210 lines
7.5 KiB
C++
210 lines
7.5 KiB
C++
// Copyright (c) 2001-2020 Hartmut Kaiser
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#if !defined(BOOST_SPIRIT_KARMA_REAL_UTILS_FEB_23_2007_0841PM)
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#define BOOST_SPIRIT_KARMA_REAL_UTILS_FEB_23_2007_0841PM
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#if defined(_MSC_VER)
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#pragma once
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#endif
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#include <boost/config.hpp>
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#include <boost/config/no_tr1/cmath.hpp>
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#include <boost/detail/workaround.hpp>
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#include <boost/limits.hpp>
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#include <boost/spirit/home/support/char_class.hpp>
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#include <boost/spirit/home/support/unused.hpp>
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#include <boost/spirit/home/support/detail/pow10.hpp>
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#include <boost/spirit/home/karma/detail/generate_to.hpp>
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#include <boost/spirit/home/karma/detail/string_generate.hpp>
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#include <boost/spirit/home/karma/numeric/detail/numeric_utils.hpp>
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namespace boost { namespace spirit { namespace karma
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{
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///////////////////////////////////////////////////////////////////////////
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//
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// The real_inserter template takes care of the floating point number to
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// string conversion. The Policies template parameter is used to allow
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// customization of the formatting process
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//
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///////////////////////////////////////////////////////////////////////////
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template <typename T>
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struct real_policies;
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template <typename T
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, typename Policies = real_policies<T>
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, typename CharEncoding = unused_type
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, typename Tag = unused_type>
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struct real_inserter
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{
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template <typename OutputIterator, typename U>
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static bool
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call (OutputIterator& sink, U n, Policies const& p = Policies())
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{
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if (traits::test_nan(n)) {
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return p.template nan<CharEncoding, Tag>(
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sink, n, p.force_sign(n));
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}
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else if (traits::test_infinite(n)) {
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return p.template inf<CharEncoding, Tag>(
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sink, n, p.force_sign(n));
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}
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return p.template call<real_inserter>(sink, n, p);
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}
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#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
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# pragma warning(push)
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# pragma warning(disable: 4100) // 'p': unreferenced formal parameter
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# pragma warning(disable: 4127) // conditional expression is constant
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# pragma warning(disable: 4267) // conversion from 'size_t' to 'unsigned int', possible loss of data
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#endif
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///////////////////////////////////////////////////////////////////////
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// This is the workhorse behind the real generator
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///////////////////////////////////////////////////////////////////////
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template <typename OutputIterator, typename U>
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static bool
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call_n (OutputIterator& sink, U n, Policies const& p)
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{
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// prepare sign and get output format
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bool force_sign = p.force_sign(n);
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bool sign_val = false;
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int flags = p.floatfield(n);
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if (traits::test_negative(n))
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{
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n = -n;
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sign_val = true;
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}
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// The scientific representation requires the normalization of the
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// value to convert.
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// get correct precision for generated number
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unsigned precision = p.precision(n);
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// allow for ADL to find the correct overloads for log10 et.al.
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using namespace std;
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bool precexp_offset = false;
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U dim = 0;
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if (0 == (Policies::fmtflags::fixed & flags) && !traits::test_zero(n))
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{
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dim = log10(n);
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if (dim > 0)
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n /= spirit::traits::pow10<U>(traits::truncate_to_long::call(dim));
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else if (n < 1.) {
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long exp = traits::truncate_to_long::call(-dim);
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dim = static_cast<U>(-exp);
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// detect and handle denormalized numbers to prevent overflow in pow10
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if (exp > std::numeric_limits<U>::max_exponent10)
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{
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n *= spirit::traits::pow10<U>(std::numeric_limits<U>::max_exponent10);
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n *= spirit::traits::pow10<U>(exp - std::numeric_limits<U>::max_exponent10);
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}
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else
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n *= spirit::traits::pow10<U>(exp);
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if (n < 1.)
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{
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n *= 10.;
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--dim;
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precexp_offset = true;
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}
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}
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}
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// prepare numbers (sign, integer and fraction part)
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U integer_part;
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U precexp = spirit::traits::pow10<U>(precision);
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U fractional_part = modf(n, &integer_part);
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if (precexp_offset)
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{
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fractional_part =
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floor((fractional_part * precexp + U(0.5)) * U(10.)) / U(10.);
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}
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else
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{
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fractional_part = floor(fractional_part * precexp + U(0.5));
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}
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if (fractional_part >= precexp)
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{
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fractional_part = floor(fractional_part - precexp);
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integer_part += 1; // handle rounding overflow
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if (integer_part >= 10. && 0 == (Policies::fmtflags::fixed & flags))
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{
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integer_part /= 10.;
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++dim;
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}
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}
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// if trailing zeros are to be omitted, normalize the precision and``
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// fractional part
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U long_int_part = floor(integer_part);
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U long_frac_part = fractional_part;
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unsigned prec = precision;
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if (!p.trailing_zeros(n))
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{
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U frac_part_floor = long_frac_part;
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if (0 != long_frac_part) {
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// remove the trailing zeros
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while (0 != prec &&
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0 == traits::remainder<10>::call(long_frac_part))
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{
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long_frac_part = traits::divide<10>::call(long_frac_part);
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--prec;
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}
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}
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else {
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// if the fractional part is zero, we don't need to output
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// any additional digits
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prec = 0;
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}
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if (precision != prec)
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{
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long_frac_part = frac_part_floor /
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spirit::traits::pow10<U>(precision-prec);
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}
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}
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// call the actual generating functions to output the different parts
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if ((force_sign || sign_val) &&
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traits::test_zero(long_int_part) &&
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traits::test_zero(long_frac_part))
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{
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sign_val = false; // result is zero, no sign please
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force_sign = false;
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}
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// generate integer part
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bool r = p.integer_part(sink, long_int_part, sign_val, force_sign);
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// generate decimal point
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r = r && p.dot(sink, long_frac_part, precision);
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// generate fractional part with the desired precision
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r = r && p.fraction_part(sink, long_frac_part, prec, precision);
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if (r && 0 == (Policies::fmtflags::fixed & flags)) {
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return p.template exponent<CharEncoding, Tag>(sink,
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traits::truncate_to_long::call(dim));
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}
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return r;
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}
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#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
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# pragma warning(pop)
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#endif
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};
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}}}
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#endif
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