src/vendor/fmt/printf.h

   1 // Formatting library for C++ - legacy printf implementation
   2 //
   3 // Copyright (c) 2012 - 2016, Victor Zverovich
   4 // All rights reserved.
   5 //
   6 // For the license information refer to format.h.
   7
   8 #ifndef FMT_PRINTF_H_
   9 #define FMT_PRINTF_H_
  10
  11 #include <algorithm>  // std::max
  12 #include <limits>     // std::numeric_limits
  13
  14 #include "format.h"
  15
  16 FMT_BEGIN_NAMESPACE
  17 FMT_MODULE_EXPORT_BEGIN
  18
  19 template <typename T> struct printf_formatter { printf_formatter() = delete; };
  20
  21 template <typename Char>
  22 class basic_printf_parse_context : public basic_format_parse_context<Char> {
  23   using basic_format_parse_context<Char>::basic_format_parse_context;
  24 };
  25
  26 template <typename OutputIt, typename Char> class basic_printf_context {
  27  private:
  28   OutputIt out_;
  29   basic_format_args<basic_printf_context> args_;
  30
  31  public:
  32   using char_type = Char;
  33   using format_arg = basic_format_arg<basic_printf_context>;
  34   using parse_context_type = basic_printf_parse_context<Char>;
  35   template <typename T> using formatter_type = printf_formatter<T>;
  36
  37   /**
  38     \rst
  39     Constructs a ``printf_context`` object. References to the arguments are
  40     stored in the context object so make sure they have appropriate lifetimes.
  41     \endrst
  42    */
  43   basic_printf_context(OutputIt out,
  44                        basic_format_args<basic_printf_context> args)
  45       : out_(out), args_(args) {}
  46
  47   OutputIt out() { return out_; }
  48   void advance_to(OutputIt it) { out_ = it; }
  49
  50   detail::locale_ref locale() { return {}; }
  51
  52   format_arg arg(int id) const { return args_.get(id); }
  53
  54   FMT_CONSTEXPR void on_error(const char* message) {
  55     detail::error_handler().on_error(message);
  56   }
  57 };
  58
  59 FMT_BEGIN_DETAIL_NAMESPACE
  60
  61 // Checks if a value fits in int - used to avoid warnings about comparing
  62 // signed and unsigned integers.
  63 template <bool IsSigned> struct int_checker {
  64   template <typename T> static bool fits_in_int(T value) {
  65     unsigned max = max_value<int>();
  66     return value <= max;
  67   }
  68   static bool fits_in_int(bool) { return true; }
  69 };
  70
  71 template <> struct int_checker<true> {
  72   template <typename T> static bool fits_in_int(T value) {
  73     return value >= (std::numeric_limits<int>::min)() &&
  74            value <= max_value<int>();
  75   }
  76   static bool fits_in_int(int) { return true; }
  77 };
  78
  79 class printf_precision_handler {
  80  public:
  81   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  82   int operator()(T value) {
  83     if (!int_checker<std::numeric_limits<T>::is_signed>::fits_in_int(value))
  84       FMT_THROW(format_error("number is too big"));
  85     return (std::max)(static_cast<int>(value), 0);
  86   }
  87
  88   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
  89   int operator()(T) {
  90     FMT_THROW(format_error("precision is not integer"));
  91     return 0;
  92   }
  93 };
  94
  95 // An argument visitor that returns true iff arg is a zero integer.
