1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP___FORMAT_FORMAT_ARG_STORE_H
11#define _LIBCPP___FORMAT_FORMAT_ARG_STORE_H
12
13#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
14#  pragma GCC system_header
15#endif
16
17#include <__concepts/arithmetic.h>
18#include <__concepts/same_as.h>
19#include <__config>
20#include <__format/concepts.h>
21#include <__format/format_arg.h>
22#include <__type_traits/conditional.h>
23#include <__type_traits/extent.h>
24#include <__type_traits/remove_const.h>
25#include <string>
26#include <string_view>
27
28_LIBCPP_BEGIN_NAMESPACE_STD
29
30#if _LIBCPP_STD_VER >= 20
31
32namespace __format {
33
34/// \returns The @c __arg_t based on the type of the formatting argument.
35///
36/// \pre \c __formattable<_Tp, typename _Context::char_type>
37template <class _Context, class _Tp>
38consteval __arg_t __determine_arg_t();
39
40// Boolean
41template <class, same_as<bool> _Tp>
42consteval __arg_t __determine_arg_t() {
43  return __arg_t::__boolean;
44}
45
46// Char
47template <class _Context, same_as<typename _Context::char_type> _Tp>
48consteval __arg_t __determine_arg_t() {
49  return __arg_t::__char_type;
50}
51#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
52template <class _Context, class _CharT>
53  requires(same_as<typename _Context::char_type, wchar_t> && same_as<_CharT, char>)
54consteval __arg_t __determine_arg_t() {
55  return __arg_t::__char_type;
56}
57#  endif
58
59// Signed integers
60template <class, __libcpp_signed_integer _Tp>
61consteval __arg_t __determine_arg_t() {
62  if constexpr (sizeof(_Tp) <= sizeof(int))
63    return __arg_t::__int;
64  else if constexpr (sizeof(_Tp) <= sizeof(long long))
65    return __arg_t::__long_long;
66#  ifndef _LIBCPP_HAS_NO_INT128
67  else if constexpr (sizeof(_Tp) == sizeof(__int128_t))
68    return __arg_t::__i128;
69#  endif
70  else
71    static_assert(sizeof(_Tp) == 0, "an unsupported signed integer was used");
72}
73
74// Unsigned integers
75template <class, __libcpp_unsigned_integer _Tp>
76consteval __arg_t __determine_arg_t() {
77  if constexpr (sizeof(_Tp) <= sizeof(unsigned))
78    return __arg_t::__unsigned;
79  else if constexpr (sizeof(_Tp) <= sizeof(unsigned long long))
80    return __arg_t::__unsigned_long_long;
81#  ifndef _LIBCPP_HAS_NO_INT128
82  else if constexpr (sizeof(_Tp) == sizeof(__uint128_t))
83    return __arg_t::__u128;
84#  endif
85  else
86    static_assert(sizeof(_Tp) == 0, "an unsupported unsigned integer was used");
87}
88
89// Floating-point
90template <class, same_as<float> _Tp>
91consteval __arg_t __determine_arg_t() {
92  return __arg_t::__float;
93}
94template <class, same_as<double> _Tp>
95consteval __arg_t __determine_arg_t() {
96  return __arg_t::__double;
97}
98template <class, same_as<long double> _Tp>
99consteval __arg_t __determine_arg_t() {
100  return __arg_t::__long_double;
101}
102
103// Char pointer
104template <class _Context, class _Tp>
105  requires(same_as<typename _Context::char_type*, _Tp> || same_as<const typename _Context::char_type*, _Tp>)
106consteval __arg_t __determine_arg_t() {
107  return __arg_t::__const_char_type_ptr;
108}
109
110// Char array
111template <class _Context, class _Tp>
112  requires(is_array_v<_Tp> && same_as<_Tp, typename _Context::char_type[extent_v<_Tp>]>)
113consteval __arg_t __determine_arg_t() {
114  return __arg_t::__string_view;
115}
116
117// String view
118template <class _Context, class _Tp>
119  requires(same_as<typename _Context::char_type, typename _Tp::value_type> &&
120           same_as<_Tp, basic_string_view<typename _Tp::value_type, typename _Tp::traits_type>>)
121consteval __arg_t __determine_arg_t() {
122  return __arg_t::__string_view;
123}
124
125// String
126template <class _Context, class _Tp>
127  requires(
128      same_as<typename _Context::char_type, typename _Tp::value_type> &&
129      same_as<_Tp, basic_string<typename _Tp::value_type, typename _Tp::traits_type, typename _Tp::allocator_type>>)
130consteval __arg_t __determine_arg_t() {
131  return __arg_t::__string_view;
132}
133
134// Pointers
135template <class, class _Ptr>
136  requires(same_as<_Ptr, void*> || same_as<_Ptr, const void*> || same_as<_Ptr, nullptr_t>)
137consteval __arg_t __determine_arg_t() {
138  return __arg_t::__ptr;
139}
140
141// Handle
142//
143// Note this version can't be constrained avoiding ambiguous overloads.
144// That means it can be instantiated by disabled formatters. To solve this, a
145// constrained version for not formattable formatters is added.
146template <class _Context, class _Tp>
147consteval __arg_t __determine_arg_t() {
148  return __arg_t::__handle;
149}
150
151// The overload for not formattable types allows triggering the static
152// assertion below.
