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

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