Lua

Lua engine Lua

INTRODUCTION lua-intro

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

:lua vim.print(package.loaded)

Nvim includes a "standard library" lua-stdlib for Lua. It complements the "editor stdlib" (vimscript-functions + Ex-commands) and the API, all of which can be used from Lua code (lua-vimscript vim.api). These three namespaces form the Nvim programming interface.

Lua plugins and user config are automatically discovered and loaded, just like Vimscript. See lua-guide for practical guidance.

You can also run Lua scripts from your shell using the -l argument:

nvim -l foo.lua [args...]

lua-compat
Lua 5.1 is the permanent interface for Nvim Lua. Plugins should target Lua 5.1 as specified in luaref; later versions (which are essentially different, incompatible, dialects) are not supported. This includes extensions such as goto that some Lua 5.1 interpreters like LuaJIT may support.

lua-luajit
While Nvim officially only requires Lua 5.1 support, it should be built with LuaJIT or a compatible fork on supported platforms for performance reasons. LuaJIT also comes with useful extensions such as ffi, lua-profile, and enhanced standard library functions; these cannot be assumed to be available, and Lua code in init.lua or plugins should check the jit global variable before using them:

if jit then
  -- code for luajit
else
  -- code for plain lua 5.1
end

One exception is the LuaJIT bit extension, which is always available: when built with PUC Lua, Nvim includes a fallback implementation which provides require("bit"). See lua-bit.

lua-profile
If Nvim is built with LuaJIT, Lua code can be profiled via

-- Start a profiling session:
require('jit.p').start('ri1', '/tmp/profile')
-- Perform arbitrary tasks (use plugins, scripts, etc.) ...
-- Stop the session. Profile is written to /tmp/profile.
require('jit.p').stop()

See https://luajit.org/ext_profiler.html or the p.lua source for details:

:lua vim.cmd.edit(package.searchpath('jit.p', package.path))

LUA CONCEPTS AND IDIOMS lua-concepts

Lua is very simple, and _consistent_: while there are some quirks, once you internalize those quirks, everything works the same everywhere. Scopes (closures) in particular are very consistent, unlike JavaScript or most other languages.

Lua has three fundamental mechanisms—one for "each major aspect of programming": tables, closures, and coroutines. https://www.lua.org/doc/cacm2018.pdf

lua-error-handling
Lua functions may throw lua-errors for exceptional (unexpected) failures, which you can handle with pcall(). lua-result-or-message
When failure is normal and expected, it's idiomatic to return nil which signals to the caller that failure is not "exceptional" and must be handled. This "result-or-message" pattern is expressed as the multi-value return type any|nil,nil|string, or in LuaLS notation:

---@return any|nil    # result on success, nil on failure.
---@return nil|string # nil on success, error message on failure.

Examples of the "result-or-message" pattern:

When a caller can't proceed on failure, it's idiomatic to assert() the "result-or-message" result:

local value = assert(fn())

Guidance: use the "result-or-message" pattern for...

iterator
An iterator is just a function that can be called repeatedly to get the "next" value of a collection (or any other iterable). This interface is expected by for-in loops, produced by pairs(), supported by vim.iter, etc. https://www.lua.org/pil/7.1.html

iterable
An "iterable" is anything that vim.iter() can consume: tables, dicts, lists, iterator functions, tables implementing the __call() metamethod, and vim.iter() objects.

list-iterator
Iterators on lua-list tables have a "middle" and "end", whereas iterators in general may be logically infinite. Therefore some vim.iter operations (e.g. Iter:rev()) make sense only on list-like tables (which are finite by definition).

lua-function-call
Lua functions can be called in multiple ways. Consider the function:

local foo = function(a, b)
    print("A: ", a)
    print("B: ", b)
end

The first way to call this function is:

foo(1, 2)
-- ==== Result ====
-- A: 1
-- B: 2

This way of calling a function is familiar from most scripting languages. In Lua, any missing arguments are passed as nil, and extra parameters are silently discarded. Example:

foo(1)
-- ==== Result ====
-- A: 1
-- B: nil

kwargs
When calling a function, you can omit the parentheses if the function takes exactly one string literal ("foo") or table literal ({1,2,3}). The latter is often used to mimic "named parameters" ("kwargs" or "keyword args") as in languages like Python and C#. Example:

local func_with_opts = function(opts)
    local will_do_foo = opts.foo
    local filename = opts.filename
    -- ...
end
func_with_opts { foo = true, filename = "hello.world" }

There's nothing special going on here except that parentheses are implicitly added. But visually, this small bit of sugar gets reasonably close to a "keyword args" interface.

lua-regex
Lua intentionally does not support regular expressions, instead it has limited lua-patterns which avoid the performance pitfalls of extended regex. Lua scripts can also use Vim regex via vim.regex().

Examples:

print(string.match("foo123bar123", "%d+"))
-- 123
print(string.match("foo123bar123", "[^%d]+"))
-- foo
print(string.match("foo123bar123", "[abc]+"))
-- ba
print(string.match("foo.bar", "%.bar"))
-- .bar

IMPORTING LUA MODULES lua-module-load

Modules are searched for under the directories specified in 'runtimepath' and packages-runtimepath, in the order they appear in the output of this command

:echo nvim_list_runtime_paths()

Any "." in the module name is treated as a directory separator when searching. For a module foo.bar, each directory is searched for lua/foo/bar.lua, then lua/foo/bar/init.lua. If no files are found, the directories are searched again for a shared library with a name matching lua/foo/bar.?, where ? is a list of suffixes (such as so or dll) derived from the initial value of package.cpath. If still no files are found, Nvim falls back to Lua's default search mechanism. The first script found is run and require() returns the value returned by the script if any, else true.

The return value is cached after the first call to require() for each module, with subsequent calls returning the cached value without searching for, or executing any script. For further details see require().

For example, if 'runtimepath' is foo,bar and package.cpath was ./?.so;./?.dll at startup, require('mod') searches these paths in order and loads the first module found ("first wins"):

foo/lua/mod.lua
foo/lua/mod/init.lua
bar/lua/mod.lua
bar/lua/mod/init.lua
foo/lua/mod.so
foo/lua/mod.dll
bar/lua/mod.so
bar/lua/mod.dll

Note:

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 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= :lua :lua {chunk} Executes Lua chunk {chunk}. If {chunk} starts with "=" the rest of the chunk is evaluated as an expression and printed. :lua =expr and :=expr are equivalent to :lua print(vim.inspect(expr)).

Examples:

:lua vim.api.nvim_command('echo "Hello, Nvim!"')

To see the Lua version:

:lua print(_VERSION)

To see the LuaJIT version:

:lua =jit.version

:{range}lua Executes buffer lines in {range} as Lua code. Unlike :source, this always treats the lines as Lua code.

Example: select the following code and type ":lua<Enter>" to execute it:

print(string.format(
    'unix time: %s', os.time()))

:lua-heredoc
:lua << [trim] [{endmarker}] {script} {endmarker} Executes Lua script {script} from within Vimscript. You can omit [endmarker] after the "<<" and use a dot "." after {script} (similar to :append, :insert). Refer to :let-heredoc for more information.

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 - 1, linenr, false)[1]
print(string.format('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
:luafile {file} Execute Lua script in {file}. The whole argument is used as the filename (like :edit), spaces do not need to be escaped. Alternatively you can :source Lua files.

Examples:

:luafile script.lua
:luafile %

luaeval() lua-eval

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 Vimscript types. If a Lua string contains a NUL byte, it will be converted to a Blob. Conversion of other Lua types is an error.

