1// Copyright (c) 2001-2010 Hartmut Kaiser
2// Copyright (c) 2001-2010 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 complex number micro generator - take 2. Look'ma no semantic actions!
10//
11// [ HK July 26, 2009 ] spirit2
12//
13///////////////////////////////////////////////////////////////////////////////
14
15#include <boost/spirit/include/qi.hpp>
16#include <boost/spirit/include/karma.hpp>
17#include <boost/phoenix/core.hpp>
18#include <boost/phoenix/operator.hpp>
19#include <boost/fusion/include/std_pair.hpp>
20
21#include <iostream>
22#include <string>
23#include <complex>
24
25namespace client
26{
27 ///////////////////////////////////////////////////////////////////////////
28 // Our complex number parser/compiler (that's just a copy of the complex
29 // number example from Qi (see examples/qi/complex_number.cpp)
30 ///////////////////////////////////////////////////////////////////////////
31 template <typename Iterator>
32 bool parse_complex(Iterator first, Iterator last, std::complex<double>& c)
33 {
34 using boost::spirit::qi::double_;
35 using boost::spirit::qi::_1;
36 using boost::spirit::qi::phrase_parse;
37 using boost::spirit::ascii::space;
38 using boost::phoenix::ref;
39
40 double rN = 0.0;
41 double iN = 0.0;
42 bool r = phrase_parse(first, last,
43 (
44 '(' >> double_[ref(rN) = _1]
45 >> -(',' >> double_[ref(iN) = _1]) >> ')'
46 | double_[ref(rN) = _1]
47 ),
48 space);
49
50 if (!r || first != last) // fail if we did not get a full match
51 return false;
52 c = std::complex<double>(rN, iN);
53 return r;
54 }
55
56 ///////////////////////////////////////////////////////////////////////////
57 // Our complex number generator
58 ///////////////////////////////////////////////////////////////////////////
59 //[tutorial_karma_complex_number_easier
60 template <typename OutputIterator>
61 bool generate_complex(OutputIterator sink, std::complex<double> const& c)
62 {
63 using boost::spirit::karma::double_;
64 using boost::spirit::karma::omit;
65 using boost::spirit::karma::generate;
66
67 return generate(sink,
68
69 // Begin grammar
70 (
71 !double_(0.0) << '(' << double_ << ", " << double_ << ')'
72 | omit[double_] << double_ << omit[double_]
73 ),
74 // End grammar
75
76 c.imag(), c.real(), c.imag() // Data to output
77 );
78 }
79 //]
80}
81
82///////////////////////////////////////////////////////////////////////////////
83// Main program
84///////////////////////////////////////////////////////////////////////////////
85int main()
86{
87 std::cout << "/////////////////////////////////////////////////////////\n\n";
88 std::cout << "\t\tA complex number micro generator for Spirit...\n\n";
89 std::cout << "/////////////////////////////////////////////////////////\n\n";
90
91 std::cout << "Give me a complex number of the form r or (r) or (r,i) \n";
92 std::cout << "Type [q or Q] to quit\n\n";
93
94 std::string str;
95 while (getline(is&: std::cin, str&: str))
96 {
97 if (str.empty() || str[0] == 'q' || str[0] == 'Q')
98 break;
99
100 std::complex<double> c;
101 if (client::parse_complex(first: str.begin(), last: str.end(), c))
102 {
103 std::cout << "-------------------------\n";
104
105 std::string generated;
106 std::back_insert_iterator<std::string> sink(generated);
107 if (!client::generate_complex(sink, c))
108 {
109 std::cout << "-------------------------\n";
110 std::cout << "Generating failed\n";
111 std::cout << "-------------------------\n";
112 }
113 else
114 {
115 std::cout << "-------------------------\n";
116 std::cout << "Generated: " << generated << "\n";
117 std::cout << "-------------------------\n";
118 }
119 }
120 else
121 {
122 std::cout << "-------------------------\n";
123 std::cout << "Parsing failed\n";
124 std::cout << "-------------------------\n";
125 }
126 }
127
128 std::cout << "Bye... :-) \n\n";
129 return 0;
130}
131
132
133

source code of boost/libs/spirit/example/karma/complex_number_easier.cpp