factorial.cpp 1.6 KB

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  1. // Copyright (C) 2009-2012 Lorenzo Caminiti
  2. // Distributed under the Boost Software License, Version 1.0
  3. // (see accompanying file LICENSE_1_0.txt or a copy at
  4. // http://www.boost.org/LICENSE_1_0.txt)
  5. // Home at http://www.boost.org/libs/local_function
  6. #include <boost/config.hpp>
  7. #ifdef BOOST_NO_CXX11_VARIADIC_MACROS
  8. # error "variadic macros required"
  9. #else
  10. #include <boost/local_function.hpp>
  11. #include <boost/typeof/typeof.hpp>
  12. #include BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP()
  13. #include <boost/detail/lightweight_test.hpp>
  14. #include <algorithm>
  15. #include <vector>
  16. struct calculator;
  17. BOOST_TYPEOF_REGISTER_TYPE(calculator) // Register before `bind this_` below.
  18. //[factorial
  19. struct calculator {
  20. std::vector<int> results;
  21. void factorials(const std::vector<int>& nums) {
  22. int BOOST_LOCAL_FUNCTION(bind this_, int num,
  23. bool recursion, default false) {
  24. int result = 0;
  25. if(num <= 0) result = 1;
  26. else result = num * factorial(num - 1, true); // Recursive call.
  27. if(!recursion) this_->results.push_back(result);
  28. return result;
  29. } BOOST_LOCAL_FUNCTION_NAME(recursive factorial) // Recursive.
  30. std::for_each(nums.begin(), nums.end(), factorial);
  31. }
  32. };
  33. //]
  34. int main(void) {
  35. std::vector<int> v(3);
  36. v[0] = 1; v[1] = 3; v[2] = 4;
  37. calculator calc;
  38. calc.factorials(v);
  39. BOOST_TEST(calc.results[0] == 1);
  40. BOOST_TEST(calc.results[1] == 6);
  41. BOOST_TEST(calc.results[2] == 24);
  42. return boost::report_errors();
  43. }
  44. #endif // VARIADIC_MACROS