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 #include <ostream>
  14
  15 #include "format.h"
  16
  17 FMT_BEGIN_NAMESPACE
  18 FMT_MODULE_EXPORT_BEGIN
  19
  20 template <typename T> struct printf_formatter { printf_formatter() = delete; };
  21
  22 template <typename Char>
  23 class basic_printf_parse_context : public basic_format_parse_context<Char> {
  24   using basic_format_parse_context<Char>::basic_format_parse_context;
  25 };
  26
  27 template <typename OutputIt, typename Char> class basic_printf_context {
  28  private:
  29   OutputIt out_;
  30   basic_format_args<basic_printf_context> args_;
  31
  32  public:
  33   using char_type = Char;
  34   using format_arg = basic_format_arg<basic_printf_context>;
  35   using parse_context_type = basic_printf_parse_context<Char>;
  36   template <typename T> using formatter_type = printf_formatter<T>;
  37
  38   /**
  39     \rst
  40     Constructs a ``printf_context`` object. References to the arguments are
  41     stored in the context object so make sure they have appropriate lifetimes.
  42     \endrst
  43    */
  44   basic_printf_context(OutputIt out,
  45                        basic_format_args<basic_printf_context> args)
  46       : out_(out), args_(args) {}
  47
  48   OutputIt out() { return out_; }
  49   void advance_to(OutputIt it) { out_ = it; }
  50
  51   detail::locale_ref locale() { return {}; }
  52
  53   format_arg arg(int id) const { return args_.get(id); }
  54
  55   FMT_CONSTEXPR void on_error(const char* message) {
  56     detail::error_handler().on_error(message);
  57   }
  58 };
  59
  60 FMT_BEGIN_DETAIL_NAMESPACE
  61
  62 // Checks if a value fits in int - used to avoid warnings about comparing
  63 // signed and unsigned integers.
  64 template <bool IsSigned> struct int_checker {
  65   template <typename T> static bool fits_in_int(T value) {
  66     unsigned max = max_value<int>();
  67     return value <= max;
  68   }
  69   static bool fits_in_int(bool) { return true; }
  70 };
  71
  72 template <> struct int_checker<true> {
  73   template <typename T> static bool fits_in_int(T value) {
  74     return value >= (std::numeric_limits<int>::min)() &&
  75            value <= max_value<int>();
  76   }
  77   static bool fits_in_int(int) { return true; }
  78 };
  79
  80 class printf_precision_handler {
  81  public:
  82   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  83   int operator()(T value) {
  84     if (!int_checker<std::numeric_limits<T>::is_signed>::fits_in_int(value))
  85       FMT_THROW(format_error("number is too big"));
  86     return (std::max)(static_cast<int>(value), 0);
  87   }
  88
  89   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
  90   int operator()(T) {
  91     FMT_THROW(format_error("precision is not integer"));
  92     return 0;
  93   }
  94 };
  95
  96 // An argument visitor that returns true iff arg is a zero integer.
  97 class is_zero_int {
  98  public:
  99   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
 100   bool operator()(T value) {
 101     return value == 0;
 102   }
 103
 104   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
 105   bool operator()(T) {
 106     return false;
 107   }
 108 };
 109
 110 template <typename T> struct make_unsigned_or_bool : std::make_unsigned<T> {};
 111
 112 template <> struct make_unsigned_or_bool<bool> { using type = bool; };
 113
 114 template <typename T, typename Context> class arg_converter {
 115  private:
 116   using char_type = typename Context::char_type;
 117
 118   basic_format_arg<Context>& arg_;
 119   char_type type_;
 120
 121  public:
 122   arg_converter(basic_format_arg<Context>& arg, char_type type)
 123       : arg_(arg), type_(type) {}
 124
 125   void operator()(bool value) {
 126     if (type_ != 's') operator()<bool>(value);
 127   }
 128
 129   template <typename U, FMT_ENABLE_IF(std::is_integral<U>::value)>
 130   void operator()(U value) {
 131     bool is_signed = type_ == 'd' || type_ == 'i';
 132     using target_type = conditional_t<std::is_same<T, void>::value, U, T>;
 133     if (const_check(sizeof(target_type) <= sizeof(int))) {
 134       // Extra casts are used to silence warnings.
