The New Yet another Readline for Go (go-readline-ny)

The New Yet another Readline for Go (go-readline-ny) is a one-line input library for CUI applications written in Go that is extensible for different needs. It has been running inside the command line shell "NYAGOS" for a long time.

• Emacs-like key-bindings
• History
• Word Completion (file names, command names, or any names in given array)
• Syntax Highlighting
• Supported OS: Windows and Linux
• Suported Unicode (UTF8)
  • Surrogate-pair
  • Emoji (via clipboard)
  • Zero-Width-Joiner (via clipboard)
  • Variation Selector (via clipboard pasted by Ctrl-Y)
• Add-Ons:
  • SKK (Japanese method editor)
  • Multi-lines Editing
• MIT License

example1.go

The most simple sample.

package main

import (
    "context"
    "fmt"

    "github.com/nyaosorg/go-readline-ny"
)

func main() {
    var editor readline.Editor
    text, err := editor.ReadLine(context.Background())
    if err != nil {
        fmt.Printf("ERR=%s\n", err.Error())
    } else {
        fmt.Printf("TEXT=%s\n", text)
    }
}

If the target platform includes Windows, you have to import and use go-colorable like example2.go .

example2.go

Tiny Shell. This is a sample of prompt change, colorization, filename completion and history browsing.

package main

import (
    "context"
    "fmt"
    "io"
    "os"
    "os/exec"
    "strings"

    "github.com/mattn/go-colorable"

    "github.com/nyaosorg/go-readline-ny"
    "github.com/nyaosorg/go-readline-ny/coloring"
    "github.com/nyaosorg/go-readline-ny/completion"
    "github.com/nyaosorg/go-readline-ny/keys"
    "github.com/nyaosorg/go-readline-ny/simplehistory"
)

func main() {
    history := simplehistory.New()

    editor := &readline.Editor{
        PromptWriter: func(w io.Writer) (int, error) {
            return io.WriteString(w, "\x1B[1;36m$ \x1B[0m") // print `$ ` with cyan
        },
        Writer:         colorable.NewColorableStdout(),
        History:        history,
        Coloring:       &coloring.VimBatch{},
        HistoryCycling: true,
        PredictColor:   [...]string{"\x1B[3;22;34m", "\x1B[23;39m"},
    }

    editor.BindKey(keys.CtrlI, completion.CmdCompletionOrList{
        Completion: completion.File{},
        Postfix:    " ",
    })
    // If you do not want to list files with double-tab-key,
    // use `CmdCompletion` instead of `CmdCompletionOrList`

    fmt.Println("Tiny Shell. Type Ctrl-D to quit.")
    for {
        text, err := editor.ReadLine(context.Background())

        if err != nil {
            fmt.Printf("ERR=%s\n", err.Error())
            return
        }

        fields := strings.Fields(text)
        if len(fields) <= 0 {
            continue
        }
        cmd := exec.Command(fields[0], fields[1:]...)
        cmd.Stdout = os.Stdout
        cmd.Stderr = os.Stderr
        cmd.Stdin = os.Stdin

        cmd.Run()

        history.Add(text)
    }
}

example3.go

• example3.go

This is a sample to change key-bindings to diamond cursor.

example4.go

• example4.go

This is a sample that implements the function to start the text editor defined by the environment variable EDITOR and import the edited contents when the ESCAPE key is pressed.