fmt/include/fmt/printf.h

// Formatting library for C++
//
// Copyright (c) 2012 - 2016, Victor Zverovich
// All rights reserved.
//
// For the license information refer to format.h.

#ifndef FMT_PRINTF_H_
#define FMT_PRINTF_H_

#include <algorithm>  // std::fill_n
#include <limits>     // std::numeric_limits

#include "ostream.h"

FMT_BEGIN_NAMESPACE
namespace internal {

// A helper function to suppress bogus "conditional expression is constant"
// warnings.
template <typename T> inline T const_check(T value) { return value; }

// Checks if a value fits in int - used to avoid warnings about comparing
// signed and unsigned integers.
template <bool IsSigned> struct int_checker {
  template <typename T> static bool fits_in_int(T value) {
    unsigned max = std::numeric_limits<int>::max();
    return value <= max;
  }
  static bool fits_in_int(bool) { return true; }
};

template <> struct int_checker<true> {
  template <typename T> static bool fits_in_int(T value) {
    return value >= std::numeric_limits<int>::min() &&
           value <= std::numeric_limits<int>::max();
  }
  static bool fits_in_int(int) { return true; }
};

class printf_precision_handler : public function<int> {
 public:
  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  int operator()(T value) {
    if (!int_checker<std::numeric_limits<T>::is_signed>::fits_in_int(value))
      FMT_THROW(format_error("number is too big"));
    return static_cast<int>(value);
  }

  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
  int operator()(T) {
    FMT_THROW(format_error("precision is not integer"));
    return 0;
  }
};

// An argument visitor that returns true iff arg is a zero integer.
class is_zero_int : public function<bool> {
 public:
  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  bool operator()(T value) {
    return value == 0;
  }

  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
  bool operator()(T) {
    return false;
  }
};

template <typename T> struct make_unsigned_or_bool : std::make_unsigned<T> {};

template <> struct make_unsigned_or_bool<bool> { typedef bool type; };

template <typename T, typename Context>
class arg_converter : public function<void> {
 private:
  typedef typename Context::char_type Char;

  basic_format_arg<Context>& arg_;
  typename Context::char_type type_;

 public:
  arg_converter(basic_format_arg<Context>& arg, Char type)
      : arg_(arg), type_(type) {}

  void operator()(bool value) {
    if (type_ != 's') operator()<bool>(value);
  }

  template <typename U, FMT_ENABLE_IF(std::is_integral<U>::value)>
  void operator()(U value) {
    bool is_signed = type_ == 'd' || type_ == 'i';
    typedef typename std::conditional<std::is_same<T, void>::value, U, T>::type
        TargetType;
    if (const_check(sizeof(TargetType) <= sizeof(int))) {
      // Extra casts are used to silence warnings.
      if (is_signed) {
        arg_ = internal::make_arg<Context>(
            static_cast<int>(static_cast<TargetType>(value)));
      } else {
        typedef typename make_unsigned_or_bool<TargetType>::type Unsigned;
        arg_ = internal::make_arg<Context>(
            static_cast<unsigned>(static_cast<Unsigned>(value)));
      }
    } else {
      if (is_signed) {
        // glibc's printf doesn't sign extend arguments of smaller types:
        //   std::printf("%lld", -42);  // prints "4294967254"
        // but we don't have to do the same because it's a UB.
        arg_ = internal::make_arg<Context>(static_cast<long long>(value));
      } else {
        arg_ = internal::make_arg<Context>(
            static_cast<typename make_unsigned_or_bool<U>::type>(value));
      }
    }
  }

  template <typename U, FMT_ENABLE_IF(!std::is_integral<U>::value)>
  void operator()(U) {}  // No conversion needed for non-integral types.
};

// Converts an integer argument to T for printf, if T is an integral type.
// If T is void, the argument is converted to corresponding signed or unsigned
// type depending on the type specifier: 'd' and 'i' - signed, other -
// unsigned).
template <typename T, typename Context, typename Char>
void convert_arg(basic_format_arg<Context>& arg, Char type) {
  visit_format_arg(arg_converter<T, Context>(arg, type), arg);
}

// Converts an integer argument to char for printf.
template <typename Context> class char_converter : public function<void> {
 private:
  basic_format_arg<Context>& arg_;

 public:
  explicit char_converter(basic_format_arg<Context>& arg) : arg_(arg) {}

  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  void operator()(T value) {
    typedef typename Context::char_type Char;
    arg_ = internal::make_arg<Context>(static_cast<Char>(value));
  }

  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
  void operator()(T) {}  // No conversion needed for non-integral types.
};