  96 class is_zero_int {
  97  public:
  98   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  99   bool operator()(T value) {
 100     return value == 0;
 101   }
 102
 103   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
 104   bool operator()(T) {
 105     return false;
 106   }
 107 };
 108
 109 template <typename T> struct make_unsigned_or_bool : std::make_unsigned<T> {};
 110
 111 template <> struct make_unsigned_or_bool<bool> { using type = bool; };
 112
 113 template <typename T, typename Context> class arg_converter {
 114  private:
 115   using char_type = typename Context::char_type;
 116
 117   basic_format_arg<Context>& arg_;
 118   char_type type_;
 119
 120  public:
 121   arg_converter(basic_format_arg<Context>& arg, char_type type)
 122       : arg_(arg), type_(type) {}
 123
 124   void operator()(bool value) {
 125     if (type_ != 's') operator()<bool>(value);
 126   }
 127
 128   template <typename U, FMT_ENABLE_IF(std::is_integral<U>::value)>
 129   void operator()(U value) {
 130     bool is_signed = type_ == 'd' || type_ == 'i';
 131     using target_type = conditional_t<std::is_same<T, void>::value, U, T>;
 132     if (const_check(sizeof(target_type) <= sizeof(int))) {
 133       // Extra casts are used to silence warnings.
 134       if (is_signed) {
 135         arg_ = detail::make_arg<Context>(
 136             static_cast<int>(static_cast<target_type>(value)));
 137       } else {
 138         using unsigned_type = typename make_unsigned_or_bool<target_type>::type;
 139         arg_ = detail::make_arg<Context>(
 140             static_cast<unsigned>(static_cast<unsigned_type>(value)));
 141       }
 142     } else {
 143       if (is_signed) {
 144         // glibc's printf doesn't sign extend arguments of smaller types:
 145         //   std::printf("%lld", -42);  // prints "4294967254"
 146         // but we don't have to do the same because it's a UB.
 147         arg_ = detail::make_arg<Context>(static_cast<long long>(value));
 148       } else {
 149         arg_ = detail::make_arg<Context>(
 150             static_cast<typename make_unsigned_or_bool<U>::type>(value));
 151       }
 152     }
 153   }
 154
 155   template <typename U, FMT_ENABLE_IF(!std::is_integral<U>::value)>
 156   void operator()(U) {}  // No conversion needed for non-integral types.
 157 };
 158
 159 // Converts an integer argument to T for printf, if T is an integral type.
 160 // If T is void, the argument is converted to corresponding signed or unsigned
 161 // type depending on the type specifier: 'd' and 'i' - signed, other -
 162 // unsigned).
 163 template <typename T, typename Context, typename Char>
 164 void convert_arg(basic_format_arg<Context>& arg, Char type) {
 165   visit_format_arg(arg_converter<T, Context>(arg, type), arg);
 166 }
 167
 168 // Converts an integer argument to char for printf.
 169 template <typename Context> class char_converter {
 170  private:
 171   basic_format_arg<Context>& arg_;
 172
 173  public:
 174   explicit char_converter(basic_format_arg<Context>& arg) : arg_(arg) {}
 175
 176   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
 177   void operator()(T value) {
 178     arg_ = detail::make_arg<Context>(
 179         static_cast<typename Context::char_type>(value));
 180   }
 181
 182   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
 183   void operator()(T) {}  // No conversion needed for non-integral types.
 184 };
 185
 186 // An argument visitor that return a pointer to a C string if argument is a
 187 // string or null otherwise.
 188 template <typename Char> struct get_cstring {
 189   template <typename T> const Char* operator()(T) { return nullptr; }
 190   const Char* operator()(const Char* s) { return s; }
 191 };
 192
 193 // Checks if an argument is a valid printf width specifier and sets
 194 // left alignment if it is negative.
 195 template <typename Char> class printf_width_handler {
 196  private:
 197   using format_specs = basic_format_specs<Char>;
 198
 199   format_specs& specs_;
 200
 201  public:
 202   explicit printf_width_handler(format_specs& specs) : specs_(specs) {}
 203
 204   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
 205   unsigned operator()(T value) {
 206     auto width = static_cast<uint32_or_64_or_128_t<T>>(value);
 207     if (detail::is_negative(value)) {
 208       specs_.align = align::left;
 209       width = 0 - width;
 210     }
 211     unsigned int_max = max_value<int>();
 212     if (width > int_max) FMT_THROW(format_error("number is too big"));
 213     return static_cast<unsigned>(width);
 214   }
 215
 216   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
 217   unsigned operator()(T) {
 218     FMT_THROW(format_error("width is not integer"));
 219     return 0;
 220   }
 221 };
 222
 223 // The ``printf`` argument formatter.
