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 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef _LIBCPP_SYNCSTREAM
 #define _LIBCPP_SYNCSTREAM
 
 /*
     syncstream synopsis
 
 #include <ostream>  // see [ostream.syn]
 
 namespace std {
     template<class charT, class traits, class Allocator>
     class basic_syncbuf;
 
     // [syncstream.syncbuf.special], specialized algorithms
     template<class charT, class traits, class Allocator>
       void swap(basic_syncbuf<charT, traits, Allocator>&,
                 basic_syncbuf<charT, traits, Allocator>&);
 
     using syncbuf = basic_syncbuf<char>;
     using wsyncbuf = basic_syncbuf<wchar_t>;
 
     template<class charT, class traits, class Allocator>
     class basic_osyncstream;
 
     using osyncstream = basic_osyncstream<char>;
     using wosyncstream = basic_osyncstream<wchar_t>;
 
     template<class charT, class traits, class Allocator>
     class basic_syncbuf : public basic_streambuf<charT, traits> {
     public:
         using char_type      = charT;
         using int_type       = typename traits::int_type;
         using pos_type       = typename traits::pos_type;
         using off_type       = typename traits::off_type;
         using traits_type    = traits;
         using allocator_type = Allocator;
 
         using streambuf_type = basic_streambuf<charT, traits>;
 
         // [syncstream.syncbuf.cons], construction and destruction
         basic_syncbuf()
           : basic_syncbuf(nullptr) {}
         explicit basic_syncbuf(streambuf_type* obuf)
           : basic_syncbuf(obuf, Allocator()) {}
         basic_syncbuf(streambuf_type*, const Allocator&);
         basic_syncbuf(basic_syncbuf&&);
         ~basic_syncbuf();
 
         // [syncstream.syncbuf.assign], assignment and swap
         basic_syncbuf& operator=(basic_syncbuf&&);
         void swap(basic_syncbuf&);
 
         // [syncstream.syncbuf.members], member functions
         bool emit();
         streambuf_type* get_wrapped() const noexcept;
         allocator_type get_allocator() const noexcept;
         void set_emit_on_sync(bool) noexcept;
 
     protected:
         // [syncstream.syncbuf.virtuals], overridden virtual functions
         int sync() override;
 
     private:
         streambuf_type* wrapped;    // exposition only
         bool emit_on_sync{};        // exposition only
     };
 
     // [syncstream.syncbuf.special], specialized algorithms
     template<class charT, class traits, class Allocator>
     void swap(basic_syncbuf<charT, traits, Allocator>&,
               basic_syncbuf<charT, traits, Allocator>&);
 
     template<class charT, class traits, class Allocator>
     class basic_osyncstream : public basic_ostream<charT, traits> {
     public:
         using char_type   = charT;
         using int_type    = typename traits::int_type;
         using pos_type    = typename traits::pos_type;
         using off_type    = typename traits::off_type;
         using traits_type = traits;
 
         using allocator_type = Allocator;
         using streambuf_type = basic_streambuf<charT, traits>;
         using syncbuf_type   = basic_syncbuf<charT, traits, Allocator>;
 
         // [syncstream.osyncstream.cons], construction and destruction
         basic_osyncstream(streambuf_type*, const Allocator&);
         explicit basic_osyncstream(streambuf_type* obuf)
           : basic_osyncstream(obuf, Allocator()) {}
         basic_osyncstream(basic_ostream<charT, traits>& os, const Allocator& allocator)
           : basic_osyncstream(os.rdbuf(), allocator) {}
         explicit basic_osyncstream(basic_ostream<charT, traits>& os)
           : basic_osyncstream(os, Allocator()) {}
         basic_osyncstream(basic_osyncstream&&) noexcept;
         ~basic_osyncstream();
 
         // [syncstream.osyncstream.assign], assignment
         basic_osyncstream& operator=(basic_osyncstream&&);
 
