neovim/runtime/doc/lua.txt

*lua.txt*    Nvim


			    NVIM REFERENCE MANUAL


Lua engine						*lua* *Lua*

                                      Type |gO| to see the table of contents.

==============================================================================
Introduction						*lua-intro*

The Lua 5.1 language is builtin and always available.  Try this command to get
an idea of what lurks beneath: >

    :lua print(vim.inspect(package.loaded))

Nvim includes a "standard library" |lua-stdlib| for Lua.  It complements the
"editor stdlib" (|functions| and Ex commands) and the |API|, all of which can
be used from Lua code.

Module conflicts are resolved by "last wins".  For example if both of these
are on 'runtimepath':
    runtime/lua/foo.lua
    ~/.config/nvim/lua/foo.lua
then `require('foo')` loads "~/.config/nvim/lua/foo.lua", and
"runtime/lua/foo.lua" is not used.  See |lua-require| to understand how Nvim
finds and loads Lua modules.  The conventions are similar to VimL plugins,
with some extra features.  See |lua-require-example| for a walkthrough.

==============================================================================
Importing Lua modules					*lua-require*

                                                        *lua-package-path*
Nvim automatically adjusts `package.path` and `package.cpath` according to
effective 'runtimepath' value.  Adjustment happens whenever 'runtimepath' is
changed.  `package.path` is adjusted by simply appending `/lua/?.lua` and
`/lua/?/init.lua` to each directory from 'runtimepath' (`/` is actually the
first character of `package.config`).

Similarly to `package.path`, modified directories from 'runtimepath' are also
added to `package.cpath`.  In this case, instead of appending `/lua/?.lua` and
`/lua/?/init.lua` to each runtimepath, all unique `?`-containing suffixes of
the existing `package.cpath` are used.  Example:

1. Given that
   - 'runtimepath' contains `/foo/bar,/xxx;yyy/baz,/abc`;
   - initial (defined at compile-time or derived from 
     `$LUA_CPATH`/`$LUA_INIT`) `package.cpath` contains 
     `./?.so;/def/ghi/a?d/j/g.elf;/def/?.so`.
2. It finds `?`-containing suffixes `/?.so`, `/a?d/j/g.elf` and `/?.so`, in 
   order: parts of the path starting from the first path component containing 
   question mark and preceding path separator.
3. The suffix of `/def/?.so`, namely `/?.so` is not unique, as it’s the same 
   as the suffix of the first path from `package.path` (i.e. `./?.so`).  Which 
   leaves `/?.so` and `/a?d/j/g.elf`, in this order.
4. 'runtimepath' has three paths: `/foo/bar`, `/xxx;yyy/baz` and `/abc`.  The 
   second one contains semicolon which is a paths separator so it is out, 
   leaving only `/foo/bar` and `/abc`, in order.
5. The cartesian product of paths from 4. and suffixes from 3. is taken, 
   giving four variants. In each variant `/lua` path segment is inserted 
   between path and suffix, leaving

   - `/foo/bar/lua/?.so`
   - `/foo/bar/lua/a?d/j/g.elf`
   - `/abc/lua/?.so`
   - `/abc/lua/a?d/j/g.elf`

6. New paths are prepended to the original `package.cpath`.

The result will look like this:

    `/foo/bar,/xxx;yyy/baz,/abc` ('runtimepath')
    × `./?.so;/def/ghi/a?d/j/g.elf;/def/?.so` (`package.cpath`)

    = `/foo/bar/lua/?.so;/foo/bar/lua/a?d/j/g.elf;/abc/lua/?.so;/abc/lua/a?d/j/g.elf;./?.so;/def/ghi/a?d/j/g.elf;/def/?.so`

Note:

- To track 'runtimepath' updates, paths added at previous update are
  remembered and removed at the next update, while all paths derived from the
  new 'runtimepath' are prepended as described above.  This allows removing
  paths when path is removed from 'runtimepath', adding paths when they are
  added and reordering `package.path`/`package.cpath` content if 'runtimepath'
  was reordered.

- Although adjustments happen automatically, Nvim does not track current
  values of `package.path` or `package.cpath`.  If you happen to delete some
  paths from there you can set 'runtimepath' to trigger an update: >
      let &runtimepath = &runtimepath

- Skipping paths from 'runtimepath' which contain semicolons applies both to
  `package.path` and `package.cpath`.  Given that there are some badly written
  plugins using shell which will not work with paths containing semicolons it
  is better to not have them in 'runtimepath' at all.

------------------------------------------------------------------------------
LUA PLUGIN EXAMPLE					*lua-require-example*

The following example plugin adds a command `:MakeCharBlob` which transforms 
current buffer into a long `unsigned char` array.  Lua contains transformation 
function in a module `lua/charblob.lua` which is imported in 
`autoload/charblob.vim` (`require("charblob")`).  Example plugin is supposed 
to be put into any directory from 'runtimepath', e.g. `~/.config/nvim` (in 
this case `lua/charblob.lua` means `~/.config/nvim/lua/charblob.lua`).

autoload/charblob.vim: >

    function charblob#encode_buffer()
      call setline(1, luaeval(
      \    'require("charblob").encode(unpack(_A))',
      \    [getline(1, '$'), &textwidth, '  ']))
    endfunction

plugin/charblob.vim: >

    if exists('g:charblob_loaded')
      finish
    endif
    let g:charblob_loaded = 1

    command MakeCharBlob :call charblob#encode_buffer()

lua/charblob.lua: >

    local function charblob_bytes_iter(lines)
      local init_s = {
        next_line_idx = 1,
        next_byte_idx = 1,
        lines = lines,
      }
      local function next(s, _)
        if lines[s.next_line_idx] == nil then
          return nil
        end
        if s.next_byte_idx > #(lines[s.next_line_idx]) then
          s.next_line_idx = s.next_line_idx + 1
          s.next_byte_idx = 1
          return ('\n'):byte()
        end
        local ret = lines[s.next_line_idx]:byte(s.next_byte_idx)
        if ret == ('\n'):byte() then
          ret = 0  -- See :h NL-used-for-NUL.
        end
        s.next_byte_idx = s.next_byte_idx + 1
        return ret
      end
      return next, init_s, nil
    end

    local function charblob_encode(lines, textwidth, indent)
      local ret = {
        'const unsigned char blob[] = {',
        indent,
      }
      for byte in charblob_bytes_iter(lines) do
        --                .- space + number (width 3) + comma
        if #(ret[#ret]) + 5 > textwidth then
          ret[#ret + 1] = indent
        else
          ret[#ret] = ret[#ret] .. ' '
        end
        ret[#ret] = ret[#ret] .. (('%3u,'):format(byte))
      end
      ret[#ret + 1] = '};'
      return ret
    end

    return {
      bytes_iter = charblob_bytes_iter,
      encode = charblob_encode,
    }

