metric.go

package units

import (
	"math"
)

type magnitude struct {
	Symbol string
	Prefix string
	Power  float64
}

var mags = map[string]magnitude{
	"quetta": {"Q", "quetta", 30.0},
	"ronna":  {"R", "ronna", 27.0},
	"yotta":  {"Y", "yotta", 24.0},
	"zetta":  {"Z", "zetta", 21.0},
	"exa":    {"E", "exa", 18.0},
	"peta":   {"P", "peta", 15.0},
	"tera":   {"T", "tera", 12.0},
	"giga":   {"G", "giga", 9.0},
	"mega":   {"M", "mega", 6.0},
	"kilo":   {"k", "kilo", 3.0},
	"hecto":  {"h", "hecto", 2.0},
	"deca":   {"da", "deca", 1.0},
	"deci":   {"d", "deci", -1.0},
	"centi":  {"c", "centi", -2.0},
	"milli":  {"m", "milli", -3.0},
	"micro":  {"μ", "micro", -6.0},
	"nano":   {"n", "nano", -9.0},
	"pico":   {"p", "pico", -12.0},
	"femto":  {"f", "femto", -15.0},
	"atto":   {"a", "atto", -18.0},
	"zepto":  {"z", "zepto", -21.0},
	"yocto":  {"y", "yocto", -24.0},
	"ronto":  {"r", "ronto", -27.0},
	"quecto": {"q", "quecto", -30.0},
}

// Magnitude prefix methods create and return a new Unit, while automatically registering
// conversions to and from the provided base Unit
func Quetta(b Unit, o ...UnitOption) Unit { return mags["quetta"].makeUnit(b, o...) }
func Ronna(b Unit, o ...UnitOption) Unit  { return mags["ronna"].makeUnit(b, o...) }
func Yotta(b Unit, o ...UnitOption) Unit  { return mags["yotta"].makeUnit(b, o...) }
func Zetta(b Unit, o ...UnitOption) Unit  { return mags["zetta"].makeUnit(b, o...) }
func Exa(b Unit, o ...UnitOption) Unit    { return mags["exa"].makeUnit(b, o...) }
func Peta(b Unit, o ...UnitOption) Unit   { return mags["peta"].makeUnit(b, o...) }
func Tera(b Unit, o ...UnitOption) Unit   { return mags["tera"].makeUnit(b, o...) }
func Giga(b Unit, o ...UnitOption) Unit   { return mags["giga"].makeUnit(b, o...) }
func Mega(b Unit, o ...UnitOption) Unit   { return mags["mega"].makeUnit(b, o...) }
func Kilo(b Unit, o ...UnitOption) Unit   { return mags["kilo"].makeUnit(b, o...) }
func Hecto(b Unit, o ...UnitOption) Unit  { return mags["hecto"].makeUnit(b, o...) }
func Deca(b Unit, o ...UnitOption) Unit   { return mags["deca"].makeUnit(b, o...) }
func Deci(b Unit, o ...UnitOption) Unit   { return mags["deci"].makeUnit(b, o...) }
func Centi(b Unit, o ...UnitOption) Unit  { return mags["centi"].makeUnit(b, o...) }
func Milli(b Unit, o ...UnitOption) Unit  { return mags["milli"].makeUnit(b, o...) }
func Micro(b Unit, o ...UnitOption) Unit  { return mags["micro"].makeUnit(b, o...) }
func Nano(b Unit, o ...UnitOption) Unit   { return mags["nano"].makeUnit(b, o...) }
func Pico(b Unit, o ...UnitOption) Unit   { return mags["pico"].makeUnit(b, o...) }
func Femto(b Unit, o ...UnitOption) Unit  { return mags["femto"].makeUnit(b, o...) }
func Atto(b Unit, o ...UnitOption) Unit   { return mags["atto"].makeUnit(b, o...) }
func Zepto(b Unit, o ...UnitOption) Unit  { return mags["zepto"].makeUnit(b, o...) }
func Yocto(b Unit, o ...UnitOption) Unit  { return mags["yocto"].makeUnit(b, o...) }
func Ronto(b Unit, o ...UnitOption) Unit  { return mags["ronto"].makeUnit(b, o...) }
func Quecto(b Unit, o ...UnitOption) Unit { return mags["quecto"].makeUnit(b, o...) }

// Create magnitude unit and conversion given a base unit
func (mag magnitude) makeUnit(base Unit, addOpts ...UnitOption) Unit {
	name := mag.Prefix + base.Name
	symbol := mag.Symbol + base.Symbol

	// set system to metric by default
	opts := []UnitOption{SI}

	// create prefixed aliases if needed
	for _, alias := range base.aliases {
		magAlias := mag.Prefix + alias
		opts = append(opts, UnitOptionAliases(magAlias))
	}

	// append any supplmental options
	opts = append(opts, addOpts...)

	// append quantity name opt
	opts = append(opts, UnitOptionQuantity(base.Quantity))

	u := NewUnit(name, symbol, opts...)

	// only create conversions to and from base unit
	ratio := 1.0 * math.Pow(10.0, mag.Power)
	NewRatioConversion(u, base, ratio)

	return u
}