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1 | // Copyright (c) 2009-2016 Vladimir Batov. |
2 | // Use, modification and distribution are subject to the Boost Software License, | |
3 | // Version 1.0. See http://www.boost.org/LICENSE_1_0.txt. | |
4 | ||
5 | #include <boost/convert.hpp> | |
6 | #include <boost/convert/stream.hpp> | |
7 | #include <boost/convert/lexical_cast.hpp> | |
8 | #include <boost/detail/lightweight_test.hpp> | |
9 | #include <boost/array.hpp> | |
10 | #include <boost/bind.hpp> | |
11 | #include <vector> | |
12 | ||
13 | using std::string; | |
14 | ||
15 | static | |
16 | void | |
17 | introduction() | |
18 | { | |
19 | //[algorithm_introduction | |
20 | ||
21 | /*`The following code demonstrates conversion of an array of integers from their textual ['hexadecimal] | |
22 | representation. It assigns -1 to those which fail to convert: | |
23 | */ | |
24 | ||
25 | boost::array<char const*, 3> strs = {{ " 5", "0XF", "not an int" }}; | |
26 | std::vector<int> ints; | |
27 | boost::cnv::cstream cnv; | |
28 | ||
29 | // Configure converter to read hexadecimal, skip (leading) white spaces. | |
30 | cnv(std::hex)(std::skipws); | |
31 | ||
32 | std::transform(strs.begin(), strs.end(), std::back_inserter(ints), | |
33 | boost::cnv::apply<int>(boost::cref(cnv)).value_or(-1)); | |
34 | ||
35 | BOOST_TEST(ints.size() == 3); // Number of values processed. | |
36 | BOOST_TEST(ints[0] == 5); // " 5" | |
37 | BOOST_TEST(ints[1] == 15); // "0XF" | |
38 | BOOST_TEST(ints[2] == -1); // "not an int" | |
39 | //] | |
40 | } | |
41 | ||
42 | static | |
43 | void | |
44 | example1() | |
45 | { | |
46 | //[algorithm_example1 | |
47 | /*`The following code demonstrates a failed attempt (and one of the reasons ['Boost.Convert] | |
48 | has been developed) to convert a few `string`s to `int`s with `boost::lexical_cast`: | |
49 | */ | |
50 | ||
51 | boost::array<char const*, 3> strs = {{ " 5", "0XF", "not an int" }}; | |
52 | std::vector<int> ints; | |
53 | ||
54 | try | |
55 | { | |
56 | std::transform(strs.begin(), strs.end(), std::back_inserter(ints), | |
57 | boost::bind(boost::lexical_cast<int, string>, _1)); | |
58 | ||
59 | BOOST_TEST(0 && "Never reached!"); | |
60 | } | |
61 | catch (std::exception&) | |
62 | { | |
63 | BOOST_TEST(ints.size() == 0); // No strings converted. | |
64 | } | |
65 | //] | |
66 | } | |
67 | ||
68 | static | |
69 | void | |
70 | example2() | |
71 | { | |
72 | //[algorithm_example2 | |
73 | /*`If the exception-throwing behavior is the desired behavior, then ['Boost.Convert] supports that. | |
74 | In addition, it also supports a non-throwing process-flow: | |
75 | */ | |
76 | boost::array<char const*, 3> strs = {{ " 5", "0XF", "not an int" }}; | |
77 | std::vector<int> ints; | |
78 | ||
79 | std::transform(strs.begin(), strs.end(), std::back_inserter(ints), | |
80 | boost::cnv::apply<int>(boost::cnv::lexical_cast()).value_or(-1)); | |
81 | ||
82 | BOOST_TEST(ints.size() == 3); | |
83 | BOOST_TEST(ints[0] == -1); // Failed conversion does not throw. | |
84 | BOOST_TEST(ints[1] == -1); // Failed conversion does not throw. | |
85 | BOOST_TEST(ints[2] == -1); // Failed conversion does not throw. | |
86 | //] | |
87 | } | |
88 | ||
89 | static | |
90 | void | |
91 | example3() | |
92 | { | |
93 | //[algorithm_example3 | |
94 | /*`Deploying `boost::cnv::cstream` with better formatting capabilities yields | |
