|
| 1 | +// Formatting library for C++ - dynamic format arguments |
| 2 | +// |
| 3 | +// Copyright (c) 2012 - present, Victor Zverovich |
| 4 | +// All rights reserved. |
| 5 | +// |
| 6 | +// For the license information refer to format.h. |
| 7 | + |
| 8 | +#ifndef FMT_ARGS_H_ |
| 9 | +#define FMT_ARGS_H_ |
| 10 | + |
| 11 | +#include <functional> // std::reference_wrapper |
| 12 | +#include <memory> // std::unique_ptr |
| 13 | +#include <vector> |
| 14 | + |
| 15 | +#include "core.h" |
| 16 | + |
| 17 | +FMT_BEGIN_NAMESPACE |
| 18 | + |
| 19 | +namespace detail { |
| 20 | + |
| 21 | +template <typename T> struct is_reference_wrapper : std::false_type {}; |
| 22 | +template <typename T> |
| 23 | +struct is_reference_wrapper<std::reference_wrapper<T>> : std::true_type {}; |
| 24 | + |
| 25 | +template <typename T> const T& unwrap(const T& v) { return v; } |
| 26 | +template <typename T> const T& unwrap(const std::reference_wrapper<T>& v) { |
| 27 | + return static_cast<const T&>(v); |
| 28 | +} |
| 29 | + |
| 30 | +class dynamic_arg_list { |
| 31 | + // Workaround for clang's -Wweak-vtables. Unlike for regular classes, for |
| 32 | + // templates it doesn't complain about inability to deduce single translation |
| 33 | + // unit for placing vtable. So storage_node_base is made a fake template. |
| 34 | + template <typename = void> struct node { |
| 35 | + virtual ~node() = default; |
| 36 | + std::unique_ptr<node<>> next; |
| 37 | + }; |
| 38 | + |
| 39 | + template <typename T> struct typed_node : node<> { |
| 40 | + T value; |
| 41 | + |
| 42 | + template <typename Arg> |
| 43 | + FMT_CONSTEXPR typed_node(const Arg& arg) : value(arg) {} |
| 44 | + |
| 45 | + template <typename Char> |
| 46 | + FMT_CONSTEXPR typed_node(const basic_string_view<Char>& arg) |
| 47 | + : value(arg.data(), arg.size()) {} |
| 48 | + }; |
| 49 | + |
| 50 | + std::unique_ptr<node<>> head_; |
| 51 | + |
| 52 | + public: |
| 53 | + template <typename T, typename Arg> const T& push(const Arg& arg) { |
| 54 | + auto new_node = std::unique_ptr<typed_node<T>>(new typed_node<T>(arg)); |
| 55 | + auto& value = new_node->value; |
| 56 | + new_node->next = std::move(head_); |
| 57 | + head_ = std::move(new_node); |
| 58 | + return value; |
| 59 | + } |
| 60 | +}; |
| 61 | +} // namespace detail |
| 62 | + |
| 63 | +/** |
| 64 | + \rst |
| 65 | + A dynamic version of `fmt::format_arg_store`. |
| 66 | + It's equipped with a storage to potentially temporary objects which lifetimes |
| 67 | + could be shorter than the format arguments object. |
| 68 | +
|
| 69 | + It can be implicitly converted into `~fmt::basic_format_args` for passing |
| 70 | + into type-erased formatting functions such as `~fmt::vformat`. |
| 71 | + \endrst |
| 72 | + */ |
| 73 | +template <typename Context> |
| 74 | +class dynamic_format_arg_store |
| 75 | +#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409 |
| 76 | + // Workaround a GCC template argument substitution bug. |
| 77 | + : public basic_format_args<Context> |
| 78 | +#endif |
| 79 | +{ |
| 80 | + private: |
| 81 | + using char_type = typename Context::char_type; |
| 82 | + |
| 83 | + template <typename T> struct need_copy { |
| 84 | + static constexpr detail::type mapped_type = |
| 85 | + detail::mapped_type_constant<T, Context>::value; |
| 86 | + |
| 87 | + enum { |
| 88 | + value = !(detail::is_reference_wrapper<T>::value || |
| 89 | + std::is_same<T, basic_string_view<char_type>>::value || |
| 90 | + std::is_same<T, detail::std_string_view<char_type>>::value || |
| 91 | + (mapped_type != detail::type::cstring_type && |
| 92 | + mapped_type != detail::type::string_type && |
| 93 | + mapped_type != detail::type::custom_type)) |
| 94 | + }; |
| 95 | + }; |
| 96 | + |
| 97 | + template <typename T> |
| 98 | + using stored_type = conditional_t< |
| 99 | + std::is_convertible<T, std::basic_string<char_type>>::value && |
| 100 | + !detail::is_reference_wrapper<T>::value, |
| 101 | + std::basic_string<char_type>, T>; |
| 102 | + |
| 103 | + // Storage of basic_format_arg must be contiguous. |
| 104 | + std::vector<basic_format_arg<Context>> data_; |
| 105 | + std::vector<detail::named_arg_info<char_type>> named_info_; |
| 106 | + |
| 107 | + // Storage of arguments not fitting into basic_format_arg must grow |
| 108 | + // without relocation because items in data_ refer to it. |
| 109 | + detail::dynamic_arg_list dynamic_args_; |
| 110 | + |
| 111 | + friend class basic_format_args<Context>; |
| 112 | + |
| 113 | + unsigned long long get_types() const { |
| 114 | + return detail::is_unpacked_bit | data_.size() | |
| 115 | + (named_info_.empty() |
| 116 | + ? 0ULL |
