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package volume
import (
"errors"
"fmt"
)
type unit float32
const (
CubicCentimetre unit = 1
Litre unit = 1_000
CubicMetre unit = 1_000_000
CubicInch unit = 16.38706
)
// UnitStrings returns a slice of strings, each representing a
// unit.
// This is necessary because giu.Combo only works with strings.
func UnitStrings() []string {
return []string{"cc", "L", "m³", "in³"}
}
const (
DefaultUnit unit = CubicCentimetre
// DefaulUnitIndex is used to index UnitStrings().
DefaultUnitIndex int32 = 0 // cc
)
func UnitFromString(s string) (unit, error) {
// Each case corresponds to a value in UnitStrings().
switch s {
case "cc":
return CubicCentimetre, nil
case "L":
return Litre, nil
case "m³":
return CubicMetre, nil
case "in³":
return CubicInch, nil
default:
return *new(unit), errors.New(fmt.Sprintf("invalid volume unit: '%s'", s))
}
}
type Volume struct {
Val float32
Unit unit
}
func (v Volume) AsUnit(u unit) float32 {
cc := v.Val * float32(v.Unit) // Convert to cubic centimetres.
return cc / float32(u) // Convert to desired unit.
}
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