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4d8268fbf4
This optimizes the __format_arg_store type to allow a more efficient storage of the basic_format_args. It stores the data in two arrays: - A struct with the tag of the exposition only variant's type and the offset of the element in the data array. Since this array only depends on the type information it's calculated at compile time and can be shared by different instances of this class. - The arguments converted to the types used in the exposition only variant of basic_format_arg. This means the packed data can be directly copied to an element of this variant. The new code uses rvalue reference arguments in preparation for P2418. The handle class also has some changes to prepare for P2418. The real changed for P2418 will be done separately, but these parts make it easier to implement that paper. Some parts of existing test code are removed since they were no longer valid after the changes, but new tests have been added. Implements parts of: - P2418 Add support for std::generator-like types to std::format Completes: - LWG3473 Normative encouragement in non-normative note Depends on D121138 Reviewed By: #libc, vitaut, Mordante Differential Revision: https://reviews.llvm.org/D121514
80 lines
2.4 KiB
C++
80 lines
2.4 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___FORMAT_FORMAT_ARGS_H
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#define _LIBCPP___FORMAT_FORMAT_ARGS_H
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#include <__availability>
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#include <__config>
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#include <__format/format_arg.h>
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#include <__format/format_arg_store.h>
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#include <__format/format_fwd.h>
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#include <cstddef>
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#include <cstdint>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER > 17
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template <class _Context>
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class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT basic_format_args {
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public:
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_LIBCPP_HIDE_FROM_ABI basic_format_args() noexcept = default;
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template <class... _Args>
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_LIBCPP_HIDE_FROM_ABI basic_format_args(const __format_arg_store<_Context, _Args...>& __store) noexcept
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: __size_(sizeof...(_Args)) {
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if constexpr (sizeof...(_Args) != 0) {
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if constexpr (__format::__use_packed_format_arg_store(sizeof...(_Args))) {
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__values_ = __store.__storage.__values_;
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__types_ = __store.__storage.__types_;
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} else
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__args_ = __store.__storage.__args_;
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}
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}
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_LIBCPP_HIDE_FROM_ABI
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basic_format_arg<_Context> get(size_t __id) const noexcept {
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if (__id >= __size_)
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return basic_format_arg<_Context>{};
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if (__format::__use_packed_format_arg_store(__size_))
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return basic_format_arg<_Context>{__format::__get_packed_type(__types_, __id), __values_[__id]};
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return __args_[__id];
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}
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_LIBCPP_HIDE_FROM_ABI size_t __size() const noexcept { return __size_; }
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private:
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size_t __size_{0};
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// [format.args]/5
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// [Note 1: Implementations are encouraged to optimize the representation of
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// basic_format_args for small number of formatting arguments by storing
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// indices of type alternatives separately from values and packing the
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// former. - end note]
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union {
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struct {
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const __basic_format_arg_value<_Context>* __values_;
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uint64_t __types_;
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};
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const basic_format_arg<_Context>* __args_;
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};
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};
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#endif //_LIBCPP_STD_VER > 17
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___FORMAT_FORMAT_ARGS_H
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