// Checks if an argument is a valid printf width specifier and sets
// left alignment if it is negative.
template <typename Char>
class printf_width_handler : public function<unsigned> {
 private:
  typedef basic_format_specs<Char> format_specs;

  format_specs& spec_;

 public:
  explicit printf_width_handler(format_specs& spec) : spec_(spec) {}

  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  unsigned operator()(T value) {
    typedef typename internal::int_traits<T>::main_type UnsignedType;
    UnsignedType width = static_cast<UnsignedType>(value);
    if (internal::is_negative(value)) {
      spec_.align_ = ALIGN_LEFT;
      width = 0 - width;
    }
    unsigned int_max = std::numeric_limits<int>::max();
    if (width > int_max) FMT_THROW(format_error("number is too big"));
    return static_cast<unsigned>(width);
  }

  template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
  unsigned operator()(T) {
    FMT_THROW(format_error("width is not integer"));
    return 0;
  }
};

template <typename Char, typename Context>
void printf(buffer<Char>& buf, basic_string_view<Char> format,
            basic_format_args<Context> args) {
  Context(std::back_inserter(buf), format, args).format();
}

template <typename OutputIt, typename Char, typename Context>
internal::truncating_iterator<OutputIt> printf(
    internal::truncating_iterator<OutputIt> it, basic_string_view<Char> format,
    basic_format_args<Context> args) {
  return Context(it, format, args).format();
}
}  // namespace internal

using internal::printf;  // For printing into memory_buffer.

template <typename Range> class printf_arg_formatter;

template <typename OutputIt, typename Char,
          typename ArgFormatter =
              printf_arg_formatter<back_insert_range<internal::buffer<Char>>>>
class basic_printf_context;

/**
  \rst
  The ``printf`` argument formatter.
  \endrst
 */
template <typename Range>
class printf_arg_formatter
    : public internal::function<
          typename internal::arg_formatter_base<Range>::iterator>,
      public internal::arg_formatter_base<Range> {
 private:
  typedef typename Range::value_type char_type;
  typedef decltype(internal::declval<Range>().begin()) iterator;
  typedef internal::arg_formatter_base<Range> base;
  typedef basic_printf_context<iterator, char_type, printf_arg_formatter>
      context_type;

  context_type& context_;

  void write_null_pointer(char) {
    this->spec()->type = 0;
    this->write("(nil)");
  }

  void write_null_pointer(wchar_t) {
    this->spec()->type = 0;
    this->write(L"(nil)");
  }

 public:
  typedef typename base::format_specs format_specs;

  /**
    \rst
    Constructs an argument formatter object.
    *buffer* is a reference to the output buffer and *spec* contains format
    specifier information for standard argument types.
    \endrst
   */
  printf_arg_formatter(iterator iter, format_specs& spec, context_type& ctx)
      : base(Range(iter), &spec, internal::locale_ref()), context_(ctx) {}

  template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
  iterator operator()(T value) {
    // MSVC2013 fails to compile separate overloads for bool and char_type so
    // use std::is_same instead.
    if (std::is_same<T, bool>::value) {
      format_specs& fmt_spec = *this->spec();
      if (fmt_spec.type != 's') return base::operator()(value ? 1 : 0);
      fmt_spec.type = 0;
      this->write(value != 0);
    } else if (std::is_same<T, char_type>::value) {
      format_specs& fmt_spec = *this->spec();
      if (fmt_spec.type && fmt_spec.type != 'c')
        return (*this)(static_cast<int>(value));
      fmt_spec.flags = 0;
      fmt_spec.align_ = ALIGN_RIGHT;
      return base::operator()(value);
    } else {
      return base::operator()(value);
    }
    return this->out();
  }

  template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
  iterator operator()(T value) {
    return base::operator()(value);
  }

  /** Formats a null-terminated C string. */
  iterator operator()(const char* value) {
    if (value)
      base::operator()(value);
    else if (this->spec()->type == 'p')
      write_null_pointer(char_type());
    else
      this->write("(null)");
    return this->out();
  }

  /** Formats a null-terminated wide C string. */
  iterator operator()(const wchar_t* value) {
    if (value)
      base::operator()(value);
    else if (this->spec()->type == 'p')
      write_null_pointer(char_type());
    else
      this->write(L"(null)");
    return this->out();
  }

  iterator operator()(basic_string_view<char_type> value) {
    return base::operator()(value);
  }

  iterator operator()(monostate value) { return base::operator()(value); }

  /** Formats a pointer. */
  iterator operator()(const void* value) {
    if (value) return base::operator()(value);
    this->spec()->type = 0;
    write_null_pointer(char_type());
    return this->out();
  }