 135       if (is_signed) {
 136         arg_ = detail::make_arg<Context>(
 137             static_cast<int>(static_cast<target_type>(value)));
 138       } else {
 139         using unsigned_type = typename make_unsigned_or_bool<target_type>::type;
 140         arg_ = detail::make_arg<Context>(
 141             static_cast<unsigned>(static_cast<unsigned_type>(value)));
 142       }
 143     } else {
 144       if (is_signed) {
 145         // glibc's printf doesn't sign extend arguments of smaller types:
 146         //   std::printf("%lld", -42);  // prints "4294967254"
 147         // but we don't have to do the same because it's a UB.
 148         arg_ = detail::make_arg<Context>(static_cast<long long>(value));
 149       } else {
 150         arg_ = detail::make_arg<Context>(
 151             static_cast<typename make_unsigned_or_bool<U>::type>(value));
 152       }
 153     }
 154   }
 155
 156   template <typename U, FMT_ENABLE_IF(!std::is_integral<U>::value)>
 157   void operator()(U) {}  // No conversion needed for non-integral types.
 158 };
 159
 160 // Converts an integer argument to T for printf, if T is an integral type.
 161 // If T is void, the argument is converted to corresponding signed or unsigned
 162 // type depending on the type specifier: 'd' and 'i' - signed, other -
 163 // unsigned).
 164 template <typename T, typename Context, typename Char>
 165 void convert_arg(basic_format_arg<Context>& arg, Char type) {
 166   visit_format_arg(arg_converter<T, Context>(arg, type), arg);
 167 }
 168
 169 // Converts an integer argument to char for printf.
 170 template <typename Context> class char_converter {
 171  private:
 172   basic_format_arg<Context>& arg_;
 173
 174  public:
 175   explicit char_converter(basic_format_arg<Context>& arg) : arg_(arg) {}
 176
 177   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
 178   void operator()(T value) {
 179     arg_ = detail::make_arg<Context>(
 180         static_cast<typename Context::char_type>(value));
 181   }
 182
 183   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
 184   void operator()(T) {}  // No conversion needed for non-integral types.
 185 };
 186
 187 // An argument visitor that return a pointer to a C string if argument is a
 188 // string or null otherwise.
 189 template <typename Char> struct get_cstring {
 190   template <typename T> const Char* operator()(T) { return nullptr; }
 191   const Char* operator()(const Char* s) { return s; }
 192 };
 193
 194 // Checks if an argument is a valid printf width specifier and sets
 195 // left alignment if it is negative.
 196 template <typename Char> class printf_width_handler {
 197  private:
 198   using format_specs = basic_format_specs<Char>;
 199
 200   format_specs& specs_;
 201
 202  public:
 203   explicit printf_width_handler(format_specs& specs) : specs_(specs) {}
 204
 205   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
 206   unsigned operator()(T value) {
 207     auto width = static_cast<uint32_or_64_or_128_t<T>>(value);
 208     if (detail::is_negative(value)) {
 209       specs_.align = align::left;
 210       width = 0 - width;
 211     }
 212     unsigned int_max = max_value<int>();
 213     if (width > int_max) FMT_THROW(format_error("number is too big"));
 214     return static_cast<unsigned>(width);
 215   }
 216
 217   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
 218   unsigned operator()(T) {
 219     FMT_THROW(format_error("width is not integer"));
 220     return 0;
 221   }
 222 };
 223
 224 // The ``printf`` argument formatter.
 225 template <typename OutputIt, typename Char>
 226 class printf_arg_formatter : public arg_formatter<Char> {
 227  private:
 228   using base = arg_formatter<Char>;
 229   using context_type = basic_printf_context<OutputIt, Char>;
 230   using format_specs = basic_format_specs<Char>;
 231
 232   context_type& context_;
 233
 234   OutputIt write_null_pointer(bool is_string = false) {
 235     auto s = this->specs;
 236     s.type = presentation_type::none;
 237     return write_bytes(this->out, is_string ? "(null)" : "(nil)", s);
 238   }
 239
 240  public:
 241   printf_arg_formatter(OutputIt iter, format_specs& s, context_type& ctx)
 242       : base{iter, s, locale_ref()}, context_(ctx) {}
 243
 244   OutputIt operator()(monostate value) { return base::operator()(value); }
 245
 246   template <typename T, FMT_ENABLE_IF(detail::is_integral<T>::value)>
 247   OutputIt operator()(T value) {
 248     // MSVC2013 fails to compile separate overloads for bool and Char so use
 249     // std::is_same instead.
