namespace ArrDirectionalTraits {

/*!
\ingroup PkgBooleanSetOperations2Concepts
\cgalConcept

\cgalRefines `AdaptableUnaryFunction`

\cgalHasModel `ArrangementDirectionalXMonotoneTraits_2::Compare_endpoints_xy_2`

*/

class CompareEndpointsXy_2 {
public:

/// \name Operations
/// A model of this concept must provide:
/// @{

/*!
accepts an input curve `xc` and compares its source and target 
points. It returns `SMALLER` if the curve is directed from 
lexicographically left to right, and `LARGER` if it is directed 
from lexicographically right to left. 
*/ 
Comparison_result operator()(ArrDirectionalTraits::X_monotone_curve_2 xc); 

/// @}

}; /* end ArrDirectionalTraits::CompareEndpointsXy_2 */

}