==============================================================================
Commands						*lua-commands*

These commands execute a Lua chunk from either the command line (:lua, :luado)
or a file (:luafile) on the given line [range]. As always in Lua, each chunk
has its own scope (closure), so only global variables are shared between
command calls. The |lua-stdlib| modules, user modules, and anything else on
|lua-package-path| are available.

The Lua print() function redirects its output to the Nvim message area, with
arguments separated by " " (space) instead of "\t" (tab).

                                                        *:lua*
:[range]lua {chunk}
                        Executes Lua chunk {chunk}.

                        Examples: >
                            :lua vim.api.nvim_command('echo "Hello, Nvim!"')
<                        To see the Lua version: >
                            :lua print(_VERSION)
<                        To see the LuaJIT version: >
                            :lua print(jit.version)
<
                                                        *:lua-heredoc*
:[range]lua << [endmarker]
{script}
{endmarker}
                        Executes Lua script {script} from within Vimscript.
                        {endmarker} must NOT be preceded by whitespace. You
                        can omit [endmarker] after the "<<" and use a dot "."
                        after {script} (similar to |:append|, |:insert|).

                        Example:
                        >
                            function! CurrentLineInfo()
                            lua << EOF
                            local linenr = vim.api.nvim_win_get_cursor(0)[1]
                            local curline = vim.api.nvim_buf_get_lines(
                                    0, linenr, linenr + 1, false)[1]
                            print(string.format("Current line [%d] has %d bytes",
                                    linenr, #curline))
                            EOF
                            endfunction

<                        Note that the `local` variables will disappear when
                        the block finishes. But not globals.

                                                        *:luado*
:[range]luado {body}    Executes Lua chunk "function(line, linenr) {body} end"
                        for each buffer line in [range], where `line` is the
                        current line text (without <EOL>), and `linenr` is the
                        current line number. If the function returns a string
                        that becomes the text of the corresponding buffer
                        line. Default [range] is the whole file: "1,$".

                        Examples:
                        >
                            :luado return string.format("%s\t%d", line:reverse(), #line)

                            :lua require"lpeg"
                            :lua -- balanced parenthesis grammar:
                            :lua bp = lpeg.P{ "(" * ((1 - lpeg.S"()") + lpeg.V(1))^0 * ")" }
                            :luado if bp:match(line) then return "-->\t" .. line end
<

							*:luafile*
:[range]luafile {file}
			Execute Lua script in {file}.
			The whole argument is used as a single file name.

                        Examples:
                        >
                            :luafile script.lua
                            :luafile %
<

==============================================================================
luaeval()						*lua-eval* *luaeval()*

The (dual) equivalent of "vim.eval" for passing Lua values to Nvim is
"luaeval". "luaeval" takes an expression string and an optional argument used 
for _A inside expression and returns the result of the expression. It is 
semantically equivalent in Lua to:
>
    local chunkheader = "local _A = select(1, ...) return "
    function luaeval (expstr, arg)
        local chunk = assert(loadstring(chunkheader .. expstr, "luaeval"))
        return chunk(arg) -- return typval
    end

Lua nils, numbers, strings, tables and booleans are converted to their
respective VimL types. An error is thrown if conversion of any other Lua types
is attempted.

The magic global "_A" contains the second argument to luaeval().

Example: >
    :echo luaeval('_A[1] + _A[2]', [40, 2])
    42
    :echo luaeval('string.match(_A, "[a-z]+")', 'XYXfoo123')
    foo

Lua tables are used as both dictionaries and lists, so it is impossible to
determine whether empty table is meant to be empty list or empty dictionary.
Additionally Lua does not have integer numbers. To distinguish between these
cases there is the following agreement:

0. Empty table is empty list.
1. Table with N incrementally growing integral numbers, starting from 1 and 
   ending with N is considered to be a list.
2. Table with string keys, none of which contains NUL byte, is considered to 
   be a dictionary.
3. Table with string keys, at least one of which contains NUL byte, is also 
   considered to be a dictionary, but this time it is converted to 
   a |msgpack-special-map|.
							*lua-special-tbl*
4. Table with `vim.type_idx` key may be a dictionary, a list or floating-point 
   value:
   - `{[vim.type_idx]=vim.types.float, [vim.val_idx]=1}` is converted to 
     a floating-point 1.0. Note that by default integral Lua numbers are 
     converted to |Number|s, non-integral are converted to |Float|s. This 
     variant allows integral |Float|s.
   - `{[vim.type_idx]=vim.types.dictionary}` is converted to an empty 
     dictionary, `{[vim.type_idx]=vim.types.dictionary, [42]=1, a=2}` is 
     converted to a dictionary `{'a': 42}`: non-string keys are ignored. 
     Without `vim.type_idx` key tables with keys not fitting in 1., 2. or 3. 
     are errors.
   - `{[vim.type_idx]=vim.types.list}` is converted to an empty list. As well 
     as `{[vim.type_idx]=vim.types.list, [42]=1}`: integral keys that do not 
     form a 1-step sequence from 1 to N are ignored, as well as all 
     non-integral keys.

