Terminal host¶

Since v0.1.0

The host pieces and the terminal package arrive in v0.1.0.

The editing core is pure: it needs no interpreter and no tty. Everything that touches a real terminal sits behind the reline.IO interface (GetC, UngetC, GetScreenSize, Write, MoveCursorColumn, EraseAfterCursor, ClearScreen). A NullIO (fixed 24×80, recording) ships for tests and headless use.

Host pieces in the root package¶

The host-side parts of MRI that are still pure Go live in github.com/go-ruby-reline/reline:

API	Port of
`ReadKeys(config, io)`	`Reline::Core#read_io`: bytes to keys through the keymap, with the `keyseq-timeout` wait on a lone ESC
`SetANSIKeyBindings(config)`	`Reline::ANSI#set_default_key_bindings`: cursor keys in CSI and SS3 form, Ctrl/Meta arrows, Delete, Home/End, Page Up/Down, Shift-Tab, M-space, C-x C-x, bracketed paste start
`Config.AddDefaultKeyBinding`	the default key-binding table behind the ANSI bindings
`key_delete`	the Delete command
`MenuLines(list, width)`	`MenuInfo#lines`: the completion menu's columns
`LineEditor.TakeMenu()`	hands the pending completion menu to the host

The root package imports neither golang.org/x/term nor golang.org/x/sys.

On a real terminal: `terminal`¶

import "github.com/go-ruby-reline/reline/terminal"

The terminal package is the IO seam, wired: a reline.IO on a real terminal (raw mode and window size through golang.org/x/term; virtual-terminal output enabled on the Windows console). It puts the terminal in raw mode for one read, decodes the keys, drives the LineEditor, and redraws the edited lines, their prompts and the completion menu after every key (MRI Reline.readline / Reline.readmultiline over Reline::ANSI).

It supports multiline reads with a termination predicate, per-line prompts, Tab completion with the menu drawn below the line, history, bracketed paste and Ctrl-L. It runs on Linux, macOS and Windows 10+. The module requires golang.org/x/term and golang.org/x/sys.

t := terminal.New(os.Stdin, os.Stdout) // os.Stdin must be a terminal
for {
    line, err := t.Readline(terminal.Options{
        Prompt:     "> ",
        Terminate:  complete,     // multiline: Enter submits when this accepts the buffer
        Complete:   candidates,   // Tab
        AddHistory: true,
    })
    if err == io.EOF { break }                 // Ctrl-D on an empty line
    if errors.Is(err, terminal.ErrInterrupt) { continue } // Ctrl-C
    run(line)
}

terminal.Options has the fields Prompt, Terminate, PromptProc, Complete, AppendCharacter and AddHistory. Readline returns io.EOF on Ctrl-D or end of input, and terminal.ErrInterrupt on Ctrl-C.

Between two reads the terminal is back in its normal mode, so a program's own output needs no care. go-notebook's notebook irb is built on it.

Terminal host¶

Host pieces in the root package¶

On a real terminal: terminal¶

On a real terminal: `terminal`¶