// Description: header and in-line definitions for sweep status structure and associated function object classes

// Revision history: 5/8/99/LY



#ifndef SWEEP

#define SWEEP



#include "decl.h"



// Function object class used in key comparison operations on sweep status structure

// operator() effectively computes whether the upper endpoint of sw_lhs lies to the left or

// sw_rhs, and returns true or false accordingly. See sweep.cpp for definition.

class SweepKeyCmp

{

	public:

		bool operator() (const SweepElementKey& sw_lhs, const SweepElementKey& sw_rhs) const;

};



// function object class for representing key fields of elements in sweep status structure

class SweepElementKey

{	

	public:

		SweepElementKey(const Coordinates& upper_endpoint, const Coordinates& lower_endpoint):

		upper(upper_endpoint), lower(lower_endpoint)

		{	slope = calc_slope(upper_endpoint, lower_endpoint);	}

		bool operator==(const SweepElementKey& rhs) const

		{	return upper == rhs.upper && lower == rhs.lower;	}

		bool operator<(const SweepElementKey& rhs) const

		{	return upper < rhs.upper || (upper == rhs.upper && lower < rhs.lower);	}

		Coordinates	upper, lower;

		double slope;

	private:	// calc_slope finds slope dx/dy and returns it

		double calc_slope(const Coordinates& upper_endpoint, const Coordinates& lower_endpoint)

		{	return (lower_endpoint.first - upper_endpoint.first) / (lower_endpoint.second - upper_endpoint.second);	}

};



// function object class for finding line segments intersecting the sweep line whose upper endpoint 

// coincide with the event point (used in conjunction with the equal_range algorithm)

class SweepCmp

{

	public:

		bool operator() (const pair<SweepElementKey, HalfEdge*>& sw_elem, const pair<SweepElementKey, HalfEdge*>& value)

		{	

			if (sw_elem.first.upper == value.first.upper)

			{	return false;	}

			return (SweepKeyCmp())(sw_elem.first, value.first);

		}

};



#endif