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-table-ambiguous
Lua tables are used as both dictionaries and lists, so it is impossible to decide whether empty table is a list or a dict. Also Lua does not have integer numbers. To disambiguate these cases, we define: lua-list
0. Empty table is a list. Use vim.empty_dict() to represent empty dict. 1. Table with N consecutive (no nil values, aka "holes") integer keys 1…N is a list. See also list-iterator. lua-dict
2. Table with string keys, none of which contains NUL byte, is a dict. 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:

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 is converted ("marshalled") from Vimscript to Lua, so changes to Lua containers do not affect values in Vimscript. Return value is also always converted. When converting, msgpack-special-dicts 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

call v:lua.func(arg1, arg2)

is equivalent to the Lua chunk

return func(...)

where the args are converted to Lua values. The expression

call v:lua.somemod.func(args)

is equivalent to the Lua chunk

return somemod.func(...)

Lua module functions can be accessed like:

call v:lua.require'mypack'.func(arg1, arg2)
call v:lua.require'mypack.submod'.func(arg1, arg2)

Note: Only single quote form without parens is allowed. Using require"mypack" or require('mypack') as a prefix does NOT work.

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
-- Note: The module ("mymod") must be a Lua global, or use require() as
-- shown above to access it from a package.
vim.bo[buf].omnifunc = 'v:lua.mymod.omnifunc'

You can also use v:lua to call Lua functions as Vimscript methods:

:eval arg1->v:lua.somemod.func(arg2)

Note: v:lua without a call is not allowed in a Vimscript expression: Funcrefs 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 vim.print(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.UV lua-loop vim.uv

vim.uv exposes the "luv" Lua bindings for the libUV library that Nvim uses for networking, filesystem, and process management, see luvref.txt. In particular, it allows interacting with the main Nvim luv-event-loop.

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

local timer = vim.uv.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.uv.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.uv.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.uv.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>'))")

inotify-limitations
When on Linux you may need to increase the maximum number of inotify watches and queued events as the default limit can be too low. To increase the limit, run:

sysctl fs.inotify.max_user_watches=494462

This will increase the limit to 494462 watches and queued events. These lines can be added to /etc/sysctl.conf to make the changes persistent.

Note that each watch is a structure in the Kernel, thus available memory is also a bottleneck for using inotify. In fact, a watch can take up to 1KB of space. This means a million watches could result in 1GB of extra RAM usage.

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.uv.new_tcp()
  server:bind(host, port)
  server:listen(128, function(err)
    assert(not err, err)  -- Check for errors.
    local sock = vim.uv.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)

Multithreading lua-loop-threading

Plugins can perform work in separate (os-level) threads using the threading APIs in luv, for instance vim.uv.new_thread. Each thread has its own separate Lua interpreter state, with no access to Lua globals on the main thread. Neither can the editor state (buffers, windows, etc) be directly accessed from threads.

A subset of the vim.* stdlib is available in threads, including:

VIM.HL vim.hl

vim.hl.on_yank({opts}) vim.hl.on_yank()
Highlight the yanked text during a TextYankPost event.

Add the following to your init.vim:

autocmd TextYankPost * silent! lua vim.hl.on_yank {higroup='Visual', timeout=300}

vim.hl.priorities vim.hl.priorities
Table with default priorities used for highlighting:

vim.hl.range()
vim.hl.range({bufnr}, {ns}, {higroup}, {start}, {finish}, {opts}) Apply highlight group to range of text.

(uv.uv_timer_t?) range_timer A timer which manages how much time the highlight has left (fun()?) range_clear A function which allows clearing the highlight manually. nil is returned if timeout is not specified

VIM.DIFF vim.diff

vim.diff({a}, {b}, {opts}) vim.diff()
Run diff on strings {a} and {b}. Any indices returned by this function, either directly or via callback arguments, are 1-based.

Examples:

vim.diff('a\n', 'b\nc\n')
-- =>
-- @@ -1 +1,2 @@
-- -a
-- +b
-- +c
vim.diff('a\n', 'b\nc\n', {result_type = 'indices'})
-- =>
-- {
--   {1, 1, 1, 2}
-- }

(string|integer[][]?) See {opts.result_type}. nil if {opts.on_hunk} is given.

VIM.MPACK vim.mpack

This module provides encoding and decoding of Lua objects to and from msgpack-encoded strings. Supports vim.NIL and vim.empty_dict().

vim.mpack.decode({str}) vim.mpack.decode()
Decodes (or "unpacks") the msgpack-encoded {str} to a Lua object.

(any)

vim.mpack.encode({obj}) vim.mpack.encode()
Encodes (or "packs") Lua object {obj} as msgpack in a Lua string.

(string)

VIM.JSON vim.json

This module provides encoding and decoding of Lua objects to and from JSON-encoded strings. Supports vim.NIL and vim.empty_dict().

vim.json.decode({str}, {opts}) vim.json.decode()
Decodes (or "unpacks") the JSON-encoded {str} to a Lua object.

Example:

vim.print(vim.json.decode('{"bar":[],"foo":{},"zub":null}'))
-- { bar = {}, foo = vim.empty_dict(), zub = vim.NIL }

(any)

vim.json.encode({obj}, {opts}) vim.json.encode()
Encodes (or "packs") Lua object {obj} as JSON in a Lua string.

(string)

VIM.BASE64 vim.base64

vim.base64.decode({str}) vim.base64.decode()
Decode a Base64 encoded string.

(string) Decoded string

vim.base64.encode({str}) vim.base64.encode()
Encode {str} using Base64.

(string) Encoded string

VIM.SPELL vim.spell

vim.spell.check({str}) vim.spell.check()
Check {str} for spelling errors. Similar to the Vimscript function spellbadword().

Note: The behaviour of this function is dependent on: 'spelllang', 'spellfile', 'spellcapcheck' and 'spelloptions' which can all be local to the buffer. Consider calling this with nvim_buf_call().

Example:

vim.spell.check("the quik brown fox")
-- =>
-- {
--     {'quik', 'bad', 5}
-- }

([string, 'bad'|'rare'|'local'|'caps', integer][]) List of tuples with three items:

VIM vim.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.NIL vim.NIL
Special value representing NIL in RPC and v:null in Vimscript conversion, and similar cases. Lua nil cannot be used as part of a Lua table representing a Dictionary or Array, because it is treated as missing: {"foo", nil} is the same as {"foo"}.

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 Floats. 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.

log_levels vim.log.levels Log levels are one of the values defined in vim.log.levels:

vim.log.levels.DEBUG vim.log.levels.ERROR vim.log.levels.INFO vim.log.levels.TRACE vim.log.levels.WARN vim.log.levels.OFF

vim.empty_dict() vim.empty_dict()
Creates a special empty table (marked with a metatable), which Nvim converts to an empty dictionary when translating Lua values to Vimscript or API types. Nvim by default converts an empty table {} without this metatable to an list/array.

Note: If numeric keys are present in the table, Nvim ignores the metatable marker and converts the dict to a list/array anyway.

(table)

vim.iconv({str}, {from}, {to}) vim.iconv()
The result is a String, which is the text {str} converted from encoding {from} to encoding {to}. When the conversion fails nil is returned. When some characters could not be converted they are replaced with "?". The encoding names are whatever the iconv() library function can accept, see ":Man 3 iconv".

(string?) Converted string if conversion succeeds, nil otherwise.

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.rpcnotify({channel}, {method}, {...}) 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}, {...}) 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.schedule({fn}) vim.schedule()
Schedules {fn} to be invoked soon by the main event-loop. Useful to avoid textlock or other temporary restrictions.

vim.str_utf_end({str}, {index}) vim.str_utf_end()
Gets the distance (in bytes) from the last byte of the codepoint (character) that {index} points to.