  /** Formats an argument of a custom (user-defined) type. */
  iterator operator()(typename basic_format_arg<context_type>::handle handle) {
    handle.format(context_.parse_context(), context_);
    return this->out();
  }
};

template <typename T> struct printf_formatter {
  template <typename ParseContext>
  auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
    return ctx.begin();
  }

  template <typename FormatContext>
  auto format(const T& value, FormatContext& ctx) -> decltype(ctx.out()) {
    internal::format_value(internal::get_container(ctx.out()), value);
    return ctx.out();
  }
};

/** This template formats data and writes the output to a writer. */
template <typename OutputIt, typename Char, typename ArgFormatter>
class basic_printf_context {
 public:
  /** The character type for the output. */
  typedef Char char_type;
  typedef basic_format_arg<basic_printf_context> format_arg;

  template <typename T> struct formatter_type {
    typedef printf_formatter<T> type;
  };

 private:
  typedef basic_format_specs<char_type> format_specs;

  OutputIt out_;
  basic_format_args<basic_printf_context> args_;
  basic_parse_context<Char> parse_ctx_;

  static void parse_flags(format_specs& spec, const Char*& it, const Char* end);

  // Returns the argument with specified index or, if arg_index is equal
  // to the maximum unsigned value, the next argument.
  format_arg get_arg(unsigned arg_index = std::numeric_limits<unsigned>::max());

  // Parses argument index, flags and width and returns the argument index.
  unsigned parse_header(const Char*& it, const Char* end, format_specs& spec);

 public:
  /**
   \rst
   Constructs a ``printf_context`` object. References to the arguments and
   the writer are stored in the context object so make sure they have
   appropriate lifetimes.
   \endrst
   */
  basic_printf_context(OutputIt out, basic_string_view<char_type> format_str,
                       basic_format_args<basic_printf_context> args)
      : out_(out), args_(args), parse_ctx_(format_str) {}

  OutputIt out() { return out_; }
  void advance_to(OutputIt it) { out_ = it; }

  format_arg arg(unsigned id) const { return args_.get(id); }

  basic_parse_context<Char>& parse_context() { return parse_ctx_; }

  FMT_CONSTEXPR void on_error(const char* message) {
    parse_ctx_.on_error(message);
  }

  /** Formats stored arguments and writes the output to the range. */
  OutputIt format();
};

template <typename OutputIt, typename Char, typename AF>
void basic_printf_context<OutputIt, Char, AF>::parse_flags(format_specs& spec,
                                                           const Char*& it,
                                                           const Char* end) {
  for (; it != end; ++it) {
    switch (*it) {
    case '-':
      spec.align_ = ALIGN_LEFT;
      break;
    case '+':
      spec.flags |= SIGN_FLAG | PLUS_FLAG;
      break;
    case '0':
      spec.fill_ = '0';
      break;
    case ' ':
      spec.flags |= SIGN_FLAG;
      break;
    case '#':
      spec.flags |= HASH_FLAG;
      break;
    default:
      return;
    }
  }
}

template <typename OutputIt, typename Char, typename AF>
typename basic_printf_context<OutputIt, Char, AF>::format_arg
basic_printf_context<OutputIt, Char, AF>::get_arg(unsigned arg_index) {
  if (arg_index == std::numeric_limits<unsigned>::max())
    arg_index = parse_ctx_.next_arg_id();
  else
    parse_ctx_.check_arg_id(--arg_index);
  return internal::get_arg(*this, arg_index);
}

template <typename OutputIt, typename Char, typename AF>
unsigned basic_printf_context<OutputIt, Char, AF>::parse_header(
    const Char*& it, const Char* end, format_specs& spec) {
  unsigned arg_index = std::numeric_limits<unsigned>::max();
  char_type c = *it;
  if (c >= '0' && c <= '9') {
    // Parse an argument index (if followed by '$') or a width possibly
    // preceded with '0' flag(s).
    internal::error_handler eh;
    unsigned value = parse_nonnegative_int(it, end, eh);
    if (it != end && *it == '$') {  // value is an argument index
      ++it;
      arg_index = value;
    } else {
      if (c == '0') spec.fill_ = '0';
      if (value != 0) {
        // Nonzero value means that we parsed width and don't need to
        // parse it or flags again, so return now.
        spec.width_ = value;
        return arg_index;
      }
    }
  }
  parse_flags(spec, it, end);
  // Parse width.
  if (it != end) {
    if (*it >= '0' && *it <= '9') {
      internal::error_handler eh;
      spec.width_ = parse_nonnegative_int(it, end, eh);
    } else if (*it == '*') {
      ++it;
      spec.width_ = visit_format_arg(
          internal::printf_width_handler<char_type>(spec), get_arg());
    }
  }
  return arg_index;
}

