# README

Liner

This fork adds minimal support for vi editing to Liner. Projects that make use of Liner have users that may be looking for vi editing functionality. The modifications in this repository offer basic vi editing behavior.

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We implement basic, single-action, vi editing functions. At present, we do not support number keys to execute multiple operations, a repeat key, or undo actions.

Users may expect a method to visually discern between vi normal and insert modes. Though we do not support changing cursor behavior, however, we can send terminal escape codes change the appearance of text in the terminal.

Vi Keys Supported

key	function
r	replace character under cursor
i	enter insert mode
I	enter insert mode at beginning of line
a	enter insert mode one character to the right
A	enter insert mode at end of line
^ H	move cursor to the beginning of line
$ L	move cursor to the end of line
h	move cursor one character to the left
l	move cursor one character to the right
w	move cursor to the next word
W	move cursor to the next Word
e	move cursor to the end of next word
E	move cursor to the end of next Word
b	move cursor to the previous word
x	delete the character under cursor
X	delete the character before cursor
d	delete the next word
D	delete from cursor to end of line
C	change text from cursor to end of line
j	next matching history
k	previous matching history
p	paste from yank buffer
~	change character case

default keys supported

key	function
Ctrl-A, Home	move cursor to the beginning of line
Ctrl-E, End	move cursor to the end of line
Ctrl-B, Left	move cursor one character to the left
Ctrl-F, Right	move cursor one character to the right
Ctrl-Left, Alt-B	move cursor to the previous word
Ctrl-Right, Alt-F	move cursor to the next word
Ctrl-D, Del	delete character under cursor if line is not empty
Ctrl-D	end of file/exit if line is empty
Ctrl-C	abort input
Ctrl-L	clear screen
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

Vi Functions

EnableViMode(bool)      // enable or disable vi editing functionality
EnableViPrompt(bool)    // allow liner prompt to change based on current vi mode
SetViMode(vimode)       // explicitly se the vi mode (normal, insert, replace)
SetViNormalStyle(style) // style used when in vi normal mode
SetViInsertStyle(style) // style used when in vi insert mode

# Functions

NewLiner

NewLiner initializes a new *State, and sets the terminal into raw mode.

TerminalMode

TerminalMode returns the current terminal input mode as an InputModeSetter.

TerminalSupported

TerminalSupported returns true if the current terminal supports line editing features, and false if liner will use the 'dumb' fallback for input.