Examples: >

    :echo luaeval('math.pi')
    :function Rand(x,y) " random uniform between x and y
    :  return luaeval('(_A.y-_A.x)*math.random()+_A.x', {'x':a:x,'y':a:y})
    :  endfunction
    :echo Rand(1,10)

Note: second argument to `luaeval` undergoes VimL to Lua conversion
("marshalled"), so changes to Lua containers do not affect values in VimL.
Return value is also always converted. When converting,
|msgpack-special-dict|s are treated specially.

==============================================================================
Vimscript v:lua interface				*v:lua-call*

From Vimscript the special `v:lua` prefix can be used to call Lua functions
which are global or accessible from global tables. The expression >
    v:lua.func(arg1, arg2)
is equivalent to the Lua chunk >
    return func(...)
where the args are converted to Lua values. The expression >
    v:lua.somemod.func(args)
is equivalent to the Lua chunk >
    return somemod.func(...)

You can use `v:lua` in "func" options like 'tagfunc', 'omnifunc', etc.
For example consider the following Lua omnifunc handler: >

    function mymod.omnifunc(findstart, base)
      if findstart == 1 then
        return 0
      else
        return {'stuff', 'steam', 'strange things'}
      end
    end
    vim.api.nvim_buf_set_option(0, 'omnifunc', 'v:lua.mymod.omnifunc')

Note: the module ("mymod" in the above example) must be a Lua global.

Note: `v:lua` without a call is not allowed in a Vimscript expression:
|Funcref|s cannot represent Lua functions. The following are errors: >

    let g:Myvar = v:lua.myfunc        " Error
    call SomeFunc(v:lua.mycallback)   " Error
    let g:foo = v:lua                 " Error
    let g:foo = v:['lua']             " Error


==============================================================================
Lua standard modules					*lua-stdlib*

The Nvim Lua "standard library" (stdlib) is the `vim` module, which exposes
various functions and sub-modules.  It is always loaded, thus require("vim")
is unnecessary.

You can peek at the module properties: >

    :lua print(vim.inspect(vim))

Result is something like this: >

    {
      _os_proc_children = <function 1>,
      _os_proc_info = <function 2>,
      ...
      api = {
        nvim__id = <function 5>,
        nvim__id_array = <function 6>,
        ...
      },
      deepcopy = <function 106>,
      gsplit = <function 107>,
      ...
    }

To find documentation on e.g. the "deepcopy" function: >

    :help vim.deepcopy()

Note that underscore-prefixed functions (e.g. "_os_proc_children") are
internal/private and must not be used by plugins.

------------------------------------------------------------------------------
VIM.LOOP						*lua-loop* *vim.loop*

`vim.loop` exposes all features of the Nvim event-loop.  This is a low-level
API that provides functionality for networking, filesystem, and process
management.  Try this command to see available functions: >

    :lua print(vim.inspect(vim.loop))

Reference: http://docs.libuv.org
Examples:  https://github.com/luvit/luv/tree/master/examples

						*E5560* *lua-loop-callbacks*
It is an error to directly invoke `vim.api` functions (except |api-fast|) in
`vim.loop` callbacks.  For example, this is an error: >

    local timer = vim.loop.new_timer()
    timer:start(1000, 0, function()
      vim.api.nvim_command('echomsg "test"')
    end)

To avoid the error use |vim.schedule_wrap()| to defer the callback: >

    local timer = vim.loop.new_timer()
    timer:start(1000, 0, vim.schedule_wrap(function()
      vim.api.nvim_command('echomsg "test"')
    end))

(For one-shot timers, see |vim.defer_fn()|, which automatically adds the wrapping.)

Example: repeating timer
    1. Save this code to a file.
    2. Execute it with ":luafile %". >

    -- Create a timer handle (implementation detail: uv_timer_t).
    local timer = vim.loop.new_timer()
    local i = 0
    -- Waits 1000ms, then repeats every 750ms until timer:close().
    timer:start(1000, 750, function()
      print('timer invoked! i='..tostring(i))
      if i > 4 then
        timer:close()  -- Always close handles to avoid leaks.
      end
      i = i + 1
    end)
    print('sleeping');


Example: File-change detection				*watch-file*
    1. Save this code to a file.
    2. Execute it with ":luafile %".
    3. Use ":Watch %" to watch any file.
    4. Try editing the file from another text editor.
    5. Observe that the file reloads in Nvim (because on_change() calls
       |:checktime|). >

    local w = vim.loop.new_fs_event()
    local function on_change(err, fname, status)
      -- Do work...
      vim.api.nvim_command('checktime')
      -- Debounce: stop/start.
      w:stop()
      watch_file(fname)
    end
    function watch_file(fname)
      local fullpath = vim.api.nvim_call_function(
        'fnamemodify', {fname, ':p'})
      w:start(fullpath, {}, vim.schedule_wrap(function(...)
        on_change(...) end))
    end
    vim.api.nvim_command(
      "command! -nargs=1 Watch call luaeval('watch_file(_A)', expand('<args>'))")


Example: TCP echo-server				*tcp-server*
    1. Save this code to a file.
    2. Execute it with ":luafile %".
    3. Note the port number.
    4. Connect from any TCP client (e.g. "nc 0.0.0.0 36795"): >

    local function create_server(host, port, on_connect)
      local server = vim.loop.new_tcp()
      server:bind(host, port)
      server:listen(128, function(err)
        assert(not err, err)  -- Check for errors.
        local sock = vim.loop.new_tcp()
        server:accept(sock)  -- Accept client connection.
        on_connect(sock)  -- Start reading messages.
      end)
      return server
    end
    local server = create_server('0.0.0.0', 0, function(sock)
      sock:read_start(function(err, chunk)
        assert(not err, err)  -- Check for errors.
        if chunk then
          sock:write(chunk)  -- Echo received messages to the channel.
        else  -- EOF (stream closed).
          sock:close()  -- Always close handles to avoid leaks.
        end
      end)
    end)
    print('TCP echo-server listening on port: '..server:getsockname().port)

------------------------------------------------------------------------------
VIM.TREESITTER						*lua-treesitter*

Nvim integrates the tree-sitter library for incremental parsing of buffers.

