text: /*=============================================================================
      Copyright (c) 2001-2011 Joel de Guzman
      Copyright (c) 2001-2011 Hartmut Kaiser
  
      Distributed under the Boost Software License, Version 1.0. (See accompanying
      file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  ==============================================================================*/
  #if !defined(SPIRIT_REAL_POLICIES_APRIL_17_2006_1158PM)
  #define SPIRIT_REAL_POLICIES_APRIL_17_2006_1158PM
  
  #if defined(_MSC_VER)
  #pragma once
  #endif
  
  #include <boost/spirit/home/qi/numeric/numeric_utils.hpp>
  #include <boost/spirit/home/qi/detail/string_parse.hpp>
  
  namespace boost { namespace spirit { namespace qi
  {
      ///////////////////////////////////////////////////////////////////////////
      //  Default (unsigned) real number policies
      ///////////////////////////////////////////////////////////////////////////
      template <typename T>
      struct ureal_policies
      {
          // trailing dot policy suggested by Gustavo Guerra
          static bool const allow_leading_dot = true;
          static bool const allow_trailing_dot = true;
          static bool const expect_dot = false;
  
          template <typename Iterator>
          static bool
          parse_sign(Iterator& /*first*/, Iterator const& /*last*/)
          {
              return false;
          }
  
          template <typename Iterator, typename Attribute>
          static bool
          parse_n(Iterator& first, Iterator const& last, Attribute& attr_)
          {
              return extract_uint<T, 10, 1, -1>::call(first, last, attr_);
          }
  
          template <typename Iterator>
          static bool
          parse_dot(Iterator& first, Iterator const& last)
          {
              if (first == last || *first != '.')
                  return false;
              ++first;
              return true;
          }
  
          template <typename Iterator, typename Attribute>
          static bool
          parse_frac_n(Iterator& first, Iterator const& last, Attribute& attr_)
          {
              return extract_uint<T, 10, 1, -1, true>::call(first, last, attr_);
          }
  
          template <typename Iterator>
          static bool
          parse_exp(Iterator& first, Iterator const& last)
          {
              if (first == last || (*first != 'e' && *first != 'E'))
                  return false;
              ++first;
              return true;
          }
  
          template <typename Iterator>
          static bool
          parse_exp_n(Iterator& first, Iterator const& last, int& attr_)
          {
              return extract_int<int, 10, 1, -1>::call(first, last, attr_);
          }
  
          ///////////////////////////////////////////////////////////////////////
          //  The parse_nan() and parse_inf() functions get called whenever:
          //
          //    - a number to parse does not start with a digit (after having
          //      successfully parsed an optional sign)
          //
          //  or
          //
          //    - after a floating point number of the value 1 (having no
          //      exponential part and a fractional part value of 0) has been
          //      parsed.
          //
          //  The first call allows to recognize representations of NaN or Inf
          //  starting with a non-digit character (such as NaN, Inf, QNaN etc.).
          //
          //  The second call allows to recognize representation formats starting
          //  with a 1.0 (such as 1.0#NAN or 1.0#INF etc.).
          //
          //  The functions should return true if a Nan or Inf has been found. In
          //  this case the attr should be set to the matched value (NaN or
          //  Inf). The optional sign will be automatically applied afterwards.
          //
          //  The default implementation below recognizes representations of NaN
          //  and Inf as mandated by the C99 Standard and as proposed for
          //  inclusion into the C++0x Standard: nan, nan(...), inf and infinity
          //  (the matching is performed case-insensitively).
          ///////////////////////////////////////////////////////////////////////
          template <typename Iterator, typename Attribute>
          static bool
          parse_nan(Iterator& first, Iterator const& last, Attribute& attr_)
          {
              if (first == last)
                  return false;   // end of input reached
  
              if (*first != 'n' && *first != 'N')
                  return false;   // not "nan"
  
              // nan[(...)] ?
              if (detail::string_parse("nan", "NAN", first, last, unused))
              {
                  if (first != last && *first == '(')
                  {
                      // skip trailing (...) part
                      Iterator i = first;
  
                      while (++i != last && *i != ')')
                          ;
                      if (i == last)
                          return false;     // no trailing ')' found, give up
  
                      first = ++i;
                  }
                  attr_ = std::numeric_limits<T>::quiet_NaN();
                  return true;
              }
              return false;
          }
  
          template <typename Iterator, typename Attribute>
          static bool
          parse_inf(Iterator& first, Iterator const& last, Attribute& attr_)
          {
              if (first == last)
                  return false;   // end of input reached
  
              if (*first != 'i' && *first != 'I')
                  return false;   // not "inf"
  
              // inf or infinity ?
              if (detail::string_parse("inf", "INF", first, last, unused))
              {
                  // skip allowed 'inity' part of infinity
                  detail::string_parse("inity", "INITY", first, last, unused);
                  attr_ = std::numeric_limits<T>::infinity();
                  return true;
              }
              return false;
          }
      };
  
      ///////////////////////////////////////////////////////////////////////////
      //  Default (signed) real number policies
      ///////////////////////////////////////////////////////////////////////////
      template <typename T>
      struct real_policies : ureal_policies<T>
      {
          template <typename Iterator>
          static bool
          parse_sign(Iterator& first, Iterator const& last)
          {
              return extract_sign(first, last);
          }
      };
  
      template <typename T>
      struct strict_ureal_policies : ureal_policies<T>
      {
          static bool const expect_dot = true;
      };
  
      template <typename T>
      struct strict_real_policies : real_policies<T>
      {
          static bool const expect_dot = true;
      };
  }}}
  
  #endif
  