// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package console
import (
"fmt"
"strings"
"github.com/peterh/liner"
)
// Stdin holds the stdin line reader (also using stdout for printing prompts).
// Only this reader may be used for input because it keeps an internal buffer.
var Stdin = newTerminalPrompter()
// UserPrompter defines the methods needed by the console to promt the user for
// various types of inputs.
type UserPrompter interface {
// PromptInput displays the given prompt to the user and requests some textual
// data to be entered, returning the input of the user.
PromptInput(prompt string) (string, error)
// PromptPassword displays the given prompt to the user and requests some textual
// data to be entered, but one which must not be echoed out into the terminal.
// The method returns the input provided by the user.
PromptPassword(prompt string) (string, error)
// PromptConfirm displays the given prompt to the user and requests a boolean
// choice to be made, returning that choice.
PromptConfirm(prompt string) (bool, error)
// SetHistory sets the the input scrollback history that the prompter will allow
// the user to scoll back to.
SetHistory(history []string)
// AppendHistory appends an entry to the scrollback history. It should be called
// if and only if the prompt to append was a valid command.
AppendHistory(command string)
// SetWordCompleter sets the completion function that the prompter will call to
// fetch completion candidates when the user presses tab.
SetWordCompleter(completer WordCompleter)
}
// WordCompleter takes the currently edited line with the cursor position and
// returns the completion candidates for the partial word to be completed. If
// the line is "Hello, wo!!!" and the cursor is before the first '!', ("Hello,
// wo!!!", 9) is passed to the completer which may returns ("Hello, ", {"world",
// "Word"}, "!!!") to have "Hello, world!!!".
type WordCompleter func(line string, pos int) (string, []string, string)
// terminalPrompter is a UserPrompter backed by the liner package. It supports
// prompting the user for various input, among others for non-echoing password
// input.
type terminalPrompter struct {
*liner.State
warned bool
supported bool
normalMode liner.ModeApplier
rawMode liner.ModeApplier
}
// newTerminalPrompter creates a liner based user input prompter working off the
// standard input and output streams.
func newTerminalPrompter() *terminalPrompter {
p := new(terminalPrompter)
// Get the original mode before calling NewLiner.
// This is usually regular "cooked" mode where characters echo.
normalMode, _ := liner.TerminalMode()
// Turn on liner. It switches to raw mode.
p.State = liner.NewLiner()
rawMode, err := liner.TerminalMode()
if err != nil || !liner.TerminalSupported() {
p.supported = false
} else {
p.supported = true
p.normalMode = normalMode
p.rawMode = rawMode
// Switch back to normal mode while we're not prompting.
normalMode.ApplyMode()
}
p.SetCtrlCAborts(true)
p.SetTabCompletionStyle(liner.TabPrints)
return p
}
// PromptInput displays the given prompt to the user and requests some textual
// data to be entered, returning the input of the user.
func (p *terminalPrompter) PromptInput(prompt string) (string, error) {
if p.supported {
p.rawMode.ApplyMode()
defer p.normalMode.ApplyMode()
} else {
// liner tries to be smart about printing the prompt
// and doesn't print anything if input is redirected.
// Un-smart it by printing the prompt always.
fmt.Print(prompt)
prompt = ""
defer fmt.Println()
}
return p.State.Prompt(prompt)
}
// PromptPassword displays the given prompt to the user and requests some textual
// data to be entered, but one which must not be echoed out into the terminal.
// The method returns the input provided by the user.
func (p *terminalPrompter) PromptPassword(prompt string) (passwd string, err error) {
if p.supported {
p.rawMode.ApplyMode()
defer p.normalMode.ApplyMode()
return p.State.PasswordPrompt(prompt)
}
if !p.warned {
fmt.Println("!! Unsupported terminal, password will be echoed.")
p.warned = true
}
// Just as in Prompt, handle printing the prompt here instead of relying on liner.
fmt.Print(prompt)
passwd, err = p.State.Prompt("")
fmt.Println()
return passwd, err
}
// PromptConfirm displays the given prompt to the user and requests a boolean
// choice to be made, returning that choice.
func (p *terminalPrompter) PromptConfirm(prompt string) (bool, error) {
input, err := p.Prompt(prompt + " [y/N] ")
if len(input) > 0 && strings.ToUpper(input[:1]) == "Y" {
return true, nil
}
return false, err
}
// SetHistory sets the the input scrollback history that the prompter will allow
// the user to scoll back to.
func (p *terminalPrompter) SetHistory(history []string) {
p.State.ReadHistory(strings.NewReader(strings.Join(history, "\n")))
}
// AppendHistory appends an entry to the scrollback history. It should be called
// if and only if the prompt to append was a valid command.
func (p *terminalPrompter) AppendHistory(command string) {
p.State.AppendHistory(command)
}
// SetWordCompleter sets the completion function that the prompter will call to
// fetch completion candidates when the user presses tab.
func (p *terminalPrompter) SetWordCompleter(completer WordCompleter) {
p.State.SetWordCompleter(liner.WordCompleter(completer))
}
