1 /*=============================================================================
2 Copyright (c) 2002-2003 Joel de Guzman
3 http://spirit.sourceforge.net/
4
5 Use, modification and distribution is subject to the Boost Software
6 License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
7 http://www.boost.org/LICENSE_1_0.txt)
8 =============================================================================*/
9 ///////////////////////////////////////////////////////////////////////////////
10 //
11 // A parser for a real number parser that parses thousands separated numbers
12 // with at most two decimal places and no exponent. This is discussed in the
13 // "Numerics" chapter in the Spirit User's Guide.
14 //
15 // [ JDG 12/16/2003 ]
16 //
17 ///////////////////////////////////////////////////////////////////////////////
18 #include <boost/spirit/include/classic_core.hpp>
19 #include <boost/spirit/include/classic_assign_actor.hpp>
20 #include <iostream>
21 #include <string>
22
23 ///////////////////////////////////////////////////////////////////////////////
24 using namespace std;
25 using namespace BOOST_SPIRIT_CLASSIC_NS;
26
27 template <typename T>
28 struct ts_real_parser_policies : public ureal_parser_policies<T>
29 {
30 // These policies can be used to parse thousand separated
31 // numbers with at most 2 decimal digits after the decimal
32 // point. e.g. 123,456,789.01
33
34 typedef uint_parser<int, 10, 1, 2> uint2_t;
35 typedef uint_parser<T, 10, 1, -1> uint_parser_t;
36 typedef int_parser<int, 10, 1, -1> int_parser_t;
37
38 ////////////////////////////////// 2 decimal places Max
39 template <typename ScannerT>
40 static typename parser_result<uint2_t, ScannerT>::type
parse_frac_nts_real_parser_policies41 parse_frac_n(ScannerT& scan)
42 { return uint2_t().parse(scan); }
43
44 ////////////////////////////////// No exponent
45 template <typename ScannerT>
46 static typename parser_result<chlit<>, ScannerT>::type
parse_expts_real_parser_policies47 parse_exp(ScannerT& scan)
48 { return scan.no_match(); }
49
50 ////////////////////////////////// No exponent
51 template <typename ScannerT>
52 static typename parser_result<int_parser_t, ScannerT>::type
parse_exp_nts_real_parser_policies53 parse_exp_n(ScannerT& scan)
54 { return scan.no_match(); }
55
56 ////////////////////////////////// Thousands separated numbers
57 template <typename ScannerT>
58 static typename parser_result<uint_parser_t, ScannerT>::type
parse_nts_real_parser_policies59 parse_n(ScannerT& scan)
60 {
61 typedef typename parser_result<uint_parser_t, ScannerT>::type RT;
62 static uint_parser<unsigned, 10, 1, 3> uint3_p;
63 static uint_parser<unsigned, 10, 3, 3> uint3_3_p;
64 if (RT hit = uint3_p.parse(scan))
65 {
66 T n;
67 typedef typename ScannerT::iterator_t iterator_t;
68 iterator_t save = scan.first;
69 while (match<> next = (',' >> uint3_3_p[assign_a(n)]).parse(scan))
70 {
71 hit.value((hit.value() * 1000) + n);
72 scan.concat_match(hit, next);
73 save = scan.first;
74 }
75 scan.first = save;
76 return hit;
77
78 // Note: On erroneous input such as "123,45", the result should
79 // be a partial match "123". 'save' is used to makes sure that
80 // the scanner position is placed at the last *valid* parse
81 // position.
82 }
83 return scan.no_match();
84 }
85 };
86
87 real_parser<double, ts_real_parser_policies<double> > const
88 ts_real_p = real_parser<double, ts_real_parser_policies<double> >();
89
90 ////////////////////////////////////////////////////////////////////////////
91 //
92 // Main program
93 //
94 ////////////////////////////////////////////////////////////////////////////
95 int
main()96 main()
97 {
98 cout << "/////////////////////////////////////////////////////////\n\n";
99 cout << "\t\tA real number parser that parses thousands separated\n";
100 cout << "\t\tnumbers with at most two decimal places and no exponent...\n\n";
101 cout << "/////////////////////////////////////////////////////////\n\n";
102
103 cout << "Give me a number.\n";
104 cout << "Type [q or Q] to quit\n\n";
105
106 string str;
107 double n;
108 while (getline(cin, str))
109 {
110 if (str.empty() || str[0] == 'q' || str[0] == 'Q')
111 break;
112
113 if (parse(str.c_str(), ts_real_p[assign_a(n)]).full)
114 {
115 cout << "-------------------------\n";
116 cout << "Parsing succeeded\n";
117 cout << str << " Parses OK: " << endl;
118 cout << "n=" << n << endl;
119 cout << "-------------------------\n";
120 }
121 else
122 {
123 cout << "-------------------------\n";
124 cout << "Parsing failed\n";
125 cout << "-------------------------\n";
126 }
127 }
128
129 cout << "Bye... :-) \n\n";
130 return 0;
131 }
132
133
134