include/__format/format_context.h - llvm-project/libcxx - Git at Google

 // -*- 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___FORMAT_FORMAT_CONTEXT_H
 #define _LIBCPP___FORMAT_FORMAT_CONTEXT_H

 #include <__concepts/same_as.h>
 #include <__config>
 #include <__format/buffer.h>
 #include <__format/format_arg.h>
 #include <__format/format_arg_store.h>
 #include <__format/format_args.h>
 #include <__format/format_error.h>
 #include <__fwd/format.h>
 #include <__iterator/back_insert_iterator.h>
 #include <__iterator/concepts.h>
 #include <__memory/addressof.h>
 #include <__utility/move.h>
 #include <__variant/monostate.h>
 #include <cstddef>

 #ifndef _LIBCPP_HAS_NO_LOCALIZATION
 #  include <__locale>
 #  include <optional>
 #endif

 #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

 template <class _OutIt, class _CharT>
   requires output_iterator<_OutIt, const _CharT&>
 class _LIBCPP_TEMPLATE_VIS basic_format_context;

 #  ifndef _LIBCPP_HAS_NO_LOCALIZATION
 /**
  * Helper to create a basic_format_context.
  *
  * This is needed since the constructor is private.
  */
 template <class _OutIt, class _CharT>
 _LIBCPP_HIDE_FROM_ABI basic_format_context<_OutIt, _CharT>
 __format_context_create(_OutIt __out_it,
                         basic_format_args<basic_format_context<_OutIt, _CharT>> __args,
                         optional<std::locale>&& __loc = nullopt) {
   return std::basic_format_context(std::move(__out_it), __args, std::move(__loc));
 }
 #  else
 template <class _OutIt, class _CharT>
 _LIBCPP_HIDE_FROM_ABI basic_format_context<_OutIt, _CharT>
 __format_context_create(_OutIt __out_it, basic_format_args<basic_format_context<_OutIt, _CharT>> __args) {
   return std::basic_format_context(std::move(__out_it), __args);
 }
 #  endif

 using format_context = basic_format_context<back_insert_iterator<__format::__output_buffer<char>>, char>;
 #  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 using wformat_context = basic_format_context< back_insert_iterator<__format::__output_buffer<wchar_t>>, wchar_t>;
 #  endif

 template <class _OutIt, class _CharT>
   requires output_iterator<_OutIt, const _CharT&>
 class
     // clang-format off
     _LIBCPP_TEMPLATE_VIS
     _LIBCPP_PREFERRED_NAME(format_context)
     _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wformat_context))
     // clang-format on
     basic_format_context {
 public:
   using iterator  = _OutIt;
   using char_type = _CharT;
   template <class _Tp>
   using formatter_type = formatter<_Tp, _CharT>;

   _LIBCPP_HIDE_FROM_ABI basic_format_arg<basic_format_context> arg(size_t __id) const noexcept {
     return __args_.get(__id);
   }
 #  ifndef _LIBCPP_HAS_NO_LOCALIZATION
   _LIBCPP_HIDE_FROM_ABI std::locale locale() {
     if (!__loc_)
       __loc_ = std::locale{};
     return *__loc_;
   }
 #  endif
   _LIBCPP_HIDE_FROM_ABI iterator out() { return std::move(__out_it_); }
   _LIBCPP_HIDE_FROM_ABI void advance_to(iterator __it) { __out_it_ = std::move(__it); }

 private:
   iterator __out_it_;
   basic_format_args<basic_format_context> __args_;
 #  ifndef _LIBCPP_HAS_NO_LOCALIZATION

   // The Standard doesn't specify how the locale is stored.
   // [format.context]/6
   // std::locale locale();
   //   Returns: The locale passed to the formatting function if the latter
   //   takes one, and std::locale() otherwise.
   // This is done by storing the locale of the constructor in this optional. If
   // locale() is called and the optional has no value the value will be created.
   // This allows the implementation to lazily create the locale.
   // TODO FMT Validate whether lazy creation is the best solution.
   optional<std::locale> __loc_;

   template <class _OtherOutIt, class _OtherCharT>
   friend _LIBCPP_HIDE_FROM_ABI basic_format_context<_OtherOutIt, _OtherCharT> __format_context_create(
       _OtherOutIt, basic_format_args<basic_format_context<_OtherOutIt, _OtherCharT>>, optional<std::locale>&&);