Currently Nvim does not provide the tree-sitter parsers, instead these must
be built separately, for instance using the tree-sitter utility. The only
exception is a C parser being included in official builds for testing
purposes. Parsers are searched for as `parser/{lang}.*` in any 'runtimepath'
directory. A parser can also be loaded manually using a full path: >

    vim.treesitter.require_language("python", "/path/to/python.so")

<Create a parser for a buffer and a given language (if another plugin uses the
same buffer/language combination, it will be safely reused). Use >

    parser = vim.treesitter.get_parser(bufnr, lang)

<`bufnr=0` can be used for current buffer. `lang` will default to 'filetype'  (this
doesn't work yet for some filetypes like "cpp") Currently, the parser will be
retained for the lifetime of a buffer but this is subject to change. A plugin
should keep a reference to the parser object as long as it wants incremental
updates.

Parser methods						*lua-treesitter-parser*

tsparser:parse()					*tsparser:parse()*
Whenever you need to access the current syntax tree, parse the buffer: >

    tstree = parser:parse()

<This will return an immutable tree that represents the current state of the
buffer. When the plugin wants to access the state after a (possible) edit
it should call `parse()` again. If the buffer wasn't edited, the same tree will
be returned again without extra work. If the buffer was parsed before,
incremental parsing will be done of the changed parts.

NB: to use the parser directly inside a |nvim_buf_attach| Lua callback, you must
call `get_parser()` before you register your callback. But preferably parsing
shouldn't be done directly in the change callback anyway as they will be very
frequent. Rather a plugin that does any kind of analysis on a tree should use
a timer to throttle too frequent updates.

tsparser:set_included_ranges(ranges)			*tsparser:set_included_ranges()*
	Changes the ranges the parser should consider. This is used for
	language injection.  `ranges` should be of the form (all zero-based): >
	{
		{start_node, end_node},
		...
	}
<
	NOTE: `start_node` and `end_node` are both inclusive.

Tree methods						*lua-treesitter-tree*

tstree:root()						*tstree:root()*
	Return the root node of this tree.


Node methods						*lua-treesitter-node*

tsnode:parent()						*tsnode:parent()*
	Get the node's immediate parent.

tsnode:child_count()					*tsnode:child_count()*
	Get the node's number of children.

tsnode:child(N)						*tsnode:child()*
	Get the node's child at the given index, where zero represents the
	first child.

tsnode:named_child_count()			*tsnode:named_child_count()*
	Get the node's number of named children.

tsnode:named_child(N)					*tsnode:named_child()*
	Get the node's named child at the given index, where zero represents
	the first named child.

tsnode:start()						*tsnode:start()*
	Get the node's start position. Return three values: the row, column
	and total byte count (all zero-based).

tsnode:end_()						*tsnode:end_()*
	Get the node's end position. Return three values: the row, column
	and total byte count (all zero-based).

tsnode:range()						*tsnode:range()*
	Get the range of the node. Return four values: the row, column
	of the start position, then the row, column of the end position.

tsnode:type()						*tsnode:type()*
	Get the node's type as a string.

tsnode:symbol()						*tsnode:symbol()*
	Get the node's type as a numerical id.

tsnode:named()						*tsnode:named()*
	Check if the node is named. Named nodes correspond to named rules in
	the  grammar, whereas anonymous nodes correspond to string literals
	in the grammar.

tsnode:missing()					*tsnode:missing()*
	Check if the node is missing. Missing nodes are inserted by the
	parser in order to recover from certain kinds of syntax errors.

tsnode:has_error()					*tsnode:has_error()*
	Check if the node is a syntax error or contains any syntax errors.

tsnode:sexpr()						*tsnode:sexpr()*
	Get an S-expression representing the node as a string.

tsnode:descendant_for_range(start_row, start_col, end_row, end_col)
						*tsnode:descendant_for_range()*
	Get the smallest node within this node that spans the given range of
	(row, column) positions

tsnode:named_descendant_for_range(start_row, start_col, end_row, end_col)
					*tsnode:named_descendant_for_range()*
	Get the smallest named node within this node that spans the given
	range of (row, column) positions

Query methods						*lua-treesitter-query*

Tree-sitter queries are supported, with some limitations. Currently, the only
supported match predicate is `eq?` (both comparing a capture against a string
and two captures against each other).

vim.treesitter.parse_query(lang, query)
						*vim.treesitter.parse_query(()*
	Parse the query as a string. (If the query is in a file, the caller
        should read the contents into a string before calling).

query:iter_captures(node, bufnr, start_row, end_row)
							*query:iter_captures()*
	Iterate over all captures from all matches inside a `node`.
	`bufnr` is needed if the query contains predicates, then the caller
	must ensure to use a freshly parsed tree consistent with the current
	text of the buffer. `start_row` and `end_row` can be used to limit
	matches inside a row range (this is typically used with root node
	as the node, i e to get syntax highlight matches in the current
	viewport)

	The iterator returns two values, a numeric id identifying the capture
	and the captured node. The following example shows how to get captures
	by name:
>
	for id, node in query:iter_captures(tree:root(), bufnr, first, last) do
	  local name = query.captures[id] -- name of the capture in the query
	  -- typically useful info about the node:
	  local type = node:type() -- type of the captured node
	  local row1, col1, row2, col2 = node:range() -- range of the capture
	  ... use the info here ...
	end
<
query:iter_matches(node, bufnr, start_row, end_row)
							*query:iter_matches()*
	Iterate over all matches within a node. The arguments are the same as
	for |query:iter_captures()| but the iterated values are different:
	an (1-based) index of the pattern in the query, and a table mapping
	capture indices to nodes. If the query has more than one pattern
	the capture table might be sparse, and e.g. `pairs` should be used and not
	`ipairs`. Here an example iterating over all captures in
	every match:
>
	for pattern, match in cquery:iter_matches(tree:root(), bufnr, first, last) do
	  for id,node in pairs(match) do
	    local name = query.captures[id]
	    -- `node` was captured by the `name` capture in the match
	    ... use the info here ...
	  end
	end
>
Treesitter syntax highlighting (WIP)		    *lua-treesitter-highlight*

NOTE: This is a partially implemented feature, and not usable as a default
solution yet. What is documented here is a temporary interface indented
for those who want to experiment with this feature and contribute to
its development.

