| 85 | // Like fold, but returns default value when container is empty. |
| 86 | template <typename Container, typename Function> |
| 87 | typename Container::value_type fold1(Container const& l, Function f) { |
| 88 | typename Container::value_type res = {}; |
| 89 | typename Container::const_iterator i = l.begin(); |
| 90 | typename Container::const_iterator e = l.end(); |
| 91 | |
| 92 | if (i == e) |
| 93 | return res; |
| 94 | |
| 95 | res = *i; |
| 96 | ++i; |
| 97 | while (i != e) { |
| 98 | res = f(res, *i); |
| 99 | ++i; |
| 100 | } |
| 101 | return res; |
| 102 | } |
| 103 | |
| 104 | // Return intersection of sorted containers. |
| 105 | template <typename Container> |