NEATVI
======

Neatvi is a vi/ex editor.  It can edit bidirectional UTF-8 text.

CONFIGURATION
-------------

Edit conf.h to adjust syntax highlighting rules and text direction
patterns.  To define a new keymap, create a new array in kmap.h, like
kmap_fa, and add it to kmaps array in the same header (the first entry
of the new array specifies its name).  The current keymap may be
changed with :cm ex command.  When in input mode, ^e activates the
English keymap and ^f switches to the alternate keymap (the last
keymap specified with :cm).

Sadly, VTE-based terminals such as GNOME's implement a
backward-incompatible extension of virtual terminal escape codes to
render bidirectional text by default.  When using these terminal, the
value of LNPREF macro in conf.h needs to be edited.

COMMANDS
--------

Commands not available in ex(1):

:cm[ap][!] [kmap]
  Without kmap, prints the current keymap name.
  When kmap is specified, sets the alternate keymap to
  kmap and, unless ! is given, switches to this keymap.
:ft [filetype]
  Without filetype, prints the current file type.
  When filetype is specified, sets the file type of the
  current ex buffer.
:ta[g] tag
  Jumps to tag (tags file: TAGPATH environment variable or ./tags).
:tn[ext]
  Jumps to the next matching tag.
:tp[rev]
  Jumps to the previous matching tag.
:po[p]
  Pops tag stack.
:b[uffer] [buf]
  Without buf, prints buffer list.  Switches to the given buffer
  if buf is a buffer number or alias.  Also, buf can be -, +, !,
  and ~ to switch to the previous buffer, switch to the next buffer,
  delete the current buffer, and renumber buffers, respectively.
:ye reg
  Reads dot-terminated lines (similar to :a command) from ex input
  and copies them to the given register.

New key mappings:
- ^a in normal mode: searches for the word under the cursor.
- ^p in insert mode: inserts the contents of the default yank buffer.
- ^rX in insert mode: inserts the contents of yank buffer X.
- zL, zl, zr, and zR in normal mode: change the value of td option.
- ^e and ^f in insert mode: switches to the English and alternate keymap.
- ze and zf in normal mode: switches to the English and alternate keymap.
- gu, gU, and g~ in normal mode: switches character case.
- ^l in normal mode: updates terminal dimensions (after resizing it).
- ^] and ^t in normal mode: jumps to tag and pops tag stack.
- gf in normal mode: edits the file whose address is under the cursor.
- gl in normal mode: like gf, but it reads line and column numbers too.
- ^ws, ^wo, ^wc, ^wj, ^wk, ^wx in normal mode: manages windows.
- ^wgf, ^wgl, ^w^] in normal mode: executes gf, gl, ^] in a new window.
- zj, zk, zD: equivalent to :b+, :b-, :b !.
- zJ, zK: equivalent to :next, :prev.
- qX in normal mode: see q-commands section (X can be any letter).
- ^a in ex, search, and pipe prompts: inserts from history lines.

Other noteworthy differences with vi(1):
- Neatvi assumes POSIX extended regular expressions (ERE) in search
  patterns, conf.h variables, and even tags files.
- If paths start with =, they are assumed to be relative to the
  directory of the current file.
- Neatvi highlights files whose names ends with ls as directory
  listings; the gl command can be used to edit its files.

Note that in :ye command, input lines are read from ex input stream
(unlike :a), to make it usable in @ commands and ex scripts (files
passed to :so).  This allows setting the value of registers in ex
files, as the following example shows:

  ye a
  :!git add %
  .

OPTIONS
-------

To improve Neatvi's performance, shaping, character reordering, and
syntax highlighting can be disabled by defining the EXINIT environment
variable as "set noshape | set noorder | set nohl | set td=+2".

Options supported in Neatvi:

td, textdirection
  Current direction context.  The following values are meaningful:
  * +2: always left-to-right.
  * +1: follow conf.h's dircontexts[]; left-to-right for others.
  * -1: follow conf.h's dircontexts[]; right-to-left for others.
  * -2: always right-to-left.
shape
  If set (default), Arabic/Farsi letter shaping will be performed.
order
  If set, characters will be reordered based on the rules defined
  in conf.h.
hl, highlight
  If set (default), text will be highlighted based on syntax
  highlighting rules in conf.h.
hll, highlightline
  If set, the current line will be highlighted.
lim, linelimit
  Lines longer than this value are not reordered or highlighted.
ru, ruler
  Indicates when to redraw the status line:
  * 0: never.
  * 1: always.
  * 2: when multiple windows are visible.
  * 4: when the current file changes.
hist, history
  Indicates the number of lines remembered for ex, search, and
  pipe prompts.  Zero disables command history.
ai, autoindent
  As in vi(1).
aw, autowrite
  As in vi(1).
ic, ignorecase
  As in vi(1).
wa, writeany
  As in vi(1).

MARKS AND BUFFERS
-----------------

Special marks:
- * the position of the previous change
- [ the first line of the previous change
- ] the last line of the previous change

Special yank buffers:
- / the previous search keyword
- : the previous ex command
- ! the previous pipe command
- % the name of the current file
- " the default yank buffer
- ; the current line
- . the last vi command

Q-COMMANDS
----------

For qX command in normal mode, Neatvi executes ECMD (defined in conf.h)
with the following parameters:
- X (the key following q)
- current file
- current line number
- current line offset

ECMD must print a line of ex commands and Neatvi executes this line.
Q-commands can be used to add interesting features to Neatvi, such as
language-dependent IDE features, for instance by connecting to an LSP
(language server protocol) server.  As an example, the following
script shows how to use gopls to implement goto definition and find
references for Go.

  # Compile.
  if test "$1" = "c"; then
    go build >.make.ls 2>&1
    echo ":e +1 .make.ls | :e"
  fi
  # Goto definition; uses gopls (not very efficient without using LSP).
  if test "$1" = "d"; then
    loc=`gopls definition $2:$3:$4`
    if test -n "$loc"; then
      echo $loc | sed -E 's/^([^:]+):([^:]+):([^:]+).*$/:e +\2 \1/'
    fi
  fi
  # Find references.  Use gl command on each line.
  if test "$1" = "f"; then
    gopls references $2:$3:$4 >$OUT/.out.ls
    echo ":e +1 $OUT/.out.ls | :e"
  fi