Highlights are defined in the same query format as in the tree-sitter highlight
crate, which some limitations and additions. Set a highlight query for a
buffer with this code: >

    local query = [[
      "for" @keyword
      "if" @keyword
      "return" @keyword

      (string_literal) @string
      (number_literal) @number
      (comment) @comment

      (preproc_function_def name: (identifier) @function)

      ; ... more definitions
    ]]

    highlighter = vim.treesitter.TSHighlighter.new(query, bufnr, lang)
    -- alternatively, to use the current buffer and its filetype:
    -- highlighter = vim.treesitter.TSHighlighter.new(query)

    -- Don't recreate the highlighter for the same buffer, instead
    -- modify the query like this:
    local query2 = [[ ... ]]
    highlighter:set_query(query2)

As mentioned above the supported predicate is currently only `eq?`. `match?`
predicates behave like matching always fails. As an addition a capture which
begin with an upper-case letter like `@WarningMsg` will map directly to this
highlight group, if defined. Also if the predicate begins with upper-case and
contains a dot only the part before the first will be interpreted as the
highlight group. As an example, this warns of a binary expression with two
identical identifiers, highlighting both as |hl-WarningMsg|: >

    ((binary_expression left: (identifier) @WarningMsg.left right: (identifier) @WarningMsg.right)
     (eq? @WarningMsg.left @WarningMsg.right))

------------------------------------------------------------------------------
VIM.HIGHLIGHT                  				*lua-highlight*

Nvim includes a function for highlighting a selection on yank (see for example
https://github.com/machakann/vim-highlightedyank). To enable it, add
>
 au TextYankPost * silent! lua vim.highlight.on_yank()
<
to your `init.vim`. You can customize the highlight group and the duration of
the highlight via
>
 au TextYankPost * silent! lua vim.highlight.on_yank {higroup="IncSearch", timeout=150}
<
If you want to exclude visual selections from highlighting on yank, use
>
 au TextYankPost * silent! lua vim.highlight.on_yank {on_visual=false}
<

vim.highlight.on_yank({opts})                         *vim.highlight.on_yank()*
        Highlights the yanked text. The fields of the optional dict {opts}
        control the highlight:
          - {higroup} highlight group for yanked region (default `"IncSearch"`)
          - {timeout} time in ms before highlight is cleared (default `150`)
          - {on_macro} highlight when executing macro (default `false`)
          - {on_visual} highlight when yanking visual selection (default `true`)
          - {event} event structure (default `vim.v.event`)

vim.highlight.range({bufnr}, {ns}, {higroup}, {start}, {finish}, {rtype}, {inclusive})
                                                       *vim.highlight.range()*
        Highlights the range between {start} and {finish} (tuples of {line,col})
        in buffer {bufnr} with the highlight group {higroup} using the namespace
        {ns}. Optional arguments are the type of range (characterwise, linewise,
        or blockwise, see |setreg|; default to characterwise) and whether the
        range is inclusive (default false).

------------------------------------------------------------------------------
VIM.REGEX							*lua-regex*

Vim regexes can be used directly from lua. Currently they only allow
matching within a single line.

vim.regex({re})						*vim.regex()*

        Parse the regex {re} and return a regex object. 'magic' and
        'ignorecase' options are ignored, lua regexes always defaults to magic
        and ignoring case.  The behavior can be changed with flags in
        the beginning of the string |/magic|.

Regex objects support the following methods:

regex:match_str({str})					*regex:match_str()*
        Match the string against the regex. If the string should match the
        regex precisely, surround the regex with `^` and `$`.
        If the was a match, the byte indices for the beginning and end of
        the match is returned. When there is no match, `nil` is returned.
        As any integer is truth-y, `regex:match()` can be directly used
        as a condition in an if-statement.

regex:match_line({bufnr}, {line_idx}[, {start}, {end}])	*regex:match_line()*
        Match line {line_idx} (zero-based) in buffer {bufnr}. If {start} and
        {end} are supplied, match only this byte index range. Otherwise see
        |regex:match_str()|. If {start} is used, then the returned byte
        indices will be relative {start}.

------------------------------------------------------------------------------
VIM							*lua-builtin*

vim.api.{func}({...})					*vim.api*
        Invokes Nvim |API| function {func} with arguments {...}.
        Example: call the "nvim_get_current_line()" API function: >
            print(tostring(vim.api.nvim_get_current_line()))

vim.call({func}, {...})					*vim.call()*
        Invokes |vim-function| or |user-function| {func} with arguments {...}.
        See also |vim.fn|. Equivalent to: >
            vim.fn[func]({...})

vim.in_fast_event()					*vim.in_fast_event()*
        Returns true if the code is executing as part of a "fast" event
        handler, where most of the API is disabled. These are low-level events
        (e.g. |lua-loop-callbacks|) which can be invoked whenever Nvim polls
        for input.  When this is `false` most API functions are callable (but
        may be subject to other restrictions such as |textlock|).

vim.NIL								    *vim.NIL*
	Special value used to represent NIL in msgpack-rpc and |v:null| in
	vimL interaction, and similar cases. Lua `nil` cannot be used as
	part of a lua table representing a Dictionary or Array, as it
	is equivalent to a missing value: `{"foo", nil}` is the same as 
	`{"foo"}`

vim.empty_dict()					    *vim.empty_dict()*
	Creates a special table which will be converted to an empty
	dictionary when converting lua values to vimL or API types. The
	table is empty, and this property is marked using a metatable. An
	empty table `{}` without this metatable will default to convert to
	an array/list.

