283 lines
14 KiB
C++
Executable File
283 lines
14 KiB
C++
Executable File
// Copyright (c) 2001-2008 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_POLICIES_MAR_02_2007_0936AM)
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#define BOOST_SPIRIT_KARMA_REAL_POLICIES_MAR_02_2007_0936AM
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#if defined(_MSC_VER) && (_MSC_VER >= 1020)
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#pragma once // MS compatible compilers support #pragma once
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#endif
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#include <boost/spirit/home/support/char_class.hpp>
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#include <boost/spirit/home/karma/generate.hpp>
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#include <boost/spirit/home/karma/char.hpp>
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#include <boost/spirit/home/karma/numeric/int.hpp>
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#include <cmath>
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#include <boost/spirit/home/support/detail/math/fpclassify.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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// real_generator_policies, if you need special handling of your floating
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// point numbers, just overload this policy class and use it as a template
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// parameter to the karma::real_spec floating point specifier:
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//
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// template <typename T>
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// struct scientific_policy : karma::real_generator_policies<T>
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// {
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// // we want the numbers always to be in scientific format
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// static int floatfield(T n) { return scientific; }
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// };
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//
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// typedef
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// karma::real_spec<double, scientific_policy<double> >
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// science_type;
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//
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// karma::generate(sink, science_type(), 1.0); // will output: 1.0e00
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//
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///////////////////////////////////////////////////////////////////////////
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template <typename T>
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struct real_generator_policies
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{
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///////////////////////////////////////////////////////////////////////
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// Specifies, which representation type to use during output
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// generation.
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///////////////////////////////////////////////////////////////////////
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enum fmtflags
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{
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scientific = 0, // Generate floating-point values in scientific
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// format (with an exponent field).
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fixed = 1 // Generate floating-point values in fixed-point
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// format (with no exponent field).
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};
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///////////////////////////////////////////////////////////////////////
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// The default behavior is to not to require generating a sign. If
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// 'force_sign' is specified as true, then all generated numbers will
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// have a sign ('+' or '-', zeros will have a space instead of a sign)
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///////////////////////////////////////////////////////////////////////
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static bool const force_sign = false;
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///////////////////////////////////////////////////////////////////////
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// The 'trailing_zeros' flag instructs the floating point generator to
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// emit trailing zeros up to the required precision digits.
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///////////////////////////////////////////////////////////////////////
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static bool const trailing_zeros = false;
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///////////////////////////////////////////////////////////////////////
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// Decide, which representation type to use in the generated output.
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//
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// By default all numbers having an absolute value of zero or in
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// between 0.001 and 100000 will be generated using the fixed format,
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// all others will be generated using the scientific representation.
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//
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// The trailing_zeros flag can be used to force the output of trailing
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// zeros in the fractional part up to the number of digits returned by
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// the precision() member function. The default is not to generate
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// the trailing zeros.
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//
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// n The floating point number to output. This can be used to
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// adjust the formatting flags depending on the value of
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// this number.
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///////////////////////////////////////////////////////////////////////
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static int
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floatfield(T n)
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{
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if (detail::is_zero(n))
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return fixed;
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T abs_n = detail::absolute_value(n);
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return (abs_n >= 1e5 || abs_n < 1e-3) ? scientific : fixed;
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}
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///////////////////////////////////////////////////////////////////////
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// The 'fractional_precision' constant specifies the default number of
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// digits to generate for the fractional part of a floating point
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// number. This is used by this (default) policies implementation
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// only. If you need another fractional precision you'll have to
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// overload the precision function below.
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//
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// Note: The actual number of digits for a floating point number is
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// determined by the precision() function below. This allows to
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// have different precisions depending on the value of the
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// floating point number.
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///////////////////////////////////////////////////////////////////////
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static unsigned int const fractional_precision = 3;
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///////////////////////////////////////////////////////////////////////
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// Return the maximum number of decimal digits to generate in the
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// fractional part of the output.
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//
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// n The floating point number to output. This can be used to
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// adjust the required precision depending on the value of
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// this number. If the trailing zeros flag is specified the
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// fractional part of the output will be 'filled' with
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// zeros, if appropriate
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//
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// Note: If the trailing_zeros flag is not in effect additional
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// comments apply. See the comment for the fraction_part()
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// function below.
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///////////////////////////////////////////////////////////////////////
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static unsigned int
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precision(T)
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{
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// generate max. 'fractional_precision' fractional digits
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return fractional_precision;
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}
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///////////////////////////////////////////////////////////////////////
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// Generate the integer part of the number.
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//
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// sink The output iterator to use for generation
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// n The absolute value of the integer part of the floating
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// point number to convert (always non-negative).
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// sign The sign of the overall floating point number to convert.