   // Note: the Standard doesn't specify the required constructors.
   _LIBCPP_HIDE_FROM_ABI explicit basic_format_context(
       _OutIt __out_it, basic_format_args<basic_format_context> __args, optional<std::locale>&& __loc)
       : __out_it_(std::move(__out_it)), __args_(__args), __loc_(std::move(__loc)) {}
 #  else
   template <class _OtherOutIt, class _OtherCharT>
   friend _LIBCPP_HIDE_FROM_ABI basic_format_context<_OtherOutIt, _OtherCharT>
       __format_context_create(_OtherOutIt, basic_format_args<basic_format_context<_OtherOutIt, _OtherCharT>>);

   _LIBCPP_HIDE_FROM_ABI explicit basic_format_context(_OutIt __out_it, basic_format_args<basic_format_context> __args)
       : __out_it_(std::move(__out_it)), __args_(__args) {}
 #  endif
 };

 // A specialization for __retarget_buffer
 //
 // See __retarget_buffer for the motivation for this specialization.
 //
 // This context holds a reference to the instance of the basic_format_context
 // that is retargeted. It converts a formatting argument when it is requested
 // during formatting. It is expected that the usage of the arguments is rare so
 // the lookups are not expected to be used often. An alternative would be to
 // convert all elements during construction.
 //
 // The elements of the retargets context are only used when an underlying
 // formatter uses a locale specific formatting or an formatting argument is
 // part for the format spec. For example
 //   format("{:256:{}}", input, 8);
 // Here the width of an element in input is determined dynamically.
 // Note when the top-level element has no width the retargeting is not needed.
 template <class _CharT>
 class _LIBCPP_TEMPLATE_VIS basic_format_context<typename __format::__retarget_buffer<_CharT>::__iterator, _CharT> {
 public:
   using iterator  = typename __format::__retarget_buffer<_CharT>::__iterator;
   using char_type = _CharT;
   template <class _Tp>
   using formatter_type = formatter<_Tp, _CharT>;

   template <class _Context>
   _LIBCPP_HIDE_FROM_ABI explicit basic_format_context(iterator __out_it, _Context& __ctx)
       : __out_it_(std::move(__out_it)),
 #  ifndef _LIBCPP_HAS_NO_LOCALIZATION
         __loc_([](void* __c) { return static_cast<_Context*>(__c)->locale(); }),
 #  endif
         __ctx_(std::addressof(__ctx)),
         __arg_([](void* __c, size_t __id) {
           auto __visitor = [&](auto __arg) -> basic_format_arg<basic_format_context> {
             if constexpr (same_as<decltype(__arg), monostate>)
               return {};
             else if constexpr (same_as<decltype(__arg), typename basic_format_arg<_Context>::handle>)
               // At the moment it's not possible for formatting to use a re-targeted handle.
               // TODO FMT add this when support is needed.
               std::__throw_format_error("Re-targeting handle not supported");
             else
               return basic_format_arg<basic_format_context>{
                   __format::__determine_arg_t<basic_format_context, decltype(__arg)>(),
                   __basic_format_arg_value<basic_format_context>(__arg)};
           };
 #  if _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
           return static_cast<_Context*>(__c)->arg(__id).visit(std::move(__visitor));
 #  else
           _LIBCPP_SUPPRESS_DEPRECATED_PUSH
           return std::visit_format_arg(std::move(__visitor), static_cast<_Context*>(__c)->arg(__id));
           _LIBCPP_SUPPRESS_DEPRECATED_POP
 #  endif // _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
         }) {
   }

   _LIBCPP_HIDE_FROM_ABI basic_format_arg<basic_format_context> arg(size_t __id) const noexcept {
     return __arg_(__ctx_, __id);
   }
 #  ifndef _LIBCPP_HAS_NO_LOCALIZATION
   _LIBCPP_HIDE_FROM_ABI std::locale locale() { return __loc_(__ctx_); }
 #  endif
   _LIBCPP_HIDE_FROM_ABI iterator out() { return std::move(__out_it_); }
   _LIBCPP_HIDE_FROM_ABI void advance_to(iterator __it) { __out_it_ = std::move(__it); }

 private:
   iterator __out_it_;

 #  ifndef _LIBCPP_HAS_NO_LOCALIZATION
   std::locale (*__loc_)(void* __ctx);
 #  endif

   void* __ctx_;
   basic_format_arg<basic_format_context> (*__arg_)(void* __ctx, size_t __id);
 };

 _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(basic_format_context);
 #endif //_LIBCPP_STD_VER >= 20

