using _Container = typename __back_insert_iterator_container<_OutIt>::type;
+ // Since allocating is expensive the class has a small internal buffer. When
+ // its capacity is exceeded a dynamic buffer will be allocated.
+ static constexpr size_t __buffer_size_ = 256;
+ _CharT __buffer_[__buffer_size_];
-public:
- using type =
- conditional_t<!same_as<_Container, void>,
- __writer_container<_Container>,
- conditional_t<__enable_direct_output<_OutIt, _CharT>,
- __writer_direct<_OutIt, _CharT>,
- __writer_iterator<_OutIt, _CharT>>>;
+ _CharT* __ptr_{__buffer_};
+
+ _LIBCPP_HIDE_FROM_ABI void __grow_buffer(size_t __capacity) {
+ if (__capacity < __buffer_size_)
+ return;
+
+ _LIBCPP_ASSERT_INTERNAL(__capacity > this->__capacity(), "the buffer must
grow");
+ auto __result = std::__allocate_at_least(__alloc_, __capacity);
+ auto __guard = std::__make_exception_guard([&] {
+ allocator_traits<_Alloc>::deallocate(__alloc_, __result.ptr,
__result.count);
+ });
+ // This shouldn't throw, but just to be safe. Note that at -O1 this
+ // guard is optimized away so there is no runtime overhead.
+ new (__result.ptr) _CharT[__result.count];
+ std::copy_n(__ptr_, this->__size(), __result.ptr);
----------------
ldionne wrote:
What we'd want here is roughly `std::__relocate(__ptr_, __ptr_ +
this->__size(), __result.ptr)`.
https://github.com/llvm/llvm-project/pull/108990
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