	Note: if numeric keys are added to the table, the metatable will be
	ignored and the dict converted to a list/array anyway.

vim.region({bufnr}, {pos1}, {pos2}, {type}, {inclusive})       *vim.region()*
        Converts a selection specified by the buffer ({bufnr}), starting
        position ({pos1}, a zero-indexed pair `{line1,column1}`), ending
        position ({pos2}, same format as {pos1}), the type of the register
        for the selection ({type}, see |regtype|), and a boolean indicating
        whether the selection is inclusive or not, into a zero-indexed table 
        of linewise selections of the form `{linenr = {startcol, endcol}}` .

vim.rpcnotify({channel}, {method}[, {args}...])		    *vim.rpcnotify()*
	Sends {event} to {channel} via |RPC| and returns immediately.
	If {channel} is 0, the event is broadcast to all channels.

	This function also works in a fast callback |lua-loop-callbacks|.

vim.rpcrequest({channel}, {method}[, {args}...])	    *vim.rpcrequest()*
	Sends a request to {channel} to invoke {method} via
	|RPC| and blocks until a response is received.

	Note: NIL values as part of the return value is represented as
	|vim.NIL| special value

vim.stricmp({a}, {b})					*vim.stricmp()*
        Compares strings case-insensitively.  Returns 0, 1 or -1 if strings
        are equal, {a} is greater than {b} or {a} is lesser than {b},
        respectively.

vim.str_utfindex({str}[, {index}])			*vim.str_utfindex()*
        Convert byte index to UTF-32 and UTF-16 indicies. If {index} is not
        supplied, the length of the string is used. All indicies are zero-based.
        Returns two values: the UTF-32 and UTF-16 indicies respectively.

        Embedded NUL bytes are treated as terminating the string. Invalid
        UTF-8 bytes, and embedded surrogates are counted as one code
        point each. An {index} in the middle of a UTF-8 sequence is rounded
        upwards to the end of that sequence.

vim.str_byteindex({str}, {index}[, {use_utf16}])	*vim.str_byteindex()*
        Convert UTF-32 or UTF-16 {index} to byte index. If {use_utf16} is not
        supplied, it defaults to false (use UTF-32). Returns the byte index.

        Invalid UTF-8 and NUL is treated like by |vim.str_byteindex()|. An {index}
        in the middle of a UTF-16 sequence is rounded upwards to the end of that
        sequence.

vim.schedule({callback})				*vim.schedule()*
        Schedules {callback} to be invoked soon by the main event-loop. Useful
        to avoid |textlock| or other temporary restrictions.


vim.defer_fn({fn}, {timeout})                                    *vim.defer_fn*
    Defers calling {fn} until {timeout} ms passes.  Use to do a one-shot timer
    that calls {fn}.

    Note: The {fn} is |schedule_wrap|ped automatically, so API functions are
    safe to call.

    Parameters: ~
        {fn}        Callback to call once {timeout} expires
        {timeout}   Time in ms to wait before calling {fn}

    Returns: ~
        |vim.loop|.new_timer() object

vim.wait({time}, {callback} [, {interval}])                         *vim.wait()*
        Wait for {time} in milliseconds until {callback} returns `true`.

        Executes {callback} immediately and at approximately {interval}
        milliseconds (default 200). Nvim still processes other events during
        this time.


    Returns: ~
        If {callback} returns `true` during the {time}:
            `true, nil`

        If {callback} never returns `true` during the {time}:
            `false, -1`

        If {callback} is interrupted during the {time}:
            `false, -2`

        If {callback} errors, the error is raised.

        Examples: >

    ---
    -- Wait for 100 ms, allowing other events to process
    vim.wait(100, function() end)

    ---
    -- Wait for 100 ms or until global variable set.
    vim.wait(100, function() return vim.g.waiting_for_var end)

    ---
    -- Wait for 1 second or until global variable set, checking every ~500 ms
    vim.wait(1000, function() return vim.g.waiting_for_var end, 500)

    ---
    -- Schedule a function to set a value in 100ms
    vim.defer_fn(function() vim.g.timer_result = true end, 100)

    -- Would wait ten seconds if results blocked. Actually only waits  100 ms
    if vim.wait(10000, function() return vim.g.timer_result end) then
      print('Only waiting a little bit of time!')
    end
<

vim.fn.{func}({...})					*vim.fn*
        Invokes |vim-function| or |user-function| {func} with arguments {...}.
        To call autoload functions, use the syntax: >
            vim.fn['some#function']({...})
<
        Unlike vim.api.|nvim_call_function| this converts directly between Vim
        objects and Lua objects. If the Vim function returns a float, it will
        be represented directly as a Lua number. Empty lists and dictionaries
        both are represented by an empty table.

        Note: |v:null| values as part of the return value is represented as
        |vim.NIL| special value

        Note: vim.fn keys are generated lazily, thus `pairs(vim.fn)` only
        enumerates functions that were called at least once.

vim.type_idx						*vim.type_idx*
	Type index for use in |lua-special-tbl|.  Specifying one of the 
	values from |vim.types| allows typing the empty table (it is 
	unclear whether empty Lua table represents empty list or empty array) 
	and forcing integral numbers to be |Float|.  See |lua-special-tbl| for 
	more details.

vim.val_idx						*vim.val_idx*
	Value index for tables representing |Float|s.  A table representing 
	floating-point value 1.0 looks like this: >
            {
              [vim.type_idx] = vim.types.float,
              [vim.val_idx] = 1.0,
            }
<	See also |vim.type_idx| and |lua-special-tbl|.

vim.types						*vim.types*
	Table with possible values for |vim.type_idx|.  Contains two sets 
	of key-value pairs: first maps possible values for |vim.type_idx| 
	to human-readable strings, second maps human-readable type names to 
	values for |vim.type_idx|.  Currently contains pairs for `float`, 
	`array` and `dictionary` types.

	Note: one must expect that values corresponding to `vim.types.float`, 
	`vim.types.array` and `vim.types.dictionary` fall under only two 
	following assumptions:
	1. Value may serve both as a key and as a value in a table.  Given the 
	   properties of Lua tables this basically means “value is not `nil`”.
	2. For each value in `vim.types` table `vim.types[vim.types[value]]` 
	   is the same as `value`.
	No other restrictions are put on types, and it is not guaranteed that 
	values corresponding to `vim.types.float`, `vim.types.array` and 
	`vim.types.dictionary` will not change or that `vim.types` table will 
	only contain values for these three types.

