| // -*- 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 <__availability> |
| #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 <__format/format_fwd.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_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<_VSTD::locale>&& __loc = nullopt) { |
| return _VSTD::basic_format_context(_VSTD::move(__out_it), __args, _VSTD::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 _VSTD::basic_format_context(_VSTD::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 _VSTD::locale locale() { |
| if (!__loc_) |
| __loc_ = _VSTD::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<_VSTD::locale> __loc_; |
| |
| template <class __OutIt, class __CharT> |
| friend _LIBCPP_HIDE_FROM_ABI basic_format_context<__OutIt, __CharT> |
| __format_context_create(__OutIt, basic_format_args<basic_format_context<__OutIt, __CharT>>, |
| optional<_VSTD::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<_VSTD::locale>&& __loc) |
| : __out_it_(_VSTD::move(__out_it)), __args_(__args), |
| __loc_(_VSTD::move(__loc)) {} |
| #else |
| template <class __OutIt, class __CharT> |
| friend _LIBCPP_HIDE_FROM_ABI basic_format_context<__OutIt, __CharT> |
| __format_context_create(__OutIt, basic_format_args<basic_format_context<__OutIt, __CharT>>); |
| |
| _LIBCPP_HIDE_FROM_ABI |
| explicit basic_format_context(_OutIt __out_it, |
| basic_format_args<basic_format_context> __args) |
| : __out_it_(_VSTD::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) { |
| return std::visit_format_arg( |
| [&](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)}; |
| }, |
| static_cast<_Context*>(__c)->arg(__id)); |
| }) { |
| } |
| |
| _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 _VSTD::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 |
| |
| #endif // _LIBCPP___FORMAT_FORMAT_CONTEXT_H |