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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___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 > 17
template <class _OutIt, class _CharT>
requires output_iterator<_OutIt, const _CharT&>
class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT 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_AVAILABILITY_FORMAT
_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 _LIBCPP_AVAILABILITY_FORMAT
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 > 17
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___FORMAT_FORMAT_CONTEXT_H
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