1// Copyright (c) 2012 Robert Ramey
2//
3// Distributed under the Boost Software License, Version 1.0. (See
4// accompanying file LICENSE_1_0.txt or copy at
5// http://www.boost.org/LICENSE_1_0.txt)
6
7#include <boost/safe_numerics/checked_result.hpp>
8#include <boost/safe_numerics/checked_result_operations.hpp>
9#include <boost/safe_numerics/checked_integer.hpp>
10
11// note: T should be of tyme checked_result<R> for some integer type R
12template<class T>
13constexpr bool test_checked_subtract(
14 const T & v1,
15 const T & v2,
16 char expected_result
17){
18 using namespace boost::safe_numerics;
19 const T result = v1 - v2;
20 switch(expected_result){
21 case '.':
22 if(result.exception()){
23 return false;
24 }
25 return true;
26 case '-':
27 if(safe_numerics_error::negative_overflow_error == result.m_e)
28 return true;
29 case '+':
30 if(safe_numerics_error::positive_overflow_error == result.m_e)
31 return true;
32 case '!':
33 if(safe_numerics_error::range_error == result.m_e)
34 return true;
35 }
36 return false;
37}
38
39#include "test_checked_subtract.hpp"
40
41template<typename T, typename First, typename Second>
42struct test_signed_pair {
43 static const std::size_t i = First();
44 static const std::size_t j = Second();
45 // note: is constexpr really required here? compilers disagree!
46 constexpr static const bool value = test_checked_subtract(
47 signed_values<T>[i],
48 signed_values<T>[j],
49 signed_subtraction_results[i][j]
50 );
51};
52
53template<typename T, typename First, typename Second>
54struct test_unsigned_pair {
55 static const std::size_t i = First();
56 static const std::size_t j = Second();
57 // note: is constexpr really required here? compilers disagree!
58 constexpr static const bool value = test_checked_subtract(
59 unsigned_values<T>[i],
60 unsigned_values<T>[j],
61 unsigned_subtraction_results[i][j]
62 );
63};
64
65#include <boost/mp11/algorithm.hpp>
66
67int main(){
68 using namespace boost::mp11;
69
70 static_assert(
71 mp_all_of<
72 mp_product<
73 test_signed_pair,
74 signed_test_types,
75 signed_value_indices, signed_value_indices
76 >,
77 mp_to_bool
78 >(),
79 "all values for all signed types correctly subtracted"
80 );
81
82 static_assert(
83 mp_all_of<
84 mp_product<
85 test_unsigned_pair,
86 unsigned_test_types,
87 unsigned_value_indices, unsigned_value_indices
88 >,
89 mp_to_bool
90 >(),
91 "all values for all unsigned types correctly subtracted"
92 );
93 return 0;
94}
95

source code of boost/libs/safe_numerics/test/test_checked_subtract_constexpr.cpp