         // [syncstream.osyncstream.members], member functions
         void emit();
         streambuf_type* get_wrapped() const noexcept;
         syncbuf_type* rdbuf() const noexcept { return const_cast<syncbuf_type*>(addressof(sb)); }
 
     private:
         syncbuf_type sb;    // exposition only
     };
 }
 
 */
 
 #if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
 #  include <__cxx03/syncstream>
 #else
 #  include <__config>
 
 #  if _LIBCPP_HAS_LOCALIZATION
 
 #    include <__mutex/lock_guard.h>
 #    include <__utility/move.h>
 #    include <ios>
 #    include <iosfwd> // required for declaration of default arguments
 #    include <streambuf>
 #    include <string>
 
 #    if _LIBCPP_HAS_THREADS
 #      include <map>
 #      include <shared_mutex>
 #    endif
 
 // standard-mandated includes
 
 // [syncstream.syn]
 #    include <ostream>
 
 #    if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #      pragma GCC system_header
 #    endif
 
 _LIBCPP_PUSH_MACROS
 #    include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 #    if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_EXPERIMENTAL_SYNCSTREAM
 
 // [syncstream.syncbuf.overview]/1
 //   Class template basic_syncbuf stores character data written to it,
 //   known as the associated output, into internal buffers allocated
 //   using the object's allocator. The associated output is transferred
 //   to the wrapped stream buffer object *wrapped when emit() is called
 //   or when the basic_syncbuf object is destroyed. Such transfers are
 //   atomic with respect to transfers by other basic_syncbuf objects
 //   with the same wrapped stream buffer object.
 //
 // This helper singleton is used to implement the required
 // synchronisation guarantees.
 #      if _LIBCPP_HAS_THREADS
 class __wrapped_streambuf_mutex {
   _LIBCPP_HIDE_FROM_ABI __wrapped_streambuf_mutex() = default;
 
 public:
   __wrapped_streambuf_mutex(const __wrapped_streambuf_mutex&)            = delete;
   __wrapped_streambuf_mutex& operator=(const __wrapped_streambuf_mutex&) = delete;
 
   _LIBCPP_HIDE_FROM_ABI void __inc_reference([[maybe_unused]] void* __ptr) {
     _LIBCPP_ASSERT_INTERNAL(__ptr != nullptr, "non-wrapped streambufs are never written to");
     unique_lock __lock{__mutex_};
     ++__lut_[reinterpret_cast<uintptr_t>(__ptr)].__count;
   }
 
   // pre: __ptr is in __lut_
   _LIBCPP_HIDE_FROM_ABI void __dec_reference([[maybe_unused]] void* __ptr) noexcept {
     unique_lock __lock{__mutex_};
 
     auto __it = __get_it(__ptr);
     if (__it->second.__count == 1)
       __lut_.erase(__it);
     else
       --__it->second.__count;
   }
 
   // TODO
   // This function causes emit() aquire two mutexes:
   // - __mutex_ shared
   // _ __get_it(__ptr)->second.__mutex exclusive
   //
   // Instead store a pointer to __get_it(__ptr)->second.__mutex when
   // calling __inc_reference.
   //
   // pre: __ptr is in __lut_
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI lock_guard<mutex> __get_lock([[maybe_unused]] void* __ptr) noexcept {
     shared_lock __lock{__mutex_};
     return lock_guard{__get_it(__ptr)->second.__mutex};
   }
 
   // This function is used for testing.
   //
   // It is allowed to call this function with a non-registered pointer.
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI size_t __get_count([[maybe_unused]] void* __ptr) noexcept {
     _LIBCPP_ASSERT_INTERNAL(__ptr != nullptr, "non-wrapped streambufs are never written to");
     shared_lock __lock{__mutex_};
 
     auto __it = __lut_.find(reinterpret_cast<uintptr_t>(__ptr));
     return __it != __lut_.end() ? __it->second.__count : 0;
   }
 
   [[nodiscard]] static _LIBCPP_HIDE_FROM_ABI __wrapped_streambuf_mutex& __instance() noexcept {
     static __wrapped_streambuf_mutex __result;
     return __result;
   }
 
 private:
   struct __value {
     mutex __mutex;
     size_t __count{0};
   };
 
   shared_mutex __mutex_;
   map<uintptr_t, __value> __lut_;
 
