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Diffstat (limited to 'libs/local_function/example/phoenix_factorial.cpp')
-rw-r--r-- | libs/local_function/example/phoenix_factorial.cpp | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/libs/local_function/example/phoenix_factorial.cpp b/libs/local_function/example/phoenix_factorial.cpp new file mode 100644 index 000000000..bdc8306f6 --- /dev/null +++ b/libs/local_function/example/phoenix_factorial.cpp @@ -0,0 +1,40 @@ + +// Copyright (C) 2009-2012 Lorenzo Caminiti +// Distributed under the Boost Software License, Version 1.0 +// (see accompanying file LICENSE_1_0.txt or a copy at +// http://www.boost.org/LICENSE_1_0.txt) +// Home at http://www.boost.org/libs/local_function + +#include <boost/phoenix/core.hpp> +#include <boost/phoenix/function.hpp> +#include <boost/detail/lightweight_test.hpp> + +//[phoenix_factorial +struct factorial_impl { // Phoenix function from global functor. + template<typename Sig> + struct result; + + template<typename This, typename Arg> + struct result<This (Arg)> : result<This (Arg const&)> {}; + + template<typename This, typename Arg> + struct result<This (Arg&)> { typedef Arg type; }; + + template<typename Arg> // Polymorphic. + Arg operator()(Arg n) const { + return (n <= 0) ? 1 : n * (*this)(n - 1); + } +}; + +int main(void) { + using boost::phoenix::arg_names::arg1; + + boost::phoenix::function<factorial_impl> factorial; + + int i = 4; + BOOST_TEST(factorial(i)() == 24); // Call. + BOOST_TEST(factorial(arg1)(i) == 24); // Lazy call. + return boost::report_errors(); +} +//] + |