template <typename OutputIt, typename Char, typename AF>
OutputIt basic_printf_context<OutputIt, Char, AF>::format() {
  auto out = this->out();
  const Char* start = parse_ctx_.begin();
  const Char* end = parse_ctx_.end();
  auto it = start;
  while (it != end) {
    char_type c = *it++;
    if (c != '%') continue;
    if (it != end && *it == c) {
      out = std::copy(start, it, out);
      start = ++it;
      continue;
    }
    out = std::copy(start, it - 1, out);

    format_specs spec;
    spec.align_ = ALIGN_RIGHT;

    // Parse argument index, flags and width.
    unsigned arg_index = parse_header(it, end, spec);

    // Parse precision.
    if (it != end && *it == '.') {
      ++it;
      c = it != end ? *it : 0;
      if ('0' <= c && c <= '9') {
        internal::error_handler eh;
        spec.precision = static_cast<int>(parse_nonnegative_int(it, end, eh));
      } else if (c == '*') {
        ++it;
        spec.precision =
            visit_format_arg(internal::printf_precision_handler(), get_arg());
      } else {
        spec.precision = 0;
      }
    }

    format_arg arg = get_arg(arg_index);
    if (spec.has(HASH_FLAG) && visit_format_arg(internal::is_zero_int(), arg))
      spec.flags = static_cast<uint_least8_t>(
          spec.flags & (~internal::to_unsigned<int>(HASH_FLAG)));
    if (spec.fill_ == '0') {
      if (arg.is_arithmetic())
        spec.align_ = ALIGN_NUMERIC;
      else
        spec.fill_ = ' ';  // Ignore '0' flag for non-numeric types.
    }

    // Parse length and convert the argument to the required type.
    c = it != end ? *it++ : 0;
    char_type t = it != end ? *it : 0;
    using internal::convert_arg;
    switch (c) {
    case 'h':
      if (t == 'h') {
        ++it;
        t = it != end ? *it : 0;
        convert_arg<signed char>(arg, t);
      } else {
        convert_arg<short>(arg, t);
      }
      break;
    case 'l':
      if (t == 'l') {
        ++it;
        t = it != end ? *it : 0;
        convert_arg<long long>(arg, t);
      } else {
        convert_arg<long>(arg, t);
      }
      break;
    case 'j':
      convert_arg<intmax_t>(arg, t);
      break;
    case 'z':
      convert_arg<std::size_t>(arg, t);
      break;
    case 't':
      convert_arg<std::ptrdiff_t>(arg, t);
      break;
    case 'L':
      // printf produces garbage when 'L' is omitted for long double, no
      // need to do the same.
      break;
    default:
      --it;
      convert_arg<void>(arg, c);
    }

    // Parse type.
    if (it == end) FMT_THROW(format_error("invalid format string"));
    spec.type = static_cast<char>(*it++);
    if (arg.is_integral()) {
      // Normalize type.
      switch (spec.type) {
      case 'i':
      case 'u':
        spec.type = 'd';
        break;
      case 'c':
        visit_format_arg(internal::char_converter<basic_printf_context>(arg),
                         arg);
        break;
      }
    }

    start = it;

    // Format argument.
    visit_format_arg(AF(out, spec, *this), arg);
  }
  return std::copy(start, it, out);
}

template <typename Buffer> struct basic_printf_context_t {
  typedef basic_printf_context<std::back_insert_iterator<Buffer>,
                               typename Buffer::value_type>
      type;
};

typedef basic_printf_context_t<internal::buffer<char>>::type printf_context;
typedef basic_printf_context_t<internal::buffer<wchar_t>>::type wprintf_context;

typedef basic_format_args<printf_context> printf_args;
typedef basic_format_args<wprintf_context> wprintf_args;

/**
  \rst
  Constructs an `~fmt::format_arg_store` object that contains references to
  arguments and can be implicitly converted to `~fmt::printf_args`.
  \endrst
 */
template <typename... Args>
inline format_arg_store<printf_context, Args...> make_printf_args(
    const Args&... args) {
  return {args...};
}

/**
  \rst
  Constructs an `~fmt::format_arg_store` object that contains references to
  arguments and can be implicitly converted to `~fmt::wprintf_args`.
  \endrst
 */
template <typename... Args>
inline format_arg_store<wprintf_context, Args...> make_wprintf_args(
    const Args&... args) {
  return {args...};
}

template <typename S, typename Char = FMT_CHAR(S)>
inline std::basic_string<Char> vsprintf(
    const S& format,
    basic_format_args<
        typename basic_printf_context_t<internal::buffer<Char>>::type>
        args) {
  basic_memory_buffer<Char> buffer;
  printf(buffer, to_string_view(format), args);
  return to_string(buffer);
}

/**
  \rst
  Formats arguments and returns the result as a string.

