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

   1 //  Copyright (c) 2001-2020 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/karma/detail/generate_to.hpp>
  22 #include <boost/spirit/home/karma/detail/string_generate.hpp>
  23 #include <boost/spirit/home/karma/numeric/detail/numeric_utils.hpp>
  24
  25 namespace boost { namespace spirit { namespace karma
  26 {
  27     ///////////////////////////////////////////////////////////////////////////
  28     //
  29     //  The real_inserter template takes care of the floating point number to
  30     //  string conversion. The Policies template parameter is used to allow
  31     //  customization of the formatting process
  32     //
  33     ///////////////////////////////////////////////////////////////////////////
  34     template <typename T>
  35     struct real_policies;
  36
  37     template <typename T
  38       , typename Policies = real_policies<T>
  39       , typename CharEncoding = unused_type
  40       , typename Tag = unused_type>
  41     struct real_inserter
  42     {
  43         template <typename OutputIterator, typename U>
  44         static bool
  45         call (OutputIterator& sink, U n, Policies const& p = Policies())
  46         {
  47             if (traits::test_nan(n)) {
  48                 return p.template nan<CharEncoding, Tag>(
  49                     sink, n, p.force_sign(n));
  50             }
  51             else if (traits::test_infinite(n)) {
  52                 return p.template inf<CharEncoding, Tag>(
  53                     sink, n, p.force_sign(n));
  54             }
  55             return p.template call<real_inserter>(sink, n, p);
  56         }
  57
  58 #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
  59 # pragma warning(push)
  60 # pragma warning(disable: 4100)   // 'p': unreferenced formal parameter
  61 # pragma warning(disable: 4127)   // conditional expression is constant
  62 # pragma warning(disable: 4267)   // conversion from 'size_t' to 'unsigned int', possible loss of data
  63 #endif
  64         ///////////////////////////////////////////////////////////////////////
  65         //  This is the workhorse behind the real generator
  66         ///////////////////////////////////////////////////////////////////////
  67         template <typename OutputIterator, typename U>
  68         static bool
  69         call_n (OutputIterator& sink, U n, Policies const& p)
  70         {
  71         // prepare sign and get output format
  72             bool force_sign = p.force_sign(n);
  73             bool sign_val = false;
  74             int flags = p.floatfield(n);
  75             if (traits::test_negative(n))
  76             {
  77                 n = -n;
  78                 sign_val = true;
  79             }
  80
  81         // The scientific representation requires the normalization of the
  82         // value to convert.
  83
  84             // get correct precision for generated number
  85             unsigned precision = p.precision(n);
  86
  87             // allow for ADL to find the correct overloads for log10 et.al.
  88             using namespace std;
  89
  90             bool precexp_offset = false;
  91             U dim = 0;
  92             if (0 == (Policies::fmtflags::fixed & flags) && !traits::test_zero(n))
  93             {
  94                 dim = log10(n);
  95                 if (dim > 0)
  96                     n /= spirit::traits::pow10<U>(traits::truncate_to_long::call(dim));
  97                 else if (n < 1.) {
  98                     long exp = traits::truncate_to_long::call(-dim);
  99
 100                     dim = static_cast<U>(-exp);
 101
 102                     // detect and handle denormalized numbers to prevent overflow in pow10
 103                     if (exp > std::numeric_limits<U>::max_exponent10)
 104                     {
 105                         n *= spirit::traits::pow10<U>(std::numeric_limits<U>::max_exponent10);
 106                         n *= spirit::traits::pow10<U>(exp - std::numeric_limits<U>::max_exponent10);
 107                     }
 108                     else
 109                         n *= spirit::traits::pow10<U>(exp);
 110
 111                     if (n < 1.)
 112                     {
 113                         n *= 10.;
 114                         --dim;
 115                         precexp_offset = true;
 116                     }
 117                 }
 118             }
 119
 120         // prepare numbers (sign, integer and fraction part)
 121             U integer_part;
 122             U precexp = spirit::traits::pow10<U>(precision);
 123             U fractional_part = modf(n, &integer_part);
 124
 125             if (precexp_offset)
 126             {
 127                 fractional_part =
 128                     floor((fractional_part * precexp + U(0.5)) * U(10.)) / U(10.);
 129             }
 130             else
 131             {
 132                 fractional_part = floor(fractional_part * precexp + U(0.5));
 133             }
 134
 135             if (fractional_part >= precexp)
 136             {
 137                 fractional_part = floor(fractional_part - precexp);
 138                 integer_part += 1;    // handle rounding overflow
 139                 if (integer_part >= 10. && 0 == (Policies::fmtflags::fixed & flags))
 140                 {
 141                     integer_part /= 10.;
 142                     ++dim;
 143                 }
 144             }
 145
 146         // if trailing zeros are to be omitted, normalize the precision and``
 147         // fractional part
 148             U long_int_part = floor(integer_part);
 149             U long_frac_part = fractional_part;
 150             unsigned prec = precision;
 151             if (!p.trailing_zeros(n))
 152             {
 153                 U frac_part_floor = long_frac_part;
 154                 if (0 != long_frac_part) {
 155                     // remove the trailing zeros
 156                     while (0 != prec &&
 157                            0 == traits::remainder<10>::call(long_frac_part))
 158                     {
 159                         long_frac_part = traits::divide<10>::call(long_frac_part);
 160                         --prec;
 161                     }
 162                 }
 163                 else {
 164                     // if the fractional part is zero, we don't need to output
 165                     // any additional digits
 166                     prec = 0;
 167                 }
 168
 169                 if (precision != prec)
 170                 {
 171                     long_frac_part = frac_part_floor /
 172                         spirit::traits::pow10<U>(precision-prec);
 173                 }
 174             }
 175
 176         // call the actual generating functions to output the different parts
 177             if ((force_sign || sign_val) &&
 178                 traits::test_zero(long_int_part) &&
 179                 traits::test_zero(long_frac_part))
 180             {
 181                 sign_val = false;     // result is zero, no sign please
 182                 force_sign = false;
 183             }
 184
 185         // generate integer part
 186             bool r = p.integer_part(sink, long_int_part, sign_val, force_sign);
 187
 188         // generate decimal point
 189             r = r && p.dot(sink, long_frac_part, precision);
 190
 191         // generate fractional part with the desired precision
 192             r = r && p.fraction_part(sink, long_frac_part, prec, precision);
 193
 194             if (r && 0 == (Policies::fmtflags::fixed & flags)) {
 195                 return p.template exponent<CharEncoding, Tag>(sink,
 196                     traits::truncate_to_long::call(dim));
 197             }
 198             return r;
 199         }
 200
 201 #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
 202 # pragma warning(pop)
 203 #endif
 204
 205     };
 206 }}}
 207
 208 #endif
 209