mle.1

.Dd March 1, 2023
.Dt MLE 1
.Os
.Sh NAME
.Nm mle
.Nd flexible terminal-based text editor
.Sh SYNOPSIS
.Nm mle
.Op Fl abceHhiKklMmNnpSstuvwxyz
.Op Ar file[:line]
.Li ...
.Sh DESCRIPTION
.Nm
is a small, flexible, terminal-based text editor written in C.
It runs on Linux, Windows (Cygwin or WSL), FreeBSD, macOS, and more.
.Ss Basic usage
.Bd -literal
  $ mle             # Open blank buffer
  $ mle one.c       # Edit one.c
  $ mle one.c:100   # Edit one.c at line 100
  $ mle one.c two.c # Edit one.c and two.c
  $ mle -h          # Show command line help
.Ed
.Pp
The default key bindings are intuitive.
Input text as normal, use directional keys to move around, use
`Ctrl-S` to save, `Ctrl-O` to open, `Ctrl-X` to exit.
.Pp
Press `F2` for full help.
.Ss Options
.Bl -tag -width ".Fl foo barbaz" -offset indent
.It Fl h
Show help
.It Fl a Aq 1|0
Enable/disable tab to space (default: 1)
.It Fl b Aq 1|0
Enable/disable highlight bracket pairs (default: 1)
.It Fl c Ar column
Color column (default: -1, disabled)
.It Fl e Aq 1|0
Enable/disable mouse support (default: 0)
.It Fl H Aq 1|0
Enable/disable headless mode (default: 1 if no tty, else 0)
.It Fl i Aq 1|0
Enable/disable auto indent (default: 0)
.It Fl K Ar kdef
Make a kmap definition (use with -k).
.Pp
.Ar kdef
is formatted as
.Li `<name>,<default_cmd>,<allow_fallthru>` ,
where
.Ar name
is the name of the kmap,
.Ar default_cmd
is the default command handler (can be empty), and
.Ar allow_fallthru
is a 0 or 1 specifying whether unhandled key input should
be forwarded to the previous kmap on the stack or not.
.It Fl k Ar kbind
Add key binding to current kmap definition (use after -K).
.Pp
.Ar kbind
is formatted as
.Li `<cmd>,<key>,<param>` ,
where
.Ar cmd
is a command name,
.Ar key
is a key name, and
.Ar param
is a static parameter passed to the command (can be empty).
.It Fl l Ar ltype
Set linenum type (default: 0, absolute).
.Pp
.Ar ltype
can be 0 (absolute), 1 (relative), or 2 (both)
.It Fl M Ar macro
Add a macro.
.Pp
.Ar macro
is formatted as
.Li `<name> <key1> <key2> ... <keyN>` ,
where
.Ar name
is the name of the macro, and
.Ar keyN
are space-separated key names.
.It Fl m Ar key
Set macro toggle key (default: M-r).
.Ar key
is a key name.
.It Fl N
Skip reading of rc file
.It Fl n Ar kmap
Set init kmap (default: mle_normal).
.Ar kmap
is a kmap name.
.It Fl p Ar macro
Set startup macro.
.Ar macro
is a macro name.
.It Fl S Ar syndef
Make a syntax definition (use with -s).
.Pp
.Ar syndef
is formatted as
.Li `<name>,<path_pattern>,<tab_width>,<tab_to_space>` ,
where
.Ar name
is a syntax name,
.Ar path_pattern
is a path matching regex (PCRE),
.Ar tab_width
is the default tab width,
.Ar tab_to_space
is a 0 or 1 specifying whether to convert tabs to spaces or not.
.It Fl s Ar synrule
Add syntax rule to current syntax definition (use after -S).
.Pp
.Ar synrule
is formatted as
.Li `<start>,<end>,<fg>,<bg>` ,
where
.Ar start
and
.Ar end
are text matching regexes (PCRE), and
.Ar fg
and
.Ar bg
are attributes to apply to matching text.
.Pp
If both
.Ar start
and
.Ar end
are supplied, the rule applies to all text matched in
between the regexes, potentially spanning multiple lines.
If only
.Ar start
is specified, the rule applies to text matched by the regex
on a single line.
.Pp
Attributes for
.Ar fg
and
.Ar bg
are as follows:
.Bl -tag -width "####" -offset indent
.It 0
default
.It 1
black
.It 2
red
.It 4
yellow
.It 5
blue
.It 6
magenta
.It 7
cyan
.It 8
white
.It 256
bold
.It 512
underline
.It 1024
reverse
.It 2048
italic
.El
.It Fl t Ar size
Set tab size (default: 4)
.It Fl u Aq 1|0
Enable/disable coarse undo/redo (default: 0)
.It Fl v
Print version and exit
.It Fl w Aq 1|0
Enable/disable soft word wrap (default: 0)
.It Fl x Ar uscript
Run a Lua user script (experimental)
.It Fl y Ar syntax
Set override syntax for files opened at start up.
If '-' is specified, use the built-in generic syntax.
.Ar syntax
is any syntax name.
.It Fl z Aq 1|0
Enable/disable trimmed paste (default: 1)
.El
.Sh KEY NAMES
Key names for -k, -M, and -m are formatted as `<key>` or `<mod>-<key>`.
.Pp
.Ar key
is any character or one of the following:
space, tab, enter, backspace, comma, up, down, left, right, insert, delete,
home, end, pgup, pgdn, backtab, f1, f2, f3, f4, f5, f6, f7, f8, f9, f10, f11,
f12.
.Pp
.Ar mod
is one of
.Bl -tag -width "############" -offset indent
.It S
Shift
.It M
Alt (Meta)
.It MS
Alt-Shift
.It C
Ctrl
.It CS
Ctrl-Shift
.It CM
Ctrl-Alt
.It CMS
Ctrl-Alt-Shift
.El
.Pp
Not all key names are valid or supported by all terminals.
Run with `-Qk` to display key names for given input.
.Sh ADVANCED USAGE
Below are some advanced things you can do with mle.
.Ss rc file
To customize the editor, make an rc file named
.Pa ~/.mlerc
or
.Pa /etc/mlerc .
The contents of the rc file are any number of cli options separated
by newlines.
Lines that begin with a semi-colon are interpreted as comments.
.Pp
If the rc file is executable, mle executes it and interprets the
resulting stdout as described above.
For example, consider the following snippet from an executable
.Ar ~/.mlerc
.Xr bash 1
script:
.Bd -literal
  ...
  # Define 'test' kmap
  echo '-Ktest,,1'