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///////////////////////////////////////////////////////////////////////
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template <bool ForceSign, typename OutputIterator>
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static bool
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integer_part (OutputIterator& sink, T n, bool sign)
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{
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return sign_inserter<ForceSign>::call(
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sink, detail::is_zero(n), sign) &&
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int_inserter<10>::call(sink, n);
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}
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///////////////////////////////////////////////////////////////////////
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// Generate the decimal point.
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//
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// sink The output iterator to use for generation
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// n The fractional part of the floating point number to
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// convert. Note that this number is scaled such, that
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// it represents the number of units which correspond
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// to the value returned from the precision() function
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// earlier. I.e. a fractional part of 0.01234 is
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// represented as 1234 when the 'Precision' is 5.
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//
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// This is given to allow to decide, whether a decimal point
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// has to be generated at all.
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//
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// Note: If the trailing_zeros flag is not in effect additional
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// comments apply. See the comment for the fraction_part()
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// function below.
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///////////////////////////////////////////////////////////////////////
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template <typename OutputIterator>
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static bool
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dot (OutputIterator& sink, T)
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{
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return char_inserter<>::call(sink, '.'); // generate the dot by default
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}
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///////////////////////////////////////////////////////////////////////
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// Generate the fractional part of the number.
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//
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// sink The output iterator to use for generation
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// n The fractional part of the floating point number to
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// convert. This number is scaled such, that it represents
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// the number of units which correspond to the 'Precision'.
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// I.e. a fractional part of 0.01234 is represented as 1234
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// when the 'precision_' parameter is 5.
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//
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// Note: If the trailing_zeros flag is not returned from the
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// floatfield() function, the 'precision_' parameter will have
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// been corrected from the value the precision() function
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// returned earlier (defining the maximal number of fractional
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// digits) in the sense, that it takes into account trailing
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// zeros. I.e. a floating point number 0.0123 and a value of 5
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// returned from precision() will result in:
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//
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// trailing_zeros is not specified:
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// n 123
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// precision_ 4
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//
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// trailing_zeros is specified:
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// n 1230
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// precision_ 5
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//
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///////////////////////////////////////////////////////////////////////
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template <typename OutputIterator>
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static bool
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fraction_part (OutputIterator& sink, T n, unsigned precision_)
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{
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// allow for ADL to find the correct overload for floor and log10
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using namespace std;
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// The following is equivalent to:
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// generate(sink, right_align(precision, '0')[ulong], n);
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// but it's spelled out to avoid inter-modular dependencies.
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T digits = (detail::is_zero(n) ? 0 : floor(log10(n))) + 1;
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bool r = true;
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for (/**/; r && digits < precision_; digits = digits + 1)
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r = char_inserter<>::call(sink, '0');
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return r && int_inserter<10>::call(sink, n);
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}
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///////////////////////////////////////////////////////////////////////
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// Generate the exponential part of the number (this is called only
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// if the floatfield() function returned the 'scientific' flag).
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//
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// sink The output iterator to use for generation
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// n The (signed) exponential part of the floating point
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// number to convert.
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//
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// The Tag template parameter is either of the type unused_type or
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// describes the character class and conversion to be applied to any
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// output possibly influenced by either the lower[...] or upper[...]
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// directives.
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///////////////////////////////////////////////////////////////////////
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template <typename Tag, typename OutputIterator>
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static bool
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exponent (OutputIterator& sink, T n)
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{
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T abs_n = detail::absolute_value(n);
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bool r = char_inserter<Tag>::call(sink, 'e') &&
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sign_inserter<false>::call(
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sink, detail::is_zero(n), detail::is_negative(n));
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// the C99 Standard requires at least two digits in the exponent
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if (r && abs_n < 10)
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r = char_inserter<Tag>::call(sink, '0');
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return r && int_inserter<10>::call(sink, abs_n);
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}
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///////////////////////////////////////////////////////////////////////
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// Print the textual representations for non-normal floats (NaN and
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// Inf)
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//
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// sink The output iterator to use for generation
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// n The (signed) floating point number to convert.
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//
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// The Tag template parameter is either of the type unused_type or
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// describes the character class and conversion to be applied to any
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// output possibly influenced by either the lower[...] or upper[...]
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// directives.
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//
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// Note: These functions get called only if fpclassify() returned
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// FP_INFINITY or FP_NAN.
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///////////////////////////////////////////////////////////////////////
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template <bool ForceSign, typename Tag, typename OutputIterator>
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static bool
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nan (OutputIterator& sink, T n)
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{
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return sign_inserter<ForceSign>::call(
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sink, false, detail::is_negative(n)) &&
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string_inserter<Tag>::call(sink, "nan");
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}
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template <bool ForceSign, typename Tag, typename OutputIterator>
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static bool
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inf (OutputIterator& sink, T n)
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{
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return sign_inserter<ForceSign>::call(
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sink, false, detail::is_negative(n)) &&
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string_inserter<Tag>::call(sink, "inf");
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}
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};
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}}}
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#endif // defined(BOOST_SPIRIT_KARMA_REAL_POLICIES_MAR_02_2007_0936AM)
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