fmt-11.0.2/include/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 #ifndef FMT_MODULE
  12 #  include <algorithm>  // std::max
  13 #  include <limits>     // std::numeric_limits
  14 #endif
  15
  16 #include "format.h"
  17
  18 FMT_BEGIN_NAMESPACE
  19 FMT_BEGIN_EXPORT
  20
  21 template <typename T> struct printf_formatter {
  22   printf_formatter() = delete;
  23 };
  24
  25 template <typename Char> class basic_printf_context {
  26  private:
  27   basic_appender<Char> out_;
  28   basic_format_args<basic_printf_context> args_;
  29
  30   static_assert(std::is_same<Char, char>::value ||
  31                     std::is_same<Char, wchar_t>::value,
  32                 "Unsupported code unit type.");
  33
  34  public:
  35   using char_type = Char;
  36   using parse_context_type = basic_format_parse_context<Char>;
  37   template <typename T> using formatter_type = printf_formatter<T>;
  38
  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   basic_printf_context(basic_appender<Char> out,
  42                        basic_format_args<basic_printf_context> args)
  43       : out_(out), args_(args) {}
  44
  45   auto out() -> basic_appender<Char> { return out_; }
  46   void advance_to(basic_appender<Char>) {}
  47
  48   auto locale() -> detail::locale_ref { return {}; }
  49
  50   auto arg(int id) const -> basic_format_arg<basic_printf_context> {
  51     return args_.get(id);
  52   }
  53 };
  54
  55 namespace detail {
  56
  57 // Checks if a value fits in int - used to avoid warnings about comparing
  58 // signed and unsigned integers.
  59 template <bool IsSigned> struct int_checker {
  60   template <typename T> static auto fits_in_int(T value) -> bool {
  61     unsigned max = to_unsigned(max_value<int>());
  62     return value <= max;
  63   }
  64   static auto fits_in_int(bool) -> bool { return true; }
  65 };
  66
  67 template <> struct int_checker<true> {
  68   template <typename T> static auto fits_in_int(T value) -> bool {
  69     return value >= (std::numeric_limits<int>::min)() &&
  70            value <= max_value<int>();
  71   }
  72   static auto fits_in_int(int) -> bool { return true; }
  73 };
  74
  75 struct printf_precision_handler {
  76   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  77   auto operator()(T value) -> int {
  78     if (!int_checker<std::numeric_limits<T>::is_signed>::fits_in_int(value))
  79       report_error("number is too big");
  80     return (std::max)(static_cast<int>(value), 0);
  81   }
  82
  83   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
  84   auto operator()(T) -> int {
  85     report_error("precision is not integer");
  86     return 0;
  87   }
  88 };
  89
  90 // An argument visitor that returns true iff arg is a zero integer.
  91 struct is_zero_int {
  92   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  93   auto operator()(T value) -> bool {
  94     return value == 0;
  95   }
  96
  97   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
  98   auto operator()(T) -> bool {
  99     return false;
 100   }
 101 };
 102
 103 template <typename T> struct make_unsigned_or_bool : std::make_unsigned<T> {};
 104
 105 template <> struct make_unsigned_or_bool<bool> {
 106   using type = bool;
 107 };
 108
 109 template <typename T, typename Context> class arg_converter {
 110  private:
 111   using char_type = typename Context::char_type;
 112
 113   basic_format_arg<Context>& arg_;
 114   char_type type_;
 115
 116  public:
 117   arg_converter(basic_format_arg<Context>& arg, char_type type)
 118       : arg_(arg), type_(type) {}
 119
 120   void operator()(bool value) {
 121     if (type_ != 's') operator()<bool>(value);
 122   }
 123
 124   template <typename U, FMT_ENABLE_IF(std::is_integral<U>::value)>
 125   void operator()(U value) {
 126     bool is_signed = type_ == 'd' || type_ == 'i';
 127     using target_type = conditional_t<std::is_same<T, void>::value, U, T>;
 128     if (const_check(sizeof(target_type) <= sizeof(int))) {
 129       // Extra casts are used to silence warnings.
