1/*=============================================================================
2 Copyright (c) 2003 Sam Nabialek
3 Copyright (c) 2001-2010 Joel de Guzman
4
5 Distributed under the Boost Software License, Version 1.0. (See accompanying
6 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7=============================================================================*/
8///////////////////////////////////////////////////////////////////////////////
9//
10// The Nabialek trick.
11//
12// [ Sam Nabialek; Somewhere, sometime in 2003... ] spirit1
13// [ JDG November 17, 2009 ] spirit2
14// [ JDG January 10, 2010 ] Updated to use rule pointers
15// for efficiency.
16//
17///////////////////////////////////////////////////////////////////////////////
18
19#include <boost/spirit/include/qi.hpp>
20#include <boost/phoenix/operator.hpp>
21#include <iostream>
22#include <string>
23
24namespace client
25{
26 namespace qi = boost::spirit::qi;
27 namespace ascii = boost::spirit::ascii;
28
29 ///////////////////////////////////////////////////////////////////////////////
30 // Our nabialek_trick grammar
31 ///////////////////////////////////////////////////////////////////////////////
32 template <typename Iterator>
33 struct nabialek_trick : qi::grammar<
34 Iterator, ascii::space_type, qi::locals<qi::rule<Iterator, ascii::space_type>*> >
35 {
36 nabialek_trick() : nabialek_trick::base_type(start)
37 {
38 using ascii::alnum;
39 using qi::lexeme;
40 using qi::lazy;
41 using qi::_a;
42 using qi::_1;
43
44 id = lexeme[*(ascii::alnum | '_')];
45 one = id;
46 two = id >> ',' >> id;
47
48 keyword.add
49 ("one", &one)
50 ("two", &two)
51 ;
52
53 start = *(keyword[_a = _1] >> lazy(*_a));
54 }
55
56 qi::rule<Iterator, ascii::space_type> id, one, two;
57 qi::rule<Iterator, ascii::space_type, qi::locals<qi::rule<Iterator, ascii::space_type>*> > start;
58 qi::symbols<char, qi::rule<Iterator, ascii::space_type>*> keyword;
59 };
60}
61
62///////////////////////////////////////////////////////////////////////////////
63// Main program
64///////////////////////////////////////////////////////////////////////////////
65int
66main()
67{
68 using boost::spirit::ascii::space;
69 typedef std::string::const_iterator iterator_type;
70 typedef client::nabialek_trick<iterator_type> nabialek_trick;
71
72 nabialek_trick g; // Our grammar
73
74 std::string str = "one only\none again\ntwo first,second";
75 std::string::const_iterator iter = str.begin();
76 std::string::const_iterator end = str.end();
77 bool r = phrase_parse(first&: iter, last: end, expr&: g, skipper: space);
78
79 if (r && iter == end)
80 {
81 std::cout << "-------------------------\n";
82 std::cout << "Parsing succeeded\n";
83 std::cout << "-------------------------\n";
84 }
85 else
86 {
87 std::string rest(iter, end);
88 std::cout << "-------------------------\n";
89 std::cout << "Parsing failed\n";
90 std::cout << "stopped at: \": " << rest << "\"\n";
91 std::cout << "-------------------------\n";
92 }
93
94 return 0;
95}
96
97
98

source code of boost/libs/spirit/example/qi/nabialek.cpp