Refactor Oasis Ranker

[CodeBear801]

Current status:

• Ranker provide two interface:

// Ranker used to ranking a group of points
type Ranker interface {

	// RankPointIDsByGreatCircleDistance ranks a group of points based on great circle distance to given location
	RankPointIDsByGreatCircleDistance(center Location, targets []*PointInfo) []*RankedPointInfo

	// RankPointIDsByShortestDistance ranks a group of points based on shortest path distance to given location
	RankPointIDsByShortestDistance(center Location, targets []*PointInfo) []*RankedPointInfo
}

There is factory to create different rankers:

// CreateRanker creates implementations of interface Ranker
func CreateRanker(rankerType string, oc *osrmconnector.OSRMConnector) spatialindexer.Ranker {
	switch rankerType {
	case SimpleRanker:
		return newSimpleRanker()
	case OSRMBasedRanker:
		return newOsrmRanker(oc)
	default:
		return newSimpleRanker()
	}
}

• Adjust spatialindexer/interface.go
  // RankedPointInfo used to record ranking result to center point
  // Distance record distance from center point to current point
  // Duration records duration from center point to current point

type RankedPointInfo struct {
	PointInfo
	Distance float64
         // todo
        Duration float64
}

Target

1. Just use one interface function

// Ranker used to ranking a group of points
type Ranker interface {

	// RankPointIDs ranks a group of points based on ranking strategy
	RankPointIDs(center Location, targets []*PointInfo) []*RankedPointInfo
}

2. Refine names

// CreateRanker creates implementations of interface Ranker
func CreateRanker(rankerType string, oc *osrmconnector.OSRMConnector) spatialindexer.Ranker {
	switch rankerType {
	case GreatCircleDistanceBasedRanker:
		return newSimpleRanker()
	case ShortestpathBasedRanker:
		return newOsrmRanker(oc)
	default:
		return newSimpleRanker()
	}
}