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https://github.com/fmtlib/fmt.git
synced 2025-12-02 15:19:41 +01:00
Minor tweaks for dynamic_format_arg_store
This commit is contained in:
Victor Zverovich
@@ -1205,6 +1205,62 @@ template <bool IS_PACKED, typename Context, typename T,
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inline basic_format_arg<Context> make_arg(const T& value) {
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return make_arg<Context>(value);
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}
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template <typename T, typename Char> struct is_string_view : std::false_type {};
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template <typename Char>
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struct is_string_view<basic_string_view<Char>, Char> : std::true_type {};
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template <typename Char>
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struct is_string_view<std_string_view<Char>, Char> : std::true_type {};
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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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class dyn_arg_storage {
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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 storage_node_base {
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using owning_ptr = std::unique_ptr<storage_node_base<>>;
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virtual ~storage_node_base() = default;
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owning_ptr next;
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};
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template <typename T> struct storage_node : storage_node_base<> {
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T value;
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template <typename Arg>
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FMT_CONSTEXPR storage_node(const Arg& arg, owning_ptr&& next) : value(arg) {
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this->next = std::move(next); // Must be initialised after value.
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}
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template <typename Char>
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FMT_CONSTEXPR storage_node(const basic_string_view<Char>& arg,
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owning_ptr&& next)
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: value(arg.data(), arg.size()) {
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this->next = std::move(next); // Must be initialised after value.
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}
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};
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storage_node_base<>::owning_ptr head_{nullptr};
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public:
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dyn_arg_storage() = default;
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dyn_arg_storage(const dyn_arg_storage&) = delete;
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dyn_arg_storage(dyn_arg_storage&&) = default;
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dyn_arg_storage& operator=(const dyn_arg_storage&) = delete;
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dyn_arg_storage& operator=(dyn_arg_storage&&) = default;
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template <typename T, typename Arg> const T& push(const Arg& arg) {
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auto node = new storage_node<T>(arg, std::move(head_));
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head_.reset(node);
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return node->value;
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}
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};
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} // namespace internal
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// Formatting context.
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@@ -1314,7 +1370,108 @@ inline format_arg_store<Context, Args...> make_format_args(
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return {args...};
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}
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template <typename Context> class dynamic_format_arg_store;
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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 lifetime
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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 < 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_dyn_copy {
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static constexpr internal::type mapped_type =
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internal::mapped_type_constant<T, Context>::value;
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using type = std::integral_constant<
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bool, !(internal::is_reference_wrapper<T>::value ||
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internal::is_string_view<T, char_type>::value ||
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(mapped_type != internal::type::cstring_type &&
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mapped_type != internal::type::string_type &&
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mapped_type != internal::type::custom_type &&
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mapped_type != internal::type::named_arg_type))>;
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};
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template <typename T>
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using stored_type = conditional_t<internal::is_string<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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// 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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internal::dyn_arg_storage storage_;
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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 internal::is_unpacked_bit | data_.size();
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}
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template <typename T> void emplace_arg(const T& arg) {
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data_.emplace_back(internal::make_arg<Context>(arg));
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}
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public:
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dynamic_format_arg_store() = default;
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~dynamic_format_arg_store() = default;
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dynamic_format_arg_store(const dynamic_format_arg_store&) = delete;
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dynamic_format_arg_store& operator=(const dynamic_format_arg_store&) = delete;
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dynamic_format_arg_store(dynamic_format_arg_store&&) = default;
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dynamic_format_arg_store& operator=(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 formating
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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 with dynamic memory (in addition to resizing vector).
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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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static_assert(
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!std::is_base_of<internal::named_arg_base<char_type>, T>::value,
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"named arguments are not supported yet");
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if (internal::const_check(need_dyn_copy<T>::type::value))
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emplace_arg(storage_.push<stored_type<T>>(arg));
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else
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emplace_arg(arg);
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}
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/**
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Adds a reference to the argument into the dynamic store for later passing to
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a formating function.
