blob: 4726ea3c4eaf6329196623dbce66f54191aa8def [file] [log] [blame]
// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package color provides functions for printing in different colors.
package color
import (
"fmt"
"os"
"go.fuchsia.dev/tools/isatty"
)
// Colorfn is a function type that takes a formatted string and returns it in a certain color.
type Colorfn func(format string, a ...interface{}) string
const (
escape = "\033["
clear = escape + "0m"
)
// ColorCode represents the int used for coloring formatted strings in a certain color.
type ColorCode int
// Foreground text colors
const (
BlackFg ColorCode = iota + 30
RedFg
GreenFg
YellowFg
BlueFg
MagentaFg
CyanFg
WhiteFg
DefaultFg
)
// Color provides an interface for a color or monochrome type that will be returned by NewColor()
// based on whether coloring is enabled or not.
type Color interface {
Black(format string, a ...interface{}) string
Red(format string, a ...interface{}) string
Green(format string, a ...interface{}) string
Yellow(format string, a ...interface{}) string
Blue(format string, a ...interface{}) string
Magenta(format string, a ...interface{}) string
Cyan(format string, a ...interface{}) string
White(format string, a ...interface{}) string
DefaultColor(format string, a ...interface{}) string
WithColor(code ColorCode, format string, a ...interface{}) string
Enabled() bool
}
type color struct{}
func (color) Black(format string, a ...interface{}) string { return colorString(BlackFg, format, a...) }
func (color) Red(format string, a ...interface{}) string { return colorString(RedFg, format, a...) }
func (color) Green(format string, a ...interface{}) string { return colorString(GreenFg, format, a...) }
func (color) Yellow(format string, a ...interface{}) string {
return colorString(YellowFg, format, a...)
}
func (color) Blue(format string, a ...interface{}) string { return colorString(BlueFg, format, a...) }
func (color) Magenta(format string, a ...interface{}) string {
return colorString(MagentaFg, format, a...)
}
func (color) Cyan(format string, a ...interface{}) string { return colorString(CyanFg, format, a...) }
func (color) White(format string, a ...interface{}) string { return colorString(WhiteFg, format, a...) }
func (color) DefaultColor(format string, a ...interface{}) string {
return colorString(DefaultFg, format, a...)
}
func (color) WithColor(code ColorCode, format string, a ...interface{}) string {
return colorString(code, format, a...)
}
func (color) Enabled() bool {
return true
}
func colorString(c ColorCode, format string, a ...interface{}) string {
if c == DefaultFg {
return fmt.Sprintf(format, a...)
}
return fmt.Sprintf("%v%vm%v%v", escape, c, fmt.Sprintf(format, a...), clear)
}
type monochrome struct{}
func (monochrome) Black(format string, a ...interface{}) string { return fmt.Sprintf(format, a...) }
func (monochrome) Red(format string, a ...interface{}) string { return fmt.Sprintf(format, a...) }
func (monochrome) Green(format string, a ...interface{}) string { return fmt.Sprintf(format, a...) }
func (monochrome) Yellow(format string, a ...interface{}) string { return fmt.Sprintf(format, a...) }
func (monochrome) Blue(format string, a ...interface{}) string { return fmt.Sprintf(format, a...) }
func (monochrome) Magenta(format string, a ...interface{}) string { return fmt.Sprintf(format, a...) }
func (monochrome) Cyan(format string, a ...interface{}) string { return fmt.Sprintf(format, a...) }
func (monochrome) White(format string, a ...interface{}) string { return fmt.Sprintf(format, a...) }
func (monochrome) DefaultColor(format string, a ...interface{}) string {
return fmt.Sprintf(format, a...)
}
func (monochrome) WithColor(_ ColorCode, format string, a ...interface{}) string {
return fmt.Sprintf(format, a...)
}
func (monochrome) Enabled() bool {
return false
}
// EnableColor represents whether or not to return colored strings.
type EnableColor int
const (
ColorNever EnableColor = iota
ColorAuto
ColorAlways
)
func isColorAvailable() bool {
term := os.Getenv("TERM")
switch term {
case "dumb", "":
return false
}
return isatty.IsTerminal()
}
// NewColor returns a color or monochrome type depending on the value of enableColor.
// A monochrome type will always return the string in the default color.
func NewColor(enableColor EnableColor) Color {
ec := enableColor != ColorNever
if enableColor == ColorAuto {
ec = isColorAvailable()
}
if ec {
return color{}
} else {
return monochrome{}
}
}
// String returns the string value of the EnableColor type.
func (ec *EnableColor) String() string {
switch *ec {
case ColorNever:
return "never"
case ColorAuto:
return "auto"
case ColorAlways:
return "always"
}
return ""
}
// Set sets the EnableColor type based on the string value.
func (ec *EnableColor) Set(s string) error {
switch s {
case "never":
*ec = ColorNever
case "auto":
*ec = ColorAuto
case "always":
*ec = ColorAlways
default:
return fmt.Errorf("%s is not a valid color value", s)
}
return nil
}