Examples:

-- The character 'æ' is stored as the bytes '\xc3\xa6' (using UTF-8)
-- Returns 0 because the index is pointing at the last byte of a character
vim.str_utf_end('æ', 2)
-- Returns 1 because the index is pointing at the penultimate byte of a character
vim.str_utf_end('æ', 1)

(integer)

vim.str_utf_pos({str}) vim.str_utf_pos()
Gets a list of the starting byte positions of each UTF-8 codepoint in the given string.

Embedded NUL bytes are treated as terminating the string.

(integer[])

vim.str_utf_start({str}, {index}) vim.str_utf_start()
Gets the distance (in bytes) from the starting byte of the codepoint (character) that {index} points to.

The result can be added to {index} to get the starting byte of a character.

Examples:

-- The character 'æ' is stored as the bytes '\xc3\xa6' (using UTF-8)
-- Returns 0 because the index is pointing at the first byte of a character
vim.str_utf_start('æ', 1)
-- Returns -1 because the index is pointing at the second byte of a character
vim.str_utf_start('æ', 2)

(integer)

vim.stricmp({a}, {b}) vim.stricmp()
Compares strings case-insensitively.

(0|1|-1) if strings are equal, {a} is greater than {b} or {a} is lesser than {b}, respectively.

vim.ui_attach({ns}, {opts}, {callback}) vim.ui_attach()
WARNING: This feature is experimental/unstable.

Subscribe to ui-events, similar to nvim_ui_attach() but receive events in a Lua callback. Used to implement screen elements like popupmenu or message handling in Lua.

{callback} receives event name plus additional parameters. See ui-popupmenu and the sections below for event format for respective events.

Callbacks for msg_show events are executed in api-fast context; showing the message should be scheduled.

Excessive errors inside the callback will result in forced detachment.

WARNING: This api is considered experimental. Usability will vary for different screen elements. In particular ext_messages behavior is subject to further changes and usability improvements. This is expected to be used to handle messages when setting 'cmdheight' to zero (which is likewise experimental).

Example (stub for a ui-popupmenu implementation):

ns = vim.api.nvim_create_namespace('my_fancy_pum')
vim.ui_attach(ns, {ext_popupmenu=true}, function(event, ...)
  if event == 'popupmenu_show' then
    local items, selected, row, col, grid = ...
    print('display pum ', #items)
  elseif event == 'popupmenu_select' then
    local selected = ...
    print('selected', selected)
  elseif event == 'popupmenu_hide' then
    print('FIN')
  end
end)

vim.ui_detach({ns}) vim.ui_detach()
Detach a callback previously attached with vim.ui_attach() for the given namespace {ns}.

vim.wait({time}, {callback}, {interval}, {fast_only}) 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.

Cannot be called while in an api-fast event.

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

(boolean) (-1|-2?)

LUA-VIMSCRIPT BRIDGE lua-vimscript

Nvim Lua provides an interface or "bridge" to Vimscript variables and functions, and editor commands and options.

Objects passed over this bridge are COPIED (marshalled): there are no "references". lua-guide-variables For example, using vim.fn.remove() on a Lua list copies the list object to Vimscript and does NOT modify the Lua list:

local list = { 1, 2, 3 }
vim.fn.remove(list, 0)
vim.print(list)  --> "{ 1, 2, 3 }"

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

vim.fn[func]({...})

vim.cmd({command}) See vim.cmd().

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.

Note: The majority of functions cannot run in api-fast callbacks with some undocumented exceptions which are allowed.

lua-vim-variables
The Vim editor global dictionaries g: w: b: t: v: can be accessed from Lua conveniently and idiomatically by referencing the vim.* Lua tables described below. In this way you can easily read and modify global Vimscript variables from Lua.

Example:

vim.g.foo = 5     -- Set the g:foo Vimscript variable.
print(vim.g.foo)  -- Get and print the g:foo Vimscript variable.
vim.g.foo = nil   -- Delete (:unlet) the Vimscript variable.
vim.b[2].foo = 6  -- Set b:foo for buffer 2

Note that setting dictionary fields directly will not write them back into Nvim. This is because the index into the namespace simply returns a copy. Instead the whole dictionary must be written as one. This can be achieved by creating a short-lived temporary.

Example:

vim.g.my_dict.field1 = 'value'  -- Does not work
local my_dict = vim.g.my_dict   --
my_dict.field1 = 'value'        -- Instead do
vim.g.my_dict = my_dict         --

vim.g vim.g
Global (g:) editor variables. Key with no value returns nil.

vim.b vim.b
Buffer-scoped (b:) variables for the current buffer. Invalid or unset key returns nil. Can be indexed with an integer to access variables for a specific buffer.

vim.w vim.w
Window-scoped (w:) variables for the current window. Invalid or unset key returns nil. Can be indexed with an integer to access variables for a specific window.

vim.t vim.t
Tabpage-scoped (t:) variables for the current tabpage. Invalid or unset key returns nil. Can be indexed with an integer to access variables for a specific tabpage.

vim.v vim.v
v: variables. Invalid or unset key returns nil.

lua-options
lua-vim-options
lua-vim-set
lua-vim-setlocal

Vim options can be accessed through vim.o, which behaves like Vimscript :set.

To set a boolean toggle: Vimscript: set number Lua: vim.o.number = true

To set a string value: Vimscript: set wildignore=*.o,*.a,__pycache__ Lua: vim.o.wildignore = '*.o,*.a,__pycache__'

Similarly, there is vim.bo and vim.wo for setting buffer-scoped and window-scoped options. Note that this must NOT be confused with local-options and :setlocal. There is also vim.go that only accesses the global value of a global-local option, see :setglobal.

vim.opt_local
vim.opt_global
vim.opt

A special interface vim.opt exists for conveniently interacting with list- and map-style options from Lua: It allows accessing them as Lua tables and offers object-oriented method for adding and removing entries.

The following methods of setting a list-style option are equivalent: In Vimscript:

set wildignore=*.o,*.a,__pycache__

In Lua using vim.o:

vim.o.wildignore = '*.o,*.a,__pycache__'

In Lua using vim.opt:

vim.opt.wildignore = { '*.o', '*.a', '__pycache__' }

To replicate the behavior of :set+=, use:

vim.opt.wildignore:append { "*.pyc", "node_modules" }

To replicate the behavior of :set^=, use:

vim.opt.wildignore:prepend { "new_first_value" }

To replicate the behavior of :set-=, use:

vim.opt.wildignore:remove { "node_modules" }

The following methods of setting a map-style option are equivalent: In Vimscript:

set listchars=space:_,tab:>~

In Lua using vim.o:

vim.o.listchars = 'space:_,tab:>~'

In Lua using vim.opt:

vim.opt.listchars = { space = '_', tab = '>~' }

Note that vim.opt returns an Option object, not the value of the option, which is accessed through vim.opt:get():

The following methods of getting a list-style option are equivalent: In Vimscript:

echo wildignore

In Lua using vim.o:

print(vim.o.wildignore)

In Lua using vim.opt:

vim.print(vim.opt.wildignore:get())

In any of the above examples, to replicate the behavior :setlocal, use vim.opt_local. Additionally, to replicate the behavior of :setglobal, use vim.opt_global.

Option:append({value}) vim.opt:append()
Append a value to string-style options. See :set+=

These are equivalent:

vim.opt.formatoptions:append('j')
vim.opt.formatoptions = vim.opt.formatoptions + 'j'

Option:get() vim.opt:get()
Returns a Lua-representation of the option. Boolean, number and string values will be returned in exactly the same fashion.