 130       if (is_signed) {
 131         auto n = static_cast<int>(static_cast<target_type>(value));
 132         arg_ = detail::make_arg<Context>(n);
 133       } else {
 134         using unsigned_type = typename make_unsigned_or_bool<target_type>::type;
 135         auto n = static_cast<unsigned>(static_cast<unsigned_type>(value));
 136         arg_ = detail::make_arg<Context>(n);
 137       }
 138     } else {
 139       if (is_signed) {
 140         // glibc's printf doesn't sign extend arguments of smaller types:
 141         //   std::printf("%lld", -42);  // prints "4294967254"
 142         // but we don't have to do the same because it's a UB.
 143         auto n = static_cast<long long>(value);
 144         arg_ = detail::make_arg<Context>(n);
 145       } else {
 146         auto n = static_cast<typename make_unsigned_or_bool<U>::type>(value);
 147         arg_ = detail::make_arg<Context>(n);
 148       }
 149     }
 150   }
 151
 152   template <typename U, FMT_ENABLE_IF(!std::is_integral<U>::value)>
 153   void operator()(U) {}  // No conversion needed for non-integral types.
 154 };
 155
 156 // Converts an integer argument to T for printf, if T is an integral type.
 157 // If T is void, the argument is converted to corresponding signed or unsigned
 158 // type depending on the type specifier: 'd' and 'i' - signed, other -
 159 // unsigned).
 160 template <typename T, typename Context, typename Char>
 161 void convert_arg(basic_format_arg<Context>& arg, Char type) {
 162   arg.visit(arg_converter<T, Context>(arg, type));
 163 }
 164
 165 // Converts an integer argument to char for printf.
 166 template <typename Context> class char_converter {
 167  private:
 168   basic_format_arg<Context>& arg_;
 169
 170  public:
 171   explicit char_converter(basic_format_arg<Context>& arg) : arg_(arg) {}
 172
 173   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
 174   void operator()(T value) {
 175     auto c = static_cast<typename Context::char_type>(value);
 176     arg_ = detail::make_arg<Context>(c);
 177   }
 178
 179   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
 180   void operator()(T) {}  // No conversion needed for non-integral types.
 181 };
 182
 183 // An argument visitor that return a pointer to a C string if argument is a
 184 // string or null otherwise.
 185 template <typename Char> struct get_cstring {
 186   template <typename T> auto operator()(T) -> const Char* { return nullptr; }
 187   auto operator()(const Char* s) -> const Char* { return s; }
 188 };
 189
 190 // Checks if an argument is a valid printf width specifier and sets
 191 // left alignment if it is negative.
 192 class printf_width_handler {
 193  private:
 194   format_specs& specs_;
 195
 196  public:
 197   explicit printf_width_handler(format_specs& specs) : specs_(specs) {}
 198
 199   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
 200   auto operator()(T value) -> unsigned {
 201     auto width = static_cast<uint32_or_64_or_128_t<T>>(value);
 202     if (detail::is_negative(value)) {
 203       specs_.align = align::left;
 204       width = 0 - width;
 205     }
 206     unsigned int_max = to_unsigned(max_value<int>());
 207     if (width > int_max) report_error("number is too big");
 208     return static_cast<unsigned>(width);
 209   }
 210
 211   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
 212   auto operator()(T) -> unsigned {
 213     report_error("width is not integer");
 214     return 0;
 215   }
 216 };
 217
 218 // Workaround for a bug with the XL compiler when initializing
 219 // printf_arg_formatter's base class.
 220 template <typename Char>
 221 auto make_arg_formatter(basic_appender<Char> iter, format_specs& s)
 222     -> arg_formatter<Char> {
 223   return {iter, s, locale_ref()};
 224 }
 225
 226 // The `printf` argument formatter.
