#include <boost/mpl/assert.hpp> #include <boost/mpl/at.hpp> #include <boost/mpl/back_inserter.hpp> #include <boost/mpl/copy.hpp> #include <boost/mpl/divides.hpp> #include <boost/mpl/empty_sequence.hpp> #include <boost/mpl/equal.hpp> #include <boost/mpl/equal_to.hpp> #include <boost/mpl/fold.hpp> #include <boost/mpl/for_each.hpp> #include <boost/mpl/if.hpp> #include <boost/mpl/joint_view.hpp> #include <boost/mpl/less.hpp> #include <boost/mpl/minus.hpp> #include <boost/mpl/modulus.hpp> #include <boost/mpl/push_back.hpp> #include <boost/mpl/range_c.hpp> #include <boost/mpl/string.hpp> #include <boost/mpl/transform.hpp> #include <boost/mpl/vector.hpp> #include <iostream> using namespace boost::mpl; template <typename n> struct NumberInEnglish { // Can't handle >= 100 BOOST_MPL_ASSERT(( less<n, int_<100> > )); typedef int_<10> ten; typedef int_<20> twenty; typedef char_<'-'> dash; typedef vector< string<>, // use Ones vector string<>, // use Teens vector string<'twen','ty'>, string<'thir','ty'>, string<'four','ty'>, string<'fift','y'>, string<'sixt','y'>, string<'seve','nty'>, string<'eigh','ty'>, string<'nine','ty'> > Tens; typedef vector< string<'no ','more'>, string<'one'>, string<'two'>, string<'thre','e'>, string<'four'>, string<'five'>, string<'six'>, string<'seve','n'>, string<'eigh','t'>, string<'nine'> > Ones; typedef vector< string<'ten'>, string<'elev','en'>, string<'twel','ve'>, string<'thir','teen'>, string<'four','teen'>, string<'fift','een'>, string<'sixt','een'>, string<'seve','ntee','n'>, string<'eigh','teen'>, string<'nine','teen'> > Teens; typedef if_< modulus<n, ten>, typename copy< joint_view< typename push_back<typename at<Tens, divides<n, ten> >::type, dash>::type, typename at<Ones, modulus<n, ten> >::type>, back_inserter<string<> > >::type, typename at<Tens, divides<n, ten> >::type > DoubleDigit; typedef typename if_< less<n, ten>, typename at<Ones, n>::type, typename if_< less<n, twenty>, typename at<Teens, minus<n, ten> >::type, typename DoubleDigit::type >::type >::type type; }; BOOST_MPL_ASSERT(( equal< NumberInEnglish<int_<4> >::type, string<'four'> > )); BOOST_MPL_ASSERT(( equal< NumberInEnglish<int_<14> >::type, string<'four','teen'> > )); BOOST_MPL_ASSERT(( equal< NumberInEnglish<int_<20> >::type, string<'twen','ty'> > )); BOOST_MPL_ASSERT(( equal< NumberInEnglish<int_<44> >::type, string<'four','ty-f','our'> > )); template <typename n> struct CountBottles { typedef string<'bott','le'> Bottle; typedef typename copy< joint_view< typename push_back< typename NumberInEnglish<n>::type, char_<' '> >::type, typename if_< equal_to<n, int_<1> >, Bottle, push_back<Bottle, char_<'s'> >::type >::type >, back_inserter<string<> > >::type type; }; BOOST_MPL_ASSERT(( equal< CountBottles<int_<0> >::type, string<'no m','ore ','bott','les'> > )); BOOST_MPL_ASSERT(( equal< CountBottles<int_<1> >::type, string<'one ','bott','le'> > )); BOOST_MPL_ASSERT(( equal< CountBottles<int_<14> >::type, string<'four','teen',' bot','tles'> > )); template <typename n> struct Verse { typedef string<'\n'> NL; typedef string<',\n'> CommaNL; typedef string<' of ','beer'> OfBeer; typedef string<' on ','the ','wall'> OnTheWall; typedef string<'take',' one',' dow','n, p','ass ','it a','roun','d,\n'> TakeOneDownPassItAround; typedef typename transform< vector< typename CountBottles<n>::type, OfBeer, OnTheWall, CommaNL, typename CountBottles<n>::type, OfBeer, CommaNL, TakeOneDownPassItAround, typename CountBottles<typename prior<n>::type>::type, OfBeer, NL, NL >, c_str<_1> >::type strings; }; struct PrintValue { PrintValue(std::ostream& os) : os_(os) {} std::ostream& os_; template <typename T> void operator() (T t) { os_ << T::value; } }; template <typename n> std::ostream& operator<< (std::ostream& os, Verse<n> verse) { boost::mpl::for_each<typename Verse<n>::strings>(PrintValue(os)); }; struct PrintTo { PrintTo(std::ostream& os) : os_(os) {} std::ostream& os_; template <typename T> void operator() (T t) { os_ << t; } }; int main() { boost::mpl::for_each< range_c<int, 1, 100>, lambda< Verse<minus<int_<100>, _1> > >::type>( PrintTo(std::cout)); return 0; }
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