For values that are comma-separated lists, an array will be returned with the values as entries in the array:

vim.cmd [[set wildignore=*.pyc,*.o]]
vim.print(vim.opt.wildignore:get())
-- { "*.pyc", "*.o", }
for _, ignore_pattern in ipairs(vim.opt.wildignore:get()) do
    print("Will ignore:", ignore_pattern)
end
-- Will ignore: *.pyc
-- Will ignore: *.o

For values that are comma-separated maps, a table will be returned with the names as keys and the values as entries:

vim.cmd [[set listchars=space:_,tab:>~]]
vim.print(vim.opt.listchars:get())
--  { space = "_", tab = ">~", }
for char, representation in pairs(vim.opt.listchars:get()) do
    print(char, "=>", representation)
end

For values that are lists of flags, a set will be returned with the flags as keys and true as entries.

vim.cmd [[set formatoptions=njtcroql]]
vim.print(vim.opt.formatoptions:get())
-- { n = true, j = true, c = true, ... }
local format_opts = vim.opt.formatoptions:get()
if format_opts.j then
    print("J is enabled!")
end

(string|integer|boolean?) value of option

Option:prepend({value}) vim.opt:prepend()
Prepend a value to string-style options. See :set^=

These are equivalent:

vim.opt.wildignore:prepend('*.o')
vim.opt.wildignore = vim.opt.wildignore ^ '*.o'

Option:remove({value}) vim.opt:remove()
Remove a value from string-style options. See :set-=

These are equivalent:

vim.opt.wildignore:remove('*.pyc')
vim.opt.wildignore = vim.opt.wildignore - '*.pyc'

vim.bo[{bufnr}] vim.bo
Get or set buffer-scoped options for the buffer with number {bufnr}. Like :setlocal. If {bufnr} is omitted then the current buffer is used. Invalid {bufnr} or key is an error.

Example:

local bufnr = vim.api.nvim_get_current_buf()
vim.bo[bufnr].buflisted = true    -- same as vim.bo.buflisted = true
print(vim.bo.comments)
print(vim.bo.baz)                 -- error: invalid key

vim.env vim.env
Environment variables defined in the editor session. See expand-env and :let-environment for the Vimscript behavior. Invalid or unset key returns nil.

Example:

vim.env.FOO = 'bar'
print(vim.env.TERM)

vim.go vim.go
Get or set global options. Like :setglobal. Invalid key is an error.

Note: this is different from vim.o because this accesses the global option value and thus is mostly useful for use with global-local options.

Example:

vim.go.cmdheight = 4
print(vim.go.columns)
print(vim.go.bar)     -- error: invalid key

vim.o vim.o
Get or set options. Works like :set, so buffer/window-scoped options target the current buffer/window. Invalid key is an error.

Example:

vim.o.cmdheight = 4
print(vim.o.columns)
print(vim.o.foo)     -- error: invalid key

vim.wo[{winid}][{bufnr}] vim.wo
Get or set window-scoped options for the window with handle {winid} and buffer with number {bufnr}. Like :setlocal if setting a global-local option or if {bufnr} is provided, like :set otherwise. If {winid} is omitted then the current window is used. Invalid {winid}, {bufnr} or key is an error.

Note: only {bufnr} with value 0 (the current buffer in the window) is supported.

Example:

local winid = vim.api.nvim_get_current_win()
vim.wo[winid].number = true    -- same as vim.wo.number = true
print(vim.wo.foldmarker)
print(vim.wo.quux)             -- error: invalid key
vim.wo[winid][0].spell = false -- like ':setlocal nospell'

Lua module: vim lua-vim

vim.cmd({command}) vim.cmd()
Executes Vimscript (Ex-commands).

Note that vim.cmd can be indexed with a command name to return a callable function to the command.

Example:

vim.cmd('echo 42')
vim.cmd([[
  augroup My_group
    autocmd!
    autocmd FileType c setlocal cindent
  augroup END
]])
-- Ex command :echo "foo"
-- Note string literals need to be double quoted.
vim.cmd('echo "foo"')
vim.cmd { cmd = 'echo', args = { '"foo"' } }
vim.cmd.echo({ args = { '"foo"' } })
vim.cmd.echo('"foo"')
-- Ex command :write! myfile.txt
vim.cmd('write! myfile.txt')
vim.cmd { cmd = 'write', args = { "myfile.txt" }, bang = true }
vim.cmd.write { args = { "myfile.txt" }, bang = true }
vim.cmd.write { "myfile.txt", bang = true }
-- Ex command :colorscheme blue
vim.cmd('colorscheme blue')
vim.cmd.colorscheme('blue')

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 vim.schedule_wrap()ped automatically, so API functions are safe to call.

(table) timer luv timer object

vim.deprecate()
vim.deprecate({name}, {alternative}, {version}, {plugin}, {backtrace}) Shows a deprecation message to the user.

(string?) Deprecated message, or nil if no message was shown.

vim.inspect() vim.inspect()
Gets a human-readable representation of the given object.

(string)

vim.keycode({str}) vim.keycode()
Translates keycodes.

Example:

local k = vim.keycode
vim.g.mapleader = k'<bs>'

(string)

vim.lua_omnifunc({find_start}) vim.lua_omnifunc()
Omnifunc for completing Lua values from the runtime Lua interpreter, similar to the builtin completion for the :lua command.

Activate using set omnifunc=v:lua.vim.lua_omnifunc in a Lua buffer.

vim.notify({msg}, {level}, {opts}) vim.notify()
Displays a notification to the user.

This function can be overridden by plugins to display notifications using a custom provider (such as the system notification provider). By default, writes to :messages.

vim.notify_once({msg}, {level}, {opts}) vim.notify_once()
Displays a notification only one time.

Like vim.notify(), but subsequent calls with the same message will not display a notification.

(boolean) true if message was displayed, else false

vim.on_key({fn}, {ns_id}, {opts}) vim.on_key()
Adds Lua function {fn} with namespace id {ns_id} as a listener to every, yes every, input key.

The Nvim command-line option -w is related but does not support callbacks and cannot be toggled dynamically.

(integer) Namespace id associated with {fn}. Or count of all callbacks if on_key() is called without arguments.

vim.paste({lines}, {phase}) vim.paste()
Paste handler, invoked by nvim_paste().

Note: This is provided only as a "hook", don't call it directly; call nvim_paste() instead, which arranges redo (dot-repeat) and invokes vim.paste.

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
    return overridden(lines, phase)
  end
end)(vim.paste)

(boolean) result false if client should cancel the paste.

vim.print({...}) vim.print()
"Pretty prints" the given arguments and returns them unmodified.

Example:

local hl_normal = vim.print(vim.api.nvim_get_hl(0, { name = 'Normal' }))

(any) given arguments.

vim.schedule_wrap({fn}) vim.schedule_wrap()
Returns a function which calls {fn} via vim.schedule().

The returned function passes all arguments to {fn}.

Example:

function notify_readable(_err, readable)
  vim.notify("readable? " .. tostring(readable))
end
vim.uv.fs_access(vim.fn.stdpath("config"), "R", vim.schedule_wrap(notify_readable))

(function)

vim.str_byteindex()
vim.str_byteindex({s}, {encoding}, {index}, {strict_indexing}) Convert UTF-32, UTF-16 or UTF-8 {index} to byte index. If {strict_indexing} is false then then an out of range index will return byte length instead of throwing an error.

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

(integer)

vim.str_utfindex()
vim.str_utfindex({s}, {encoding}, {index}, {strict_indexing}) Convert byte index to UTF-32, UTF-16 or UTF-8 indices. If {index} is not supplied, the length of the string is used. All indices are zero-based.

If {strict_indexing} is false then an out of range index will return string length instead of throwing an error. 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.

(integer)

vim.system({cmd}, {opts}, {on_exit}) vim.system()
Runs a system command or throws an error if {cmd} cannot be run.