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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_dyn_copy<T>::type::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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/**
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\rst
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@@ -1639,180 +1796,6 @@ inline void print(const S& format_str, Args&&... args) {
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internal::make_args_checked<Args...>(format_str, args...));
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#endif
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}
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namespace internal {
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template <typename T, typename Char> struct is_string_view : std::false_type {};
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template <typename Char>
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struct is_string_view<basic_string_view<Char>, Char> : std::true_type {};
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template <typename Char>
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struct is_string_view<std_string_view<Char>, Char> : std::true_type {};
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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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class dyn_arg_storage {
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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 storage_node_base {
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using owning_ptr = std::unique_ptr<storage_node_base<>>;
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virtual ~storage_node_base() = default;
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owning_ptr next;
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};
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template <typename T> struct storage_node : storage_node_base<> {
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T value;
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template <typename Arg>
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FMT_CONSTEXPR storage_node(const Arg& arg, owning_ptr&& next) : value{arg} {
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// Must be initialised after value_
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this->next = std::move(next);
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}
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template <typename Char>
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FMT_CONSTEXPR storage_node(const basic_string_view<Char>& arg,
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owning_ptr&& next)
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: value{arg.data(), arg.size()} {
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// Must be initialised after value
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this->next = std::move(next);
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}
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};
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storage_node_base<>::owning_ptr head_{nullptr};
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public:
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dyn_arg_storage() = default;
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dyn_arg_storage(const dyn_arg_storage&) = delete;
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dyn_arg_storage(dyn_arg_storage&&) = default;
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dyn_arg_storage& operator=(const dyn_arg_storage&) = delete;
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dyn_arg_storage& operator=(dyn_arg_storage&&) = default;
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template <typename T, typename Arg> const T& push(const Arg& arg) {
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auto node = new storage_node<T>{arg, std::move(head_)};
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head_.reset(node);
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return node->value;
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}
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};
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} // namespace internal
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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 lifetime
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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 < 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_dyn_copy {
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static constexpr internal::type mapped_type =
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internal::mapped_type_constant<T, Context>::value;
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// static_assert(
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// mapped_type != internal::type::named_arg_type,
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// "Bug indicator. Named arguments must be processed separately");
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using type = std::integral_constant<
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bool, !(internal::is_reference_wrapper<T>::value ||
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internal::is_string_view<T, char_type>::value ||
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(mapped_type != internal::type::cstring_type &&
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mapped_type != internal::type::string_type &&
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mapped_type != internal::type::custom_type &&
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mapped_type != internal::type::named_arg_type))>;
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};
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template <typename T>
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using stored_type = conditional_t<internal::is_string<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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// Required by basic_format_args::args_ which is just a pointer.
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std::vector<basic_format_arg<Context>> data_;
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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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internal::dyn_arg_storage storage_;
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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 internal::is_unpacked_bit | data_.size();
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}
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template <typename T> void emplace_arg(const T& arg) {
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data_.emplace_back(internal::make_arg<Context>(arg));
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}
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public:
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dynamic_format_arg_store() = default;
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~dynamic_format_arg_store() = default;
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dynamic_format_arg_store(const dynamic_format_arg_store&) = delete;
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dynamic_format_arg_store& operator=(const dynamic_format_arg_store&) = delete;
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dynamic_format_arg_store(dynamic_format_arg_store&&) = default;
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dynamic_format_arg_store& operator=(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 formating
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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 with dynamic memory (in addition to resizing vector).
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**Example**::
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#include <fmt/core.h>
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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("abc1");
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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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static_assert(
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!std::is_base_of<internal::named_arg_base<char_type>, T>::value,
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"Named arguments are not supported yet");
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if (internal::const_check(need_dyn_copy<T>::type::value))
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emplace_arg(storage_.push<stored_type<T>>(arg));
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else
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emplace_arg(arg);
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}
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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 formating
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function without copying into type-erasing list.
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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_dyn_copy<T>::type::value,
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"Primitive types and string views directly supported by "
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"basic_format_arg. Passing them by reference is not allowed");
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emplace_arg(arg.get());
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}
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};
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FMT_END_NAMESPACE
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#endif // FMT_CORE_H_
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