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- /*=============================================================================
- Copyright (c) 2001-2014 Joel de Guzman
- Copyright (c) 2001-2011 Hartmut Kaiser
- http://spirit.sourceforge.net/
- Distributed under the Boost Software License, Version 1.0. (See accompanying
- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- =============================================================================*/
- #if !defined(BOOST_SPIRIT_X3_EXTRACT_REAL_APRIL_18_2006_0901AM)
- #define BOOST_SPIRIT_X3_EXTRACT_REAL_APRIL_18_2006_0901AM
- #include <cmath>
- #include <boost/limits.hpp>
- #include <boost/type_traits/is_same.hpp>
- #include <boost/spirit/home/x3/support/unused.hpp>
- #include <boost/spirit/home/x3/support/numeric_utils/pow10.hpp>
- #include <boost/spirit/home/x3/support/numeric_utils/sign.hpp>
- #include <boost/spirit/home/x3/support/traits/move_to.hpp>
- #include <boost/assert.hpp>
- #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
- # pragma warning(push)
- # pragma warning(disable: 4100) // 'p': unreferenced formal parameter
- # pragma warning(disable: 4127) // conditional expression is constant
- #endif
- namespace boost { namespace spirit { namespace x3 { namespace extension
- {
- using x3::traits::pow10;
- template <typename T>
- inline bool
- scale(int exp, T& n)
- {
- constexpr auto max_exp = std::numeric_limits<T>::max_exponent10;
- constexpr auto min_exp = std::numeric_limits<T>::min_exponent10;
- if (exp >= 0)
- {
- // return false if exp exceeds the max_exp
- // do this check only for primitive types!
- if (is_floating_point<T>() && exp > max_exp)
- return false;
- n *= pow10<T>(exp);
- }
- else
- {
- if (exp < min_exp)
- {
- n /= pow10<T>(-min_exp);
- // return false if exp still exceeds the min_exp
- // do this check only for primitive types!
- exp += -min_exp;
- if (is_floating_point<T>() && exp < min_exp)
- return false;
- n /= pow10<T>(-exp);
- }
- else
- {
- n /= pow10<T>(-exp);
- }
- }
- return true;
- }
- inline bool
- scale(int /*exp*/, unused_type /*n*/)
- {
- // no-op for unused_type
- return true;
- }
- template <typename T>
- inline bool
- scale(int exp, int frac, T& n)
- {
- return scale(exp - frac, n);
- }
- inline bool
- scale(int /*exp*/, int /*frac*/, unused_type /*n*/)
- {
- // no-op for unused_type
- return true;
- }
- inline float
- negate(bool neg, float n)
- {
- return neg ? x3::changesign(n) : n;
- }
- inline double
- negate(bool neg, double n)
- {
- return neg ? x3::changesign(n) : n;
- }
- inline long double
- negate(bool neg, long double n)
- {
- return neg ? x3::changesign(n) : n;
- }
- template <typename T>
- inline T
- negate(bool neg, T const& n)
- {
- return neg ? -n : n;
- }
- inline unused_type
- negate(bool /*neg*/, unused_type n)
- {
- // no-op for unused_type
- return n;
- }
- }}}}
- namespace boost { namespace spirit { namespace x3
- {
- template <typename T, typename RealPolicies>
- struct extract_real
- {
- template <typename Iterator, typename Attribute>
- static bool
- parse(Iterator& first, Iterator const& last, Attribute& attr,
- RealPolicies const& p)
- {
- if (first == last)
- return false;
- Iterator save = first;
- // Start by parsing the sign. neg will be true if
- // we got a "-" sign, false otherwise.
- bool neg = p.parse_sign(first, last);
- // Now attempt to parse an integer
- T n = 0;
- bool got_a_number = p.parse_n(first, last, n);
- // If we did not get a number it might be a NaN, Inf or a leading
- // dot.
- if (!got_a_number)
- {
- // Check whether the number to parse is a NaN or Inf
- if (p.parse_nan(first, last, n) ||
- p.parse_inf(first, last, n))
- {
- // If we got a negative sign, negate the number
- traits::move_to(extension::negate(neg, n), attr);
- return true; // got a NaN or Inf, return early
- }
- // If we did not get a number and our policies do not
- // allow a leading dot, fail and return early (no-match)
- if (!p.allow_leading_dot)
- {
- first = save;
- return false;
- }
- }
- bool e_hit = false;
- Iterator e_pos;
- int frac_digits = 0;
- // Try to parse the dot ('.' decimal point)
- if (p.parse_dot(first, last))
- {
- // We got the decimal point. Now we will try to parse
- // the fraction if it is there. If not, it defaults
- // to zero (0) only if we already got a number.
- Iterator savef = first;
- if (p.parse_frac_n(first, last, n))
- {
- // Optimization note: don't compute frac_digits if T is
- // an unused_type. This should be optimized away by the compiler.
- if (!is_same<T, unused_type>::value)
- frac_digits =
- static_cast<int>(std::distance(savef, first));
- BOOST_ASSERT(frac_digits >= 0);
- }
- else if (!got_a_number || !p.allow_trailing_dot)
- {
- // We did not get a fraction. If we still haven't got a
- // number and our policies do not allow a trailing dot,
- // return no-match.
- first = save;
- return false;
- }
- // Now, let's see if we can parse the exponent prefix
- e_pos = first;
- e_hit = p.parse_exp(first, last);
- }
- else
- {
- // No dot and no number! Return no-match.
- if (!got_a_number)
- {
- first = save;
- return false;
- }
- // If we must expect a dot and we didn't see an exponent
- // prefix, return no-match.
- e_pos = first;
- e_hit = p.parse_exp(first, last);
- if (p.expect_dot && !e_hit)
- {
- first = save;
- return false;
- }
- }
- if (e_hit)
- {
- // We got the exponent prefix. Now we will try to parse the
- // actual exponent. It is an error if it is not there.
- int exp = 0;
- if (p.parse_exp_n(first, last, exp))
- {
- // Got the exponent value. Scale the number by
- // exp-frac_digits.
- if (!extension::scale(exp, frac_digits, n))
- return false;
- }
- else
- {
- // If there is no number, disregard the exponent altogether.
- // by resetting 'first' prior to the exponent prefix (e|E)
- first = e_pos;
- // Scale the number by -frac_digits.
- if (!extension::scale(-frac_digits, n))
- return false;
- }
- }
- else if (frac_digits)
- {
- // No exponent found. Scale the number by -frac_digits.
- if (!extension::scale(-frac_digits, n))
- return false;
- }
- // If we got a negative sign, negate the number
- traits::move_to(extension::negate(neg, n), attr);
- // Success!!!
- return true;
- }
- };
- #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
- # pragma warning(pop)
- #endif
- }}}
- #endif
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