Examples:

local on_exit = function(obj)
  print(obj.code)
  print(obj.signal)
  print(obj.stdout)
  print(obj.stderr)
end
-- Runs asynchronously:
vim.system({'echo', 'hello'}, { text = true }, on_exit)
-- Runs synchronously:
local obj = vim.system({'echo', 'hello'}, { text = true }):wait()
-- { code = 0, signal = 0, stdout = 'hello\n', stderr = '' }

See uv.spawn() for more details. Note: unlike uv.spawn(), vim.system throws an error if {cmd} cannot be run.

(vim.SystemObj) Object with the fields:

Lua module: vim.inspector vim.inspector

vim.inspect_pos({bufnr}, {row}, {col}, {filter}) vim.inspect_pos()
Get all the items at a given buffer position.

Can also be pretty-printed with :Inspect!. :Inspect!

Since: 0.9.0

(table) a table with the following key-value pairs. Items are in "traversal order":

vim.show_pos({bufnr}, {row}, {col}, {filter}) vim.show_pos()
Show all the items at a given buffer position.

Can also be shown with :Inspect. :Inspect

Example: To bind this function to the vim-scriptease inspired zS in Normal mode:

vim.keymap.set('n', 'zS', vim.show_pos)

Since: 0.9.0

vim.Ringbuf

Ringbuf:clear() Ringbuf:clear()
Clear all items

Ringbuf:peek() Ringbuf:peek()
Returns the first unread item without removing it

(any?)

Ringbuf:pop() Ringbuf:pop()
Removes and returns the first unread item

(any?)

Ringbuf:push({item}) Ringbuf:push()
Adds an item, overriding the oldest item if the buffer is full.

vim.deep_equal({a}, {b}) vim.deep_equal()
Deep compare values for equality

Tables are compared recursively unless they both provide the eq metamethod. All other types are compared using the equality == operator.

(boolean) true if values are equals, else false

vim.deepcopy({orig}, {noref}) 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.

Note: noref=true is much more performant on tables with unique table fields, while noref=false is more performant on tables that reuse table fields.

(table) Table of copied keys and (nested) values.

vim.defaulttable({createfn}) vim.defaulttable()
Creates a table whose missing keys are provided by {createfn} (like Python's "defaultdict").

If {createfn} is nil it defaults to defaulttable() itself, so accessing nested keys creates nested tables:

local a = vim.defaulttable()
a.b.c = 1

(table) Empty table with __index metamethod.

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

(boolean) true if suffix is a suffix of s

vim.gsplit({s}, {sep}, {opts}) vim.gsplit()
Gets an iterator that splits a string at each instance of a separator, in "lazy" fashion (as opposed to vim.split() which is "eager").

Example:

for s in vim.gsplit(':aa::b:', ':', {plain=true}) do
  print(s)
end

If you want to also inspect the separator itself (instead of discarding it), use string.gmatch(). Example:

for word, num in ('foo111bar222'):gmatch('([^0-9]*)(%d*)') do
  print(('word: %s num: %s'):format(word, num))
end

(fun():string?) Iterator over the split components

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

(boolean) true if f is callable, else false

vim.isarray({t}) vim.isarray()
Tests if t is an "array": a table indexed only by integers (potentially non-contiguous).

If the indexes start from 1 and are contiguous then the array is also a list. vim.islist()

Empty table {} is an array, unless it was created by vim.empty_dict() or returned as a dict-like API or Vimscript result, for example from rpcrequest() or vim.fn.

(boolean) true if array-like table, else false.

vim.islist({t}) vim.islist()
Tests if t is a "list": a table indexed only by contiguous integers starting from 1 (what lua-length calls a "regular array").

Empty table {} is a list, unless it was created by vim.empty_dict() or returned as a dict-like API or Vimscript result, for example from rpcrequest() or vim.fn.

(boolean) true if list-like table, else false.

vim.list_contains({t}, {value}) vim.list_contains()
Checks if a list-like table (integer keys without gaps) contains value.

(boolean) true if t contains value

vim.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!

(table) dst

vim.list_slice({list}, {start}, {finish}) vim.list_slice()
Creates a copy of a table containing only elements from start to end (inclusive)

(any[]) Copy of table sliced from start to finish (inclusive)

vim.pesc({s}) vim.pesc()
Escapes magic chars in lua-patterns.

(string) %-escaped pattern string

vim.ringbuf({size}) vim.ringbuf()
Create a ring buffer limited to a maximal number of items. Once the buffer is full, adding a new entry overrides the oldest entry.

local ringbuf = vim.ringbuf(4)
ringbuf:push("a")
ringbuf:push("b")
ringbuf:push("c")
ringbuf:push("d")
ringbuf:push("e")    -- overrides "a"
print(ringbuf:pop()) -- returns "b"
print(ringbuf:pop()) -- returns "c"
-- Can be used as iterator. Pops remaining items:
for val in ringbuf do
  print(val)
end

Returns a Ringbuf instance with the following methods:

(vim.Ringbuf) ringbuf See vim.Ringbuf.

vim.spairs({t}) vim.spairs()
Enumerates key-value pairs of a table, ordered by key.

(fun(table: table<K, V>, index?: K):K, V) for-in iterator over sorted keys and their values (table)

vim.split({s}, {sep}, {opts}) vim.split()
Splits a string at each instance of a separator and returns the result as a table (unlike vim.gsplit()).

Examples:

split(":aa::b:", ":")                   --> {'','aa','','b',''}
split("axaby", "ab?")                   --> {'','x','y'}
split("x*yz*o", "*", {plain=true})      --> {'x','yz','o'}
split("|x|y|z|", "|", {trimempty=true}) --> {'x', 'y', 'z'}

(string[]) List of split components

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

(boolean) true if prefix is a prefix of s

vim.tbl_contains({t}, {value}, {opts}) vim.tbl_contains()
Checks if a table contains a given value, specified either directly or via a predicate that is checked for each value.

Example:

vim.tbl_contains({ 'a', { 'b', 'c' } }, function(v)
  return vim.deep_equal(v, { 'b', 'c' })
end, { predicate = true })
-- true

(boolean) true if t contains value

vim.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

(integer) Number of non-nil values in table

vim.tbl_deep_extend({behavior}, {...}) vim.tbl_deep_extend()
Merges recursively two or more tables.

Only values that are empty tables or tables that are not lua-lists (indexed by consecutive integers starting from 1) are merged recursively. This is useful for merging nested tables like default and user configurations where lists should be treated as literals (i.e., are overwritten instead of merged).

(table) Merged table

vim.tbl_extend({behavior}, {...}) vim.tbl_extend()
Merges two or more tables.

(table) Merged table

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

(any[]) Table of filtered values

vim.tbl_get({o}, {...}) vim.tbl_get()
Index into a table (first argument) via string keys passed as subsequent arguments. Return nil if the key does not exist.

Examples:

vim.tbl_get({ key = { nested_key = true }}, 'key', 'nested_key') == true
vim.tbl_get({ key = {}}, 'key', 'nested_key') == nil

(any) Nested value indexed by key (if it exists), else nil

vim.tbl_isempty({t}) vim.tbl_isempty()
Checks if a table is empty.

(boolean) true if t is empty

vim.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.

(any[]) List of keys

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

(table) Table of transformed values

vim.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.

(any[]) List of values

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

(string) String with whitespace removed from its beginning and end

vim.validate()
vim.validate({name}, {value}, {validator}, {optional}, {message}) Validate function arguments.

