234 lines
7.3 KiB
C++
Executable file
234 lines
7.3 KiB
C++
Executable file
// Formatting library for C++ - dynamic format arguments
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//
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// Copyright (c) 2012 - present, Victor Zverovich
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// All rights reserved.
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//
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// For the license information refer to format.h.
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#ifndef FMT_ARGS_H_
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#define FMT_ARGS_H_
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#include <functional> // std::reference_wrapper
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#include <memory> // std::unique_ptr
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#include <vector>
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#include "core.h"
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FMT_BEGIN_NAMESPACE
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namespace detail {
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template <typename T> struct is_reference_wrapper : std::false_type {};
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template <typename T>
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struct is_reference_wrapper<std::reference_wrapper<T>> : std::true_type {};
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template <typename T> const T& unwrap(const T& v) { return v; }
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template <typename T> const T& unwrap(const std::reference_wrapper<T>& v) {
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return static_cast<const T&>(v);
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}
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class dynamic_arg_list {
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// Workaround for clang's -Wweak-vtables. Unlike for regular classes, for
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// templates it doesn't complain about inability to deduce single translation
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// unit for placing vtable. So storage_node_base is made a fake template.
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template <typename = void> struct node {
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virtual ~node() = default;
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std::unique_ptr<node<>> next;
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};
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template <typename T> struct typed_node : node<> {
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T value;
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template <typename Arg>
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FMT_CONSTEXPR typed_node(const Arg& arg) : value(arg) {}
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template <typename Char>
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FMT_CONSTEXPR typed_node(const basic_string_view<Char>& arg)
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: value(arg.data(), arg.size()) {}
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};
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std::unique_ptr<node<>> head_;
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public:
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template <typename T, typename Arg> const T& push(const Arg& arg) {
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auto new_node = std::unique_ptr<typed_node<T>>(new typed_node<T>(arg));
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auto& value = new_node->value;
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new_node->next = std::move(head_);
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head_ = std::move(new_node);
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return value;
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}
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};
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} // namespace detail
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/**
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\rst
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A dynamic version of `fmt::format_arg_store`.
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It's equipped with a storage to potentially temporary objects which lifetimes
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could be shorter than the format arguments object.
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It can be implicitly converted into `~fmt::basic_format_args` for passing
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into type-erased formatting functions such as `~fmt::vformat`.
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\endrst
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*/
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template <typename Context>
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class dynamic_format_arg_store
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#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
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// Workaround a GCC template argument substitution bug.
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: public basic_format_args<Context>
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#endif
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{
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private:
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using char_type = typename Context::char_type;
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template <typename T> struct need_copy {
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static constexpr detail::type mapped_type =
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detail::mapped_type_constant<T, Context>::value;
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enum {
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value = !(detail::is_reference_wrapper<T>::value ||
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std::is_same<T, basic_string_view<char_type>>::value ||
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std::is_same<T, detail::std_string_view<char_type>>::value ||
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(mapped_type != detail::type::cstring_type &&
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mapped_type != detail::type::string_type &&
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mapped_type != detail::type::custom_type))
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};
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};
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template <typename T>
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using stored_type = conditional_t<detail::is_string<T>::value &&
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!has_formatter<T, Context>::value &&
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!detail::is_reference_wrapper<T>::value,
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std::basic_string<char_type>, T>;
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// Storage of basic_format_arg must be contiguous.
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std::vector<basic_format_arg<Context>> data_;
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std::vector<detail::named_arg_info<char_type>> named_info_;
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// Storage of arguments not fitting into basic_format_arg must grow
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// without relocation because items in data_ refer to it.
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detail::dynamic_arg_list dynamic_args_;
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friend class basic_format_args<Context>;
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unsigned long long get_types() const {
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return detail::is_unpacked_bit | data_.size() |
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(named_info_.empty()
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? 0ULL
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: static_cast<unsigned long long>(detail::has_named_args_bit));
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}
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const basic_format_arg<Context>* data() const {
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return named_info_.empty() ? data_.data() : data_.data() + 1;
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}
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template <typename T> void emplace_arg(const T& arg) {
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data_.emplace_back(detail::make_arg<Context>(arg));
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}
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template <typename T>
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void emplace_arg(const detail::named_arg<char_type, T>& arg) {
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if (named_info_.empty()) {
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constexpr const detail::named_arg_info<char_type>* zero_ptr{nullptr};
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data_.insert(data_.begin(), {zero_ptr, 0});
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}
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data_.emplace_back(detail::make_arg<Context>(detail::unwrap(arg.value)));
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auto pop_one = [](std::vector<basic_format_arg<Context>>* data) {
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data->pop_back();
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};
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std::unique_ptr<std::vector<basic_format_arg<Context>>, decltype(pop_one)>
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guard{&data_, pop_one};
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named_info_.push_back({arg.name, static_cast<int>(data_.size() - 2u)});
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data_[0].value_.named_args = {named_info_.data(), named_info_.size()};
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guard.release();
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}
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public:
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constexpr dynamic_format_arg_store() = default;
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/**
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\rst
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Adds an argument into the dynamic store for later passing to a formatting
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function.
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Note that custom types and string types (but not string views) are copied
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into the store dynamically allocating memory if necessary.
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**Example**::
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fmt::dynamic_format_arg_store<fmt::format_context> store;
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store.push_back(42);
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store.push_back("abc");
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store.push_back(1.5f);
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std::string result = fmt::vformat("{} and {} and {}", store);
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\endrst
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*/
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template <typename T> void push_back(const T& arg) {
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if (detail::const_check(need_copy<T>::value))
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emplace_arg(dynamic_args_.push<stored_type<T>>(arg));
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else
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emplace_arg(detail::unwrap(arg));
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}
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/**
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\rst
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Adds a reference to the argument into the dynamic store for later passing to
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a formatting function.
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**Example**::
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fmt::dynamic_format_arg_store<fmt::format_context> store;
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char band[] = "Rolling Stones";
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store.push_back(std::cref(band));
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band[9] = 'c'; // Changing str affects the output.
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std::string result = fmt::vformat("{}", store);
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// result == "Rolling Scones"
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\endrst
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*/
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template <typename T> void push_back(std::reference_wrapper<T> arg) {
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static_assert(
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need_copy<T>::value,
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"objects of built-in types and string views are always copied");
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emplace_arg(arg.get());
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}
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/**
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Adds named argument into the dynamic store for later passing to a formatting
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function. ``std::reference_wrapper`` is supported to avoid copying of the
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argument. The name is always copied into the store.
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*/
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template <typename T>
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void push_back(const detail::named_arg<char_type, T>& arg) {
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const char_type* arg_name =
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dynamic_args_.push<std::basic_string<char_type>>(arg.name).c_str();
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if (detail::const_check(need_copy<T>::value)) {
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emplace_arg(
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fmt::arg(arg_name, dynamic_args_.push<stored_type<T>>(arg.value)));
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} else {
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emplace_arg(fmt::arg(arg_name, arg.value));
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}
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}
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/** Erase all elements from the store */
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void clear() {
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data_.clear();
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named_info_.clear();
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dynamic_args_ = detail::dynamic_arg_list();
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}
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/**
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\rst
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Reserves space to store at least *new_cap* arguments including
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*new_cap_named* named arguments.
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\endrst
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*/
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void reserve(size_t new_cap, size_t new_cap_named) {
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FMT_ASSERT(new_cap >= new_cap_named,
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"Set of arguments includes set of named arguments");
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data_.reserve(new_cap);
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named_info_.reserve(new_cap_named);
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}
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};
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FMT_END_NAMESPACE
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#endif // FMT_ARGS_H_
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