vendor/github.com/manifoldco/promptui/codes.go

package promptui

import (
	"fmt"
	"strconv"
	"strings"
	"text/template"
)

const esc = "\033["

type attribute int

// The possible state of text inside the application, either Bold, faint, italic or underline.
//
// These constants are called through the use of the Styler function.
const (
	reset attribute = iota

	FGBold
	FGFaint
	FGItalic
	FGUnderline
)

// The possible colors of text inside the application.
//
// These constants are called through the use of the Styler function.
const (
	FGBlack attribute = iota + 30
	FGRed
	FGGreen
	FGYellow
	FGBlue
	FGMagenta
	FGCyan
	FGWhite
)

// The possible background colors of text inside the application.
//
// These constants are called through the use of the Styler function.
const (
	BGBlack attribute = iota + 40
	BGRed
	BGGreen
	BGYellow
	BGBlue
	BGMagenta
	BGCyan
	BGWhite
)

// ResetCode is the character code used to reset the terminal formatting
var ResetCode = fmt.Sprintf("%s%dm", esc, reset)

const (
	hideCursor = esc + "?25l"
	showCursor = esc + "?25h"
	clearLine  = esc + "2K"
)

// FuncMap defines template helpers for the output. It can be extended as a regular map.
//
// The functions inside the map link the state, color and background colors strings detected in templates to a Styler
// function that applies the given style using the corresponding constant.
var FuncMap = template.FuncMap{
	"black":     Styler(FGBlack),
	"red":       Styler(FGRed),
	"green":     Styler(FGGreen),
	"yellow":    Styler(FGYellow),
	"blue":      Styler(FGBlue),
	"magenta":   Styler(FGMagenta),
	"cyan":      Styler(FGCyan),
	"white":     Styler(FGWhite),
	"bgBlack":   Styler(BGBlack),
	"bgRed":     Styler(BGRed),
	"bgGreen":   Styler(BGGreen),
	"bgYellow":  Styler(BGYellow),
	"bgBlue":    Styler(BGBlue),
	"bgMagenta": Styler(BGMagenta),
	"bgCyan":    Styler(BGCyan),
	"bgWhite":   Styler(BGWhite),
	"bold":      Styler(FGBold),
	"faint":     Styler(FGFaint),
	"italic":    Styler(FGItalic),
	"underline": Styler(FGUnderline),
}

func upLine(n uint) string {
	return movementCode(n, 'A')
}

func movementCode(n uint, code rune) string {
	return esc + strconv.FormatUint(uint64(n), 10) + string(code)
}

// Styler is a function that accepts multiple possible styling transforms from the state,
// color and background colors constants and transforms them into a templated string
// to apply those styles in the CLI.
//
// The returned styling function accepts a string that will be extended with
// the wrapping function's styling attributes.
func Styler(attrs ...attribute) func(interface{}) string {
	attrstrs := make([]string, len(attrs))
	for i, v := range attrs {
		attrstrs[i] = strconv.Itoa(int(v))
	}

	seq := strings.Join(attrstrs, ";")

	return func(v interface{}) string {
		end := ""
		s, ok := v.(string)
		if !ok || !strings.HasSuffix(s, ResetCode) {
			end = ResetCode
		}
		return fmt.Sprintf("%s%sm%v%s", esc, seq, v, end)
	}
}