This function has two valid forms: 1. vim.validate(name, value, validator[, optional][, message]) Validates that argument {name} with value {value} satisfies {validator}. If {optional} is given and is true, then {value} may be nil. If {message} is given, then it is used as the expected type in the error message. Example:

 function vim.startswith(s, prefix)
  vim.validate('s', s, 'string')
  vim.validate('prefix', prefix, 'string')
  -- ...
end

2. vim.validate(spec) (deprecated) where spec is of type table<string,[value:any, validator: vim.validate.Validator, optional_or_msg? : boolean|string]>) Validates a argument specification. Specs are evaluated in alphanumeric order, until the first failure. 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')
   --> NOP (success)
vim.validate('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')

If multiple types are valid they can be given as a list.

vim.validate('arg1', {'foo'}, {'table', 'string'})
vim.validate('arg2', 'foo', {'table', 'string'})
-- NOP (success)
vim.validate('arg1', 1, {'string', 'table'})
-- error('arg1: expected string|table, got number')

Lua module: vim.loader vim.loader

vim.loader.enable({enable}) vim.loader.enable()
WARNING: This feature is experimental/unstable.

Enables or disables the experimental Lua module loader:

Enable (enable=true):

Disable (enable=false):

vim.loader.find({modname}, {opts}) vim.loader.find()
WARNING: This feature is experimental/unstable.

Finds Lua modules for the given module name.

(table[]) A list of objects with the following fields:

vim.loader.reset({path}) vim.loader.reset()
WARNING: This feature is experimental/unstable.

Resets the cache for the path, or all the paths if path is nil.

Lua module: vim.uri vim.uri

vim.uri_decode({str}) vim.uri_decode()
URI-decodes a string containing percent escapes.

(string) decoded string

vim.uri_encode({str}, {rfc}) vim.uri_encode()
URI-encodes a string using percent escapes.

(string) encoded string

vim.uri_from_bufnr({bufnr}) vim.uri_from_bufnr()
Gets a URI from a bufnr.

(string) URI

vim.uri_from_fname({path}) vim.uri_from_fname()
Gets a URI from a file path.

(string) URI

vim.uri_to_bufnr({uri}) vim.uri_to_bufnr()
Gets the buffer for a uri. Creates a new unloaded buffer if no buffer for the uri already exists.

(integer) bufnr

vim.uri_to_fname({uri}) vim.uri_to_fname()
Gets a filename from a URI.

(string) filename or unchanged URI for non-file URIs

Lua module: vim.ui vim.ui

vim.ui.input({opts}, {on_confirm}) vim.ui.input()
Prompts the user for input, allowing arbitrary (potentially asynchronous) work until on_confirm.

Example:

vim.ui.input({ prompt = 'Enter value for shiftwidth: ' }, function(input)
    vim.o.shiftwidth = tonumber(input)
end)

vim.ui.open({path}, {opt}) vim.ui.open()
Opens path with the system default handler (macOS open, Windows explorer.exe, Linux xdg-open, …), or returns (but does not show) an error message on failure.

Can also be invoked with :Open. :Open

Expands "~/" and environment variables in filesystem paths.

Examples:

-- Asynchronous.
vim.ui.open("https://neovim.io/")
vim.ui.open("~/path/to/file")
-- Use the "osurl" command to handle the path or URL.
vim.ui.open("gh#neovim/neovim!29490", { cmd = { 'osurl' } })
-- Synchronous (wait until the process exits).
local cmd, err = vim.ui.open("$VIMRUNTIME")
if cmd then
  cmd:wait()
end

(vim.SystemObj?) Command object, or nil if not found. (string?) Error message on failure, or nil on success.

vim.ui.select({items}, {opts}, {on_choice}) vim.ui.select()
Prompts the user to pick from a list of items, allowing arbitrary (potentially asynchronous) work until on_choice.

Example:

vim.ui.select({ 'tabs', 'spaces' }, {
    prompt = 'Select tabs or spaces:',
    format_item = function(item)
        return "I'd like to choose " .. item
    end,
}, function(choice)
    if choice == 'spaces' then
        vim.o.expandtab = true
    else
        vim.o.expandtab = false
    end
end)

Lua module: vim._extui vim._extui

WARNING: This is an experimental interface intended to replace the message grid in the TUI.

To enable the experimental UI (default opts shown):

require('vim._extui').enable({
 enable = true, -- Whether to enable or disable the UI.
 msg = { -- Options related to the message module.
   ---@type 'box'|'cmd' Type of window used to place messages, either in the
   ---cmdline or in a separate message box window with ephemeral messages.
   pos = 'cmd',
   box = { -- Options related to the message box window.
     timeout = 4000, -- Time a message is visible.
   },
 },
})

There are four separate window types used by this interface:

These four windows are assigned the "cmdline", "msgbox", "msgmore" and "msgprompt" 'filetype' respectively. Use a FileType autocommand to configure any local options for these windows and their respective buffers.

Lua module: vim.filetype vim.filetype

vim.filetype.add({filetypes}) vim.filetype.add()
Add new filetype mappings.

Filetype mappings can be added either by extension or by filename (either the "tail" or the full file path). The full file path is checked first, followed by the file name. If a match is not found using the filename, then the filename is matched against the list of lua-patterns (sorted by priority) until a match is found. Lastly, if pattern matching does not find a filetype, then the file extension is used.

The filetype can be either a string (in which case it is used as the filetype directly) or a function. If a function, it takes the full path and buffer number of the file as arguments (along with captures from the matched pattern, if any) and should return a string that will be used as the buffer's filetype. Optionally, the function can return a second function value which, when called, modifies the state of the buffer. This can be used to, for example, set filetype-specific buffer variables. This function will be called by Nvim before setting the buffer's filetype.

Filename patterns can specify an optional priority to resolve cases when a file path matches multiple patterns. Higher priorities are matched first. When omitted, the priority defaults to 0. A pattern can contain environment variables of the form "${SOME_VAR}" that will be automatically expanded. If the environment variable is not set, the pattern won't be matched.

See $VIMRUNTIME/lua/vim/filetype.lua for more examples.

Example:

vim.filetype.add({
  extension = {
    foo = 'fooscript',
    bar = function(path, bufnr)
      if some_condition() then
        return 'barscript', function(bufnr)
          -- Set a buffer variable
          vim.b[bufnr].barscript_version = 2
        end
      end
      return 'bar'
    end,
  },
  filename = {
    ['.foorc'] = 'toml',
    ['/etc/foo/config'] = 'toml',
  },
  pattern = {
    ['.*/etc/foo/.*'] = 'fooscript',
    -- Using an optional priority
    ['.*/etc/foo/.*%.conf'] = { 'dosini', { priority = 10 } },
    -- A pattern containing an environment variable
    ['${XDG_CONFIG_HOME}/foo/git'] = 'git',
    ['.*README.(%a+)'] = function(path, bufnr, ext)
      if ext == 'md' then
        return 'markdown'
      elseif ext == 'rst' then
        return 'rst'
      end
    end,
  },
})

To add a fallback match on contents, use

vim.filetype.add {
  pattern = {
    ['.*'] = {
      function(path, bufnr)
        local content = vim.api.nvim_buf_get_lines(bufnr, 0, 1, false)[1] or ''
        if vim.regex([[^#!.*\\<mine\\>]]):match_str(content) ~= nil then
          return 'mine'
        elseif vim.regex([[\\<drawing\\>]]):match_str(content) ~= nil then
          return 'drawing'
        end
      end,
      { priority = -math.huge },
    },
  },
}

vim.filetype.get_option()
vim.filetype.get_option({filetype}, {option}) Get the default option value for a {filetype}.

The returned value is what would be set in a new buffer after 'filetype' is set, meaning it should respect all FileType autocmds and ftplugin files.

Example:

vim.filetype.get_option('vim', 'commentstring')

Note: this uses nvim_get_option_value() but caches the result. This means ftplugin and FileType autocommands are only triggered once and may not reflect later changes.

Since: 0.9.0

(string|boolean|integer) Option value

vim.filetype.match({args}) vim.filetype.match()
Perform filetype detection.