153template <class _Context, class _Tp>
154  requires(!__formattable<_Tp, typename _Context::char_type>)
155consteval __arg_t __determine_arg_t() {
156  return __arg_t::__none;
157}
158
159// Pseudo constuctor for basic_format_arg
160//
161// Modeled after template<class T> explicit basic_format_arg(T& v) noexcept;
162// [format.arg]/4-6
163template <class _Context, class _Tp>
164_LIBCPP_HIDE_FROM_ABI basic_format_arg<_Context> __create_format_arg(_Tp& __value) noexcept {
165  using _Dp               = remove_const_t<_Tp>;
166  constexpr __arg_t __arg = __determine_arg_t<_Context, _Dp>();
167  static_assert(__arg != __arg_t::__none, "the supplied type is not formattable");
168
169  static_assert(__formattable_with<_Tp, _Context>);
170
171  // Not all types can be used to directly initialize the
172  // __basic_format_arg_value.  First handle all types needing adjustment, the
173  // final else requires no adjustment.
174  if constexpr (__arg == __arg_t::__char_type)
175
176#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
177    if constexpr (same_as<typename _Context::char_type, wchar_t> && same_as<_Dp, char>)
178      return basic_format_arg<_Context>{__arg, static_cast<wchar_t>(static_cast<unsigned char>(__value))};
179    else
180#  endif
181      return basic_format_arg<_Context>{__arg, __value};
182  else if constexpr (__arg == __arg_t::__int)
183    return basic_format_arg<_Context>{__arg, static_cast<int>(__value)};
184  else if constexpr (__arg == __arg_t::__long_long)
185    return basic_format_arg<_Context>{__arg, static_cast<long long>(__value)};
186  else if constexpr (__arg == __arg_t::__unsigned)
187    return basic_format_arg<_Context>{__arg, static_cast<unsigned>(__value)};
188  else if constexpr (__arg == __arg_t::__unsigned_long_long)
189    return basic_format_arg<_Context>{__arg, static_cast<unsigned long long>(__value)};
190  else if constexpr (__arg == __arg_t::__string_view)
191    // Using std::size on a character array will add the NUL-terminator to the size.
192    if constexpr (is_array_v<_Dp>)
193      return basic_format_arg<_Context>{
194          __arg, basic_string_view<typename _Context::char_type>{__value, extent_v<_Dp> - 1}};
195    else
196      // When the _Traits or _Allocator are different an implicit conversion will
197      // fail.
198      return basic_format_arg<_Context>{
199          __arg, basic_string_view<typename _Context::char_type>{__value.data(), __value.size()}};
200  else if constexpr (__arg == __arg_t::__ptr)
201    return basic_format_arg<_Context>{__arg, static_cast<const void*>(__value)};
202  else if constexpr (__arg == __arg_t::__handle)
203    return basic_format_arg<_Context>{__arg, typename __basic_format_arg_value<_Context>::__handle{__value}};
204  else
205    return basic_format_arg<_Context>{__arg, __value};
206}
207
208template <class _Context, class... _Args>
209_LIBCPP_HIDE_FROM_ABI void
210__create_packed_storage(uint64_t& __types, __basic_format_arg_value<_Context>* __values, _Args&... __args) noexcept {
211  int __shift = 0;
212  (
213      [&] {
214        basic_format_arg<_Context> __arg = __format::__create_format_arg<_Context>(__args);
215        if (__shift != 0)
216          __types |= static_cast<uint64_t>(__arg.__type_) << __shift;
217        else
218          // Assigns the initial value.
219          __types = static_cast<uint64_t>(__arg.__type_);
220        __shift += __packed_arg_t_bits;
221        *__values++ = __arg.__value_;
222      }(),
223      ...);
224}
225
226template <class _Context, class... _Args>
227_LIBCPP_HIDE_FROM_ABI void __store_basic_format_arg(basic_format_arg<_Context>* __data, _Args&... __args) noexcept {
228  ([&] { *__data++ = __format::__create_format_arg<_Context>(__args); }(), ...);
229}
230
231template <class _Context, size_t _Np>
232struct __packed_format_arg_store {
233  __basic_format_arg_value<_Context> __values_[_Np];
234  uint64_t __types_ = 0;
235};
236
237template <class _Context, size_t _Np>
238struct __unpacked_format_arg_store {
239  basic_format_arg<_Context> __args_[_Np];
240};
241
242} // namespace __format
243
244template <class _Context, class... _Args>
245struct _LIBCPP_TEMPLATE_VIS __format_arg_store {
246  _LIBCPP_HIDE_FROM_ABI __format_arg_store(_Args&... __args) noexcept {
247    if constexpr (sizeof...(_Args) != 0) {
248      if constexpr (__format::__use_packed_format_arg_store(sizeof...(_Args)))
249        __format::__create_packed_storage(__storage.__types_, __storage.__values_, __args...);
250      else
251        __format::__store_basic_format_arg<_Context>(__storage.__args_, __args...);
252    }
253  }
254
255  using _Storage =
256      conditional_t<__format::__use_packed_format_arg_store(sizeof...(_Args)),
257                    __format::__packed_format_arg_store<_Context, sizeof...(_Args)>,
258                    __format::__unpacked_format_arg_store<_Context, sizeof...(_Args)>>;
259
260  _Storage __storage;
261};
262
263#endif //_LIBCPP_STD_VER >= 20
264
265_LIBCPP_END_NAMESPACE_STD
266
267#endif // _LIBCPP___FORMAT_FORMAT_ARG_STORE_H
268