1 // -- control_structures.cpp -- The Boost Lambda Library ------------------
2 //
3 // Copyright (C) 2000-2003 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi)
4 // Copyright (C) 2000-2003 Gary Powell (powellg@amazon.com)
5 //
6 // Distributed under the Boost Software License, Version 1.0. (See
7 // accompanying file LICENSE_1_0.txt or copy at
8 // http://www.boost.org/LICENSE_1_0.txt)
9 //
10 // For more information, see www.boost.org
11
12 // -----------------------------------------------------------------------
13
14 #include <boost/core/lightweight_test.hpp>
15
16 #include "boost/lambda/lambda.hpp"
17 #include "boost/lambda/if.hpp"
18 #include "boost/lambda/loops.hpp"
19
20 #include <iostream>
21 #include <algorithm>
22 #include <vector>
23
24 using namespace boost;
25
26 using boost::lambda::constant;
27 using boost::lambda::_1;
28 using boost::lambda::_2;
29 using boost::lambda::_3;
30 using boost::lambda::make_const;
31 using boost::lambda::for_loop;
32 using boost::lambda::while_loop;
33 using boost::lambda::do_while_loop;
34 using boost::lambda::if_then;
35 using boost::lambda::if_then_else;
36 using boost::lambda::if_then_else_return;
37
38 // 2 container for_each
39 template <class InputIter1, class InputIter2, class Function>
for_each(InputIter1 first,InputIter1 last,InputIter2 first2,Function f)40 Function for_each(InputIter1 first, InputIter1 last,
41 InputIter2 first2, Function f) {
42 for ( ; first != last; ++first, ++first2)
43 f(*first, *first2);
44 return f;
45 }
46
simple_loops()47 void simple_loops() {
48
49 // for loops ---------------------------------------------------------
50 int i;
51 int arithmetic_series = 0;
52 for_loop(_1 = 0, _1 < 10, _1++, arithmetic_series += _1)(i);
53 BOOST_TEST_EQ(arithmetic_series, 45);
54
55 // no body case
56 for_loop(boost::lambda::var(i) = 0, boost::lambda::var(i) < 100, ++boost::lambda::var(i))();
57 BOOST_TEST_EQ(i, 100);
58
59 // while loops -------------------------------------------------------
60 int a = 0, b = 0, c = 0;
61
62 while_loop((_1 + _2) >= (_1 * _2), (++_1, ++_2, ++_3))(a, b, c);
63 BOOST_TEST_EQ(c, 3);
64
65 int count;
66 count = 0; i = 0;
67 while_loop(_1++ < 10, ++boost::lambda::var(count))(i);
68 BOOST_TEST_EQ(count, 10);
69
70 // note that the first parameter of do_while_loop is the condition
71 count = 0; i = 0;
72 do_while_loop(_1++ < 10, ++boost::lambda::var(count))(i);
73 BOOST_TEST_EQ(count, 11);
74
75 a = 0;
76 do_while_loop(constant(false), _1++)(a);
77 BOOST_TEST_EQ(a, 1);
78
79 // no body cases
80 a = 40; b = 30;
81 while_loop(--_1 > _2)(a, b);
82 BOOST_TEST_EQ(a, b);
83
84 // (the no body case for do_while_loop is pretty redundant)
85 a = 40; b = 30;
86 do_while_loop(--_1 > _2)(a, b);
87 BOOST_TEST_EQ(a, b);
88
89
90 }
91
simple_ifs()92 void simple_ifs () {
93
94 int value = 42;
95 if_then(_1 < 0, _1 = 0)(value);
96 BOOST_TEST_EQ(value, 42);
97
98 value = -42;
99 if_then(_1 < 0, _1 = -_1)(value);
100 BOOST_TEST_EQ(value, 42);
101
102 int min;
103 if_then_else(_1 < _2, boost::lambda::var(min) = _1, boost::lambda::var(min) = _2)
104 (make_const(1), make_const(2));
105 BOOST_TEST_EQ(min, 1);
106
107 if_then_else(_1 < _2, boost::lambda::var(min) = _1, boost::lambda::var(min) = _2)
108 (make_const(5), make_const(3));
109 BOOST_TEST_EQ(min, 3);
110
111 int x, y;
112 x = -1; y = 1;
113 BOOST_TEST_EQ(if_then_else_return(_1 < _2, _2, _1)(x, y), (std::max)(x ,y));
114 BOOST_TEST_EQ(if_then_else_return(_1 < _2, _2, _1)(y, x), (std::max)(x ,y));
115 }
116
117
main()118 int main()
119 {
120 simple_loops();
121 simple_ifs();
122 return boost::report_errors();
123 }
124