==============================================================================
Vim Internal Variables                              *lua-vim-internal-variables*

Built-in Vim dictionaries can be accessed and set idiomatically in Lua by each
of the following tables.

To set a value: >

  vim.g.my_global_variable = 5
<

To read a value: >

  print(vim.g.my_global_variable)
<

To delete a value: >

  vim.g.my_global_variable = nil
<

vim.g                                                                 *vim.g*
        Table with values from |g:|
        Keys with no values set will result in `nil`.

vim.b                                                                 *vim.b*
        Gets a buffer-scoped (b:) variable for the current buffer.
        Keys with no values set will result in `nil`.

vim.w                                                                 *vim.w*
        Gets a window-scoped (w:) variable for the current window.
        Keys with no values set will result in `nil`.

vim.t                                                                 *vim.t*
        Gets a tabpage-scoped (t:) variable for the current table.
        Keys with no values set will result in `nil`.

vim.v                                                                 *vim.v*
        Gets a v: variable.
        Keys with no values set will result in `nil`.


Vim Internal Options                                *lua-vim-internal-options*

Read, set and clear vim |options| in Lua by each of the following tables.


vim.o                                                                 *vim.o*
        Table with values from |options|
        Invalid keys will result in an error.

vim.bo                                                                *vim.bo*
        Gets a buffer-scoped option for the current buffer.
        Invalid keys will result in an error.

vim.wo                                                                *vim.wo*
        Gets a window-scoped option for the current window.
        Invalid keys will result in an error.


==============================================================================
Lua module: vim                                                      *lua-vim*

inspect({object}, {options})                                   *vim.inspect()*
                Return a human-readable representation of the given object.

                See also: ~
                    https://github.com/kikito/inspect.lua
                    https://github.com/mpeterv/vinspect

make_meta_accessor({get}, {set}, {del})             *vim.make_meta_accessor()*
                TODO: Documentation

paste({lines}, {phase})                                          *vim.paste()*
                Paste handler, invoked by |nvim_paste()| when a conforming UI
                (such as the |TUI|) pastes text into the editor.

                Example: To remove ANSI color codes when pasting: >

                 vim.paste = (function(overridden)
                   return function(lines, phase)
                     for i,line in ipairs(lines) do
                       -- Scrub ANSI color codes from paste input.
                       lines[i] = line:gsub('\27%[[0-9;mK]+', '')
                     end
                     overridden(lines, phase)
                   end
                 end)(vim.paste)
<

                Parameters: ~
                    {lines}  |readfile()|-style list of lines to paste.
                             |channel-lines|
                    {phase}  -1: "non-streaming" paste: the call contains all
                             lines. If paste is "streamed", `phase` indicates the stream state:
                             • 1: starts the paste (exactly once)
                             • 2: continues the paste (zero or more times)
                             • 3: ends the paste (exactly once)

                Return: ~
                    false if client should cancel the paste.

                See also: ~
                    |paste|

schedule_wrap({cb})                                      *vim.schedule_wrap()*
                Defers callback `cb` until the Nvim API is safe to call.

                See also: ~
                    |lua-loop-callbacks|
                    |vim.schedule()|
                    |vim.in_fast_event()|




deep_equal({a}, {b})                                        *vim.deep_equal()*
                TODO: Documentation

deepcopy({orig})                                              *vim.deepcopy()*
                Returns a deep copy of the given object. Non-table objects are
                copied as in a typical Lua assignment, whereas table objects
                are copied recursively. Functions are naively copied, so
                functions in the copied table point to the same functions as
                those in the input table. Userdata and threads are not copied
                and will throw an error.

                Parameters: ~
                    {orig}  Table to copy

                Return: ~
                    New table of copied keys and (nested) values.

endswith({s}, {suffix})                                       *vim.endswith()*
                Tests if `s` ends with `suffix` .

                Parameters: ~
                    {s}       (string) a string
                    {suffix}  (string) a suffix

                Return: ~
                    (boolean) true if `suffix` is a suffix of s

gsplit({s}, {sep}, {plain})                                     *vim.gsplit()*
                Splits a string at each instance of a separator.

                Parameters: ~
                    {s}      String to split
                    {sep}    Separator string or pattern
                    {plain}  If `true` use `sep` literally (passed to
                             String.find)

                Return: ~
                    Iterator over the split components

                See also: ~
                    |vim.split()|
                    https://www.lua.org/pil/20.2.html
                    http://lua-users.org/wiki/StringLibraryTutorial

is_callable({f})                                           *vim.is_callable()*
                Returns true if object `f` can be called as a function.

                Parameters: ~
                    {f}  Any object

                Return: ~
                    true if `f` is callable, else false

list_extend({dst}, {src}, {start}, {finish})               *vim.list_extend()*
                Extends a list-like table with the values of another list-like
                table.

                NOTE: This mutates dst!

                Parameters: ~
                    {dst}     list which will be modified and appended to.
                    {src}     list from which values will be inserted.
                    {start}   Start index on src. defaults to 1
                    {finish}  Final index on src. defaults to #src

                Return: ~
                    dst

                See also: ~
                    |vim.tbl_extend()|

pesc({s})                                                         *vim.pesc()*
                Escapes magic chars in a Lua pattern.

                Parameters: ~
                    {s}  String to escape

                Return: ~
                    %-escaped pattern string

                See also: ~
                    https://github.com/rxi/lume

split({s}, {sep}, {plain})                                       *vim.split()*
                Splits a string at each instance of a separator.

                Examples: >
                 split(":aa::b:", ":")     --> {'','aa','','bb',''}
                 split("axaby", "ab?")     --> {'','x','y'}
                 split(x*yz*o, "*", true)  --> {'x','yz','o'}
<

                Parameters: ~
                    {s}      String to split
                    {sep}    Separator string or pattern
                    {plain}  If `true` use `sep` literally (passed to
                             String.find)

                Return: ~
                    List-like table of the split components.

