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#ifndef FOR_H
#define FOR_H
#include <iterator>
/* FOR(type, elem, container)
* FORX(type, elem, container, step)
*
* Iterate over container, which has type type, and optionally do step on every iteration.
* The current element is put into elem.
* elem can be
* - a plain variable name (x), which makes a copy of the element
* - a const copy (const x)
* - a reference (& x) or
* - a const reference (const& x).
*
* This simplifies the usual pattern
* for (vector<int>::iterator i = container.begin(), end = container.end(); i != end; ++i) {
* int& elem = *i;
* ...
* }
* to
* FOR(vector<int>, & elem, container) {
* ...
* }
*
* FORT()/FORTX() need to be used, if type is a dependent name.
*/
template<typename T, typename SEL> struct for_sel_ref { typedef T const& ref; };
template<typename T> struct for_sel_ref<T, void (int&)> { typedef T& ref; };
template<typename T, typename SEL> struct for_sel_iter { typedef typename T::const_iterator iter; };
template<typename T> struct for_sel_iter<T, void (int&)> { typedef typename T::iterator iter; };
#define LNAME__(name, line) name##__##line
#define LNAME_(name, line) LNAME__(name, line)
#define LNAME(name) LNAME_(name, __LINE__)
#define FORX_(typename, type, elem, container, step) \
if (bool LNAME(once0) = false) {} else \
for (typename for_sel_ref<type, void(int elem)>::ref LNAME(container_) = (container); !LNAME(once0); LNAME(once0) = true) \
if (bool LNAME(break) = false) {} else \
for (typename for_sel_iter<type, void(int elem)>::iter LNAME(iter) = LNAME(container_).begin(), LNAME(end) = LNAME(container_).end(); !LNAME(break) && LNAME(iter) != LNAME(end); LNAME(break) ? (void)0 : (void)((step), ++LNAME(iter))) \
if (bool LNAME(once1) = (LNAME(break) = true, false)) {} else \
for (typename std::iterator_traits<typename for_sel_iter<type, void(int elem)>::iter>::value_type elem = *LNAME(iter); !LNAME(once1); LNAME(break) = false, LNAME(once1) = true)
#define FORX(type, elem, container, step) FORX_(, type, elem, container, (step))
#define FOR(type, elem, container) FORX(type, elem, container, (void)0)
#define FORTX(type, elem, container, step) FORX_(typename , type, elem, container, (step))
#define FORT(type, elem, container) FORTX(type, elem, container, (void)0)
#endif
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