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// The purpose of this example is to show how to parse arbitrary key/value
7// pairs delimited by some separator into a std::map. Parsing the URL query
8// format is the example we use to demonstrate how this can be done
9// (i.e. things like: key1=value1;key2=value2;...;keyN=valueN).
10//
11// For a more elaborate explanation see here: http://spirit.sourceforge.net/home/?p=371
12
13#include <boost/spirit/include/qi.hpp>
14#include <boost/fusion/include/std_pair.hpp>
15
16#include <iostream>
17#include <map>
18
19namespace client
20{
21 namespace qi = boost::spirit::qi;
22
23 typedef std::map<std::string, std::string> pairs_type;
24
25 template <typename Iterator>
26 struct key_value_sequence
27 : qi::grammar<Iterator, pairs_type()>
28 {
29 key_value_sequence()
30 : key_value_sequence::base_type(query)
31 {
32 query = pair >> *((qi::lit(';') | '&') >> pair);
33 pair = key >> -('=' >> value);
34 key = qi::char_("a-zA-Z_") >> *qi::char_("a-zA-Z_0-9");
35 value = +qi::char_("a-zA-Z_0-9");
36 }
37
38 qi::rule<Iterator, pairs_type()> query;
39 qi::rule<Iterator, std::pair<std::string, std::string>()> pair;
40 qi::rule<Iterator, std::string()> key, value;
41 };
42}
43
44///////////////////////////////////////////////////////////////////////////////
45int main()
46{
47 namespace qi = boost::spirit::qi;
48
49 std::string input("key1=value1;key2;key3=value3");
50 std::string::iterator begin = input.begin();
51 std::string::iterator end = input.end();
52
53 client::key_value_sequence<std::string::iterator> p;
54 client::pairs_type m;
55
56 if (!qi::parse(first&: begin, last: end, expr: p, attr&: m))
57 {
58 std::cout << "-------------------------------- \n";
59 std::cout << "Parsing failed\n";
60 std::cout << "-------------------------------- \n";
61 }
62 else
63 {
64 std::cout << "-------------------------------- \n";
65 std::cout << "Parsing succeeded, found entries:\n";
66 client::pairs_type::iterator end = m.end();
67 for (client::pairs_type::iterator it = m.begin(); it != end; ++it)
68 {
69 std::cout << (*it).first;
70 if (!(*it).second.empty())
71 std::cout << "=" << (*it).second;
72 std::cout << std::endl;
73 }
74 std::cout << "---------------------------------\n";
75 }
76 return 0;
77}
78
79

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