libstdc++-v3/include/std/print

// <print> Print functions -*- C++ -*-

// Copyright The GNU Toolchain Authors.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file include/print
 *  This is a Standard C++ Library header.
 */

#ifndef _GLIBCXX_PRINT
#define _GLIBCXX_PRINT 1

#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif

#include <bits/requires_hosted.h> // for std::format

#define __glibcxx_want_print
#include <bits/version.h>

#ifdef __cpp_lib_print // C++ >= 23

#include <format>             // format_args (TODO: move to bits/formatfwd.h?)
#include <cstdio>             // FILE, EOF, putc
#include <cerrno>             // EACCES, EIO
#include <bits/functexcept.h> // __throw_system_error

#ifdef _WIN32
# include <system_error>
#endif

#ifndef _GLIBCXX_NO_INLINE_PRINT
# include <bits/print.h>
#endif

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  void
  vprint_nonunicode(FILE* __stream, string_view __fmt, format_args __args);

  void
  vprint_nonunicode_buffered(FILE* __stream, string_view __fmt,
			     format_args __args);

  void
  vprint_unicode(FILE* __stream, string_view __fmt, format_args __args);

  void
  vprint_unicode_buffered(FILE* __stream, string_view __fmt,
			  format_args __args);

  void
  vprint_unicode_buffered(string_view __fmt, format_args __args);

  void
  vprint_nonunicode_buffered(string_view __fmt, format_args __args);

  template<typename... _Args>
    inline void
    print(FILE* __stream, format_string<_Args...> __fmt, _Args&&... __args)
    {
      constexpr bool __locksafe =
	(enable_nonlocking_formatter_optimization<remove_cvref_t<_Args>> && ...);

      auto __fmtargs = std::make_format_args(__args...);
#if defined(_WIN32) && !defined(__CYGWIN__)
      if constexpr (__unicode::__literal_encoding_is_utf8())
	std::vprint_unicode_buffered(__stream, __fmt.get(), __fmtargs);
      else
#endif

      if constexpr (__locksafe)
	std::vprint_nonunicode(__stream, __fmt.get(), __fmtargs);
      else
	std::vprint_nonunicode_buffered(__stream, __fmt.get(), __fmtargs);
    }

  template<typename... _Args>
    inline void
    print(format_string<_Args...> __fmt, _Args&&... __args)
    { std::print(stdout, __fmt, std::forward<_Args>(__args)...); }

  template<typename... _Args>
    inline void
    println(FILE* __stream, format_string<_Args...> __fmt, _Args&&... __args)
    {
      constexpr bool __locksafe =
	(enable_nonlocking_formatter_optimization<remove_cvref_t<_Args>> && ...);

      // The standard wants us to call
      // print(stream, dynamic_format(string(fmt.get()) + '\n'), args...)
      // here, but we can avoid that string concatenation in most cases,
      // and we know what that would call, so we can call that directly.

      auto __fmtargs = std::make_format_args(__args...);

#if defined(_WIN32) && !defined(__CYGWIN__)
      if constexpr (__unicode::__literal_encoding_is_utf8())
	{
	  // We can't avoid the string concatenation here, but we can call
	  // vprint_unicode_buffered directly, since that's what print would do.
	  string __fmtn;
	  __fmtn.reserve(__fmt.get().size() + 1);
	  __fmtn = __fmt.get();
	  __fmtn += '\n';
	  std::vprint_unicode_buffered(__stream, __fmtn, __fmtargs);
	}
      else
#endif

#ifdef _GLIBCXX_NO_INLINE_PRINT
	{
	  string __fmtn;
	  __fmtn.reserve(__fmt.get().size() + 1);
	  __fmtn = __fmt.get();
	  __fmtn += '\n';
	  std::vprint_nonunicode(__stream, __fmtn, __fmtargs);
	}
#else
      // For non-Windows and for non-Unicode on Windows, we know that print
      // would call vprint_nonunicode or vprint_nonunicode_buffered with a
      // newline appended to the format-string. Use a _File_sink that adds
      // the newline automatically and write to it directly.
      if constexpr (__locksafe)
	std::vformat_to(__format::_File_sink(__stream, true).out(),
			__fmt.get(), __fmtargs);
      else
	{
	  // Format to a string buffer first, then write the result to a
	  // _File_sink that adds a newline.
	  __format::_Str_sink<char> __buf;
	  std::vformat_to(__buf.out(), __fmt.get(), __fmtargs);
	  string_view __s(__buf.view());
	  __format::_File_sink(__stream, true).out() = __s;
	}
#endif
    }

  template<typename... _Args>
    inline void
    println(format_string<_Args...> __fmt, _Args&&... __args)
    { std::println(stdout, __fmt, std::forward<_Args>(__args)...); }

  inline void
  vprint_unicode_buffered(string_view __fmt, format_args __args)
  { std::vprint_unicode_buffered(stdout, __fmt, __args); }

  inline void
  vprint_nonunicode_buffered(string_view __fmt, format_args __args)
  { std::vprint_nonunicode_buffered(stdout, __fmt, __args); }

  // Defined for C++26, supported as an extension to C++23.
  inline void println(FILE* __stream)
  {
#if defined(_WIN32) && !defined(__CYGWIN__)
    if constexpr (__unicode::__literal_encoding_is_utf8())
      std::vprint_unicode_buffered(__stream, "\n", std::make_format_args());
    else
#endif
      if (std::putc('\n', __stream) == EOF)
	__throw_system_error(EIO);
  }

  inline void println() { std::println(stdout); }

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // __cpp_lib_print
#endif // _GLIBCXX_PRINT