float.go

package enigma

import (
	"math"
	"strconv"
)

// Float64 is an enigma-go equivalent of float64 which adds support for the Qlik Associative Engine specific way of marshalling and unmarshalling "Infinity", "-Infinity" and "NaN" as json strings.
// It can always safely be typecasted to plain float64 including these special cases.
type Float64 float64

// UnmarshalJSON implements the Unmarshaler interface for custom unmarshalling.
func (value *Float64) UnmarshalJSON(arg []byte) error {
	switch string(arg) {
	case `"NaN"`:
		*value = Float64(math.NaN())
	case `"Infinity"`, `"+Infinity"`:
		*value = Float64(math.Inf(1))
	case `"-Infinity"`:
		*value = Float64(math.Inf(-1))
	default:
		float, err := strconv.ParseFloat(string(arg), 64)
		*value = Float64(float)
		return err
	}
	return nil
}

// MarshalJSON implements the Marshaler interface for custom marshalling.
func (value Float64) MarshalJSON() ([]byte, error) {
	val := float64(value)
	if math.IsNaN(val) {
		return []byte(`"NaN"`), nil
	} else if math.IsInf(val, 1) {
		return []byte(`"Infinity"`), nil
	} else if math.IsInf(val, -1) {
		return []byte(`"-Infinity"`), nil
	}
	str := strconv.FormatFloat(val, 'f', -1, 64)
	return []byte(str), nil
}