 227 template <typename Char>
 228 class printf_arg_formatter : public arg_formatter<Char> {
 229  private:
 230   using base = arg_formatter<Char>;
 231   using context_type = basic_printf_context<Char>;
 232
 233   context_type& context_;
 234
 235   void write_null_pointer(bool is_string = false) {
 236     auto s = this->specs;
 237     s.type = presentation_type::none;
 238     write_bytes<Char>(this->out, is_string ? "(null)" : "(nil)", s);
 239   }
 240
 241  public:
 242   printf_arg_formatter(basic_appender<Char> iter, format_specs& s,
 243                        context_type& ctx)
 244       : base(make_arg_formatter(iter, s)), context_(ctx) {}
 245
 246   void operator()(monostate value) { base::operator()(value); }
 247
 248   template <typename T, FMT_ENABLE_IF(detail::is_integral<T>::value)>
 249   void operator()(T value) {
 250     // MSVC2013 fails to compile separate overloads for bool and Char so use
 251     // std::is_same instead.
 252     if (!std::is_same<T, Char>::value) {
 253       base::operator()(value);
 254       return;
 255     }
 256     format_specs s = this->specs;
 257     if (s.type != presentation_type::none && s.type != presentation_type::chr) {
 258       return (*this)(static_cast<int>(value));
 259     }
 260     s.sign = sign::none;
 261     s.alt = false;
 262     s.fill = ' ';  // Ignore '0' flag for char types.
 263     // align::numeric needs to be overwritten here since the '0' flag is
 264     // ignored for non-numeric types
 265     if (s.align == align::none || s.align == align::numeric)
 266       s.align = align::right;
 267     write<Char>(this->out, static_cast<Char>(value), s);
 268   }
 269
 270   template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
 271   void operator()(T value) {
 272     base::operator()(value);
 273   }
 274
 275   void operator()(const char* value) {
 276     if (value)
 277       base::operator()(value);
 278     else
 279       write_null_pointer(this->specs.type != presentation_type::pointer);
 280   }
 281
 282   void operator()(const wchar_t* value) {
 283     if (value)
 284       base::operator()(value);
 285     else
 286       write_null_pointer(this->specs.type != presentation_type::pointer);
 287   }
 288
 289   void operator()(basic_string_view<Char> value) { base::operator()(value); }
 290
 291   void operator()(const void* value) {
 292     if (value)
 293       base::operator()(value);
 294     else
 295       write_null_pointer();
 296   }
 297
 298   void operator()(typename basic_format_arg<context_type>::handle handle) {
 299     auto parse_ctx = basic_format_parse_context<Char>({});
 300     handle.format(parse_ctx, context_);
 301   }
 302 };
 303
 304 template <typename Char>
 305 void parse_flags(format_specs& specs, const Char*& it, 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';
 316       break;
 317     case ' ':
 318       if (specs.sign != sign::plus) specs.sign = sign::space;
 319       break;
 320     case '#':
 321       specs.alt = true;
 322       break;
 323     default:
 324       return;
 325     }
 326   }
 327 }
 328
 329 template <typename Char, typename GetArg>
 330 auto parse_header(const Char*& it, const Char* end, format_specs& specs,
 331                   GetArg get_arg) -> int {
 332   int arg_index = -1;
 333   Char c = *it;
 334   if (c >= '0' && c <= '9') {
 335     // Parse an argument index (if followed by '$') or a width possibly
 336     // preceded with '0' flag(s).
 337     int value = parse_nonnegative_int(it, end, -1);
 338     if (it != end && *it == '$') {  // value is an argument index
 339       ++it;
 340       arg_index = value != -1 ? value : max_value<int>();
 341     } else {
 342       if (c == '0') specs.fill = '0';
 343       if (value != 0) {
 344         // Nonzero value means that we parsed width and don't need to
 345         // parse it or flags again, so return now.