 _LIBCPP_END_NAMESPACE_STD

 _LIBCPP_POP_MACROS

 #endif // _LIBCPP___FORMAT_FORMAT_CONTEXT_H
	// -- 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___FORMAT_FORMAT_CONTEXT_H
	#define _LIBCPP___FORMAT_FORMAT_CONTEXT_H

	#include <__concepts/same_as.h>
	#include <__config>
	#include <__format/buffer.h>
	#include <__format/format_arg.h>
	#include <__format/format_arg_store.h>
	#include <__format/format_args.h>
	#include <__format/format_error.h>
	#include <__fwd/format.h>
	#include <__iterator/back_insert_iterator.h>
	#include <__iterator/concepts.h>
	#include <__memory/addressof.h>
	#include <__utility/move.h>
	#include <__variant/monostate.h>
	#include <cstddef>

	#ifndef _LIBCPP_HAS_NO_LOCALIZATION
	# include <__locale>
	# include <optional>
	#endif

	#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

	template <class _OutIt, class _CharT>
	requires output_iterator<_OutIt, const _CharT&>
	class _LIBCPP_TEMPLATE_VIS basic_format_context;

	# ifndef _LIBCPP_HAS_NO_LOCALIZATION
	/**
	* Helper to create a basic_format_context.
	*
	* This is needed since the constructor is private.
	*/
	template <class _OutIt, class _CharT>
	_LIBCPP_HIDE_FROM_ABI basic_format_context<_OutIt, _CharT>
	__format_context_create(_OutIt __out_it,
	basic_format_args<basic_format_context<_OutIt, _CharT>> __args,
	optional<std::locale>&& __loc = nullopt) {
	return std::basic_format_context(std::move(__out_it), __args, std::move(__loc));
	}
	# else
	template <class _OutIt, class _CharT>
	_LIBCPP_HIDE_FROM_ABI basic_format_context<_OutIt, _CharT>
	__format_context_create(_OutIt __out_it, basic_format_args<basic_format_context<_OutIt, _CharT>> __args) {
	return std::basic_format_context(std::move(__out_it), __args);
	}
	# endif

	using format_context = basic_format_context<back_insert_iterator<__format::__output_buffer<char>>, char>;
	# ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
	using wformat_context = basic_format_context< back_insert_iterator<__format::__output_buffer<wchar_t>>, wchar_t>;
	# endif

	template <class _OutIt, class _CharT>
	requires output_iterator<_OutIt, const _CharT&>
	class
	// clang-format off
	_LIBCPP_TEMPLATE_VIS
	_LIBCPP_PREFERRED_NAME(format_context)
	_LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wformat_context))
	// clang-format on
	basic_format_context {
	public:
	using iterator = _OutIt;
	using char_type = _CharT;
	template <class _Tp>
	using formatter_type = formatter<_Tp, _CharT>;

	_LIBCPP_HIDE_FROM_ABI basic_format_arg<basic_format_context> arg(size_t __id) const noexcept {
	return __args_.get(__id);
	}
	# ifndef _LIBCPP_HAS_NO_LOCALIZATION
	_LIBCPP_HIDE_FROM_ABI std::locale locale() {
	if (!__loc_)
	__loc_ = std::locale{};
	return *__loc_;
	}
	# endif
	_LIBCPP_HIDE_FROM_ABI iterator out() { return std::move(__out_it_); }
	_LIBCPP_HIDE_FROM_ABI void advance_to(iterator __it) { __out_it_ = std::move(__it); }

	private:
	iterator __out_it_;
	basic_format_args<basic_format_context> __args_;
	# ifndef _LIBCPP_HAS_NO_LOCALIZATION

	// The Standard doesn't specify how the locale is stored.
	// [format.context]/6
	// std::locale locale();
	// Returns: The locale passed to the formatting function if the latter
	// takes one, and std::locale() otherwise.
	// This is done by storing the locale of the constructor in this optional. If
	// locale() is called and the optional has no value the value will be created.
	// This allows the implementation to lazily create the locale.
	// TODO FMT Validate whether lazy creation is the best solution.
	optional<std::locale> __loc_;

	template <class _OtherOutIt, class _OtherCharT>
	friend _LIBCPP_HIDE_FROM_ABI basic_format_context<_OtherOutIt, _OtherCharT> __format_context_create(
	_OtherOutIt, basic_format_args<basic_format_context<_OtherOutIt, _OtherCharT>>, optional<std::locale>&&);

