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Contents
// Package scale provides a sample implementation
package scale
import (
"strings"
)
var chromaticScale = []string{"C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A",
"A#", "B"}
var flatChromaticScale = []string{"C", "Db", "D", "Eb", "E", "F", "Gb", "G", "Ab",
"A", "Bb", "B"}
var flatKeys = []string{"F", "Bb", "Eb", "Ab", "Db", "Gb", "d", "g", "c", "f", "bb",
"eb"}
// Scale returns a type of scale based on the inputs
func Scale(tonic, interval string) []string {
if interval == "" {
interval = strings.Repeat("m", 12)
}
ft := formatTonic(tonic)
scale := chromaticScale
if flatKey(tonic, flatKeys) {
scale = flatChromaticScale
}
start := findStart(ft, scale)
return printScale(ft, interval, start, scale)
}
func printScale(tonic, interval string, start int, arr []string) []string {
res := []string{tonic}
for _, e := range interval[:len(interval)-1] {
if e == 'm' {
start++
} else if e == 'M' {
start += 2
} else if e == 'A' {
start += 3
}
res = append(res, arr[start%12])
}
return res
}
func findStart(tonic string, arr []string) int {
for i := range arr {
if arr[i] == tonic {
return i
}
}
return -1
}
func flatKey(tonic string, arr []string) bool {
return findStart(tonic, arr) > -1
}
func formatTonic(tonic string) string {
if len(tonic) == 1 {
return strings.ToUpper(tonic)
}
return strings.Title(tonic)
}
Version data entries
68 entries across 68 versions & 1 rubygems