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI map<uintptr_t, __value>::iterator __get_it(void* __ptr) noexcept {
     _LIBCPP_ASSERT_INTERNAL(__ptr != nullptr, "non-wrapped streambufs are never written to");
 
     auto __it = __lut_.find(reinterpret_cast<uintptr_t>(__ptr));
     _LIBCPP_ASSERT_INTERNAL(__it != __lut_.end(), "using a wrapped streambuf that has not been registered");
     _LIBCPP_ASSERT_INTERNAL(__it->second.__count >= 1, "found an inactive streambuf wrapper");
     return __it;
   }
 };
 #      endif // _LIBCPP_HAS_THREADS
 
 // basic_syncbuf
 
 // The class uses a basic_string<_CharT, _Traits, _Allocator> as
 // internal buffer. Per [syncstream.syncbuf.cons]/4
 //   Remarks: A copy of allocator is used to allocate memory for
 //   internal buffers holding the associated output.
 //
 // Therefore the allocator used in the constructor is passed to the
 // basic_string. The class does not keep a copy of this allocator.
 template <class _CharT, class _Traits, class _Allocator>
 class _LIBCPP_TEMPLATE_VIS basic_syncbuf : public basic_streambuf<_CharT, _Traits> {
 public:
   using char_type      = _CharT;
   using traits_type    = _Traits;
   using int_type       = typename traits_type::int_type;
   using pos_type       = typename traits_type::pos_type;
   using off_type       = typename traits_type::off_type;
   using allocator_type = _Allocator;
 
   using streambuf_type = basic_streambuf<_CharT, _Traits>;
 
   // [syncstream.syncbuf.cons], construction and destruction
 
   _LIBCPP_HIDE_FROM_ABI basic_syncbuf() : basic_syncbuf(nullptr) {}
 
   _LIBCPP_HIDE_FROM_ABI explicit basic_syncbuf(streambuf_type* __obuf) : basic_syncbuf(__obuf, _Allocator()) {}
 
   _LIBCPP_HIDE_FROM_ABI basic_syncbuf(streambuf_type* __obuf, _Allocator const& __alloc)
       : __wrapped_(__obuf), __str_(__alloc) {
     __inc_reference();
   }
 
   _LIBCPP_HIDE_FROM_ABI basic_syncbuf(basic_syncbuf&& __other)
       : __wrapped_(__other.get_wrapped()), __str_(std::move(__other.__str_)), __emit_on_sync_(__other.__emit_on_sync_) {
     __move_common(__other);
   }
 
   _LIBCPP_HIDE_FROM_ABI ~basic_syncbuf() {
 #      if _LIBCPP_HAS_EXCEPTIONS
     try {
 #      endif // _LIBCPP_HAS_EXCEPTIONS
       emit();
 #      if _LIBCPP_HAS_EXCEPTIONS
     } catch (...) {
     }
 #      endif // _LIBCPP_HAS_EXCEPTIONS
     __dec_reference();
   }
 
   // [syncstream.syncbuf.assign], assignment and swap
 
   _LIBCPP_HIDE_FROM_ABI basic_syncbuf& operator=(basic_syncbuf&& __other) {
     // The function is specified to call emit. This call should
     // propagate the exception thrown.
     emit();
     __dec_reference();
 
     __wrapped_      = __other.get_wrapped();
     __str_          = std::move(__other.__str_);
     __emit_on_sync_ = __other.__emit_on_sync_;
 
     __move_common(__other);
 
     return *this;
   }
 
   _LIBCPP_HIDE_FROM_ABI void swap(basic_syncbuf& __other) {
     _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
         allocator_traits<_Allocator>::propagate_on_container_swap::value || get_allocator() == __other.get_allocator(),
         "violates the mandated swap precondition");
 
     basic_syncbuf __tmp(std::move(__other));
     __other = std::move(*this);
     *this   = std::move(__tmp);
   }
 
