A small, self-contained text editor for the Unix console or standard terminal emulators.
UTF-8 encoding - PLE was initially designed to support only 8-bit character encodings (eg. pure ASCII, Latin1, ISO-8859-x). The latest release supporting 8-bit character encodings is v0.3-8bit-chars.
PLE has been modified to support UTF-8 encoding, which is nowdays the standard encoding for Unicode text files. 8-bit character encodings are no longer supported.
PLE is a self-contained text editor that does not rely on any external library (no termcap, terminfo, ncurses, no POSIX libraries).
This is not intended to compete with large established editors (emacs, vim) or even smaller ones (joe, zile). PLE is rather intended to be used for example with a statically compiled Lua in the sort of environment where busybox is usually found.
The editor is entirely written in Lua. The only external dependencies are the terminal itself which must support basic ANSI sequences and the unix command stty which is used to save/restore the terminal mode, and set the terminal in raw mode (required to read keys one at a time).
It is written and tested with Lua 5.3.
PLE has been inspired by Antirez' Kilo editor. PLE structure and code have nothing to do with Kilo, but the idea to directly use standard ANSI sequences and bypass the usual terminfo and ncurses libraries comes in part from Kilo and also from Antirez' more established linenoise library.
- UTF-8: wide characters (more than one column) and right-to-left scripts are not supported.
- no sentence- or paragraph-based movement.
- the search and replace functions do not work with special characters, new lines and regular expressions - plain text in a line, case sensitive only.
- no provision for automatic backup files.
- no automatic redimensioning of windows for X terminals (no SIGWINCH handling - but the redisplay function (^L) ) can be invoked to refresh the screen to the new size)
- no syntax coloring.
- no complex support for extension modules ("modes" a la emacs, syntax coloring, etc.)
- probably many others things that you would expect from a text editor!
On the other hand, the editor already support:
- a keybinding loosely inspired by Emacs (but much limited!)
- basic editing functions
- basic search and replace functions (plain text only)
- support for long lines (horizontal scroll, no provision for wrapping long lines)
- selection, selection highlight, cut and paste (mark, wipe and yank in emacs parlance)
- unlimited undo/redo functions
- multiple buffers (but just one window at a time for the moment)
- read, write, save files.
- a minimal help command (F1 or ^X^H - give a short description of the basic bindings)
Configuration -- the editor can be configured / customized with a
Lua file loaded at initialization. The Lua configuration file is loaded
with the Lua function loadfile. It is executed in the environment of the editor. The editor global object is visible and can be used by the configuration script.
The configuration file is looked for in sequence at the following locations:
- the file which pathname is in the environment variable
PLE_INIT ./ple_init.lua~/config/ple/ple_init.lua
The first file found, if any, is loaded.
The OUT buffer is an ephemeral buffer that can be used as a scratchpad, as a sort of extended clipboard, and also to receive the output of programs launched by the editor from the current buffer. In addition, any errors ple encounters while executing key-bindings are reported in the OUT buffer.
A sample ple_init.lua file is provided. It defines an editor command to execute the current line as a shell command and insert the result in the current buffer at the cursor.
--
At the moment, the complete editor is ~50KB. It has been tested on xterm, rxvt, vte-based terminals, and the Linux console.
As they say, it works on my PC...
Cursor movement
Arrows, PageUp, PageDown, Home, End
^A, ^E go to beginning, end of line
^B, ^F go backward, forward
^N, ^P go to next line, previous line
^K, ^J go to next word, previous word
^U, ^V page up, page down
^X< go to beginning of buffer
^X> go to end of buffer
^S forward search (plain text, case sensitive)
^R search again (string previously entered with ^S)
^X^G prompt for a line number, go there
Edition
^D, Delete delete character at cursor
^H, bcksp delete previous character
^space, ^@ mark (set beginning of selection)
^W wipe (cut selection or cut line if no selection)
^Y yank (paste)
^X5 replace
^X7 replace again (with same strings)
Files, buffers
^X^F prompt for a filename, read the file in a new buffer
^X^W prompt for a filename, write the current buffer
^X^S save the current buffer
^X^B switch to a named buffer or create a new buffer
^X^N switch to the next buffer
^X^P switch to the previous buffer
^X^I display a list of buffers
Misc.
^X^C exit the editor
^G abort the current command
^Z undo
^X^Z redo
^O toggle between the current buffer and *OUT*
^L redisplay the screen (useful if the screen was
garbled or its dimensions changed)
F1, ^X^H this help text
lua ple.lua [filename]
The editor can be built as one standalone Lua file combining all the modules used by ple.lua. Just run the Lua script make_ple.lua in the same directory as the project files: ple.lua, buffer.lua and plterm.lua:
lua make_ple.lua
It produces a Lua script ple that can be run from the command line:
$ ./ple [filename]
The term module includes all the basic functionnalities to display strings in various colors, move the cursor, erase lines and read keys.
It is included here. To make it available for other applications, it is also distributed as a separate module. See the plterm repository.
It does not use ncurses, terminfo or termcap. It uses only very common ANSI sequences that are supported by (at least) the Linux console, xterm, rxvt and vte-based terminal emulators.
The input function reads and parses UTF-8 character sequences and the escape sequences sent by function keys (arrows, F1-F12, insert, delete, etc.). See the definitions in term.keys.
Term functions: - see plterm
clear() -- clear screen
cleareol() -- clear to end of line
golc(l, c) -- move the cursor to line l, column c
up(n)
down(n)
right(n)
left(n) -- move the cursor by n positions (default to 1)
color(f, b, m)
-- change the color used to write characters
(foreground color, background color, modifier)
see term.colors
hide()
show() -- hide or show the cursor
save()
restore() -- save and restore the position of the cursor
reset() -- reset the terminal (colors, cursor position)
input() -- input iterator (coroutine-based)
return a "next key" function that can be iteratively called
to read a key (escape sequences returned by function keys
are parsed)
rawinput() -- same, but escape sequences are not parsed.
getcurpos() -- return the current position of the cursor
getscrlc() -- return the dimensions of the screen
(number of lines and columns)
keyname() -- return a printable name for any key
- key names in term.keys for function keys,
- control characters are represented as "^A"
- the character itself for other keys
tty mode management functions
setrawmode() -- set the terminal in raw mode
setsanemode() -- set the terminal in a default "sane mode"
savemode() -- get the current mode as a string
restoremode(mode) -- restore a mode saved by savemode()
This code is published under a MIT license. Feel free to fork!