1 /*=============================================================================
2 Copyright (c) 2002-2015 Joel de Guzman
3
4 Distributed under the Boost Software License, Version 1.0. (See accompanying
5 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 =============================================================================*/
7 ///////////////////////////////////////////////////////////////////////////////
8 //
9 // A parser for summing a comma-separated list of numbers using phoenix.
10 //
11 // [ JDG June 28, 2002 ] spirit1
12 // [ JDG March 24, 2007 ] spirit2
13 // [ JDG May 12, 2015 ] spirit X3
14 //
15 ///////////////////////////////////////////////////////////////////////////////
16
17 #include <boost/config/warning_disable.hpp>
18 #include <boost/spirit/home/x3.hpp>
19 #include <iostream>
20 #include <string>
21
22 namespace client
23 {
24 namespace x3 = boost::spirit::x3;
25 namespace ascii = boost::spirit::x3::ascii;
26
27 using x3::double_;
28 using ascii::space;
29 using x3::_attr;
30
31 ///////////////////////////////////////////////////////////////////////////
32 // Our adder
33 ///////////////////////////////////////////////////////////////////////////
34
35 template <typename Iterator>
adder(Iterator first,Iterator last,double & n)36 bool adder(Iterator first, Iterator last, double& n)
37 {
38 auto assign = [&](auto& ctx){ n = _attr(ctx); };
39 auto add = [&](auto& ctx){ n += _attr(ctx); };
40
41 bool r = x3::phrase_parse(first, last,
42
43 // Begin grammar
44 (
45 double_[assign] >> *(',' >> double_[add])
46 )
47 ,
48 // End grammar
49
50 space);
51
52 if (first != last) // fail if we did not get a full match
53 return false;
54 return r;
55 }
56 }
57
58 ////////////////////////////////////////////////////////////////////////////
59 // Main program
60 ////////////////////////////////////////////////////////////////////////////
61 int
main()62 main()
63 {
64 std::cout << "/////////////////////////////////////////////////////////\n\n";
65 std::cout << "\t\tA parser for summing a list of numbers...\n\n";
66 std::cout << "/////////////////////////////////////////////////////////\n\n";
67
68 std::cout << "Give me a comma separated list of numbers.\n";
69 std::cout << "The numbers are added using Phoenix.\n";
70 std::cout << "Type [q or Q] to quit\n\n";
71
72 std::string str;
73 while (getline(std::cin, str))
74 {
75 if (str.empty() || str[0] == 'q' || str[0] == 'Q')
76 break;
77
78 double n;
79 if (client::adder(str.begin(), str.end(), n))
80 {
81 std::cout << "-------------------------\n";
82 std::cout << "Parsing succeeded\n";
83 std::cout << str << " Parses OK: " << std::endl;
84
85 std::cout << "sum = " << n;
86 std::cout << "\n-------------------------\n";
87 }
88 else
89 {
90 std::cout << "-------------------------\n";
91 std::cout << "Parsing failed\n";
92 std::cout << "-------------------------\n";
93 }
94 }
95
96 std::cout << "Bye... :-) \n\n";
97 return 0;
98 }
99