95 | better results with exception-throwing and non-throwing process-flows still supported: | |
96 | */ | |
97 | ||
98 | boost::array<char const*, 3> strs = {{ " 5", "0XF", "not an int" }}; | |
99 | std::vector<int> ints; | |
100 | boost::cnv::cstream cnv; | |
101 | ||
102 | try | |
103 | { | |
104 | std::transform(strs.begin(), strs.end(), std::back_inserter(ints), | |
105 | boost::cnv::apply<int>(boost::cref(cnv(std::hex)(std::skipws)))); | |
106 | ||
107 | BOOST_TEST(0 && "Never reached!"); | |
108 | } | |
109 | catch (boost::bad_optional_access const&) | |
110 | { | |
111 | BOOST_TEST(ints.size() == 2); // Only the first two strings converted. | |
112 | BOOST_TEST(ints[0] == 5); // " 5" | |
113 | BOOST_TEST(ints[1] == 15); // "0XF" | |
114 | ||
115 | // "not an int" causes the exception thrown. | |
116 | } | |
117 | //] | |
118 | } | |
119 | ||
120 | static | |
121 | void | |
122 | example4() | |
123 | { | |
124 | boost::array<char const*, 3> strs = {{ " 5", "0XF", "not an int" }}; | |
125 | std::vector<int> ints; | |
126 | boost::cnv::cstream cnv; | |
127 | ||
128 | //[algorithm_example4 | |
129 | ||
130 | std::transform(strs.begin(), strs.end(), std::back_inserter(ints), | |
131 | boost::cnv::apply<int>(boost::cref(cnv(std::hex)(std::skipws))).value_or(-1)); | |
132 | ||
133 | BOOST_TEST(ints.size() == 3); | |
134 | BOOST_TEST(ints[0] == 5); | |
135 | BOOST_TEST(ints[1] == 15); | |
136 | BOOST_TEST(ints[2] == -1); // Failed conversion | |
137 | ||
138 | /*`[important One notable difference in the deployment of `boost::cnv::cstream` with algorithms is | |
139 | the use of `boost::cref` (or `std::cref` in C++11). | |
140 | ||
141 | It needs to be remembered that with standard algorithms the deployed converter needs to be | |
92f5a8d4 TL |
142 | [@http://en.cppreference.com/w/cpp/named_req/TriviallyCopyable copyable] or |
143 | [@http://en.cppreference.com/w/cpp/named_req/MoveAssignable movable (C++11)] | |
7c673cae FG |
144 | and is, in fact, copied or moved by the respective algorithm before being used. |
145 | Given that `std::cstringstream` is not copyable, `boost::cnv::cstream` is not copyable either. | |
146 | That limitation is routinely worked-around using `boost::ref` or `boost::cref`.] | |
147 | */ | |
148 | //] | |
149 | } | |
150 | ||
151 | static | |
152 | void | |
153 | example5() | |
154 | { | |
155 | //[algorithm_example5 | |
156 | /*`And now an example of algorithm-based integer-to-string formatted conversion with | |
157 | `std::hex`, `std::uppercase` and `std::showbase` formatting applied: | |
158 | */ | |
159 | boost::array<int, 3> ints = {{ 15, 16, 17 }}; | |
160 | std::vector<std::string> strs; | |
161 | boost::cnv::cstream cnv; | |
162 | ||
163 | cnv(std::hex)(std::uppercase)(std::showbase); | |
164 | ||
165 | std::transform(ints.begin(), ints.end(), std::back_inserter(strs), | |
166 | boost::cnv::apply<string>(boost::cref(cnv))); | |
167 | ||
168 | BOOST_TEST(strs.size() == 3); | |
169 | BOOST_TEST(strs[0] == "0XF"); // 15 | |
170 | BOOST_TEST(strs[1] == "0X10"); // 16 | |
171 | BOOST_TEST(strs[2] == "0X11"); // 17 | |
172 | //] | |
173 | } | |
174 | ||
175 | int | |
176 | main(int, char const* []) | |
177 | { | |
178 | introduction(); | |
179 | example1(); | |
180 | example2(); | |
181 | example3(); | |
182 | example4(); | |
183 | example5(); | |
184 | ||
185 | return boost::report_errors(); | |
186 | } |