1 // Copyright Abel Sinkovics (abel@sinkovics.hu) 2011.
2 // Distributed under the Boost Software License, Version 1.0.
3 // (See accompanying file LICENSE_1_0.txt or copy at
4 // http://www.boost.org/LICENSE_1_0.txt)
5
6 #include <boost/metaparse/foldl1.hpp>
7 #include <boost/metaparse/build_parser.hpp>
8 #include <boost/metaparse/transform.hpp>
9 #include <boost/metaparse/one_of_c.hpp>
10 #include <boost/metaparse/entire_input.hpp>
11 #include <boost/metaparse/string.hpp>
12
13 #include <boost/metaparse/util/digit_to_int.hpp>
14
15 #include <boost/mpl/int.hpp>
16 #include <boost/mpl/plus.hpp>
17 #include <boost/mpl/times.hpp>
18
19 #include <iostream>
20
21 using boost::metaparse::foldl1;
22 using boost::metaparse::build_parser;
23 using boost::metaparse::transform;
24 using boost::metaparse::one_of_c;
25 using boost::metaparse::entire_input;
26
27 using boost::metaparse::util::digit_to_int;
28
29 using boost::mpl::int_;
30 using boost::mpl::plus;
31 using boost::mpl::times;
32
33 /*
34 * The grammar
35 *
36 * expression ::= ('1' | '0')*
37 */
38
39 struct next_element
40 {
41 template <class Acc, class B>
42 struct apply : plus<times<Acc, int_<2> >, B> {};
43 };
44
45 typedef
46 foldl1<transform<one_of_c<'0', '1'>, digit_to_int<> >, int_<0>, next_element>
47 S;
48
49 typedef build_parser<entire_input<S> > binary_parser;
50
51 template <class S>
52 struct binary : binary_parser::apply<S>::type {};
53
54 #ifdef _STR
55 # error _STR already defined
56 #endif
57 #define _STR BOOST_METAPARSE_STRING
58
59 #if BOOST_METAPARSE_STD < 2011
60
main()61 int main()
62 {
63 using std::cout;
64 using std::endl;
65 using boost::metaparse::string;
66
67 cout
68 << binary<string<'1','0','0'> >::value << endl
69 << binary<string<'1','0','1','1'> >::value << endl
70 << binary<string<'1'> >::value << endl;
71 }
72 #else
main()73 int main()
74 {
75 using std::cout;
76 using std::endl;
77
78 cout
79 << binary<_STR("100")>::value << endl
80 << binary<_STR("1011")>::value << endl
81 << binary<_STR("1")>::value << endl;
82 }
83 #endif
84
85
86