readline

Readline is A Pure Go Implementation of a libreadline-style Library.
The goal is to be a powerful alternater for GNU-Readline.

WHY: Readline will support most of features which GNU Readline is supported, and provide a pure go environment and a MIT license.

Demo

Also works fine in windows

You can read the source code in example/main.go.

Todo

• Vi Mode is not completely finish
• More funny examples
• Support dumb/eterm-color terminal in emacs

Features

• Support emacs/vi mode, almost all basic features that GNU-Readline is supported
• zsh-style backward/forward history search
• zsh-style completion
• Readline auto refresh when others write to Stdout while editing (it needs specify the Stdout/Stderr provided by *readline.Instance to others).
• Support colourful prompt in all platforms.

Usage

• Simplest example

import "github.com/chzyer/readline"

rl, err := readline.New("> ")
if err != nil {
	panic(err)
}
defer rl.Close()

for {
	line, err := rl.Readline()
	if err != nil { // io.EOF
		break
	}
	println(line)
}

• Example with durable history

rl, err := readline.NewEx(&readline.Config{
	Prompt: "> ",
	HistoryFile: "/tmp/readline.tmp",
})
if err != nil {
	panic(err)
}
defer rl.Close()

for {
	line, err := rl.Readline()
	if err != nil { // io.EOF
		break
	}
	println(line)
}

• Example with auto refresh

import (
	"log"
	"github.com/chzyer/readline"
)

rl, err := readline.New("> ")
if err != nil {
	panic(err)
}
defer rl.Close()
log.SetOutput(l.Stderr()) // let "log" write to l.Stderr instead of os.Stderr

go func() {
	for _ = range time.Tick(time.Second) {
		log.Println("hello")
	}
}()

for {
	line, err := rl.Readline()
	if err != nil { // io.EOF
		break
	}
	println(line)
}

• Example with auto completion

import (
	"log"
	"github.com/chzyer/readline"
)

var completer = readline.NewPrefixCompleter(
	readline.PcItem("say",
		readline.PcItem("hello"),
		readline.PcItem("bye"),
	),
	readline.PcItem("help"),
)

rl, err := readline.New(&readline.Config{
	Prompt:       "> ",
	AutoComplete: completer,
})
if err != nil {
	panic(err)
}
defer rl.Close()

for {
	line, err := rl.Readline()
	if err != nil { // io.EOF
		break
	}
	println(line)
}

Shortcut

Meta+B means press Esc and n separately.
Users can change that in terminal simulator(i.e. iTerm2) to Alt+B
Notice: Meta+B is equals with Alt+B in windows.

• Shortcut in normal mode

Shortcut	Comment
Ctrl+A	Beginning of line
Ctrl+B / ←	Backward one character
Meta+B	Backward one word
Ctrl+C	Send io.EOF
Ctrl+D	Delete one character
Meta+D	Delete one word
Ctrl+E	End of line
Ctrl+F / →	Forward one character
Meta+F	Forward one word
Ctrl+G	Cancel
Ctrl+H	Delete previous character
Ctrl+I / Tab	Command line completion
Ctrl+J	Line feed
Ctrl+K	Cut text to the end of line
Ctrl+L	Clean screen (TODO)
Ctrl+M	Same as Enter key
Ctrl+N / ↓	Next line (in history)
Ctrl+P / ↑	Prev line (in history)
Ctrl+R	Search backwards in history
Ctrl+S	Search forwards in history
Ctrl+T	Transpose characters
Meta+T	Transpose words (TODO)
Ctrl+U	Cut text to the beginning of line
Ctrl+W	Cut previous word
Backspace	Delete previous character
Meta+Backspace	Cut previous word
Enter	Line feed

• Shortcut in Search Mode (Ctrl+S or Ctrl+r to enter this mode)

Shortcut	Comment
Ctrl+S	Search forwards in history
Ctrl+R	Search backwards in history
Ctrl+C / Ctrl+G	Exit Search Mode and revert the history
Backspace	Delete previous character
Other	Exit Search Mode

• Shortcut in Complete Select Mode (double Tab to enter this mode)

Shortcut	Comment
Ctrl+F	Move Forward
Ctrl+B	Move Backward
Ctrl+N	Move to next line
Ctrl+P	Move to previous line
Ctrl+A	Move to the first candicate in current line
Ctrl+E	Move to the last candicate in current line
Tab / Enter	Use the word on cursor to complete
Ctrl+C / Ctrl+G	Exit Complete Select Mode
Other	Exit Complete Select Mode

Tested with

Environment	$TERM
Mac OS X iTerm2	xterm
Mac OS X default Terminal.app	xterm
Mac OS X iTerm2 Screen	screen
Mac OS X iTerm2 Tmux	screen
Ubuntu Server 14.04 LTS	linux
Centos 7	linux
Windows 10	-

Notice:

• Ctrl+A is not working in screen because it used as a control command by default

If you test it otherwhere, whether it works fine or not, please let me know!

Feedback

If you have any questions, please submit a github issue and any pull requests is welcomed :)