                See also: ~
                    |vim.gsplit()|

startswith({s}, {prefix})                                   *vim.startswith()*
                Tests if `s` starts with `prefix` .

                Parameters: ~
                    {s}       (string) a string
                    {prefix}  (string) a prefix

                Return: ~
                    (boolean) true if `prefix` is a prefix of s

tbl_add_reverse_lookup({o})                     *vim.tbl_add_reverse_lookup()*
                Add the reverse lookup values to an existing table. For
                example: tbl_add_reverse_lookup { A = 1 } == { [1] = 'A , A = 1 }`

                Parameters: ~
                    {o}  table The table to add the reverse to.

tbl_contains({t}, {value})                                *vim.tbl_contains()*
                Checks if a list-like (vector) table contains `value` .

                Parameters: ~
                    {t}      Table to check
                    {value}  Value to compare

                Return: ~
                    true if `t` contains `value`

tbl_count({t})                                               *vim.tbl_count()*
                Counts the number of non-nil values in table `t` .
>

    vim.tbl_count({ a=1, b=2 }) => 2
    vim.tbl_count({ 1, 2 }) => 2
<

                Parameters: ~
                    {t}  Table

                Return: ~
                    Number that is the number of the value in table

                See also: ~
                    https://github.com/Tieske/Penlight/blob/master/lua/pl/tablex.lua

tbl_deep_extend({behavior}, {...})                     *vim.tbl_deep_extend()*
                Merges recursively two or more map-like tables.

                Parameters: ~
                    {behavior}  Decides what to do if a key is found in more
                                than one map:
                                • "error": raise an error
                                • "keep": use value from the leftmost map
                                • "force": use value from the rightmost map
                    {...}       Two or more map-like tables.

                See also: ~
                    |tbl_extend()|

tbl_extend({behavior}, {...})                               *vim.tbl_extend()*
                Merges two or more map-like tables.

                Parameters: ~
                    {behavior}  Decides what to do if a key is found in more
                                than one map:
                                • "error": raise an error
                                • "keep": use value from the leftmost map
                                • "force": use value from the rightmost map
                    {...}       Two or more map-like tables.

                See also: ~
                    |extend()|

tbl_filter({func}, {t})                                     *vim.tbl_filter()*
                Filter a table using a predicate function

                Parameters: ~
                    {func}  function or callable table
                    {t}     table

tbl_flatten({t})                                           *vim.tbl_flatten()*
                Creates a copy of a list-like table such that any nested
                tables are "unrolled" and appended to the result.

                Parameters: ~
                    {t}  List-like table

                Return: ~
                    Flattened copy of the given list-like table.

                See also: ~
                    Fromhttps://github.com/premake/premake-core/blob/master/src/base/table.lua

tbl_isempty({t})                                           *vim.tbl_isempty()*
                See also: ~
                    Fromhttps://github.com/premake/premake-core/blob/master/src/base/table.lua@paramt Table to check

tbl_islist({t})                                             *vim.tbl_islist()*
                Determine whether a Lua table can be treated as an array.

                An empty table `{}` will default to being treated as an array.
                Use `vim.emtpy_dict()` to create a table treated as an empty
                dict. Empty tables returned by `rpcrequest()` and `vim.fn`
                functions can be checked using this function whether they
                represent empty API arrays and vimL lists.

                Parameters: ~
                    {t}  Table

                Return: ~
                    `true` if array-like table, else `false` .

tbl_keys({t})                                                 *vim.tbl_keys()*
                Return a list of all keys used in a table. However, the order
                of the return table of keys is not guaranteed.

                Parameters: ~
                    {t}  Table

                Return: ~
                    list of keys

                See also: ~
                    Fromhttps://github.com/premake/premake-core/blob/master/src/base/table.lua

tbl_map({func}, {t})                                           *vim.tbl_map()*
                Apply a function to all values of a table.

                Parameters: ~
                    {func}  function or callable table
                    {t}     table

tbl_values({t})                                             *vim.tbl_values()*
                Return a list of all values used in a table. However, the
                order of the return table of values is not guaranteed.

                Parameters: ~
                    {t}  Table

                Return: ~
                    list of values

trim({s})                                                         *vim.trim()*
                Trim whitespace (Lua pattern "%s") from both sides of a
                string.

                Parameters: ~
                    {s}  String to trim

                Return: ~
                    String with whitespace removed from its beginning and end

                See also: ~
                    https://www.lua.org/pil/20.2.html

validate({opt})                                               *vim.validate()*
                Validates a parameter specification (types and values).

                Usage example: >

                  function user.new(name, age, hobbies)
                    vim.validate{
                      name={name, 'string'},
                      age={age, 'number'},
                      hobbies={hobbies, 'table'},
                    }
                    ...
                  end
<

                Examples with explicit argument values (can be run directly): >

                  vim.validate{arg1={{'foo'}, 'table'}, arg2={'foo', 'string'}}
                     => NOP (success)
<
>
    vim.validate{arg1={1, 'table'}}
       => error('arg1: expected table, got number')
<
>
    vim.validate{arg1={3, function(a) return (a % 2) == 0 end, 'even number'}}
       => error('arg1: expected even number, got 3')
<

                Parameters: ~
                    {opt}  Map of parameter names to validations. Each key is
                           a parameter name; each value is a tuple in one of
                           these forms:
                           1. (arg_value, type_name, optional)
                              • arg_value: argument value
                              • type_name: string type name, one of: ("table",
                                "t", "string", "s", "number", "n", "boolean",
                                "b", "function", "f", "nil", "thread",
                                "userdata")
                              • optional: (optional) boolean, if true, `nil`
                                is valid

                           2. (arg_value, fn, msg)
                              • arg_value: argument value
                              • fn: any function accepting one argument,
                                returns true if and only if the argument is
                                valid
                              • msg: (optional) error string if validation
                                fails

 vim:tw=78:ts=8:ft=help:norl: