filter

type CompileError struct {
	Cause error // reported by the Compile{Expression|Condition} funcs

	// The parsed yaml that was used as input
	Input interface{}
}

type Condition interface {
	Eval(*Context) bool
}

type Context struct {
	Debug   bool
	Verbose bool

	FeatureID osm.FeatureID
	Geometry  orb.Geometry

	// To compute ways and/or relations if needed
	OSM *osm.OSM

	Tags map[string]string

	// OSMTags are used during post processing we need access
	// the original osm tags as well as the new filter outputs.
	OSMTags map[string]string

	WayMembership      map[osm.NodeID]osm.Ways
	RelationMembership map[osm.FeatureID]osm.Relations
	// contains filtered or unexported fields
}

type Expression interface {
	Eval(*Context) interface{}
}

type Filter struct {
	Skip bool

	RawFilter  interface{}            `yaml:"filter"`
	RawOutput  map[string]interface{} `yaml:"output"`
	RawMinZoom interface{}            `yaml:"min_zoom"`
	Table      string                 `yaml:"table"`

	MinZoom NumExpression `yaml:"-"`
	Filter  Condition     `yaml:"-"`
	// Output  map[string]Expression `yaml:"-"`
	Output []OutputExpression `yaml:"-"`
}

type NumExpression interface {
	EvalNum(*Context) float64
}

type OutputExpression struct {
	Key  string
	Expr Expression
}