#include "src/rplexternals.h"
#include "sets.h"

declareExternalFunction(intersection)
	declareObject(object1);
	declareObject(object2);
	declareObject(result);

	integer8	i;
	integer8	j;
	integer8	k;
	integer8	target(vector);

	HEADER
		declareHelpString("Intersection");
		numberOfArguments(2);
	FUNCTION
		pullFromStack(object1, external);
		returnOnError(freeObject(object1));
		pullFromStack(object2, external);
		returnOnError(freeObject(object1); freeObject(object2));

		if ((objectSubtype(object1) ne ISET) or
				(objectSubtype(object2) ne ISET)) then
			executionError("Type not allowed");
			returnOnError(freeObject(object1); freeObject(object2));
		endIf

		vector = allocate((*((set_t *) (*object1).objet)).size
				* size(integer8));

		i = 0;
		j = 0;
		k = 0;

		repeatWhile((i lt (*((set_t *) (*object1).objet)).size) and
				(j lt (*((set_t *) (*object2).objet)).size))
			if ((*((set_t *) (*object1).objet)).values[i] lt
					(*((set_t *) (*object2).objet)).values[j]) then
				postIncr(i);
			elseIf ((*((set_t *) (*object2).objet)).values[j] lt
					(*((set_t *) (*object1).objet)).values[i]) then
				postIncr(j);
			orElse
				vector[k] = (*((set_t *) (*object2).objet)).values[j];
				postIncr(i);
				postIncr(j);
				postIncr(k);
			endIf
		endWhile

		vector = reallocate(vector, k * size(integer8));

		createExternalObject(result, ISET);
		objectOf(result) = allocate(size(set_t));

		objectContainer(set_t, result)->size = k;
		objectContainer(set_t, result)->values = vector;

		freeObject(object1);
		freeObject(object2);

		pushOnStack(result);
	END
endExternalFunction

// vim: ts=4