 224 template <typename OutputIt, typename Char>
 225 class printf_arg_formatter : public arg_formatter<Char> {
 226  private:
 227   using base = arg_formatter<Char>;
 228   using context_type = basic_printf_context<OutputIt, Char>;
 229   using format_specs = basic_format_specs<Char>;
 230
 231   context_type& context_;
 232
 233   OutputIt write_null_pointer(bool is_string = false) {
 234     auto s = this->specs;
 235     s.type = presentation_type::none;
 236     return write_bytes(this->out, is_string ? "(null)" : "(nil)", s);
 237   }
 238
 239  public:
 240   printf_arg_formatter(OutputIt iter, format_specs& s, context_type& ctx)
 241       : base{iter, s, locale_ref()}, context_(ctx) {}
 242
 243   OutputIt operator()(monostate value) { return base::operator()(value); }
 244
 245   template <typename T, FMT_ENABLE_IF(detail::is_integral<T>::value)>
 246   OutputIt operator()(T value) {
 247     // MSVC2013 fails to compile separate overloads for bool and Char so use
 248     // std::is_same instead.
 249     if (std::is_same<T, Char>::value) {
 250       format_specs fmt_specs = this->specs;
 251       if (fmt_specs.type != presentation_type::none &&
 252           fmt_specs.type != presentation_type::chr) {
 253         return (*this)(static_cast<int>(value));
 254       }
 255       fmt_specs.sign = sign::none;
 256       fmt_specs.alt = false;
 257       fmt_specs.fill[0] = ' ';  // Ignore '0' flag for char types.
 258       // align::numeric needs to be overwritten here since the '0' flag is
 259       // ignored for non-numeric types
 260       if (fmt_specs.align == align::none || fmt_specs.align == align::numeric)
 261         fmt_specs.align = align::right;
 262       return write<Char>(this->out, static_cast<Char>(value), fmt_specs);
 263     }
 264     return base::operator()(value);
 265   }
 266
 267   template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
 268   OutputIt operator()(T value) {
 269     return base::operator()(value);
 270   }
 271
 272   /** Formats a null-terminated C string. */
 273   OutputIt operator()(const char* value) {
 274     if (value) return base::operator()(value);
 275     return write_null_pointer(this->specs.type != presentation_type::pointer);
 276   }
 277
 278   /** Formats a null-terminated wide C string. */
 279   OutputIt operator()(const wchar_t* value) {
 280     if (value) return base::operator()(value);
 281     return write_null_pointer(this->specs.type != presentation_type::pointer);
 282   }
 283
 284   OutputIt operator()(basic_string_view<Char> value) {
 285     return base::operator()(value);
 286   }
 287
 288   /** Formats a pointer. */
 289   OutputIt operator()(const void* value) {
 290     return value ? base::operator()(value) : write_null_pointer();
 291   }
 292
 293   /** Formats an argument of a custom (user-defined) type. */
 294   OutputIt operator()(typename basic_format_arg<context_type>::handle handle) {
 295     auto parse_ctx =
 296         basic_printf_parse_context<Char>(basic_string_view<Char>());
 297     handle.format(parse_ctx, context_);
 298     return this->out;
 299   }
 300 };
 301
 302 template <typename Char>
 303 void parse_flags(basic_format_specs<Char>& specs, const Char*& it,
 304                  const Char* end) {
 305   for (; it != end; ++it) {
 306     switch (*it) {
 307     case '-':
 308       specs.align = align::left;
 309       break;
 310     case '+':
 311       specs.sign = sign::plus;
 312       break;
 313     case '0':
 314       specs.fill[0] = '0';
 315       break;
 316     case ' ':
 317       if (specs.sign != sign::plus) {
 318         specs.sign = sign::space;
 319       }
 320       break;
 321     case '#':
 322       specs.alt = true;
 323       break;
 324     default:
 325       return;
 326     }
 327   }
 328 }
 329
 330 template <typename Char, typename GetArg>
 331 int parse_header(const Char*& it, const Char* end,
 332                  basic_format_specs<Char>& specs, GetArg get_arg) {
 333   int arg_index = -1;
 334   Char c = *it;
 335   if (c >= '0' && c <= '9') {
 336     // Parse an argument index (if followed by '$') or a width possibly
 337     // preceded with '0' flag(s).
