1// Copyright (c) 2001-2010 Hartmut Kaiser
2//
3// Distributed under the Boost Software License, Version 1.0. (See accompanying
4// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
5
6// This example demonstrates a trick allowing to adapt a template data
7// structure as a Fusion sequence in order to use is for direct attribute
8// propagation. For more information see
9// http://boost-spirit.com/home/2010/02/08/how-to-adapt-templates-as-a-fusion-sequence
10
11#include <boost/spirit/include/qi.hpp>
12
13namespace qi = boost::spirit::qi;
14namespace fusion = boost::fusion;
15
16namespace client
17{
18 template <typename A, typename B>
19 struct data
20 {
21 A a;
22 B b;
23 };
24
25 template <typename Iterator, typename A, typename B>
26 struct data_grammar : qi::grammar<Iterator, data<A, B>()>
27 {
28 data_grammar() : data_grammar::base_type(start)
29 {
30 start = real_start;
31 real_start = qi::auto_ >> ',' >> qi::auto_;
32 }
33
34 qi::rule<Iterator, data<A, B>()> start;
35 qi::rule<Iterator, fusion::vector<A&, B&>()> real_start;
36 };
37}
38
39namespace boost { namespace spirit { namespace traits
40{
41 template <typename A, typename B>
42 struct transform_attribute<client::data<A, B>, fusion::vector<A&, B&>, qi::domain>
43 {
44 typedef fusion::vector<A&, B&> type;
45
46 static type pre(client::data<A, B>& val) { return type(val.a, val.b); }
47 static void post(client::data<A, B>&, fusion::vector<A&, B&> const&) {}
48 static void fail(client::data<A, B>&) {}
49 };
50}}}
51
52///////////////////////////////////////////////////////////////////////////////
53int main()
54{
55 std::cout << "/////////////////////////////////////////////////////////\n\n";
56 std::cout << "\t\tA parser for Spirit utilizing an adapted template ...\n\n";
57 std::cout << "/////////////////////////////////////////////////////////\n\n";
58
59 std::cout << "Give me two comma separated integers:\n";
60 std::cout << "Type [q or Q] to quit\n\n";
61
62 std::string str;
63 client::data_grammar<std::string::const_iterator, long, int> g; // Our grammar
64 while (getline(is&: std::cin, str&: str))
65 {
66 if (str.empty() || str[0] == 'q' || str[0] == 'Q')
67 break;
68
69 client::data<long, int> d;
70 std::string::const_iterator iter = str.begin();
71 std::string::const_iterator end = str.end();
72 bool r = phrase_parse(first&: iter, last: end, expr: g, skipper: qi::space, attr&: d);
73
74 if (r && iter == end)
75 {
76 std::cout << "-------------------------\n";
77 std::cout << "Parsing succeeded\n";
78 std::cout << "got: " << d.a << "," << d.b << std::endl;
79 std::cout << "\n-------------------------\n";
80 }
81 else
82 {
83 std::cout << "-------------------------\n";
84 std::cout << "Parsing failed\n";
85 std::cout << "-------------------------\n";
86 }
87 }
88
89 return 0;
90}
91
92
93

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