234 lines
8.0 KiB
C++
234 lines
8.0 KiB
C++
/*=============================================================================
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Copyright (c) 2001-2019 Joel de Guzman
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Copyright (c) 2001-2011 Hartmut Kaiser
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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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==============================================================================*/
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#ifndef BOOST_SPIRIT_QI_NUMERIC_REAL_POLICIES_HPP
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#define BOOST_SPIRIT_QI_NUMERIC_REAL_POLICIES_HPP
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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/spirit/home/qi/numeric/numeric_utils.hpp>
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#include <boost/spirit/home/qi/detail/string_parse.hpp>
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#include <boost/type_traits/is_floating_point.hpp>
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namespace boost { namespace spirit { namespace traits
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{
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// So that we won't exceed the capacity of the underlying type T,
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// we limit the number of digits parsed to its max_digits10.
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// By default, the value is -1 which tells spirit to parse an
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// unbounded number of digits.
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template <typename T, typename Enable = void>
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struct max_digits10
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{
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static int const value = -1; // unbounded
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};
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template <typename T>
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struct max_digits10<T
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, typename enable_if_c<(is_floating_point<T>::value)>::type>
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{
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static int const digits = std::numeric_limits<T>::digits;
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static int const value = 2 + (digits * 30103l) / 100000l;
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};
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}}}
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namespace boost { namespace spirit { namespace qi
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{
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///////////////////////////////////////////////////////////////////////////
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// Default (unsigned) real number policies
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///////////////////////////////////////////////////////////////////////////
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template <typename T>
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struct ureal_policies
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{
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// Versioning
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typedef mpl::int_<2> version;
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// trailing dot policy suggested by Gustavo Guerra
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static bool const allow_leading_dot = true;
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static bool const allow_trailing_dot = true;
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static bool const expect_dot = false;
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template <typename Iterator>
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static bool
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parse_sign(Iterator& /*first*/, Iterator const& /*last*/)
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{
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return false;
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}
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template <typename Iterator, typename Attribute>
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static bool
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parse_n(Iterator& first, Iterator const& last, Attribute& attr_)
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{
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typedef extract_uint<Attribute, 10, 1
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, traits::max_digits10<T>::value // See notes on max_digits10 above
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, false, true>
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extract_uint;
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return extract_uint::call(first, last, attr_);
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}
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// ignore_excess_digits (required for version > 1 API)
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template <typename Iterator>
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static std::size_t
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ignore_excess_digits(Iterator& first, Iterator const& last)
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{
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Iterator save = first;
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if (extract_uint<unused_type, 10, 1, -1>::call(first, last, unused))
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return static_cast<std::size_t>(std::distance(save, first));
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return 0;
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}
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template <typename Iterator>
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static bool
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parse_dot(Iterator& first, Iterator const& last)
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{
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if (first == last || *first != '.')
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return false;
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++first;
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return true;
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}
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template <typename Iterator, typename Attribute>
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static bool
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parse_frac_n(Iterator& first, Iterator const& last, Attribute& attr_, int& frac_digits)
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{
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Iterator savef = first;
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bool r = extract_uint<Attribute, 10, 1, -1, true, true>::call(first, last, attr_);
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if (r)
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{
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#if defined(_MSC_VER) && _MSC_VER < 1900
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# pragma warning(push)
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# pragma warning(disable: 4127) // conditional expression is constant
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#endif
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// Optimization note: don't compute frac_digits if T is
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// an unused_type. This should be optimized away by the compiler.
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if (!is_same<T, unused_type>::value)
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frac_digits =
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static_cast<int>(std::distance(savef, first));
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#if defined(_MSC_VER) && _MSC_VER < 1900
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# pragma warning(pop)
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#endif
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// ignore extra (non-significant digits)
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extract_uint<unused_type, 10, 1, -1>::call(first, last, unused);
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}
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return r;
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}
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template <typename Iterator>
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static bool
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parse_exp(Iterator& first, Iterator const& last)
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{
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if (first == last || (*first != 'e' && *first != 'E'))
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return false;
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++first;
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return true;
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}
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template <typename Iterator>
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static bool
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parse_exp_n(Iterator& first, Iterator const& last, int& attr_)
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{
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return extract_int<int, 10, 1, -1>::call(first, last, attr_);
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}
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///////////////////////////////////////////////////////////////////////
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// The parse_nan() and parse_inf() functions get called whenever
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// a number to parse does not start with a digit (after having
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// successfully parsed an optional sign).
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//
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// The functions should return true if a Nan or Inf has been found. In
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// this case the attr should be set to the matched value (NaN or
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// Inf). The optional sign will be automatically applied afterwards.
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//
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// The default implementation below recognizes representations of NaN
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// and Inf as mandated by the C99 Standard and as proposed for
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// inclusion into the C++0x Standard: nan, nan(...), inf and infinity
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// (the matching is performed case-insensitively).
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///////////////////////////////////////////////////////////////////////
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template <typename Iterator, typename Attribute>
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static bool
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parse_nan(Iterator& first, Iterator const& last, Attribute& attr_)
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{
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if (first == last)
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return false; // end of input reached
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if (*first != 'n' && *first != 'N')
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return false; // not "nan"
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// nan[(...)] ?
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if (detail::string_parse("nan", "NAN", first, last, unused))
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{
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if (first != last && *first == '(')
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{
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// skip trailing (...) part
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Iterator i = first;
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while (++i != last && *i != ')')
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;
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if (i == last)
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return false; // no trailing ')' found, give up
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first = ++i;
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}
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attr_ = std::numeric_limits<T>::quiet_NaN();
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return true;
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}
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return false;
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}
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template <typename Iterator, typename Attribute>
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static bool
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parse_inf(Iterator& first, Iterator const& last, Attribute& attr_)
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{
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if (first == last)
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return false; // end of input reached
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if (*first != 'i' && *first != 'I')
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return false; // not "inf"
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// inf or infinity ?
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if (detail::string_parse("inf", "INF", first, last, unused))
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{
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// skip allowed 'inity' part of infinity
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detail::string_parse("inity", "INITY", first, last, unused);
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attr_ = std::numeric_limits<T>::infinity();
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return true;
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}
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return false;
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}
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};
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///////////////////////////////////////////////////////////////////////////
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// Default (signed) real number policies
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///////////////////////////////////////////////////////////////////////////
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template <typename T>
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struct real_policies : ureal_policies<T>
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{
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template <typename Iterator>
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static bool
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parse_sign(Iterator& first, Iterator const& last)
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{
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return extract_sign(first, last);
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}
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};
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template <typename T>
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struct strict_ureal_policies : ureal_policies<T>
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{
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static bool const expect_dot = true;
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};
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template <typename T>
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struct strict_real_policies : real_policies<T>
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{
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static bool const expect_dot = true;
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};
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}}}
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#endif
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