Range loops - Writing safe

loop2.cpp

//Positive end means [start:start+end)
//Negative end means [start:size-end)
template<typename T>
range<T> narrow_range(const T &cont, int start, int end) {

	int items = std::distance(cont.cbegin(), cont.cend());
	if( items == 0 || end == 0 ) //Checking for empty range
		return range<T>(cont.cend(), cont.cend());
  
	/*
	    Some other checkings stripped to make it less verbose
	*/
	
	if( end > 0 ) {
		return range<T>(cont.cbegin()+start, cont.cbegin()+start+end);
	} else 
		return range<T>(cont.cbegin()+start, cont.cend()+end);
}