introduces the Range interface (instead of a concrete type).

range.go

@@ -1,44 +1,41 @@
 package chart
 
-import (
-	"fmt"
-	"math"
-)
-
-// Range represents a boundary for a set of numbers.
-type Range struct {
-	Min    float64
-	Max    float64
-	Domain int
+// NameProvider is a type that returns a name.
+type NameProvider interface {
+	GetName() string
 }
 
-// IsZero returns if the range has been set or not.
-func (r Range) IsZero() bool {
-	return (r.Min == 0 || math.IsNaN(r.Min)) &&
-		(r.Max == 0 || math.IsNaN(r.Max)) &&
-		r.Domain == 0
+// StyleProvider is a type that returns a style.
+type StyleProvider interface {
+	GetStyle() Style
 }
 
-// Delta returns the difference between the min and max value.
-func (r Range) Delta() float64 {
-	return r.Max - r.Min
+// IsZeroable is a type that returns if it's been set or not.
+type IsZeroable interface {
+	IsZero() bool
 }
 
-// String returns a simple string for the range.
-func (r Range) String() string {
-	return fmt.Sprintf("Range [%.2f,%.2f] => %d", r.Min, r.Max, r.Domain)
+// Stringable is a type that has a string representation.
+type Stringable interface {
+	String() string
 }
 
-// Translate maps a given value into the range space.
-func (r Range) Translate(value float64) int {
-	normalized := value - r.Min
-	ratio := normalized / r.Delta()
-	return int(math.Ceil(ratio * float64(r.Domain)))
-}
+// Range is a
+type Range interface {
+	Stringable
+	IsZeroable
 
-// GetRoundedRangeBounds returns some `prettified` range bounds.
-func (r Range) GetRoundedRangeBounds() (min, max float64) {
-	delta := r.Max - r.Min
-	roundTo := GetRoundToForDelta(delta)
-	return RoundDown(r.Min, roundTo), RoundUp(r.Max, roundTo)
+	GetMin() float64
+	SetMin(min float64)
+
+	GetMax() float64
+	SetMax(max float64)
+
+	GetDelta() float64
+
+	GetDomain() int
+	SetDomain(domain int)
+
+	// Translate the range to the domain.
+	Translate(value float64) int
 }