Bubbline

An input line editor for line-oriented terminal applications.

Based off the bubbletea library.

Features of the line editor

Feature	Charm textarea 1	libedit 2 /readline 3	Bubbline (this library)
Multi-line editor with both horizontal and vertical cursor navigation.	✅	✅	✅
Secondary prompt for multi-line input.	✅	✅	✅
Resizes vertically automatically as the input grows.	❌	✅	✅
Supports history navigation and search.	❌	✅	✅
Word navigation across input lines.	❌	✅	✅
Enter key conditionally ends the input.	❌	✅	✅
Tab completion callback.	❌	✅	✅
Fancy presentation of completions with menu navigation.	❌	✅ 4	✅
Intelligent input interruption with Ctrl+C.	❌	✅	✅
Ctrl+Z (suspend process), Ctrl+\ (send SIGQUIT to process e.g. to get stack dump).	❌	✅	✅
Uppercase/lowercase/capitalize next word, transpose characters.	✅	✅	✅
Inline help for key bindings.	❌	❌	✅
Toggle overwrite mode.	❌ 5	❌	✅
Key combination to reflow the text to fit within a specific width.	❌	❌	✅
Hide/show the prompt to simplify copy-paste from terminal.	❌	❌	✅
Debug mode for troubleshooting.	❌	❌	✅
Open with external editor.	❌	(✅) 6	✅
Bracketed paste 7	❌ 8	✅	❌ 8

Demo / explanation

Customizable key bindings

Default keys	Description	Binding name
Ctrl+D	Terminate the input if the cursor is at the beginning of a line; delete character otherwise.	EndOfInput
Ctrl+C	Clear the input if non-empty, or interrupt input if already empty.	Interrupt
Tab	Run the AutoComplete callback if defined.	AutoComplete
Alt+.	Hide/show the prompt (eases copy-paste from terminal).	HideShowPrompt
Ctrl+L	Clear the screen and re-display the current input.	Refresh
Ctrl+G	Abort the search if currently searching; no-op otherwise.	AbortSearch
Ctrl+R	Start searching; or previous search match if already searching.	SearchBackward
Alt+P	Recall previous history entry.	HistoryPrevious
Alt+N	Recall next history entry.	HistoryNext
Enter, Ctrl+M	Enter a new line; or terminate input if CheckInputComplete returns true.	InsertNewline
Alt+Enter, Alt+Ctrl+M	Always complete the input; ignore input termination condition.	AlwaysComplete
Ctrl+O	Always insert a newline; ignore input termination condition.	AlwaysNewline
Ctrl+F, Right	Move one character to the right.	CharacterBackward
Ctrl+B, Left	Move one character to the left.	CharacterForward
Alt+F, Alt+Right, Ctrl+Right	Move cursor to the previous word.	WordForward
Alt+B, Alt+Left, Ctrl+Left	Move cursor to the next word.	WordBackward
Ctrl+A, Home	Move cursor to beginning of line.	LineNext
Ctrl+E, End	Move cursor to end of line.	LineEnd
Alt+<, Ctrl+Home	Move cursor to beginning of input.	MoveToBegin
Alt+>, Ctrl+End	Move cursor to end of input.	MoveToEnd
Ctrl+P, Up	Move cursor one line up, or to previous history entry if already on first line.	LinePrevious
Ctrl+N, Down	Move cursor one line down, or to next history entry if already on last line.	LineStart
Ctrl+T	Transpose the last two characters.	TransposeCharacterBackward
Alt+O, Insert	Toggle overwrite mode.	ToggleOverwriteMode
Alt+U	Make the next word uppercase.	UppercaseWordForward
Alt+L	Make the next word lowercase.	LowercaseWordForward
Alt+C	Capitalize the next word.	CapitalizeWordForward
Ctrl+K	Delete the line after the cursor.	DeleteAfterCursor
Ctrl+U	Delete the line before the cursor.	DeleteBeforeCursor
Backspace, Ctrl+H	Delete the character before the cursor.	DeleteCharacterBackward
Delete	Delete the character after the cursor.	DeleteCharacterForward
Ctrl+W, Alt+Backspace	Delete the word before the cursor.	DeleteWordBackward
Alt+D, Alt+Delete	Delete the word after the cursor.	DeleteWordForward
Ctrl+\	Send SIGQUIT to process.	SignalQuit
Ctrl+Z	Send SIGTSTOP to process (suspend).	SignalTTYStop
Alt+?	Toggle display of keybindings.	MoreHelp
Alt+q	Reflow the current line.	ReflowLine
Alt+Shift+Q	Reflow the entire input.	ReflowAll
Alt+2, Alt+F2	Edit with an external editor, as defined by env var EDITOR. (not enabled by default)	ExternalEdit
Ctrl+_, Ctrl+@	Print debug information about the editor. (not enabled by default)	Debug

Example use

package main

import (
    "errors"
    "fmt"
    "io"
    "log"

    tea "github.com/charmbracelet/bubbletea"
    "github.com/knz/bubbline"
)

func main() {
    // Instantiate the widget.
    m := bubbline.New()

    for {
        // Read a line of input using the widget.
        val, err := m.GetLine()

        // Handle the end of input.
        if err != nil {
            if err == io.EOF {
                // No more input.
                break
            }
            if errors.Is(err, bubbline.ErrInterrupted) {
                // Entered Ctrl+C to cancel input.
                fmt.Println("^C")
			} else if errors.Is(err, bubbline.ErrTerminated) {
				fmt.Println("terminated")
				break
            } else {
                fmt.Println("error:", err)
            }
            continue
        }

        // Handle regular input.
        fmt.Printf("\nYou have entered: %q\n", val)
        m.AddHistory(val)
    }
}

See the examples subdirectory for more examples!

Footnotes

1. https://github.com/charmbracelet/bubbles ↩

2. editline/libedit ↩

3. GNU readline ↩

4. libedit/readline's completion menu is a single line of options with wraparound. ↩

5. Pending https://github.com/charmbracelet/bubbles/pull/225 ↩

6. Possible to configure via key binding macro. ↩

7. https://en.wikipedia.org/wiki/Bracketed-paste ↩

8. Pending https://github.com/charmbracelet/bubbletea/pull/397 and https://github.com/charmbracelet/bubbletea/pull/397 ↩ ↩²