 338     int value = parse_nonnegative_int(it, end, -1);
 339     if (it != end && *it == '$') {  // value is an argument index
 340       ++it;
 341       arg_index = value != -1 ? value : max_value<int>();
 342     } else {
 343       if (c == '0') specs.fill[0] = '0';
 344       if (value != 0) {
 345         // Nonzero value means that we parsed width and don't need to
 346         // parse it or flags again, so return now.
 347         if (value == -1) FMT_THROW(format_error("number is too big"));
 348         specs.width = value;
 349         return arg_index;
 350       }
 351     }
 352   }
 353   parse_flags(specs, it, end);
 354   // Parse width.
 355   if (it != end) {
 356     if (*it >= '0' && *it <= '9') {
 357       specs.width = parse_nonnegative_int(it, end, -1);
 358       if (specs.width == -1) FMT_THROW(format_error("number is too big"));
 359     } else if (*it == '*') {
 360       ++it;
 361       specs.width = static_cast<int>(visit_format_arg(
 362           detail::printf_width_handler<Char>(specs), get_arg(-1)));
 363     }
 364   }
 365   return arg_index;
 366 }
 367
 368 template <typename Char, typename Context>
 369 void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
 370              basic_format_args<Context> args) {
 371   using OutputIt = buffer_appender<Char>;
 372   auto out = OutputIt(buf);
 373   auto context = basic_printf_context<OutputIt, Char>(out, args);
 374   auto parse_ctx = basic_printf_parse_context<Char>(format);
 375
 376   // Returns the argument with specified index or, if arg_index is -1, the next
 377   // argument.
 378   auto get_arg = [&](int arg_index) {
 379     if (arg_index < 0)
 380       arg_index = parse_ctx.next_arg_id();
 381     else
 382       parse_ctx.check_arg_id(--arg_index);
 383     return detail::get_arg(context, arg_index);
 384   };
 385
 386   const Char* start = parse_ctx.begin();
 387   const Char* end = parse_ctx.end();
 388   auto it = start;
 389   while (it != end) {
 390     if (!detail::find<false, Char>(it, end, '%', it)) {
 391       it = end;  // detail::find leaves it == nullptr if it doesn't find '%'
 392       break;
 393     }
 394     Char c = *it++;
 395     if (it != end && *it == c) {
 396       out = detail::write(
 397           out, basic_string_view<Char>(start, detail::to_unsigned(it - start)));
 398       start = ++it;
 399       continue;
 400     }
 401     out = detail::write(out, basic_string_view<Char>(
 402                                  start, detail::to_unsigned(it - 1 - start)));
 403
 404     basic_format_specs<Char> specs;
 405     specs.align = align::right;
 406
 407     // Parse argument index, flags and width.
 408     int arg_index = parse_header(it, end, specs, get_arg);
 409     if (arg_index == 0) parse_ctx.on_error("argument not found");
 410
 411     // Parse precision.
 412     if (it != end && *it == '.') {
 413       ++it;
 414       c = it != end ? *it : 0;
 415       if ('0' <= c && c <= '9') {
 416         specs.precision = parse_nonnegative_int(it, end, 0);
 417       } else if (c == '*') {
 418         ++it;
 419         specs.precision = static_cast<int>(
 420             visit_format_arg(detail::printf_precision_handler(), get_arg(-1)));
 421       } else {
 422         specs.precision = 0;
 423       }
 424     }
 425
 426     auto arg = get_arg(arg_index);
 427     // For d, i, o, u, x, and X conversion specifiers, if a precision is
 428     // specified, the '0' flag is ignored
 429     if (specs.precision >= 0 && arg.is_integral())
 430       specs.fill[0] =
 431           ' ';  // Ignore '0' flag for non-numeric types or if '-' present.