The filetype can be detected using one of three methods: 1. Using an existing buffer 2. Using only a file name 3. Using only file contents

Of these, option 1 provides the most accurate result as it uses both the buffer's filename and (optionally) the buffer contents. Options 2 and 3 can be used without an existing buffer, but may not always provide a match in cases where the filename (or contents) cannot unambiguously determine the filetype.

Each of the three options is specified using a key to the single argument of this function. Example:

-- Using a buffer number
vim.filetype.match({ buf = 42 })
-- Override the filename of the given buffer
vim.filetype.match({ buf = 42, filename = 'foo.c' })
-- Using a filename without a buffer
vim.filetype.match({ filename = 'main.lua' })
-- Using file contents
vim.filetype.match({ contents = {'#!/usr/bin/env bash'} })

(string?) If a match was found, the matched filetype. (function?) A function that modifies buffer state when called (for example, to set some filetype specific buffer variables). The function accepts a buffer number as its only argument.

Lua module: vim.keymap vim.keymap

vim.keymap.del({modes}, {lhs}, {opts}) vim.keymap.del()
Remove an existing mapping. Examples:

vim.keymap.del('n', 'lhs')
vim.keymap.del({'n', 'i', 'v'}, '<leader>w', { buffer = 5 })

vim.keymap.set({mode}, {lhs}, {rhs}, {opts}) vim.keymap.set()
Defines a mapping of keycodes to a function or keycodes.

Examples:

-- Map "x" to a Lua function:
vim.keymap.set('n', 'x', function() print("real lua function") end)
-- Map "<leader>x" to multiple modes for the current buffer:
vim.keymap.set({'n', 'v'}, '<leader>x', vim.lsp.buf.references, { buffer = true })
-- Map <Tab> to an expression (|:map-<expr>|):
vim.keymap.set('i', '<Tab>', function()
  return vim.fn.pumvisible() == 1 and "<C-n>" or "<Tab>"
end, { expr = true })
-- Map "[%%" to a <Plug> mapping:
vim.keymap.set('n', '[%%', '<Plug>(MatchitNormalMultiBackward)')

Also accepts:

Lua module: vim.fs vim.fs

vim.fs.exists()
Use uv.fs_stat() to check a file's type, and whether it exists.

Example:

if vim.uv.fs_stat(file) then
  vim.print('file exists')
end

vim.fs.abspath({path}) vim.fs.abspath()
Convert path to an absolute path. A tilde (~) character at the beginning of the path is expanded to the user's home directory. Does not check if the path exists, normalize the path, resolve symlinks or hardlinks (including . and ..), or expand environment variables. If the path is already absolute, it is returned unchanged. Also converts \ path separators to /.

(string) Absolute path

vim.fs.basename({file}) vim.fs.basename()
Return the basename of the given path

Since: 0.8.0

(string?) Basename of {file}

vim.fs.dir({path}, {opts}) vim.fs.dir()
Return an iterator over the items located in {path}

Since: 0.8.0

(Iterator) over items in {path}. Each iteration yields two values: "name" and "type". "name" is the basename of the item relative to {path}. "type" is one of the following: "file", "directory", "link", "fifo", "socket", "char", "block", "unknown".

vim.fs.dirname({file}) vim.fs.dirname()
Gets the parent directory of the given path (not expanded/resolved, the caller must do that).

Since: 0.8.0

(string?) Parent directory of {file}

vim.fs.find({names}, {opts}) vim.fs.find()
Find files or directories (or other items as specified by opts.type) in the given path.

Finds items given in {names} starting from {path}. If {upward} is "true" then the search traverses upward through parent directories; otherwise, the search traverses downward. Note that downward searches are recursive and may search through many directories! If {stop} is non-nil, then the search stops when the directory given in {stop} is reached. The search terminates when {limit} (default 1) matches are found. You can set {type} to "file", "directory", "link", "socket", "char", "block", or "fifo" to narrow the search to find only that type.

Examples:

-- List all test directories under the runtime directory.
local dirs = vim.fs.find(
  { 'test', 'tst', 'testdir' },
  { limit = math.huge, type = 'directory', path = './runtime/' }
)
-- Get all "lib/*.cpp" and "lib/*.hpp" files, using Lua patterns.
-- Or use `vim.glob.to_lpeg(…):match(…)` for glob/wildcard matching.
local files = vim.fs.find(function(name, path)
  return name:match('.*%.[ch]pp$') and path:match('[/\\]lib$')
end, { limit = math.huge, type = 'file' })

Since: 0.8.0

The function should return true if the given item is considered a match.

(string[]) Normalized paths vim.fs.normalize() of all matching items

vim.fs.joinpath({...}) vim.fs.joinpath()
Concatenates partial paths (one absolute or relative path followed by zero or more relative paths). Slashes are normalized: redundant slashes are removed, and (on Windows) backslashes are replaced with forward-slashes.

Examples:

Since: 0.10.0

(string)

vim.fs.normalize({path}, {opts}) vim.fs.normalize()
Normalize a path to a standard format. A tilde (~) character at the beginning of the path is expanded to the user's home directory and environment variables are also expanded. "." and ".." components are also resolved, except when the path is relative and trying to resolve it would result in an absolute path.

On Windows, backslash (\) characters are converted to forward slashes (/).

Examples:

[[C:\Users\jdoe]]                         => "C:/Users/jdoe"
"~/src/neovim"                            => "/home/jdoe/src/neovim"
"$XDG_CONFIG_HOME/nvim/init.vim"          => "/Users/jdoe/.config/nvim/init.vim"
"~/src/nvim/api/../tui/./tui.c"           => "/home/jdoe/src/nvim/tui/tui.c"
"./foo/bar"                               => "foo/bar"
"foo/../../../bar"                        => "../../bar"
"/home/jdoe/../../../bar"                 => "/bar"
"C:foo/../../baz"                         => "C:../baz"
"C:/foo/../../baz"                        => "C:/baz"
[[\\?\UNC\server\share\foo\..\..\..\bar]] => "//?/UNC/server/share/bar"

Since: 0.8.0

(string) Normalized path

vim.fs.parents({start}) vim.fs.parents()
Iterate over all the parents of the given path (not expanded/resolved, the caller must do that).

Example:

local root_dir
for dir in vim.fs.parents(vim.api.nvim_buf_get_name(0)) do
  if vim.fn.isdirectory(dir .. '/.git') == 1 then
    root_dir = dir
    break
  end
end
if root_dir then
  print('Found git repository at', root_dir)
end

Since: 0.8.0

(fun(_, dir: string): string?) Iterator (nil) (string?)

vim.fs.relpath({base}, {target}, {opts}) vim.fs.relpath()
Gets target path relative to base, or nil if base is not an ancestor.

Example:

vim.fs.relpath('/var', '/var/lib') -- 'lib'
vim.fs.relpath('/var', '/usr/bin') -- nil

(string?)

vim.fs.rm({path}, {opts}) vim.fs.rm()
Remove files or directories

Since: 0.11.0

vim.fs.root({source}, {marker}) vim.fs.root()
Find the first parent directory containing a specific "marker", relative to a file path or buffer.

If the buffer is unnamed (has no backing file) or has a non-empty 'buftype' then the search begins from Nvim's current-directory.

Example:

-- Find the root of a Python project, starting from file 'main.py'
vim.fs.root(vim.fs.joinpath(vim.env.PWD, 'main.py'), {'pyproject.toml', 'setup.py' })
-- Find the root of a git repository
vim.fs.root(0, '.git')
-- Find the parent directory containing any file with a .csproj extension
vim.fs.root(0, function(name, path)
  return name:match('%.csproj$') ~= nil
end)

Since: 0.10.0

(string?) Directory path containing one of the given markers, or nil if no directory was found.

