bool common_range(IteratorT& lwb, IteratorT& upb, ObjectT& x1, const ConstObjectT& x2)
{
// lwb and upb are iterators of x1 marking the lower and upper bound of
// the common range of x1 and x2.
typedef typename ConstObjectT::const_iterator ConstObject_iterator;
// ObjectT may be const or non const.
typedef typename remove_const<ObjectT>::type PureObjectT;
lwb = x1.end();
upb = x1.end();
if(icl::is_empty(x1) || icl::is_empty(x2))
return false;
IteratorT x1_fst_ = x1.begin();
IteratorT x1_lst_ = x1.end(); x1_lst_--;
ConstObject_iterator x2_fst_ = x2.begin();
ConstObject_iterator x2_lst_ = x2.end(); x2_lst_--;
typename ObjectT::key_compare key_less;
if(key_less(icl::key_value< PureObjectT>(x1_lst_),
icl::key_value<ConstObjectT>(x2_fst_))) // {x1} {x2}
return false;
if(key_less(icl::key_value<ConstObjectT>(x2_lst_),
icl::key_value< PureObjectT>(x1_fst_))) // {x2} {x1}
return false;
// We do have a common range
lwb = x1.lower_bound(icl::key_value<ConstObjectT>(x2_fst_));
upb = x1.upper_bound(icl::key_value<ConstObjectT>(x2_lst_));
return true;
}
bool intersects(const ObjectT& left, const CoObjectT& right)
{
typedef typename CoObjectT::const_iterator co_iterator;
co_iterator right_common_lower_, right_common_upper_;
if(!Set::common_range(right_common_lower_, right_common_upper_, right, left))
return false;
co_iterator right_ = right_common_lower_;
while(right_ != right_common_upper_)
if(!(left.find(key_value<CoObjectT>(right_++))==left.end()))
return true;
return false;
}