   // [syncstream.syncbuf.members], member functions
 
   _LIBCPP_HIDE_FROM_ABI bool emit() { return emit(false); }
 
   _LIBCPP_HIDE_FROM_ABI streambuf_type* get_wrapped() const noexcept { return __wrapped_; }
 
   _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const noexcept { return __str_.get_allocator(); }
 
   _LIBCPP_HIDE_FROM_ABI void set_emit_on_sync(bool __b) noexcept { __emit_on_sync_ = __b; }
 
 protected:
   // [syncstream.syncbuf.virtuals], overridden virtual functions
 
   _LIBCPP_HIDE_FROM_ABI_VIRTUAL
   int sync() override {
     if (__emit_on_sync_ && !emit(true))
       return -1;
     return 0;
   }
 
   _LIBCPP_HIDE_FROM_ABI_VIRTUAL
   int_type overflow(int_type __c = traits_type::eof()) override {
     if (traits_type::eq_int_type(__c, traits_type::eof()))
       return traits_type::not_eof(__c);
 
     if (this->pptr() == this->epptr()) {
 #      if _LIBCPP_HAS_EXCEPTIONS
       try {
 #      endif
         size_t __size = __str_.size();
         __str_.resize(__str_.capacity() + 1);
         _LIBCPP_ASSERT_INTERNAL(__str_.size() > __size, "the buffer hasn't grown");
 
         char_type* __p = static_cast<char_type*>(__str_.data());
         this->setp(__p, __p + __str_.size());
         this->pbump(__size);
 
 #      if _LIBCPP_HAS_EXCEPTIONS
       } catch (...) {
         return traits_type::eof();
       }
 #      endif
     }
 
     return this->sputc(traits_type::to_char_type(__c));
   }
 
 private:
   streambuf_type* __wrapped_;
 
   // TODO Use a more generic buffer.
   // That buffer should be light with almost no additional headers. Then
   // it can be use here, the __retarget_buffer, and place that use
   // the now removed get_temporary_buffer
 
   basic_string<_CharT, _Traits, _Allocator> __str_;
   bool __emit_on_sync_{false};
 
   _LIBCPP_HIDE_FROM_ABI bool emit(bool __flush) {
     if (!__wrapped_)
       return false;
 
 #      if _LIBCPP_HAS_THREADS
     lock_guard<mutex> __lock = __wrapped_streambuf_mutex::__instance().__get_lock(__wrapped_);
 #      endif
 
     bool __result = true;
     if (this->pptr() != this->pbase()) {
       _LIBCPP_ASSERT_INTERNAL(this->pbase() && this->pptr() && this->epptr(), "all put area pointers shold be valid");
 
       // The __str_ does not know how much of its buffer is used. This
       // information is extracted from the information of the base class.
       __result &= (__wrapped_->sputn(this->pbase(), this->pptr() - this->pbase()) != -1);
       // Clears the buffer, but keeps the contents (and) size of the
       // internal buffer.
       this->setp(this->pbase(), this->epptr());
     }
 
     if (__flush)
       __result &= (__wrapped_->pubsync() != -1);
 
     return __result;
   }
 
   _LIBCPP_HIDE_FROM_ABI void __move_common(basic_syncbuf& __other) {
     // Adjust the put area pointers to our buffer.
     char_type* __p = static_cast<char_type*>(__str_.data());
     this->setp(__p, __p + __str_.size());
     this->pbump(__other.pptr() - __other.pbase());
 
     // Clear __other_ so the destructor will act as a NOP.
     __other.setp(nullptr, nullptr);
     __other.__wrapped_ = nullptr;
   }
 
   _LIBCPP_HIDE_FROM_ABI void __inc_reference() {
 #      if _LIBCPP_HAS_THREADS
     if (__wrapped_)
       __wrapped_streambuf_mutex::__instance().__inc_reference(__wrapped_);
 #      endif
   }
 
   _LIBCPP_HIDE_FROM_ABI void __dec_reference() noexcept {
 #      if _LIBCPP_HAS_THREADS
     if (__wrapped_)
       __wrapped_streambuf_mutex::__instance().__dec_reference(__wrapped_);
 #      endif
   }
 };
 
 using std::syncbuf;
 #      if _LIBCPP_HAS_WIDE_CHARACTERS
 using std::wsyncbuf;
 #      endif
 