 250     if (std::is_same<T, Char>::value) {
 251       format_specs fmt_specs = this->specs;
 252       if (fmt_specs.type != presentation_type::none &&
 253           fmt_specs.type != presentation_type::chr) {
 254         return (*this)(static_cast<int>(value));
 255       }
 256       fmt_specs.sign = sign::none;
 257       fmt_specs.alt = false;
 258       fmt_specs.fill[0] = ' ';  // Ignore '0' flag for char types.
 259       // align::numeric needs to be overwritten here since the '0' flag is
 260       // ignored for non-numeric types
 261       if (fmt_specs.align == align::none || fmt_specs.align == align::numeric)
 262         fmt_specs.align = align::right;
 263       return write<Char>(this->out, static_cast<Char>(value), fmt_specs);
 264     }
 265     return base::operator()(value);
 266   }
 267
 268   template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
 269   OutputIt operator()(T value) {
 270     return base::operator()(value);
 271   }
 272
 273   /** Formats a null-terminated C string. */
 274   OutputIt operator()(const char* value) {
 275     if (value) return base::operator()(value);
 276     return write_null_pointer(this->specs.type != presentation_type::pointer);
 277   }
 278
 279   /** Formats a null-terminated wide C string. */
 280   OutputIt operator()(const wchar_t* value) {
 281     if (value) return base::operator()(value);
 282     return write_null_pointer(this->specs.type != presentation_type::pointer);
 283   }
 284
 285   OutputIt operator()(basic_string_view<Char> value) {
 286     return base::operator()(value);
 287   }
 288
 289   /** Formats a pointer. */
 290   OutputIt operator()(const void* value) {
 291     return value ? base::operator()(value) : write_null_pointer();
 292   }
 293
 294   /** Formats an argument of a custom (user-defined) type. */
 295   OutputIt operator()(typename basic_format_arg<context_type>::handle handle) {
 296     auto parse_ctx =
 297         basic_printf_parse_context<Char>(basic_string_view<Char>());
 298     handle.format(parse_ctx, context_);
 299     return this->out;
 300   }
 301 };
 302
 303 template <typename Char>
 304 void parse_flags(basic_format_specs<Char>& specs, const Char*& it,
 305                  const Char* end) {
 306   for (; it != end; ++it) {
 307     switch (*it) {
 308     case '-':
 309       specs.align = align::left;
 310       break;
 311     case '+':
 312       specs.sign = sign::plus;
 313       break;
 314     case '0':
 315       specs.fill[0] = '0';
 316       break;
 317     case ' ':
 318       if (specs.sign != sign::plus) {
 319         specs.sign = sign::space;
 320       }
 321       break;
 322     case '#':
 323       specs.alt = true;
 324       break;
 325     default:
 326       return;
 327     }
 328   }
 329 }
 330
 331 template <typename Char, typename GetArg>
 332 int parse_header(const Char*& it, const Char* end,
 333                  basic_format_specs<Char>& specs, GetArg get_arg) {
 334   int arg_index = -1;
 335   Char c = *it;
 336   if (c >= '0' && c <= '9') {
 337     // Parse an argument index (if followed by '$') or a width possibly
 338     // preceded with '0' flag(s).
 339     int value = parse_nonnegative_int(it, end, -1);
 340     if (it != end && *it == '$') {  // value is an argument index
 341       ++it;
 342       arg_index = value != -1 ? value : max_value<int>();
 343     } else {
 344       if (c == '0') specs.fill[0] = '0';
 345       if (value != 0) {
 346         // Nonzero value means that we parsed width and don't need to
 347         // parse it or flags again, so return now.
 348         if (value == -1) FMT_THROW(format_error("number is too big"));
 349         specs.width = value;
 350         return arg_index;
 351       }
 352     }
 353   }
 354   parse_flags(specs, it, end);
 355   // Parse width.
 356   if (it != end) {
 357     if (*it >= '0' && *it <= '9') {
 358       specs.width = parse_nonnegative_int(it, end, -1);
 359       if (specs.width == -1) FMT_THROW(format_error("number is too big"));
 360     } else if (*it == '*') {
 361       ++it;
 362       specs.width = static_cast<int>(visit_format_arg(
 363           detail::printf_width_handler<Char>(specs), get_arg(-1)));
 364     }
 365   }
 366   return arg_index;
 367 }
 368
 369 template <typename Char, typename Context>
 370 void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
 371              basic_format_args<Context> args) {
 372   using OutputIt = buffer_appender<Char>;
 373   auto out = OutputIt(buf);
 374   auto context = basic_printf_context<OutputIt, Char>(out, args);
 375   auto parse_ctx = basic_printf_parse_context<Char>(format);
 376
 377   // Returns the argument with specified index or, if arg_index is -1, the next
 378   // argument.