  **Example**::

    std::string message = fmt::sprintf("The answer is %d", 42);
  \endrst
*/
template <typename S, typename... Args,
          FMT_ENABLE_IF(internal::is_string<S>::value)>
inline std::basic_string<FMT_CHAR(S)> sprintf(const S& format,
                                              const Args&... args) {
  internal::check_format_string<Args...>(format);
  typedef internal::buffer<FMT_CHAR(S)> buffer;
  typedef typename basic_printf_context_t<buffer>::type context;
  format_arg_store<context, Args...> as{args...};
  return vsprintf(to_string_view(format), basic_format_args<context>(as));
}

template <typename S, typename Char = FMT_CHAR(S)>
inline int vfprintf(
    std::FILE* f, const S& format,
    basic_format_args<
        typename basic_printf_context_t<internal::buffer<Char>>::type>
        args) {
  basic_memory_buffer<Char> buffer;
  printf(buffer, to_string_view(format), args);
  std::size_t size = buffer.size();
  return std::fwrite(buffer.data(), sizeof(Char), size, f) < size
             ? -1
             : static_cast<int>(size);
}

/**
  \rst
  Prints formatted data to the file *f*.

  **Example**::

    fmt::fprintf(stderr, "Don't %s!", "panic");
  \endrst
 */
template <typename S, typename... Args,
          FMT_ENABLE_IF(internal::is_string<S>::value)>
inline int fprintf(std::FILE* f, const S& format, const Args&... args) {
  internal::check_format_string<Args...>(format);
  typedef internal::buffer<FMT_CHAR(S)> buffer;
  typedef typename basic_printf_context_t<buffer>::type context;
  format_arg_store<context, Args...> as{args...};
  return vfprintf(f, to_string_view(format), basic_format_args<context>(as));
}

template <typename S, typename Char = FMT_CHAR(S)>
inline int vprintf(
    const S& format,
    basic_format_args<
        typename basic_printf_context_t<internal::buffer<Char>>::type>
        args) {
  return vfprintf(stdout, to_string_view(format), args);
}

/**
  \rst
  Prints formatted data to ``stdout``.

  **Example**::

    fmt::printf("Elapsed time: %.2f seconds", 1.23);
  \endrst
 */
template <typename S, typename... Args,
          FMT_ENABLE_IF(internal::is_string<S>::value)>
inline int printf(const S& format_str, const Args&... args) {
  internal::check_format_string<Args...>(format_str);
  typedef internal::buffer<FMT_CHAR(S)> buffer;
  typedef typename basic_printf_context_t<buffer>::type context;
  format_arg_store<context, Args...> as{args...};
  return vprintf(to_string_view(format_str), basic_format_args<context>(as));
}

template <typename S, typename Char = FMT_CHAR(S)>
inline int vfprintf(
    std::basic_ostream<Char>& os, const S& format,
    basic_format_args<
        typename basic_printf_context_t<internal::buffer<Char>>::type>
        args) {
  basic_memory_buffer<Char> buffer;
  printf(buffer, to_string_view(format), args);
  internal::write(os, buffer);
  return static_cast<int>(buffer.size());
}

/**
  \rst
  Prints formatted data to the stream *os*.

  **Example**::

    fmt::fprintf(cerr, "Don't %s!", "panic");
  \endrst
 */
template <typename S, typename... Args,
          FMT_ENABLE_IF(internal::is_string<S>::value)>
inline int fprintf(std::basic_ostream<FMT_CHAR(S)>& os, const S& format_str,
                   const Args&... args) {
  internal::check_format_string<Args...>(format_str);
  typedef internal::buffer<FMT_CHAR(S)> buffer;
  typedef typename basic_printf_context_t<buffer>::type context;
  format_arg_store<context, Args...> as{args...};
  return vfprintf(os, to_string_view(format_str),
                  basic_format_args<context>(as));
}
FMT_END_NAMESPACE

#endif  // FMT_PRINTF_H_