| 117 | + : static_cast<unsigned long long>(detail::has_named_args_bit)); |
| 118 | + } |
| 119 | + |
| 120 | + const basic_format_arg<Context>* data() const { |
| 121 | + return named_info_.empty() ? data_.data() : data_.data() + 1; |
| 122 | + } |
| 123 | + |
| 124 | + template <typename T> void emplace_arg(const T& arg) { |
| 125 | + data_.emplace_back(detail::make_arg<Context>(arg)); |
| 126 | + } |
| 127 | + |
| 128 | + template <typename T> |
| 129 | + void emplace_arg(const detail::named_arg<char_type, T>& arg) { |
| 130 | + if (named_info_.empty()) { |
| 131 | + constexpr const detail::named_arg_info<char_type>* zero_ptr{nullptr}; |
| 132 | + data_.insert(data_.begin(), {zero_ptr, 0}); |
| 133 | + } |
| 134 | + data_.emplace_back(detail::make_arg<Context>(detail::unwrap(arg.value))); |
| 135 | + auto pop_one = [](std::vector<basic_format_arg<Context>>* data) { |
| 136 | + data->pop_back(); |
| 137 | + }; |
| 138 | + std::unique_ptr<std::vector<basic_format_arg<Context>>, decltype(pop_one)> |
| 139 | + guard{&data_, pop_one}; |
| 140 | + named_info_.push_back({arg.name, static_cast<int>(data_.size() - 2u)}); |
| 141 | + data_[0].value_.named_args = {named_info_.data(), named_info_.size()}; |
| 142 | + guard.release(); |
| 143 | + } |
| 144 | + |
| 145 | + public: |
| 146 | + constexpr dynamic_format_arg_store() = default; |
| 147 | + |
| 148 | + /** |
| 149 | + \rst |
| 150 | + Adds an argument into the dynamic store for later passing to a formatting |
| 151 | + function. |
| 152 | +
|
| 153 | + Note that custom types and string types (but not string views) are copied |
| 154 | + into the store dynamically allocating memory if necessary. |
| 155 | +
|
| 156 | + **Example**:: |
| 157 | +
|
| 158 | + fmt::dynamic_format_arg_store<fmt::format_context> store; |
| 159 | + store.push_back(42); |
| 160 | + store.push_back("abc"); |
| 161 | + store.push_back(1.5f); |
| 162 | + std::string result = fmt::vformat("{} and {} and {}", store); |
| 163 | + \endrst |
| 164 | + */ |
| 165 | + template <typename T> void push_back(const T& arg) { |
| 166 | + if (detail::const_check(need_copy<T>::value)) |
| 167 | + emplace_arg(dynamic_args_.push<stored_type<T>>(arg)); |
| 168 | + else |
| 169 | + emplace_arg(detail::unwrap(arg)); |
| 170 | + } |
| 171 | + |
| 172 | + /** |
| 173 | + \rst |
| 174 | + Adds a reference to the argument into the dynamic store for later passing to |
| 175 | + a formatting function. |
| 176 | +
|
| 177 | + **Example**:: |
| 178 | +
|
| 179 | + fmt::dynamic_format_arg_store<fmt::format_context> store; |
| 180 | + char band[] = "Rolling Stones"; |
| 181 | + store.push_back(std::cref(band)); |
| 182 | + band[9] = 'c'; // Changing str affects the output. |
| 183 | + std::string result = fmt::vformat("{}", store); |
| 184 | + // result == "Rolling Scones" |
| 185 | + \endrst |
| 186 | + */ |
| 187 | + template <typename T> void push_back(std::reference_wrapper<T> arg) { |
| 188 | + static_assert( |
| 189 | + need_copy<T>::value, |
| 190 | + "objects of built-in types and string views are always copied"); |
| 191 | + emplace_arg(arg.get()); |
| 192 | + } |
| 193 | + |
| 194 | + /** |
| 195 | + Adds named argument into the dynamic store for later passing to a formatting |
| 196 | + function. ``std::reference_wrapper`` is supported to avoid copying of the |
| 197 | + argument. The name is always copied into the store. |
| 198 | + */ |
| 199 | + template <typename T> |
| 200 | + void push_back(const detail::named_arg<char_type, T>& arg) { |
| 201 | + const char_type* arg_name = |
| 202 | + dynamic_args_.push<std::basic_string<char_type>>(arg.name).c_str(); |
| 203 | + if (detail::const_check(need_copy<T>::value)) { |
| 204 | + emplace_arg( |
| 205 | + fmt::arg(arg_name, dynamic_args_.push<stored_type<T>>(arg.value))); |
| 206 | + } else { |
| 207 | + emplace_arg(fmt::arg(arg_name, arg.value)); |
| 208 | + } |
| 209 | + } |
| 210 | + |
| 211 | + /** Erase all elements from the store */ |
| 212 | + void clear() { |
| 213 | + data_.clear(); |
| 214 | + named_info_.clear(); |
| 215 | + dynamic_args_ = detail::dynamic_arg_list(); |
| 216 | + } |
| 217 | + |
| 218 | + /** |
| 219 | + \rst |
| 220 | + Reserves space to store at least *new_cap* arguments including |
| 221 | + *new_cap_named* named arguments. |
| 222 | + \endrst |
| 223 | + */ |
| 224 | + void reserve(size_t new_cap, size_t new_cap_named) { |
| 225 | + FMT_ASSERT(new_cap >= new_cap_named, |
| 226 | + "Set of arguments includes set of named arguments"); |
| 227 | + data_.reserve(new_cap); |
| 228 | + named_info_.reserve(new_cap_named); |
| 229 | + } |
| 230 | +}; |
| 231 | + |
| 232 | +FMT_END_NAMESPACE |
| 233 | + |
| 234 | +#endif // FMT_ARGS_H_ |
0 commit comments