  # M-q: replace grep with git grep if `.git` exists
  if [ -d ".git" ]; then
    echo '-kcmd_grep,M-q,git grep --color=never -P -i -I -n %s 2>/dev/null'
  fi

  # Set default kmap
  echo '-n test'
  ...
.Ed
.Pp
This overrides the built-in grep command with `git grep` if
.Pa .git
exists in the current working directory.
.Ss Shell command integration
The following programs will enable or enhance certain features of
mle if they exist in
.Em PATH .
.Bl -tag -width "############" -offset indent
.It Xr bash 1
file tab completion
.It Xr fzf 1
fuzzy file search
.It Xr grep 1
file grep
.It Xr less 1
less integration
.It Xr perl 1
perl 1-liners
.It Xr readtags 1
ctags integration
.It Xr tree 1
file browsing
.El
.Pp
Arbitrary shell commands can also be run via `cmd_shell`
(M-e by default). If any text is selected, it is sent to
stdin of the command.
Any resulting stdout is inserted into the text buffer.
.Ss Headless mode
mle provides support for non-interactive editing which may be useful
for using the editor as a regular command line tool.
In headless mode, mle reads stdin into a buffer, applies a startup
macro if specified, and then writes the buffer contents to stdout.
For example:
.Bd -literal
  $ echo -n hello | mle -M 'test C-e space w o r l d enter' -p test
  hello world
.Ed
.Pp
If stdin is a pipe, mle goes into headless mode automatically.
Headless mode can be explicitly enabled or disabled with the `-H`
option.
.Pp
If stdin is a pipe and headless mode is disabled via -H0, mle reads
stdin into a new buffer and then runs as normal in interactive mode.
.Ss Scripting (experimental)
mle is extensible via the Lua programming language.
Scripts are loaded via the `-x` cli option.
Commands registered by scripts can be mapped to keys as normal via `-k`.
See
.Lk https://github.com/adsr/mle
for more info.
.Sh ACKNOWLEDGEMENTS
mle makes extensive use of the following libraries.
.Bl -tag -width "############" -offset indent
.It Em uthash
for hash maps and linked lists
.It Em termbox2
for TUI
.It Em PCRE2
for syntax highlighting and search
.El