 432     if (specs.precision >= 0 && arg.type() == detail::type::cstring_type) {
 433       auto str = visit_format_arg(detail::get_cstring<Char>(), arg);
 434       auto str_end = str + specs.precision;
 435       auto nul = std::find(str, str_end, Char());
 436       arg = detail::make_arg<basic_printf_context<OutputIt, Char>>(
 437           basic_string_view<Char>(
 438               str, detail::to_unsigned(nul != str_end ? nul - str
 439                                                       : specs.precision)));
 440     }
 441     if (specs.alt && visit_format_arg(detail::is_zero_int(), arg))
 442       specs.alt = false;
 443     if (specs.fill[0] == '0') {
 444       if (arg.is_arithmetic() && specs.align != align::left)
 445         specs.align = align::numeric;
 446       else
 447         specs.fill[0] = ' ';  // Ignore '0' flag for non-numeric types or if '-'
 448                               // flag is also present.
 449     }
 450
 451     // Parse length and convert the argument to the required type.
 452     c = it != end ? *it++ : 0;
 453     Char t = it != end ? *it : 0;
 454     using detail::convert_arg;
 455     switch (c) {
 456     case 'h':
 457       if (t == 'h') {
 458         ++it;
 459         t = it != end ? *it : 0;
 460         convert_arg<signed char>(arg, t);
 461       } else {
 462         convert_arg<short>(arg, t);
 463       }
 464       break;
 465     case 'l':
 466       if (t == 'l') {
 467         ++it;
 468         t = it != end ? *it : 0;
 469         convert_arg<long long>(arg, t);
 470       } else {
 471         convert_arg<long>(arg, t);
 472       }
 473       break;
 474     case 'j':
 475       convert_arg<intmax_t>(arg, t);
 476       break;
 477     case 'z':
 478       convert_arg<size_t>(arg, t);
 479       break;
 480     case 't':
 481       convert_arg<std::ptrdiff_t>(arg, t);
 482       break;
 483     case 'L':
 484       // printf produces garbage when 'L' is omitted for long double, no
 485       // need to do the same.
 486       break;
 487     default:
 488       --it;
 489       convert_arg<void>(arg, c);
 490     }
 491
 492     // Parse type.
 493     if (it == end) FMT_THROW(format_error("invalid format string"));
 494     char type = static_cast<char>(*it++);
 495     if (arg.is_integral()) {
 496       // Normalize type.
 497       switch (type) {
 498       case 'i':
 499       case 'u':
 500         type = 'd';
 501         break;
 502       case 'c':
 503         visit_format_arg(
 504             detail::char_converter<basic_printf_context<OutputIt, Char>>(arg),
 505             arg);
 506         break;
 507       }
 508     }
 509     specs.type = parse_presentation_type(type);
 510     if (specs.type == presentation_type::none)
 511       parse_ctx.on_error("invalid type specifier");
 512
 513     start = it;
 514
 515     // Format argument.
 516     out = visit_format_arg(
 517         detail::printf_arg_formatter<OutputIt, Char>(out, specs, context), arg);
 518   }
 519   detail::write(out, basic_string_view<Char>(start, to_unsigned(it - start)));
 520 }
 521 FMT_END_DETAIL_NAMESPACE
 522
 523 template <typename Char>
 524 using basic_printf_context_t =
 525     basic_printf_context<detail::buffer_appender<Char>, Char>;
 526
 527 using printf_context = basic_printf_context_t<char>;
 528 using wprintf_context = basic_printf_context_t<wchar_t>;
 529
 530 using printf_args = basic_format_args<printf_context>;
 531 using wprintf_args = basic_format_args<wprintf_context>;
 532
 533 /**
 534   \rst
 535   Constructs an `~fmt::format_arg_store` object that contains references to
 536   arguments and can be implicitly converted to `~fmt::printf_args`.
