Function align

MergePaths/MergePaths.cpp:1369–1388

 */
template<class iterator, class oiterator>
static dir_type
align(
    const Lengths& lengths,
    iterator it1,
    iterator last1,
    iterator it2,
    iterator last2,
    oiterator& out)
{
	assert(it1 != last1);
	assert(it2 != last2);
	while (it1 != last1 && it2 != last2)
		if (!alignOne(lengths, it1, last1, it2, last2, out))
			return DIR_X;
	assert(it1 == last1 || it2 == last2);
	out = copy(it1, last1, out);
	out = copy(it2, last2, out);
	return it1 == last1 && it2 == last2 ? DIR_B
	                                    : it1 == last1 ? DIR_F : it2 == last2 ? DIR_R : DIR_X;
}

/** Find an equivalent region of the two specified paths, starting the
 * alignment at pivot1 of path1 and pivot2 of path2.