1 ///////////////////////////////////////////////////////////////////////////////
2 // calculator.hpp
3 //
4 // Copyright 2008 Eric Niebler. Distributed under the Boost
5 // Software License, Version 1.0. (See accompanying file
6 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7
8 #include <boost/proto/core.hpp>
9 #include <boost/proto/context.hpp>
10 #include <boost/test/unit_test.hpp>
11
12 using namespace boost;
13
14 struct placeholder {};
15 proto::terminal<placeholder>::type const _1 = {{}};
16
17 struct calculator : proto::callable_context<calculator const>
18 {
19 typedef int result_type;
20
calculatorcalculator21 calculator(int i)
22 : i_(i)
23 {}
24
operator ()calculator25 int operator ()(proto::tag::terminal, placeholder) const
26 {
27 return this->i_;
28 }
29
operator ()calculator30 int operator ()(proto::tag::terminal, int j) const
31 {
32 return j;
33 }
34
35 template<typename Left, typename Right>
operator ()calculator36 int operator ()(proto::tag::plus, Left const &left, Right const &right) const
37 {
38 return proto::eval(left, *this) + proto::eval(right, *this);
39 }
40
41 template<typename Left, typename Right>
operator ()calculator42 int operator ()(proto::tag::minus, Left const &left, Right const &right) const
43 {
44 return proto::eval(left, *this) - proto::eval(right, *this);
45 }
46
47 template<typename Left, typename Right>
operator ()calculator48 int operator ()(proto::tag::multiplies, Left const &left, Right const &right) const
49 {
50 return proto::eval(left, *this) * proto::eval(right, *this);
51 }
52
53 template<typename Left, typename Right>
operator ()calculator54 int operator ()(proto::tag::divides, Left const &left, Right const &right) const
55 {
56 return proto::eval(left, *this) / proto::eval(right, *this);
57 }
58
59 private:
60 int i_;
61 };
62
63 template<typename Fun, typename Expr>
64 struct functional
65 {
66 typedef typename proto::result_of::eval<Expr, Fun>::type result_type;
67
functionalfunctional68 functional(Expr const &expr)
69 : expr_(expr)
70 {}
71
72 template<typename T>
operator ()functional73 result_type operator ()(T const &t) const
74 {
75 Fun fun(t);
76 return proto::eval(this->expr_, fun);
77 }
78
79 private:
80 Expr const &expr_;
81 };
82
83 template<typename Fun, typename Expr>
as(Expr const & expr)84 functional<Fun, Expr> as(Expr const &expr)
85 {
86 return functional<Fun, Expr>(expr);
87 }
88
test_calculator()89 void test_calculator()
90 {
91 BOOST_CHECK_EQUAL(10, proto::eval(((_1 + 42)-3)/4, calculator(1)));
92 BOOST_CHECK_EQUAL(11, proto::eval(((_1 + 42)-3)/4, calculator(5)));
93
94 BOOST_CHECK_EQUAL(10, as<calculator>(((_1 + 42)-3)/4)(1));
95 BOOST_CHECK_EQUAL(11, as<calculator>(((_1 + 42)-3)/4)(5));
96 }
97
98 using namespace unit_test;
99 ///////////////////////////////////////////////////////////////////////////////
100 // init_unit_test_suite
101 //
init_unit_test_suite(int argc,char * argv[])102 test_suite* init_unit_test_suite( int argc, char* argv[] )
103 {
104 test_suite *test = BOOST_TEST_SUITE("test immediate evaluation of proto parse trees");
105
106 test->add(BOOST_TEST_CASE(&test_calculator));
107
108 return test;
109 }
110