	// Note: the Standard doesn't specify the required constructors.
	_LIBCPP_HIDE_FROM_ABI explicit basic_format_context(
	_OutIt __out_it, basic_format_args<basic_format_context> __args, optional<std::locale>&& __loc)
	: __out_it_(std::move(__out_it)), __args_(__args), __loc_(std::move(__loc)) {}
	# else
	template <class _OtherOutIt, class _OtherCharT>
	friend _LIBCPP_HIDE_FROM_ABI basic_format_context<_OtherOutIt, _OtherCharT>
	__format_context_create(_OtherOutIt, basic_format_args<basic_format_context<_OtherOutIt, _OtherCharT>>);

	_LIBCPP_HIDE_FROM_ABI explicit basic_format_context(_OutIt __out_it, basic_format_args<basic_format_context> __args)
	: __out_it_(std::move(__out_it)), __args_(__args) {}
	# endif
	};

	// A specialization for __retarget_buffer
	//
	// See __retarget_buffer for the motivation for this specialization.
	//
	// This context holds a reference to the instance of the basic_format_context
	// that is retargeted. It converts a formatting argument when it is requested
	// during formatting. It is expected that the usage of the arguments is rare so
	// the lookups are not expected to be used often. An alternative would be to
	// convert all elements during construction.
	//
	// The elements of the retargets context are only used when an underlying
	// formatter uses a locale specific formatting or an formatting argument is
	// part for the format spec. For example
	// format("{:256:{}}", input, 8);
	// Here the width of an element in input is determined dynamically.
	// Note when the top-level element has no width the retargeting is not needed.
	template <class _CharT>
	class _LIBCPP_TEMPLATE_VIS basic_format_context<typename __format::__retarget_buffer<_CharT>::__iterator, _CharT> {
	public:
	using iterator = typename __format::__retarget_buffer<_CharT>::__iterator;
	using char_type = _CharT;
	template <class _Tp>
	using formatter_type = formatter<_Tp, _CharT>;

	template <class _Context>
	_LIBCPP_HIDE_FROM_ABI explicit basic_format_context(iterator __out_it, _Context& __ctx)
	: __out_it_(std::move(__out_it)),
	# ifndef _LIBCPP_HAS_NO_LOCALIZATION
	__loc_([](void* __c) { return static_cast<_Context*>(__c)->locale(); }),
	# endif
	__ctx_(std::addressof(__ctx)),
	__arg_([](void* __c, size_t __id) {
	auto __visitor = [&](auto __arg) -> basic_format_arg<basic_format_context> {
	if constexpr (same_as<decltype(__arg), monostate>)
	return {};
	else if constexpr (same_as<decltype(__arg), typename basic_format_arg<_Context>::handle>)
	// At the moment it's not possible for formatting to use a re-targeted handle.
	// TODO FMT add this when support is needed.
	std::__throw_format_error("Re-targeting handle not supported");
	else
	return basic_format_arg<basic_format_context>{
	__format::__determine_arg_t<basic_format_context, decltype(__arg)>(),
	__basic_format_arg_value<basic_format_context>(__arg)};
	};
	# if _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
	return static_cast<_Context*>(__c)->arg(__id).visit(std::move(__visitor));
	# else
	_LIBCPP_SUPPRESS_DEPRECATED_PUSH
	return std::visit_format_arg(std::move(__visitor), static_cast<_Context*>(__c)->arg(__id));
	_LIBCPP_SUPPRESS_DEPRECATED_POP
	# endif // _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
	}) {
	}

	_LIBCPP_HIDE_FROM_ABI basic_format_arg<basic_format_context> arg(size_t __id) const noexcept {
	return __arg_(__ctx_, __id);
	}
	# ifndef _LIBCPP_HAS_NO_LOCALIZATION
	_LIBCPP_HIDE_FROM_ABI std::locale locale() { return __loc_(__ctx_); }
	# endif
	_LIBCPP_HIDE_FROM_ABI iterator out() { return std::move(__out_it_); }
	_LIBCPP_HIDE_FROM_ABI void advance_to(iterator __it) { __out_it_ = std::move(__it); }

	private:
	iterator __out_it_;

	# ifndef _LIBCPP_HAS_NO_LOCALIZATION
	std::locale (__loc_)(void __ctx);
	# endif

	void* __ctx_;
	basic_format_arg<basic_format_context> (__arg_)(void __ctx, size_t __id);
	};

	_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(basic_format_context);
	#endif //_LIBCPP_STD_VER >= 20

	_LIBCPP_END_NAMESPACE_STD

	_LIBCPP_POP_MACROS

	#endif // _LIBCPP___FORMAT_FORMAT_CONTEXT_H