 537   \endrst
 538  */
 539 template <typename... T>
 540 inline auto make_printf_args(const T&... args)
 541     -> format_arg_store<printf_context, T...> {
 542   return {args...};
 543 }
 544
 545 /**
 546   \rst
 547   Constructs an `~fmt::format_arg_store` object that contains references to
 548   arguments and can be implicitly converted to `~fmt::wprintf_args`.
 549   \endrst
 550  */
 551 template <typename... T>
 552 inline auto make_wprintf_args(const T&... args)
 553     -> format_arg_store<wprintf_context, T...> {
 554   return {args...};
 555 }
 556
 557 template <typename S, typename Char = char_t<S>>
 558 inline auto vsprintf(
 559     const S& fmt,
 560     basic_format_args<basic_printf_context_t<type_identity_t<Char>>> args)
 561     -> std::basic_string<Char> {
 562   basic_memory_buffer<Char> buffer;
 563   vprintf(buffer, detail::to_string_view(fmt), args);
 564   return to_string(buffer);
 565 }
 566
 567 /**
 568   \rst
 569   Formats arguments and returns the result as a string.
 570
 571   **Example**::
 572
 573     std::string message = fmt::sprintf("The answer is %d", 42);
 574   \endrst
 575 */
 576 template <typename S, typename... T,
 577           typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
 578 inline auto sprintf(const S& fmt, const T&... args) -> std::basic_string<Char> {
 579   using context = basic_printf_context_t<Char>;
 580   return vsprintf(detail::to_string_view(fmt),
 581                   fmt::make_format_args<context>(args...));
 582 }
 583
 584 template <typename S, typename Char = char_t<S>>
 585 inline auto vfprintf(
 586     std::FILE* f, const S& fmt,
 587     basic_format_args<basic_printf_context_t<type_identity_t<Char>>> args)
 588     -> int {
 589   basic_memory_buffer<Char> buffer;
 590   vprintf(buffer, detail::to_string_view(fmt), args);
 591   size_t size = buffer.size();
 592   return std::fwrite(buffer.data(), sizeof(Char), size, f) < size
 593              ? -1
 594              : static_cast<int>(size);
 595 }
 596
 597 /**
 598   \rst
 599   Prints formatted data to the file *f*.
 600
 601   **Example**::
 602
 603     fmt::fprintf(stderr, "Don't %s!", "panic");
 604   \endrst
 605  */
 606 template <typename S, typename... T, typename Char = char_t<S>>
 607 inline auto fprintf(std::FILE* f, const S& fmt, const T&... args) -> int {
 608   using context = basic_printf_context_t<Char>;
 609   return vfprintf(f, detail::to_string_view(fmt),
 610                   fmt::make_format_args<context>(args...));
 611 }
 612
 613 template <typename S, typename Char = char_t<S>>
 614 inline auto vprintf(
 615     const S& fmt,
 616     basic_format_args<basic_printf_context_t<type_identity_t<Char>>> args)
 617     -> int {
 618   return vfprintf(stdout, detail::to_string_view(fmt), args);
 619 }
 620
 621 /**
 622   \rst
 623   Prints formatted data to ``stdout``.
 624
 625   **Example**::
 626
 627     fmt::printf("Elapsed time: %.2f seconds", 1.23);
 628   \endrst
 629  */
 630 template <typename S, typename... T, FMT_ENABLE_IF(detail::is_string<S>::value)>
 631 inline auto printf(const S& fmt, const T&... args) -> int {
 632   return vprintf(
 633       detail::to_string_view(fmt),
 634       fmt::make_format_args<basic_printf_context_t<char_t<S>>>(args...));
 635 }
 636
 637 FMT_MODULE_EXPORT_END
 638 FMT_END_NAMESPACE
 639
 640 #endif  // FMT_PRINTF_H_