113 lines
3.0 KiB
C++
113 lines
3.0 KiB
C++
// Boost.Convert test and usage example
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// Copyright (c) 2009-2020 Vladimir Batov.
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// Use, modification and distribution are subject to the Boost Software License,
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// Version 1.0. See http://www.boost.org/LICENSE_1_0.txt.
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#include "./test.hpp"
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#if defined(BOOST_CONVERT_IS_NOT_SUPPORTED)
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int main(int, char const* []) { return 0; }
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#else
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#include <boost/convert.hpp>
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#include <boost/convert/lexical_cast.hpp>
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#include <functional>
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using std::string;
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using boost::convert;
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using boost::lexical_cast;
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//[callable_example1
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void plain_old_func(string const& value_in, boost::optional<int>& value_out)
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//]
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{
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try
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{
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value_out = lexical_cast<int>(value_in);
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}
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catch (...)
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{
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}
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}
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template<typename TypeIn, typename TypeOut>
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void
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convert_all(TypeIn const&, boost::optional<TypeOut>&)
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{
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}
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template<typename Type>
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void
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assign(boost::optional<Type>& value_out, Type const& value_in)
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{
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value_out = value_in;
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}
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struct converter1
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{
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template<typename TypeIn, typename TypeOut>
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void
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operator()(TypeIn const&, boost::optional<TypeOut>&) const
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{
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}
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};
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//[callable_example4
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struct take_double { void operator()(double, boost::optional<string>&) const {}};
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struct take_int { void operator()(int, boost::optional<string>&) const {}};
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//]
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//[callable_example6
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struct double_only
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{
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// Declared for all types.
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template<typename TypeIn> void operator()(TypeIn, boost::optional<string>&) const;
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};
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// Defined only for certain types.
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template<> void double_only::operator()<double>(double, boost::optional<string>&) const {}
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//]
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int
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main(int, char const* [])
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{
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typedef std::function<void (string const& value_in, boost::optional<int>&)> boost_func;
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char const* const str = "-12";
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// Testing old-function-based converter.
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//[callable_example2
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int v01 = convert<int>(str, plain_old_func).value_or(-1);
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//]
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// Testing std::function-based converter.
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int v02 = convert<int>(str, boost_func(plain_old_func)).value_or(-1);
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// Testing crazy std::bind-based converter.
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//[callable_example3
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int v03 = convert<int>(str,
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std::bind(assign<int>, std::placeholders::_2,
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std::bind(boost::lexical_cast<int, string>, std::placeholders::_1))).value_or(-1);
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//]
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BOOST_TEST(v01 == -12);
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BOOST_TEST(v02 == -12);
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BOOST_TEST(v03 == -12);
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convert<int>(str, convert_all<string, int>);
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convert<string>(11, convert_all<int, string>);
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convert< int>(str, converter1());
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convert<string>(11, converter1());
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convert<string>(11.23, take_double());
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convert<string>(11, take_int());
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//[callable_example5
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convert<string>(11, take_double()); // Compiler applies int-to-double promotion to call the converter.
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convert<string>(11.23, take_int()); // Compiler applies double-to-int implicit truncation.
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//]
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//[callable_example7
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convert<string>(11.23, double_only()); // Fine.
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// convert<string>(11, double_only()); // Fails: undefined reference to double_only::operator()<int>
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//]
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return boost::report_errors();
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}
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#endif
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