aboutsummaryrefslogtreecommitdiffstats
path: root/console/prompter.go
blob: ea03694d4172d9f4f56ba5e4dd8851d9499047a2 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
// 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 scroll 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)

    // ClearHistory clears the entire history
    ClearHistory()

    // 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)
    p.SetMultiLineMode(true)
    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 scroll 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)
}

// ClearHistory clears the entire history
func (p *terminalPrompter) ClearHistory() {
    p.State.ClearHistory()
}

// 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))
}