func()

in s2/regioncoverer.go [294:334]

• 23 lines of code
• 13 McCabe index (conditional complexity)

func (c *coverer) coveringInternal(region Region) {
	c.region = region

	c.initialCandidates()
	for c.pq.Len() > 0 && (!c.interiorCovering || len(c.result) < c.maxCells) {
		cand := heap.Pop(&c.pq).(*candidate)

		// For interior covering we keep subdividing no matter how many children
		// candidate has. If we reach MaxCells before expanding all children,
		// we will just use some of them.
		// For exterior covering we cannot do this, because result has to cover the
		// whole region, so all children have to be used.
		// candidate.numChildren == 1 case takes care of the situation when we
		// already have more than MaxCells in result (minLevel is too high).
		// Subdividing of the candidate with one child does no harm in this case.
		if c.interiorCovering || int(cand.cell.level) < c.minLevel || cand.numChildren == 1 || len(c.result)+c.pq.Len()+cand.numChildren <= c.maxCells {
			for _, child := range cand.children {
				if !c.interiorCovering || len(c.result) < c.maxCells {
					c.addCandidate(child)
				}
			}
		} else {
			cand.terminal = true
			c.addCandidate(cand)
		}
	}

	c.pq.Reset()
	c.region = nil

	// Rather than just returning the raw list of cell ids, we construct a cell
	// union and then denormalize it. This has the effect of replacing four
	// child cells with their parent whenever this does not violate the covering
	// parameters specified (min_level, level_mod, etc). This significantly
	// reduces the number of cells returned in many cases, and it is cheap
	// compared to computing the covering in the first place.
	c.result.Normalize()
	if c.minLevel > 0 || c.levelMod > 1 {
		c.result.Denormalize(c.minLevel, c.levelMod)
	}
}