 346         if (value == -1) report_error("number is too big");
 347         specs.width = value;
 348         return arg_index;
 349       }
 350     }
 351   }
 352   parse_flags(specs, it, end);
 353   // Parse width.
 354   if (it != end) {
 355     if (*it >= '0' && *it <= '9') {
 356       specs.width = parse_nonnegative_int(it, end, -1);
 357       if (specs.width == -1) report_error("number is too big");
 358     } else if (*it == '*') {
 359       ++it;
 360       specs.width = static_cast<int>(
 361           get_arg(-1).visit(detail::printf_width_handler(specs)));
 362     }
 363   }
 364   return arg_index;
 365 }
 366
 367 inline auto parse_printf_presentation_type(char c, type t, bool& upper)
 368     -> presentation_type {
 369   using pt = presentation_type;
 370   constexpr auto integral_set = sint_set | uint_set | bool_set | char_set;
 371   switch (c) {
 372   case 'd':
 373     return in(t, integral_set) ? pt::dec : pt::none;
 374   case 'o':
 375     return in(t, integral_set) ? pt::oct : pt::none;
 376   case 'X':
 377     upper = true;
 378     FMT_FALLTHROUGH;
 379   case 'x':
 380     return in(t, integral_set) ? pt::hex : pt::none;
 381   case 'E':
 382     upper = true;
 383     FMT_FALLTHROUGH;
 384   case 'e':
 385     return in(t, float_set) ? pt::exp : pt::none;
 386   case 'F':
 387     upper = true;
 388     FMT_FALLTHROUGH;
 389   case 'f':
 390     return in(t, float_set) ? pt::fixed : pt::none;
 391   case 'G':
 392     upper = true;
 393     FMT_FALLTHROUGH;
 394   case 'g':
 395     return in(t, float_set) ? pt::general : pt::none;
 396   case 'A':
 397     upper = true;
 398     FMT_FALLTHROUGH;
 399   case 'a':
 400     return in(t, float_set) ? pt::hexfloat : pt::none;
 401   case 'c':
 402     return in(t, integral_set) ? pt::chr : pt::none;
 403   case 's':
 404     return in(t, string_set | cstring_set) ? pt::string : pt::none;
 405   case 'p':
 406     return in(t, pointer_set | cstring_set) ? pt::pointer : pt::none;
 407   default:
 408     return pt::none;
 409   }
 410 }
 411
 412 template <typename Char, typename Context>
 413 void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
 414              basic_format_args<Context> args) {
 415   using iterator = basic_appender<Char>;
 416   auto out = iterator(buf);
 417   auto context = basic_printf_context<Char>(out, args);
 418   auto parse_ctx = basic_format_parse_context<Char>(format);
 419
 420   // Returns the argument with specified index or, if arg_index is -1, the next
 421   // argument.
 422   auto get_arg = [&](int arg_index) {
 423     if (arg_index < 0)
 424       arg_index = parse_ctx.next_arg_id();
 425     else
 426       parse_ctx.check_arg_id(--arg_index);
 427     return detail::get_arg(context, arg_index);
 428   };
 429
 430   const Char* start = parse_ctx.begin();
 431   const Char* end = parse_ctx.end();
 432   auto it = start;
 433   while (it != end) {
 434     if (!find<false, Char>(it, end, '%', it)) {
 435       it = end;  // find leaves it == nullptr if it doesn't find '%'.
 436       break;
 437     }
 438     Char c = *it++;
 439     if (it != end && *it == c) {
 440       write(out, basic_string_view<Char>(start, to_unsigned(it - start)));
 441       start = ++it;
 442       continue;
 443     }
 444     write(out, basic_string_view<Char>(start, to_unsigned(it - 1 - start)));
 445
 446     auto specs = format_specs();
 447     specs.align = align::right;
 448
 449     // Parse argument index, flags and width.
