ceph/src/boost/boost/spirit/home/karma/numeric/detail/real_utils.hpp

   1 //  Copyright (c) 2001-2011 Hartmut Kaiser
   2 //
   3 //  Distributed under the Boost Software License, Version 1.0. (See accompanying
   4 //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   5
   6 #if !defined(BOOST_SPIRIT_KARMA_REAL_UTILS_FEB_23_2007_0841PM)
   7 #define BOOST_SPIRIT_KARMA_REAL_UTILS_FEB_23_2007_0841PM
   8
   9 #if defined(_MSC_VER)
  10 #pragma once
  11 #endif
  12
  13 #include <boost/config.hpp>
  14 #include <boost/config/no_tr1/cmath.hpp>
  15 #include <boost/detail/workaround.hpp>
  16 #include <boost/limits.hpp>
  17
  18 #include <boost/spirit/home/support/char_class.hpp>
  19 #include <boost/spirit/home/support/unused.hpp>
  20 #include <boost/spirit/home/support/detail/pow10.hpp>
  21 #include <boost/spirit/home/support/detail/sign.hpp>
  22 #include <boost/spirit/home/karma/detail/generate_to.hpp>
  23 #include <boost/spirit/home/karma/detail/string_generate.hpp>
  24 #include <boost/spirit/home/karma/numeric/detail/numeric_utils.hpp>
  25
  26 namespace boost { namespace spirit { namespace karma
  27 {
  28     ///////////////////////////////////////////////////////////////////////////
  29     //
  30     //  The real_inserter template takes care of the floating point number to
  31     //  string conversion. The Policies template parameter is used to allow
  32     //  customization of the formatting process
  33     //
  34     ///////////////////////////////////////////////////////////////////////////
  35     template <typename T>
  36     struct real_policies;
  37
  38     template <typename T
  39       , typename Policies = real_policies<T>
  40       , typename CharEncoding = unused_type
  41       , typename Tag = unused_type>
  42     struct real_inserter
  43     {
  44         template <typename OutputIterator, typename U>
  45         static bool
  46         call (OutputIterator& sink, U n, Policies const& p = Policies())
  47         {
  48             if (traits::test_nan(n)) {
  49                 return p.template nan<CharEncoding, Tag>(
  50                     sink, n, p.force_sign(n));
  51             }
  52             else if (traits::test_infinite(n)) {
  53                 return p.template inf<CharEncoding, Tag>(
  54                     sink, n, p.force_sign(n));
  55             }
  56             return p.template call<real_inserter>(sink, n, p);
  57         }
  58
  59 #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
  60 # pragma warning(push)
  61 # pragma warning(disable: 4100)   // 'p': unreferenced formal parameter
  62 # pragma warning(disable: 4127)   // conditional expression is constant
  63 # pragma warning(disable: 4267)   // conversion from 'size_t' to 'unsigned int', possible loss of data
  64 #endif
  65         ///////////////////////////////////////////////////////////////////////
  66         //  This is the workhorse behind the real generator
  67         ///////////////////////////////////////////////////////////////////////
  68         template <typename OutputIterator, typename U>
  69         static bool
  70         call_n (OutputIterator& sink, U n, Policies const& p)
  71         {
  72         // prepare sign and get output format
  73             bool force_sign = p.force_sign(n);
  74             bool sign_val = false;
  75             int flags = p.floatfield(n);
  76             if (traits::test_negative(n))
  77             {
  78                 n = -n;
  79                 sign_val = true;
  80             }
  81
  82         // The scientific representation requires the normalization of the
  83         // value to convert.
  84
  85             // get correct precision for generated number
  86             unsigned precision = p.precision(n);
  87             if (std::numeric_limits<U>::digits10)
  88             {
  89                 // limit generated precision to digits10, if defined
  90                 precision = (std::min)(precision,
  91                     (unsigned)std::numeric_limits<U>::digits10 + 1);
  92             }
  93
  94             // allow for ADL to find the correct overloads for log10 et.al.
  95             using namespace std;
  96
  97             U dim = 0;
  98             if (0 == (Policies::fmtflags::fixed & flags) && !traits::test_zero(n))
  99             {
 100                 dim = log10(n);
 101                 if (dim > 0)
 102                     n /= spirit::traits::pow10<U>(traits::truncate_to_long::call(dim));
 103                 else if (n < 1.) {
 104                     long exp = traits::truncate_to_long::call(-dim);
 105                     if (exp != -dim)
 106                         ++exp;
 107                     dim = static_cast<U>(-exp);
 108                     // detect and handle denormalized numbers to prevent overflow in pow10
 109                     if (exp > std::numeric_limits<U>::max_exponent10)
 110                     {
 111                         n *= spirit::traits::pow10<U>(std::numeric_limits<U>::max_exponent10);
 112                         n *= spirit::traits::pow10<U>(exp - std::numeric_limits<U>::max_exponent10);
 113                     } else
 114                         n *= spirit::traits::pow10<U>(exp);
 115                 }
 116             }
 117
 118         // prepare numbers (sign, integer and fraction part)
 119             U integer_part;
 120             U precexp = spirit::traits::pow10<U>(precision);
 121             U fractional_part = modf(n, &integer_part);
 122
 123             fractional_part = floor(fractional_part * precexp + U(0.5));
 124             if (fractional_part >= precexp)
 125             {
 126                 fractional_part = floor(fractional_part - precexp);
 127                 integer_part += 1;    // handle rounding overflow
 128             }
 129
 130         // if trailing zeros are to be omitted, normalize the precision and
 131         // fractional part
 132             U long_int_part = floor(integer_part);
 133             U long_frac_part = fractional_part;
 134             unsigned prec = precision;
 135             if (!p.trailing_zeros(n))
 136             {
 137                 U frac_part_floor = long_frac_part;
 138                 if (0 != long_frac_part) {
 139                     // remove the trailing zeros
 140                     while (0 != prec &&
 141                            0 == traits::remainder<10>::call(long_frac_part))
 142                     {
 143                         long_frac_part = traits::divide<10>::call(long_frac_part);
 144                         --prec;
 145                     }
 146                 }
 147                 else {
 148                     // if the fractional part is zero, we don't need to output
 149                     // any additional digits
 150                     prec = 0;
 151                 }
 152
 153                 if (precision != prec)
 154                 {
 155                     long_frac_part = frac_part_floor /
 156                         spirit::traits::pow10<U>(precision-prec);
 157                 }
 158             }
 159
 160         // call the actual generating functions to output the different parts
 161             if ((force_sign || sign_val) &&
 162                 traits::test_zero(long_int_part) &&
 163                 traits::test_zero(long_frac_part))
 164             {
 165                 sign_val = false;     // result is zero, no sign please
 166                 force_sign = false;
 167             }
 168
 169         // generate integer part
 170             bool r = p.integer_part(sink, long_int_part, sign_val, force_sign);
 171
 172         // generate decimal point
 173             r = r && p.dot(sink, long_frac_part, precision);
 174
 175         // generate fractional part with the desired precision
 176             r = r && p.fraction_part(sink, long_frac_part, prec, precision);
 177
 178             if (r && 0 == (Policies::fmtflags::fixed & flags)) {
 179                 return p.template exponent<CharEncoding, Tag>(sink,
 180                     traits::truncate_to_long::call(dim));
 181             }
 182             return r;
 183         }
 184
 185 #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
 186 # pragma warning(pop)
 187 #endif
 188
 189     };
 190 }}}
 191
 192 #endif
 193