1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
/*=============================================================================
Copyright (c) 2002-2003 Joel de Guzman
http://spirit.sourceforge.net/
Use, modification and distribution is subject to the Boost Software
License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
///////////////////////////////////////////////////////////////////////////////
//
// A primitive calculator that knows how to add and subtract.
// [ demonstrating phoenix ]
//
// [ JDG 6/28/2002 ]
//
///////////////////////////////////////////////////////////////////////////////
#include <boost/spirit/include/classic_core.hpp>
#include <boost/spirit/include/phoenix1_primitives.hpp>
#include <boost/spirit/include/phoenix1_operators.hpp>
#include <iostream>
#include <string>
///////////////////////////////////////////////////////////////////////////////
using namespace std;
using namespace BOOST_SPIRIT_CLASSIC_NS;
using namespace phoenix;
///////////////////////////////////////////////////////////////////////////////
//
// Our primitive calculator
//
///////////////////////////////////////////////////////////////////////////////
template <typename IteratorT>
bool primitive_calc(IteratorT first, IteratorT last, double& n)
{
return parse(first, last,
// Begin grammar
(
real_p[var(n) = arg1]
>> *( ('+' >> real_p[var(n) += arg1])
| ('-' >> real_p[var(n) -= arg1])
)
)
,
// End grammar
space_p).full;
}
////////////////////////////////////////////////////////////////////////////
//
// Main program
//
////////////////////////////////////////////////////////////////////////////
int
main()
{
cout << "/////////////////////////////////////////////////////////\n\n";
cout << "\t\tA primitive calculator...\n\n";
cout << "/////////////////////////////////////////////////////////\n\n";
cout << "Give me a list of numbers to be added or subtracted.\n";
cout << "Example: 1 + 10 + 3 - 4 + 9\n";
cout << "The result is computed using Phoenix.\n";
cout << "Type [q or Q] to quit\n\n";
string str;
while (getline(cin, str))
{
if (str.empty() || str[0] == 'q' || str[0] == 'Q')
break;
double n;
if (primitive_calc(str.begin(), str.end(), n))
{
cout << "-------------------------\n";
cout << "Parsing succeeded\n";
cout << str << " Parses OK: " << endl;
cout << "result = " << n;
cout << "\n-------------------------\n";
}
else
{
cout << "-------------------------\n";
cout << "Parsing failed\n";
cout << "-------------------------\n";
}
}
cout << "Bye... :-) \n\n";
return 0;
}
|