 379   auto get_arg = [&](int arg_index) {
 380     if (arg_index < 0)
 381       arg_index = parse_ctx.next_arg_id();
 382     else
 383       parse_ctx.check_arg_id(--arg_index);
 384     return detail::get_arg(context, arg_index);
 385   };
 386
 387   const Char* start = parse_ctx.begin();
 388   const Char* end = parse_ctx.end();
 389   auto it = start;
 390   while (it != end) {
 391     if (!detail::find<false, Char>(it, end, '%', it)) {
 392       it = end;  // detail::find leaves it == nullptr if it doesn't find '%'
 393       break;
 394     }
 395     Char c = *it++;
 396     if (it != end && *it == c) {
 397       out = detail::write(
 398           out, basic_string_view<Char>(start, detail::to_unsigned(it - start)));
 399       start = ++it;
 400       continue;
 401     }
 402     out = detail::write(out, basic_string_view<Char>(
 403                                  start, detail::to_unsigned(it - 1 - start)));
 404
 405     basic_format_specs<Char> specs;
 406     specs.align = align::right;
 407
 408     // Parse argument index, flags and width.
 409     int arg_index = parse_header(it, end, specs, get_arg);
 410     if (arg_index == 0) parse_ctx.on_error("argument not found");
 411
 412     // Parse precision.
 413     if (it != end && *it == '.') {
 414       ++it;
 415       c = it != end ? *it : 0;
 416       if ('0' <= c && c <= '9') {
 417         specs.precision = parse_nonnegative_int(it, end, 0);
 418       } else if (c == '*') {
 419         ++it;
 420         specs.precision = static_cast<int>(
 421             visit_format_arg(detail::printf_precision_handler(), get_arg(-1)));
 422       } else {
 423         specs.precision = 0;
 424       }
 425     }
 426
 427     auto arg = get_arg(arg_index);
 428     // For d, i, o, u, x, and X conversion specifiers, if a precision is
 429     // specified, the '0' flag is ignored
 430     if (specs.precision >= 0 && arg.is_integral())
 431       specs.fill[0] =
 432           ' ';  // Ignore '0' flag for non-numeric types or if '-' present.
 433     if (specs.precision >= 0 && arg.type() == detail::type::cstring_type) {
 434       auto str = visit_format_arg(detail::get_cstring<Char>(), arg);
 435       auto str_end = str + specs.precision;
 436       auto nul = std::find(str, str_end, Char());
 437       arg = detail::make_arg<basic_printf_context<OutputIt, Char>>(
 438           basic_string_view<Char>(
 439               str, detail::to_unsigned(nul != str_end ? nul - str
 440                                                       : specs.precision)));
 441     }
 442     if (specs.alt && visit_format_arg(detail::is_zero_int(), arg))
 443       specs.alt = false;
 444     if (specs.fill[0] == '0') {
 445       if (arg.is_arithmetic() && specs.align != align::left)
 446         specs.align = align::numeric;
 447       else
 448         specs.fill[0] = ' ';  // Ignore '0' flag for non-numeric types or if '-'
 449                               // flag is also present.
 450     }
 451
 452     // Parse length and convert the argument to the required type.
 453     c = it != end ? *it++ : 0;
 454     Char t = it != end ? *it : 0;
 455     using detail::convert_arg;
 456     switch (c) {
 457     case 'h':
 458       if (t == 'h') {
 459         ++it;
 460         t = it != end ? *it : 0;
 461         convert_arg<signed char>(arg, t);
 462       } else {
 463         convert_arg<short>(arg, t);
 464       }
 465       break;
 466     case 'l':
 467       if (t == 'l') {
 468         ++it;
 469         t = it != end ? *it : 0;
 470         convert_arg<long long>(arg, t);
 471       } else {
 472         convert_arg<long>(arg, t);
 473       }
 474       break;
 475     case 'j':
 476       convert_arg<intmax_t>(arg, t);
 477       break;
 478     case 'z':
 479       convert_arg<size_t>(arg, t);
 480       break;
 481     case 't':
 482       convert_arg<std::ptrdiff_t>(arg, t);
 483       break;
 484     case 'L':
 485       // printf produces garbage when 'L' is omitted for long double, no
 486       // need to do the same.
