1 // Copyright Antony Polukhin, 2013-2020.
2
3 // Distributed under the Boost Software License, Version 1.0.
4 // (See the accompanying file LICENSE_1_0.txt
5 // or a copy at <http://www.boost.org/LICENSE_1_0.txt>.)
6
7 #include <boost/config.hpp>
8 #ifdef BOOST_MSVC
9 # pragma warning(disable: 4512) // generic_stringize.cpp(37) : warning C4512: 'stringize_functor' : assignment operator could not be generated
10 #endif
11
12 //[lexical_cast_stringize
13 /*`
14 In this example we'll make a `stringize` method that accepts a sequence, converts
15 each element of the sequence into string and appends that string to the result.
16
17 Example is based on the example from the [@http://www.packtpub.com/boost-cplusplus-application-development-cookbook/book Boost C++ Application Development Cookbook]
18 by Antony Polukhin, ISBN 9781849514880.
19
20 Step 1: Making a functor that converts any type to a string and remembers result:
21 */
22
23 #include <boost/lexical_cast.hpp>
24
25 struct stringize_functor {
26 private:
27 std::string& result;
28
29 public:
stringize_functorstringize_functor30 explicit stringize_functor(std::string& res)
31 : result(res)
32 {}
33
34 template <class T>
operator ()stringize_functor35 void operator()(const T& v) const {
36 result += boost::lexical_cast<std::string>(v);
37 }
38 };
39
40 //` Step 2: Applying `stringize_functor` to each element in sequence:
41 #include <boost/fusion/include/for_each.hpp>
42 template <class Sequence>
stringize(const Sequence & seq)43 std::string stringize(const Sequence& seq) {
44 std::string result;
45 boost::fusion::for_each(seq, stringize_functor(result));
46 return result;
47 }
48
49 //` Step 3: Using the `stringize` with different types:
50 #include <boost/fusion/adapted/boost_tuple.hpp>
51 #include <boost/fusion/adapted/std_pair.hpp>
52
main()53 int main() {
54 boost::tuple<char, int, char, int> decim('-', 10, 'e', 5);
55 if (stringize(decim) != "-10e5") {
56 return 1;
57 }
58
59 std::pair<int, std::string> value_and_type(270, "Kelvin");
60 if (stringize(value_and_type) != "270Kelvin") {
61 return 2;
62 }
63
64 return 0;
65 }
66
67 //] [/lexical_cast_stringize]
68
69
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71