 // [syncstream.syncbuf.special], specialized algorithms
 template <class _CharT, class _Traits, class _Allocator>
 _LIBCPP_HIDE_FROM_ABI void
 swap(basic_syncbuf<_CharT, _Traits, _Allocator>& __lhs, basic_syncbuf<_CharT, _Traits, _Allocator>& __rhs) {
   __lhs.swap(__rhs);
 }
 
 // basic_osyncstream
 
 template <class _CharT, class _Traits, class _Allocator>
 class _LIBCPP_TEMPLATE_VIS basic_osyncstream : public basic_ostream<_CharT, _Traits> {
 public:
   using char_type   = _CharT;
   using traits_type = _Traits;
   using int_type    = typename traits_type::int_type;
   using pos_type    = typename traits_type::pos_type;
   using off_type    = typename traits_type::off_type;
 
   using allocator_type = _Allocator;
   using streambuf_type = basic_streambuf<char_type, traits_type>;
   using syncbuf_type   = basic_syncbuf<char_type, traits_type, allocator_type>;
 
   // [syncstream.osyncstream.cons], construction and destruction
 
   _LIBCPP_HIDE_FROM_ABI basic_osyncstream(streambuf_type* __obuf, allocator_type const& __alloc)
       : basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__obuf, __alloc) {}
 
   _LIBCPP_HIDE_FROM_ABI explicit basic_osyncstream(streambuf_type* __obuf)
       : basic_osyncstream(__obuf, allocator_type()) {}
 
   _LIBCPP_HIDE_FROM_ABI basic_osyncstream(basic_ostream<char_type, traits_type>& __os, allocator_type const& __alloc)
       : basic_osyncstream(__os.rdbuf(), __alloc) {}
 
   _LIBCPP_HIDE_FROM_ABI explicit basic_osyncstream(basic_ostream<char_type, traits_type>& __os)
       : basic_osyncstream(__os, allocator_type()) {}
 
   _LIBCPP_HIDE_FROM_ABI basic_osyncstream(basic_osyncstream&& __other) noexcept
       : basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(std::move(__other.__sb_)) {
     this->set_rdbuf(std::addressof(__sb_));
   }
 
   // [syncstream.osyncstream.assign], assignment
 
   _LIBCPP_HIDE_FROM_ABI basic_osyncstream& operator=(basic_osyncstream&& __other) = default;
 
   // [syncstream.osyncstream.members], member functions
 
   _LIBCPP_HIDE_FROM_ABI void emit() {
     // The basic_ostream::put places the sentry in a try
     // catch, this does not match the wording of the standard
     // [ostream.unformatted]
     // TODO validate other unformatted output functions.
     typename basic_ostream<char_type, traits_type>::sentry __s(*this);
     if (__s) {
 #      if _LIBCPP_HAS_EXCEPTIONS
       try {
 #      endif
 
         if (__sb_.emit() == false)
           this->setstate(ios::badbit);
 #      if _LIBCPP_HAS_EXCEPTIONS
       } catch (...) {
         this->__set_badbit_and_consider_rethrow();
       }
 #      endif
     }
   }
 
   _LIBCPP_HIDE_FROM_ABI streambuf_type* get_wrapped() const noexcept { return __sb_.get_wrapped(); }
 
   _LIBCPP_HIDE_FROM_ABI syncbuf_type* rdbuf() const noexcept {
     return const_cast<syncbuf_type*>(std::addressof(__sb_));
   }
 
 private:
   syncbuf_type __sb_;
 };
 
 using std::osyncstream;
 #      if _LIBCPP_HAS_WIDE_CHARACTERS
 using std::wosyncstream;
 #      endif
 
 #    endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_EXPERIMENTAL_SYNCSTREAM
 
 _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
 #  endif // _LIBCPP_HAS_LOCALIZATION
 #endif   // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
 
 #endif // _LIBCPP_SYNCSTREAM

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