support/numeric_utils/extract_int.hpp

0001 /*=============================================================================
0002     Copyright (c) 2001-2014 Joel de Guzman
0003     Copyright (c) 2011 Jan Frederick Eick
0004
0005     Distributed under the Boost Software License, Version 1.0. (See accompanying
0006     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0007 ==============================================================================*/
0008 #if !defined(BOOST_SPIRIT_X3_EXTRACT_INT_APRIL_17_2006_0830AM)
0009 #define BOOST_SPIRIT_X3_EXTRACT_INT_APRIL_17_2006_0830AM
0010
0011 #include <boost/spirit/home/x3/support/traits/move_to.hpp>
0012 #include <boost/spirit/home/x3/support/numeric_utils/detail/extract_int.hpp>
0013 #include <boost/assert.hpp>
0014
0015 namespace boost { namespace spirit { namespace x3
0016 {
0017     ///////////////////////////////////////////////////////////////////////////
0018     //  Extract the prefix sign (- or +), return true if a '-' was found
0019     ///////////////////////////////////////////////////////////////////////////
0020     template <typename Iterator>
0021     inline bool
0022     extract_sign(Iterator& first, Iterator const& last)
0023     {
0024         (void)last;                  // silence unused warnings
0025         BOOST_ASSERT(first != last); // precondition
0026
0027         // Extract the sign
0028         bool neg = *first == '-';
0029         if (neg || (*first == '+'))
0030         {
0031             ++first;
0032             return neg;
0033         }
0034         return false;
0035     }
0036
0037     ///////////////////////////////////////////////////////////////////////////
0038     // Low level unsigned integer parser
0039     ///////////////////////////////////////////////////////////////////////////
0040     template <typename T, unsigned Radix, unsigned MinDigits, int MaxDigits
0041       , bool Accumulate = false>
0042     struct extract_uint
0043     {
0044         // check template parameter 'Radix' for validity
0045         static_assert(
0046             (Radix >= 2 && Radix <= 36),
0047             "Error Unsupported Radix");
0048
0049         template <typename Iterator>
0050         inline static bool call(Iterator& first, Iterator const& last, T& attr)
0051         {
0052             if (first == last)
0053                 return false;
0054
0055             typedef detail::extract_int<
0056                 T
0057               , Radix
0058               , MinDigits
0059               , MaxDigits
0060               , detail::positive_accumulator<Radix>
0061               , Accumulate>
0062             extract_type;
0063
0064             Iterator save = first;
0065             if (!extract_type::parse(first, last, attr))
0066             {
0067                 first = save;
0068                 return false;
0069             }
0070             return true;
0071         }
0072
0073         template <typename Iterator, typename Attribute>
0074         inline static bool call(Iterator& first, Iterator const& last, Attribute& attr_)
0075         {
0076             // this case is called when Attribute is not T
0077             T attr;
0078             if (call(first, last, attr))
0079             {
0080                 traits::move_to(attr, attr_);
0081                 return true;
0082             }
0083             return false;
0084         }
0085     };
0086
0087     ///////////////////////////////////////////////////////////////////////////
0088     // Low level signed integer parser
0089     ///////////////////////////////////////////////////////////////////////////
0090     template <typename T, unsigned Radix, unsigned MinDigits, int MaxDigits>
0091     struct extract_int
0092     {
0093         // check template parameter 'Radix' for validity
0094         static_assert(
0095             (Radix == 2 || Radix == 8 || Radix == 10 || Radix == 16),
0096             "Error Unsupported Radix");
0097
0098         template <typename Iterator>
0099         inline static bool call(Iterator& first, Iterator const& last, T& attr)
0100         {
0101             if (first == last)
0102                 return false;
0103
0104             typedef detail::extract_int<
0105                 T, Radix, MinDigits, MaxDigits>
0106             extract_pos_type;
0107
0108             typedef detail::extract_int<
0109                 T, Radix, MinDigits, MaxDigits, detail::negative_accumulator<Radix> >
0110             extract_neg_type;
0111
0112             Iterator save = first;
0113             bool hit = extract_sign(first, last);
0114             if (hit)
0115                 hit = extract_neg_type::parse(first, last, attr);
0116             else
0117                 hit = extract_pos_type::parse(first, last, attr);
0118
0119             if (!hit)
0120             {
0121                 first = save;
0122                 return false;
0123             }
0124             return true;
0125         }
0126
0127         template <typename Iterator, typename Attribute>
0128         inline static bool call(Iterator& first, Iterator const& last, Attribute& attr_)
0129         {
0130             // this case is called when Attribute is not T
0131             T attr;
0132             if (call(first, last, attr))
0133             {
0134                 traits::move_to(attr, attr_);
0135                 return true;
0136             }
0137             return false;
0138         }
0139     };
0140 }}}
0141
0142 #endif