 487       break;
 488     default:
 489       --it;
 490       convert_arg<void>(arg, c);
 491     }
 492
 493     // Parse type.
 494     if (it == end) FMT_THROW(format_error("invalid format string"));
 495     char type = static_cast<char>(*it++);
 496     if (arg.is_integral()) {
 497       // Normalize type.
 498       switch (type) {
 499       case 'i':
 500       case 'u':
 501         type = 'd';
 502         break;
 503       case 'c':
 504         visit_format_arg(
 505             detail::char_converter<basic_printf_context<OutputIt, Char>>(arg),
 506             arg);
 507         break;
 508       }
 509     }
 510     specs.type = parse_presentation_type(type);
 511     if (specs.type == presentation_type::none)
 512       parse_ctx.on_error("invalid type specifier");
 513
 514     start = it;
 515
 516     // Format argument.
 517     out = visit_format_arg(
 518         detail::printf_arg_formatter<OutputIt, Char>(out, specs, context), arg);
 519   }
 520   detail::write(out, basic_string_view<Char>(start, to_unsigned(it - start)));
 521 }
 522 FMT_END_DETAIL_NAMESPACE
 523
 524 template <typename Char>
 525 using basic_printf_context_t =
 526     basic_printf_context<detail::buffer_appender<Char>, Char>;
 527
 528 using printf_context = basic_printf_context_t<char>;
 529 using wprintf_context = basic_printf_context_t<wchar_t>;
 530
 531 using printf_args = basic_format_args<printf_context>;
 532 using wprintf_args = basic_format_args<wprintf_context>;
 533
 534 /**
 535   \rst
 536   Constructs an `~fmt::format_arg_store` object that contains references to
 537   arguments and can be implicitly converted to `~fmt::printf_args`.
 538   \endrst
 539  */
 540 template <typename... T>
 541 inline auto make_printf_args(const T&... args)
 542     -> format_arg_store<printf_context, T...> {
 543   return {args...};
 544 }
 545
 546 /**
 547   \rst
 548   Constructs an `~fmt::format_arg_store` object that contains references to
 549   arguments and can be implicitly converted to `~fmt::wprintf_args`.
 550   \endrst
 551  */
 552 template <typename... T>
 553 inline auto make_wprintf_args(const T&... args)
 554     -> format_arg_store<wprintf_context, T...> {
 555   return {args...};
 556 }
 557
 558 template <typename S, typename Char = char_t<S>>
 559 inline auto vsprintf(
 560     const S& fmt,
 561     basic_format_args<basic_printf_context_t<type_identity_t<Char>>> args)
 562     -> std::basic_string<Char> {
 563   basic_memory_buffer<Char> buffer;
 564   vprintf(buffer, to_string_view(fmt), args);
 565   return to_string(buffer);
 566 }
 567
 568 /**
 569   \rst
 570   Formats arguments and returns the result as a string.
 571
 572   **Example**::
 573
 574     std::string message = fmt::sprintf("The answer is %d", 42);
 575   \endrst
 576 */
 577 template <typename S, typename... T,
 578           typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
 579 inline auto sprintf(const S& fmt, const T&... args) -> std::basic_string<Char> {
 580   using context = basic_printf_context_t<Char>;
 581   return vsprintf(to_string_view(fmt), 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, 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, 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, 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       to_string_view(fmt),
 634       fmt::make_format_args<basic_printf_context_t<char_t<S>>>(args...));
 635 }
 636
 637 template <typename S, typename Char = char_t<S>>
 638 FMT_DEPRECATED auto vfprintf(
 639     std::basic_ostream<Char>& os, const S& fmt,
 640     basic_format_args<basic_printf_context_t<type_identity_t<Char>>> args)
 641     -> int {
 642   basic_memory_buffer<Char> buffer;
 643   vprintf(buffer, to_string_view(fmt), args);
 644   os.write(buffer.data(), static_cast<std::streamsize>(buffer.size()));
 645   return static_cast<int>(buffer.size());
 646 }
 647 template <typename S, typename... T, typename Char = char_t<S>>
 648 FMT_DEPRECATED auto fprintf(std::basic_ostream<Char>& os, const S& fmt,
 649                             const T&... args) -> int {
 650   return vfprintf(os, to_string_view(fmt),
 651                   fmt::make_format_args<basic_printf_context_t<Char>>(args...));
 652 }
 653
 654 FMT_MODULE_EXPORT_END
 655 FMT_END_NAMESPACE
 656
 657 #endif  // FMT_PRINTF_H_