source: trunk/third/gmp/cxx/ismpf.cc @ 18191

/* operator>> -- C++-style input of mpf_t.

Copyright 2001, 2002 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.

The GNU MP 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 Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */

#include "config.h"

#include <cctype>
#include <iostream>
#include <string>

#if HAVE_LOCALE_H
#include <locale.h>    /* for localeconv */
#endif

#include "gmp.h"
#include "gmp-impl.h"

using namespace std;


/* Perhaps the decimal point should be taken from the C++ <locale> stuff,
   but that doesn't exist in g++ 2.95.x.  In any case, using plain C
   localeconv will ensure we parse exactly what mpf_set_str will expect, and
   what the current operator<< implementation produces.  */

istream &
operator>> (istream &i, mpf_ptr f)
{
  int base;
  char c = 0;
  string s;
  bool ok = false;

  i.get(c); // start reading

  if (i.flags() & ios::skipws) // skip initial whitespace
    while (isspace(c) && i.get(c))
      ;

  if (c == '-' || c == '+') // sign
    {
      if (c == '-')
        s = "-";
      i.get(c);

      while (isspace(c) && i.get(c)) // skip whitespace
        ;
    }

  base = 10; // octal/hex floats currently unsupported
  __gmp_istream_set_digits(s, i, c, ok, base); // read the number

#if HAVE_LOCALECONV
  const char  *point = localeconv()->decimal_point;
  if (c == *point) // radix point
    {
      for (;;)
        {
          s += c;
          i.get(c);
          point++;
          if (*point == '\0')
            break;
          if (c != *point)
            goto fail;
        }
      __gmp_istream_set_digits(s, i, c, ok, base); // read the mantissa
    }
#else
  if (c == '.') // radix point
    {
      s += '.';
      i.get(c);
      __gmp_istream_set_digits(s, i, c, ok, base); // read the mantissa
    }
#endif

  if (ok && (c == 'e' || c == 'E' || c == '@')) // exponent
    {
      s += c;
      i.get(c);
      ok = false; // exponent is mandatory

      if (c == '-' || c == '+') // sign
        {
          s += c;
          i.get(c);

          while (isspace(c) && i.get(c)) // skip whitespace
            ;
        }

      __gmp_istream_set_digits(s, i, c, ok, base); // read the exponent
    }

  if (i.good()) // last character read was non-numeric
    i.putback(c);
  else if (i.eof() && ok) // stopped just before eof
    i.clear();

  if (ok)
    mpf_set_str(f, s.c_str(), base); // extract the number
  else
    {
    fail:
      i.setstate(ios::failbit); // read failed
    }

  return i;
}