DEVELOPER_GUIDE.md

Developer Guide

Getting Started

Most simple example is below.

package main

import (
	"fmt"

	"github.com/c-bata/go-prompt"
)

// executor executes command and print the output.
func executor(in string) {
	fmt.Println("Your input: " + in)
}

// completer returns the completion items from user input.
func completer(d prompt.Document) []prompt.Suggest {
	s := []prompt.Suggest{
		{Text: "users", Description: "user table"},
		{Text: "sites", Description: "sites table"},
		{Text: "articles", Description: "articles table"},
		{Text: "comments", Description: "comments table"},
	}
	return prompt.FilterHasPrefix(s, d.GetWordBeforeCursor(), true)
}

func main() {
	p := prompt.New(
		executor,
		completer,
		prompt.OptionPrefix(">>> "),
		prompt.OptionTitle("sql-prompt"),
	)
	p.Run()
}

If you want to create CLI using go-prompt, I recommend you to look at the source code of kube-prompt. It is the most practical example.

Options

go-prompt has many color options. It is difficult to describe by text. So please see below figure:

• OptionPrefixTextColor(prompt.Color) : default prompt.Blue
• OptionPrefixBackgroundColor(prompt.Color) : default prompt.DefaultColor
• OptionInputTextColor(prompt.Color) : default prompt.DefaultColor
• OptionInputBGColor(prompt.Color) : default prompt.DefaultColor
• OptionPreviewSuggestionTextColor(prompt.Color) : default prompt.Green
• OptionPreviewSuggestionBGColor(prompt.Color) : default prompt.DefaultColor
• OptionSuggestionTextColor(prompt.Color) : default prompt.White
• OptionSuggestionBGColor(prompt.Color) : default prompt.Cyan
• OptionSelectedSuggestionTextColor(prompt.Color) : default prompt.Black
• OptionSelectedSuggestionBGColor(prompt.Color) : default prompt.DefaultColor
• OptionDescriptionTextColor(prompt.Color) : default prompt.Black
• OptionDescriptionBGColor(prompt.Color) : default prompt.Turquoise
• OptionSelectedDescriptionTextColor(prompt.Color) : default prompt.White
• OptionSelectedDescriptionBGColor(prompt.Color) : default prompt.Cyan

Other Options

OptionTitle(string) : default ""

Option to set title displayed at the header bar of terminal.

OptionHistory([]string) : default []string{}

Option to set history.

OptionPrefix(string) : default "> "

Option to set prefix string.

OptionMaxSuggestions(x uint16) : default 6

The max number of displayed suggestions.

OptionParser(prompt.ConsoleParser) : default VT100Parser

To set a custom ConsoleParser object. An argument should implement ConsoleParser interface.

OptionWriter(prompt.ConsoleWriter) : default VT100Writer

To set a custom ConsoleWriter object. An argument should implement ConsoleWriter interace.

SwitchKeyBindMode(prompt.KeyBindMode) : default prompt.EmacsKeyBindMode

To set a key bind mode.

OptionAddKeyBind(...KeyBind) : default []KeyBind{}

To set a custom key bind.

Architecture of go-prompt

Caution: This section is WIP.

This is a short description of go-prompt implementation. go-prompt consists of three parts.

1. Input parser
2. Emulate user input with Buffer object.
3. Render buffer object.

Input Parser

Input Parser only supports only vt100 compatible console now.

• Set raw mode.
• Read standard input.
• Parse byte array

Emulate user input

go-prompt contains Buffer class. It represents input state by handling user input key.

Buffer object has text and cursor position.

TODO prepare the sample of buffer

package main

import "github.com/c-bata/go-prompt"

func main() {
  b := prompt.NewBuffer()
  ... wip
}

Renderer

Renderer object renders a buffer object.

TODO prepare the sample of brender

package main

the output is below:

TODO prepare a screen shot