Liner
=====

Liner is a command line editor with history. It was inspired by linenoise;
everything Unix-like is a VT100 (or is trying very hard to be). If your
terminal is not pretending to be a VT100, change it. Liner also support
Windows.

Liner is intended for use by cross-platform applications. Therefore, the
decision was made to write it in pure Go, avoiding cgo, for ease of cross
compilation. Furthermore, features only supported on some platforms have
been intentionally omitted. For example, Ctrl-Z is "suspend" on Unix, but
"EOF" on Windows. In the interest of making an application behave the same
way on every supported platform, Ctrl-Z is ignored by Liner.

Liner is released under the X11 license (which is similar to the new BSD
license).

Line Editing
------------

The following line editing commands are supported on platforms and terminals
that Liner supports:

Keystroke    | Action
---------    | ------
Ctrl-A, Home | Move cursor to beginning of line
Ctrl-E, End  | Move cursor to end of line
Ctrl-B, Left | Move cursor one character left
Ctrl-F, Right| Move cursor one character right
Ctrl-Left, Alt-B    | Move cursor to previous word
Ctrl-Right, Alt-F   | Move cursor to next word
Ctrl-D, Del  | (if line is *not* empty) Delete character under cursor
Ctrl-D       | (if line *is* empty) End of File - usually quits application
Ctrl-C       | Reset input (create new empty prompt)
Ctrl-L       | Clear screen (line is unmodified)
Ctrl-T       | Transpose previous character with current character
Ctrl-H, BackSpace | Delete character before cursor
Ctrl-W, Alt-BackSpace | Delete word leading up to cursor
Alt-D        | Delete word following cursor
Ctrl-K       | Delete from cursor to end of line
Ctrl-U       | Delete from start of line to cursor
Ctrl-P, Up   | Previous match from history
Ctrl-N, Down | Next match from history
Ctrl-R       | Reverse Search history (Ctrl-S forward, Ctrl-G cancel)
Ctrl-Y       | Paste from Yank buffer (Alt-Y to paste next yank instead)
Tab          | Next completion
Shift-Tab    | (after Tab) Previous completion

Note that "Previous" and "Next match from history" will retain the part of
the line that the user has already typed, similar to zsh's
"up-line-or-beginning-search" (which is the default on some systems) or
bash's "history-search-backward" (which is my preferred behaviour, but does
not appear to be the default `Up` keybinding on any system).

Getting started
-----------------

```go
package main

import (
	"log"
	"os"
	"path/filepath"
	"strings"

	"github.com/peterh/liner"
)

var (
	history_fn = filepath.Join(os.TempDir(), ".liner_example_history")
	names      = []string{"john", "james", "mary", "nancy"}
)

func main() {
	line := liner.NewLiner()
	defer line.Close()

	line.SetCtrlCAborts(true)

	line.SetCompleter(func(line string) (c []string) {
		for _, n := range names {
			if strings.HasPrefix(n, strings.ToLower(line)) {
				c = append(c, n)
			}
		}
		return
	})

	if f, err := os.Open(history_fn); err == nil {
		line.ReadHistory(f)
		f.Close()
	}

	if name, err := line.Prompt("What is your name? "); err == nil {
		log.Print("Got: ", name)
		line.AppendHistory(name)
	} else if err == liner.ErrPromptAborted {
		log.Print("Aborted")
	} else {
		log.Print("Error reading line: ", err)
	}

	if f, err := os.Create(history_fn); err != nil {
		log.Print("Error writing history file: ", err)
	} else {
		line.WriteHistory(f)
		f.Close()
	}
}
```

For documentation, see http://godoc.org/github.com/peterh/liner