ansi

ANSI color code utilities for terminal output formatting.

Overview

The ansi package provides constants and functions for applying ANSI escape codes to terminal text. It includes predefined color combinations for common use cases (errors, warnings, success messages) and utilities for stripping ANSI codes from strings.

Constants

Basic Colors

const (
    BrightRed    = "\x1b[91m"
    BrightGreen  = "\x1b[92m"
    BrightYellow = "\x1b[93m"
    BrightCyan   = "\x1b[96m"
    BrightWhite  = "\x1b[97m"
    Bold         = "\x1b[1m"
    Reset        = "\x1b[0m"
)

Highlighted Colors (Bold + Color)

const (
    HighlightRed    = BrightRed + Bold
    HighlightGreen  = BrightGreen + Bold
    HighlightYellow = BrightYellow + Bold
    HighlightCyan   = BrightCyan + Bold
    HighlightWhite  = BrightWhite + Bold
)

API Reference

Styled Output Functions

Error

func Error(s string) string

Returns the string wrapped in HighlightRed (bright red + bold).

Success

func Success(s string) string

Returns the string wrapped in HighlightGreen (bright green + bold).

Warning

func Warning(s string) string

Returns the string wrapped in HighlightYellow (bright yellow + bold).

Info

func Info(s string) string

Returns the string wrapped in HighlightCyan (bright cyan + bold).

Low-Level Functions

WithANSI

func WithANSI(s string, ansi string) string

Wraps a string with arbitrary ANSI codes. The ANSI code is prepended and Reset is appended.

StripANSI

func StripANSI(s string) string

Removes all ANSI escape codes from a string, returning plain text.

Usage Examples

Basic Styling

package main

import (
    "fmt"
    "github.com/yusing/goutils/strings/ansi"
)

func main() {
    fmt.Println(ansi.Error("This is an error message"))
    fmt.Println(ansi.Success("Operation completed successfully"))
    fmt.Println(ansi.Warning("This is a warning"))
    fmt.Println(ansi.Info("Here is some information"))
}

Output:

[1;91mThis is an error message[0m
[1;92mOperation completed successfully[0m
[1;93mThis is a warning[0m
[1;96mHere is some information[0m

Custom ANSI Codes

// Use basic color without bold
fmt.Println(ansi.WithANSI("Blue text", ansi.BrightBlue))

// Combine multiple styles
customStyle := ansi.BrightWhite + ansi.Bold
fmt.Println(ansi.WithANSI("Bold white", customStyle))

Stripping ANSI Codes

coloredText := ansi.Error("Error message")
plainText := ansi.StripANSI(coloredText)
// plainText == "Error message"

Logging with Colors

import "github.com/rs/zerolog"

func logMessage(level string, message string) {
    switch level {
    case "error":
        zerolog.Error().Msg(ansi.Error(message))
    case "warn":
        zerolog.Warn().Msg(ansi.Warning(message))
    case "info":
        zerolog.Info().Msg(ansi.Info(message))
    case "success":
        zerolog.Info().Msg(ansi.Success(message))
    }
}

Predefined Constants Reference

Constant	ANSI Code	Description
BrightRed	\x1b[91m	Bright red text
BrightGreen	\x1b[92m	Bright green text
BrightYellow	\x1b[93m	Bright yellow text
BrightCyan	\x1b[96m	Bright cyan text
BrightWhite	\x1b[97m	Bright white text
Bold	\x1b[1m	Bold formatting
Reset	\x1b[0m	Reset all formatting
HighlightRed	\x1b[91m\x1b[1m	Bold bright red
HighlightGreen	\x1b[92m\x1b[1m	Bold bright green
HighlightYellow	\x1b[93m\x1b[1m	Bold bright yellow
HighlightCyan	\x1b[96m\x1b[1m	Bold bright cyan
HighlightWhite	\x1b[97m\x1b[1m	Bold bright white

Implementation Details

The package uses:

• regexp.MustCompile to create a pattern for stripping ANSI codes: \x1b\[[0-9;]*m
• String concatenation to combine ANSI codes with text
• The Reset code (\x1b[0m) to restore default terminal formatting after styled text

Compatibility

ANSI escape codes are supported by:

• Most terminal emulators (iTerm2, Terminal.app, GNOME Terminal, etc.)
• Console2, Windows Terminal
• Some IDE terminals
• Not supported in standard Windows cmd.exe without ANSI.sys

For cross-platform compatibility, consider using a library like github.com/mattn/go-colorable or github.com/mattn/go-isatty.