vendor/github.com/go-task/slim-sprig/numeric.go

package sprig

import (
	"fmt"
	"math"
	"reflect"
	"strconv"
	"strings"
)

// toFloat64 converts 64-bit floats
func toFloat64(v interface{}) float64 {
	if str, ok := v.(string); ok {
		iv, err := strconv.ParseFloat(str, 64)
		if err != nil {
			return 0
		}
		return iv
	}

	val := reflect.Indirect(reflect.ValueOf(v))
	switch val.Kind() {
	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
		return float64(val.Int())
	case reflect.Uint8, reflect.Uint16, reflect.Uint32:
		return float64(val.Uint())
	case reflect.Uint, reflect.Uint64:
		return float64(val.Uint())
	case reflect.Float32, reflect.Float64:
		return val.Float()
	case reflect.Bool:
		if val.Bool() {
			return 1
		}
		return 0
	default:
		return 0
	}
}

func toInt(v interface{}) int {
	//It's not optimal. Bud I don't want duplicate toInt64 code.
	return int(toInt64(v))
}

// toInt64 converts integer types to 64-bit integers
func toInt64(v interface{}) int64 {
	if str, ok := v.(string); ok {
		iv, err := strconv.ParseInt(str, 10, 64)
		if err != nil {
			return 0
		}
		return iv
	}

	val := reflect.Indirect(reflect.ValueOf(v))
	switch val.Kind() {
	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
		return val.Int()
	case reflect.Uint8, reflect.Uint16, reflect.Uint32:
		return int64(val.Uint())
	case reflect.Uint, reflect.Uint64:
		tv := val.Uint()
		if tv <= math.MaxInt64 {
			return int64(tv)
		}
		// TODO: What is the sensible thing to do here?
		return math.MaxInt64
	case reflect.Float32, reflect.Float64:
		return int64(val.Float())
	case reflect.Bool:
		if val.Bool() {
			return 1
		}
		return 0
	default:
		return 0
	}
}

func max(a interface{}, i ...interface{}) int64 {
	aa := toInt64(a)
	for _, b := range i {
		bb := toInt64(b)
		if bb > aa {
			aa = bb
		}
	}
	return aa
}

func maxf(a interface{}, i ...interface{}) float64 {
	aa := toFloat64(a)
	for _, b := range i {
		bb := toFloat64(b)
		aa = math.Max(aa, bb)
	}
	return aa
}

func min(a interface{}, i ...interface{}) int64 {
	aa := toInt64(a)
	for _, b := range i {
		bb := toInt64(b)
		if bb < aa {
			aa = bb
		}
	}
	return aa
}

func minf(a interface{}, i ...interface{}) float64 {
	aa := toFloat64(a)
	for _, b := range i {
		bb := toFloat64(b)
		aa = math.Min(aa, bb)
	}
	return aa
}

func until(count int) []int {
	step := 1
	if count < 0 {
		step = -1
	}
	return untilStep(0, count, step)
}

func untilStep(start, stop, step int) []int {
	v := []int{}

	if stop < start {
		if step >= 0 {
			return v
		}
		for i := start; i > stop; i += step {
			v = append(v, i)
		}
		return v
	}

	if step <= 0 {
		return v
	}
	for i := start; i < stop; i += step {
		v = append(v, i)
	}
	return v
}

func floor(a interface{}) float64 {
	aa := toFloat64(a)
	return math.Floor(aa)
}

func ceil(a interface{}) float64 {
	aa := toFloat64(a)
	return math.Ceil(aa)
}

func round(a interface{}, p int, rOpt ...float64) float64 {
	roundOn := .5
	if len(rOpt) > 0 {
		roundOn = rOpt[0]
	}
	val := toFloat64(a)
	places := toFloat64(p)

	var round float64
	pow := math.Pow(10, places)
	digit := pow * val
	_, div := math.Modf(digit)
	if div >= roundOn {
		round = math.Ceil(digit)
	} else {
		round = math.Floor(digit)
	}
	return round / pow
}

// converts unix octal to decimal
func toDecimal(v interface{}) int64 {
	result, err := strconv.ParseInt(fmt.Sprint(v), 8, 64)
	if err != nil {
		return 0
	}
	return result
}

func seq(params ...int) string {
	increment := 1
	switch len(params) {
	case 0:
		return ""
	case 1:
		start := 1
		end := params[0]
		if end < start {
			increment = -1
		}
		return intArrayToString(untilStep(start, end+increment, increment), " ")
	case 3:
		start := params[0]
		end := params[2]
		step := params[1]
		if end < start {
			increment = -1
			if step > 0 {
				return ""
			}
		}
		return intArrayToString(untilStep(start, end+increment, step), " ")
	case 2:
		start := params[0]
		end := params[1]
		step := 1
		if end < start {
			step = -1
		}
		return intArrayToString(untilStep(start, end+step, step), " ")
	default:
		return ""
	}
}

func intArrayToString(slice []int, delimeter string) string {
	return strings.Trim(strings.Join(strings.Fields(fmt.Sprint(slice)), delimeter), "[]")
}