Method intersectCardinality

runcontainer.go:706–798

intersectCardinality returns the cardinality of the intersection of rc (also known as 'a') and b.

(b *runContainer16)

// intersectCardinality returns the cardinality of  the
// intersection of rc (also known as 'a')  and b.
func (rc *runContainer16) intersectCardinality(b *runContainer16) int {
	answer := int(0)

	a := rc
	numa := len(a.iv)
	numb := len(b.iv)
	if numa == 0 || numb == 0 {
		return 0
	}

	if numa == 1 && numb == 1 {
		if !haveOverlap16(a.iv[0], b.iv[0]) {
			return 0
		}
	}

	var acuri int
	var bcuri int

	astart := int(a.iv[acuri].start)
	bstart := int(b.iv[bcuri].start)

	var intersection interval16
	var leftoverstart int
	var isOverlap, isLeftoverA, isLeftoverB bool
	var done bool
	pass := 0
toploop:
	for acuri < numa && bcuri < numb {
		pass++

		isOverlap, isLeftoverA, isLeftoverB, leftoverstart, intersection = intersectWithLeftover16(astart, int(a.iv[acuri].last()), bstart, int(b.iv[bcuri].last()))

		if !isOverlap {
			switch {
			case astart < bstart:
				acuri, done = a.findNextIntervalThatIntersectsStartingFrom(acuri+1, bstart)
				if done {
					break toploop
				}
				astart = int(a.iv[acuri].start)

			case astart > bstart:
				bcuri, done = b.findNextIntervalThatIntersectsStartingFrom(bcuri+1, astart)
				if done {
					break toploop
				}
				bstart = int(b.iv[bcuri].start)
			}
		} else {
			// isOverlap
			answer += int(intersection.last()) - int(intersection.start) + 1
			switch {
			case isLeftoverA:
				// note that we change astart without advancing acuri,
				// since we need to capture any 2ndary intersections with a.iv[acuri]
				astart = leftoverstart
				bcuri++