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 // Formatting library for C++ - dynamic argument lists
 //
 // 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_
 
 #ifndef FMT_MODULE
 #  include <functional>  // std::reference_wrapper
 #  include <memory>      // std::unique_ptr
 #  include <vector>
 #endif
 
 #include "format.h"  // std_string_view
 
 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> auto unwrap(const T& v) -> const T& { return v; }
 template <typename T>
 auto unwrap(const std::reference_wrapper<T>& v) -> const T& {
   return static_cast<const T&>(v);
 }
 
 // node is defined outside dynamic_arg_list to workaround a C2504 bug in MSVC
 // 2022 (v17.10.0).
 //
 // 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 node is made a fake template.
 template <typename = void> struct node {
   virtual ~node() = default;
   std::unique_ptr<node<>> next;
 };
 
 class dynamic_arg_list {
   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> auto push(const Arg& arg) -> const T& {
     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
 
 /**
  * A dynamic list of formatting arguments with storage.
  *
  * It can be implicitly converted into `fmt::basic_format_args` for passing
  * into type-erased formatting functions such as `fmt::vformat`.
  */
 template <typename Context> class dynamic_format_arg_store {
  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, char_type>::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_t = 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>;
 
   auto data() const -> const basic_format_arg<Context>* {
     return named_info_.empty() ? data_.data() : data_.data() + 1;
   }
 
   template <typename T> void emplace_arg(const T& arg) {
     data_.emplace_back(arg);
   }
 
   template <typename T>
   void emplace_arg(const detail::named_arg<char_type, T>& arg) {
     if (named_info_.empty())
       data_.insert(data_.begin(), basic_format_arg<Context>(nullptr, 0));
     data_.emplace_back(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] = {named_info_.data(), named_info_.size()};
     guard.release();
   }
 
  public:
   constexpr dynamic_format_arg_store() = default;
 
   operator basic_format_args<Context>() const {
     return basic_format_args<Context>(data(), static_cast<int>(data_.size()),
                                       !named_info_.empty());
   }
 
   /**
    * 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);
    */
   template <typename T> void push_back(const T& arg) {
     if (detail::const_check(need_copy<T>::value))
       emplace_arg(dynamic_args_.push<stored_t<T>>(arg));
     else
       emplace_arg(detail::unwrap(arg));
   }
 
   /**
    * 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"
    */
   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_t<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_ = {};
   }
 
   /// Reserves space to store at least `new_cap` arguments including
   /// `new_cap_named` named arguments.
   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);
   }
 
   /// Returns the number of elements in the store.
   size_t size() const noexcept { return data_.size(); }
 };
 
 FMT_END_NAMESPACE
 
 #endif  // FMT_ARGS_H_

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