 450     int arg_index = parse_header(it, end, specs, get_arg);
 451     if (arg_index == 0) report_error("argument not found");
 452
 453     // Parse precision.
 454     if (it != end && *it == '.') {
 455       ++it;
 456       c = it != end ? *it : 0;
 457       if ('0' <= c && c <= '9') {
 458         specs.precision = parse_nonnegative_int(it, end, 0);
 459       } else if (c == '*') {
 460         ++it;
 461         specs.precision =
 462             static_cast<int>(get_arg(-1).visit(printf_precision_handler()));
 463       } else {
 464         specs.precision = 0;
 465       }
 466     }
 467
 468     auto arg = get_arg(arg_index);
 469     // For d, i, o, u, x, and X conversion specifiers, if a precision is
 470     // specified, the '0' flag is ignored
 471     if (specs.precision >= 0 && arg.is_integral()) {
 472       // Ignore '0' for non-numeric types or if '-' present.
 473       specs.fill = ' ';
 474     }
 475     if (specs.precision >= 0 && arg.type() == type::cstring_type) {
 476       auto str = arg.visit(get_cstring<Char>());
 477       auto str_end = str + specs.precision;
 478       auto nul = std::find(str, str_end, Char());
 479       auto sv = basic_string_view<Char>(
 480           str, to_unsigned(nul != str_end ? nul - str : specs.precision));
 481       arg = make_arg<basic_printf_context<Char>>(sv);
 482     }
 483     if (specs.alt && arg.visit(is_zero_int())) specs.alt = false;
 484     if (specs.fill.template get<Char>() == '0') {
 485       if (arg.is_arithmetic() && specs.align != align::left)
 486         specs.align = align::numeric;
 487       else
 488         specs.fill = ' ';  // Ignore '0' flag for non-numeric types or if '-'
 489                            // flag is also present.
 490     }
 491
 492     // Parse length and convert the argument to the required type.
 493     c = it != end ? *it++ : 0;
 494     Char t = it != end ? *it : 0;
 495     switch (c) {
 496     case 'h':
 497       if (t == 'h') {
 498         ++it;
 499         t = it != end ? *it : 0;
 500         convert_arg<signed char>(arg, t);
 501       } else {
 502         convert_arg<short>(arg, t);
 503       }
 504       break;
 505     case 'l':
 506       if (t == 'l') {
 507         ++it;
 508         t = it != end ? *it : 0;
 509         convert_arg<long long>(arg, t);
 510       } else {
 511         convert_arg<long>(arg, t);
 512       }
 513       break;
 514     case 'j':
 515       convert_arg<intmax_t>(arg, t);
 516       break;
 517     case 'z':
 518       convert_arg<size_t>(arg, t);
 519       break;
 520     case 't':
 521       convert_arg<std::ptrdiff_t>(arg, t);
 522       break;
 523     case 'L':
 524       // printf produces garbage when 'L' is omitted for long double, no
 525       // need to do the same.
 526       break;
 527     default:
 528       --it;
 529       convert_arg<void>(arg, c);
 530     }
 531
 532     // Parse type.
 533     if (it == end) report_error("invalid format string");
 534     char type = static_cast<char>(*it++);
 535     if (arg.is_integral()) {
 536       // Normalize type.
 537       switch (type) {
 538       case 'i':
 539       case 'u':
 540         type = 'd';
 541         break;
 542       case 'c':
 543         arg.visit(char_converter<basic_printf_context<Char>>(arg));
 544         break;
 545       }
 546     }
 547     bool upper = false;
 548     specs.type = parse_printf_presentation_type(type, arg.type(), upper);
 549     if (specs.type == presentation_type::none)
 550       report_error("invalid format specifier");
 551     specs.upper = upper;
 552
 553     start = it;
 554
 555     // Format argument.
