Method insertLoop

s2/polygon.go:309–338

insertLoop adds the given loop to the loop map under the specified parent. All children of the new entry are checked to see if the need to move up to a different level.

(newLoop, parent *Loop)

// All children of the new entry are checked to see if the need to move up to
// a different level.
func (lm loopMap) insertLoop(newLoop, parent *Loop) {
	var children []*Loop
	for done := false; !done; {
		children = lm[parent]
		done = true
		for _, child := range children {
			if child.ContainsNested(newLoop) {
				parent = child
				done = false
				break
			}
		}
	}

	// Now, we have found a parent for this loop, it may be that some of the
	// children of the parent of this loop may now be children of the new loop.
	newChildren := lm[newLoop]
	for i := 0; i < len(children); {
		child := children[i]
		if newLoop.ContainsNested(child) {
			newChildren = append(newChildren, child)
			children = append(children[0:i], children[i+1:]...)
		} else {
			i++
		}
	}

	lm[newLoop] = newChildren
	lm[parent] = append(children, newLoop)
}

// loopStack simplifies access to the loops while being initialized.
type loopStack []*Loop