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
|
/*==============================================================================
Copyright (c) 2005-2010 Joel de Guzman
Copyright (c) 2011 Thomas Heller
Distributed under 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)
==============================================================================*/
#include <boost/phoenix/core.hpp>
namespace phoenix = boost::phoenix;
namespace proto = boost::proto;
// define the expression
namespace expression
{
template <typename Lhs, typename Rhs>
struct plus
: phoenix::expr<proto::tag::plus, Lhs, Rhs>
{};
}
// extend the grammar, to recognice the expression
namespace boost { namespace phoenix {
template <>
struct meta_grammar::case_<proto::tag::plus>
: enable_rule<
::expression::plus<
meta_grammar
, meta_grammar
>
>
{};
}}
// build a generator
template <typename Lhs, typename Rhs>
typename expression::plus<Lhs, Rhs>::type
plus(Lhs const & lhs, Rhs const & rhs)
{
return expression::plus<Lhs, Rhs>::make(lhs, rhs);
}
#include <boost/proto/proto.hpp>
#include <iostream>
int main()
{
plus(6, 5);
proto::display_expr(plus(6, 5));
std::cout << plus(5, 6)() << "\n";
}
|