 556     arg.visit(printf_arg_formatter<Char>(out, specs, context));
 557   }
 558   write(out, basic_string_view<Char>(start, to_unsigned(it - start)));
 559 }
 560 }  // namespace detail
 561
 562 using printf_context = basic_printf_context<char>;
 563 using wprintf_context = basic_printf_context<wchar_t>;
 564
 565 using printf_args = basic_format_args<printf_context>;
 566 using wprintf_args = basic_format_args<wprintf_context>;
 567
 568 /// Constructs an `format_arg_store` object that contains references to
 569 /// arguments and can be implicitly converted to `printf_args`.
 570 template <typename Char = char, typename... T>
 571 inline auto make_printf_args(T&... args)
 572     -> decltype(fmt::make_format_args<basic_printf_context<Char>>(args...)) {
 573   return fmt::make_format_args<basic_printf_context<Char>>(args...);
 574 }
 575
 576 template <typename Char> struct vprintf_args {
 577   using type = basic_format_args<basic_printf_context<Char>>;
 578 };
 579
 580 template <typename Char>
 581 inline auto vsprintf(basic_string_view<Char> fmt,
 582                      typename vprintf_args<Char>::type args)
 583     -> std::basic_string<Char> {
 584   auto buf = basic_memory_buffer<Char>();
 585   detail::vprintf(buf, fmt, args);
 586   return to_string(buf);
 587 }
 588
 589 /**
 590  * Formats `args` according to specifications in `fmt` and returns the result
 591  * as as string.
 592  *
 593  * **Example**:
 594  *
 595  *     std::string message = fmt::sprintf("The answer is %d", 42);
 596  */
 597 template <typename S, typename... T, typename Char = char_t<S>>
 598 inline auto sprintf(const S& fmt, const T&... args) -> std::basic_string<Char> {
 599   return vsprintf(detail::to_string_view(fmt),
 600                   fmt::make_format_args<basic_printf_context<Char>>(args...));
 601 }
 602
 603 template <typename Char>
 604 inline auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
 605                      typename vprintf_args<Char>::type args) -> int {
 606   auto buf = basic_memory_buffer<Char>();
 607   detail::vprintf(buf, fmt, args);
 608   size_t size = buf.size();
 609   return std::fwrite(buf.data(), sizeof(Char), size, f) < size
 610              ? -1
 611              : static_cast<int>(size);
 612 }
 613
 614 /**
 615  * Formats `args` according to specifications in `fmt` and writes the output
 616  * to `f`.
 617  *
 618  * **Example**:
 619  *
 620  *     fmt::fprintf(stderr, "Don't %s!", "panic");
 621  */
 622 template <typename S, typename... T, typename Char = char_t<S>>
 623 inline auto fprintf(std::FILE* f, const S& fmt, const T&... args) -> int {
 624   return vfprintf(f, detail::to_string_view(fmt),
 625                   make_printf_args<Char>(args...));
 626 }
 627
 628 template <typename Char>
 629 FMT_DEPRECATED inline auto vprintf(basic_string_view<Char> fmt,
 630                                    typename vprintf_args<Char>::type args)
 631     -> int {
 632   return vfprintf(stdout, fmt, args);
 633 }
 634
 635 /**
 636  * Formats `args` according to specifications in `fmt` and writes the output
 637  * to `stdout`.
 638  *
 639  * **Example**:
 640  *
 641  *   fmt::printf("Elapsed time: %.2f seconds", 1.23);
 642  */
 643 template <typename... T>
 644 inline auto printf(string_view fmt, const T&... args) -> int {
 645   return vfprintf(stdout, fmt, make_printf_args(args...));
 646 }
 647 template <typename... T>
 648 FMT_DEPRECATED inline auto printf(basic_string_view<wchar_t> fmt,
 649                                   const T&... args) -> int {
 650   return vfprintf(stdout, fmt, make_printf_args<wchar_t>(args...));
 651 }
 652
 653 FMT_END_EXPORT
 654 FMT_END_NAMESPACE
 655
 656 #endif  // FMT_PRINTF_H_