Lua module: vim.glob vim.glob

vim.glob.to_lpeg({pattern}) vim.glob.to_lpeg()
Parses a raw glob into an lua-lpeg pattern.

This uses glob semantics from LSP 3.17.0: https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#pattern

Glob patterns can have the following syntax:

(vim.lpeg.Pattern) pattern An lua-lpeg representation of the pattern

VIM.LPEG vim.lpeg

LPeg is a pattern-matching library for Lua, based on Parsing Expression Grammars (PEGs). https://bford.info/packrat/

lua-lpeg vim.lpeg.Pattern The LPeg library for parsing expression grammars is included as vim.lpeg (https://www.inf.puc-rio.br/~roberto/lpeg/).

In addition, its regex-like interface is available as vim.re (https://www.inf.puc-rio.br/~roberto/lpeg/re.html).

Pattern:match({subject}, {init}, {...}) Pattern:match()
Matches the given pattern against the subject string. If the match succeeds, returns the index in the subject of the first character after the match, or the captured values (if the pattern captured any value). An optional numeric argument init makes the match start at that position in the subject string. As usual in Lua libraries, a negative value counts from the end. Unlike typical pattern-matching functions, match works only in anchored mode; that is, it tries to match the pattern with a prefix of the given subject string (at position init), not with an arbitrary substring of the subject. So, if we want to find a pattern anywhere in a string, we must either write a loop in Lua or write a pattern that matches anywhere.

Example:

local pattern = lpeg.R('az') ^ 1 * -1
assert(pattern:match('hello') == 6)
assert(lpeg.match(pattern, 'hello') == 6)
assert(pattern:match('1 hello') == nil)

(any) ...

vim.lpeg.B({pattern}) vim.lpeg.B()
Returns a pattern that matches only if the input string at the current position is preceded by patt. Pattern patt must match only strings with some fixed length, and it cannot contain captures. Like the and predicate, this pattern never consumes any input, independently of success or failure.

(vim.lpeg.Pattern)

vim.lpeg.C({patt}) vim.lpeg.C()
Creates a simple capture, which captures the substring of the subject that matches patt. The captured value is a string. If patt has other captures, their values are returned after this one.

Example:

local function split (s, sep)
  sep = lpeg.P(sep)
  local elem = lpeg.C((1 - sep) ^ 0)
  local p = elem * (sep * elem) ^ 0
  return lpeg.match(p, s)
end
local a, b, c = split('a,b,c', ',')
assert(a == 'a')
assert(b == 'b')
assert(c == 'c')

(vim.lpeg.Capture)

vim.lpeg.Carg({n}) vim.lpeg.Carg()
Creates an argument capture. This pattern matches the empty string and produces the value given as the nth extra argument given in the call to lpeg.match.

(vim.lpeg.Capture)

vim.lpeg.Cb({name}) vim.lpeg.Cb()
Creates a back capture. This pattern matches the empty string and produces the values produced by the most recent group capture named name (where name can be any Lua value). Most recent means the last complete outermost group capture with the given name. A Complete capture means that the entire pattern corresponding to the capture has matched. An Outermost capture means that the capture is not inside another complete capture. In the same way that LPeg does not specify when it evaluates captures, it does not specify whether it reuses values previously produced by the group or re-evaluates them.

(vim.lpeg.Capture)

vim.lpeg.Cc({...}) vim.lpeg.Cc()
Creates a constant capture. This pattern matches the empty string and produces all given values as its captured values.

(vim.lpeg.Capture)

vim.lpeg.Cf({patt}, {func}) vim.lpeg.Cf()
Creates a fold capture. If patt produces a list of captures C1 C2 ... Cn, this capture will produce the value func(...func(func(C1, C2), C3)...,Cn), that is, it will fold (or accumulate, or reduce) the captures from patt using function func. This capture assumes that patt should produce at least one capture with at least one value (of any type), which becomes the initial value of an accumulator. (If you need a specific initial value, you may prefix a constant capture to patt.) For each subsequent capture, LPeg calls func with this accumulator as the first argument and all values produced by the capture as extra arguments; the first result from this call becomes the new value for the accumulator. The final value of the accumulator becomes the captured value.

Example:

local number = lpeg.R('09') ^ 1 / tonumber
local list = number * (',' * number) ^ 0
local function add(acc, newvalue) return acc + newvalue end
local sum = lpeg.Cf(list, add)
assert(sum:match('10,30,43') == 83)

(vim.lpeg.Capture)

vim.lpeg.Cg({patt}, {name}) vim.lpeg.Cg()
Creates a group capture. It groups all values returned by patt into a single capture. The group may be anonymous (if no name is given) or named with the given name (which can be any non-nil Lua value).

(vim.lpeg.Capture)

vim.lpeg.Cmt({patt}, {fn}) vim.lpeg.Cmt()
Creates a match-time capture. Unlike all other captures, this one is evaluated immediately when a match occurs (even if it is part of a larger pattern that fails later). It forces the immediate evaluation of all its nested captures and then calls function. The given function gets as arguments the entire subject, the current position (after the match of patt), plus any capture values produced by patt. The first value returned by function defines how the match happens. If the call returns a number, the match succeeds and the returned number becomes the new current position. (Assuming a subject sand current position i, the returned number must be in the range [i, len(s) + 1].) If the call returns true, the match succeeds without consuming any input (so, to return true is equivalent to return i). If the call returns false, nil, or no value, the match fails. Any extra values returned by the function become the values produced by the capture.

(vim.lpeg.Capture)

vim.lpeg.Cp() vim.lpeg.Cp()
Creates a position capture. It matches the empty string and captures the position in the subject where the match occurs. The captured value is a number.

Example:

local I = lpeg.Cp()
local function anywhere(p) return lpeg.P({I * p * I + 1 * lpeg.V(1)}) end
local match_start, match_end = anywhere('world'):match('hello world!')
assert(match_start == 7)
assert(match_end == 12)

(vim.lpeg.Capture)

vim.lpeg.Cs({patt}) vim.lpeg.Cs()
Creates a substitution capture. This function creates a substitution capture, which captures the substring of the subject that matches patt, with substitutions. For any capture inside patt with a value, the substring that matched the capture is replaced by the capture value (which should be a string). The final captured value is the string resulting from all replacements.

Example:

local function gsub (s, patt, repl)
  patt = lpeg.P(patt)
  patt = lpeg.Cs((patt / repl + 1) ^ 0)
  return lpeg.match(patt, s)
end
assert(gsub('Hello, xxx!', 'xxx', 'World') == 'Hello, World!')

(vim.lpeg.Capture)

vim.lpeg.Ct({patt}) vim.lpeg.Ct()
Creates a table capture. This capture returns a table with all values from all anonymous captures made by patt inside this table in successive integer keys, starting at 1. Moreover, for each named capture group created by patt, the first value of the group is put into the table with the group name as its key. The captured value is only the table.

(vim.lpeg.Capture)

vim.lpeg.locale({tab}) vim.lpeg.locale()
Returns a table with patterns for matching some character classes according to the current locale. The table has fields named alnum, alpha, cntrl, digit, graph, lower, print, punct, space, upper, and xdigit, each one containing a correspondent pattern. Each pattern matches any single character that belongs to its class. If called with an argument table, then it creates those fields inside the given table and returns that table.

Example:

lpeg.locale(lpeg)
local space = lpeg.space ^ 0
local name = lpeg.C(lpeg.alpha ^ 1) * space
local sep = lpeg.S(',;') * space
local pair = lpeg.Cg(name * '=' * space * name) * sep ^ -1
local list = lpeg.Cf(lpeg.Ct('') * pair ^ 0, rawset)
local t = list:match('a=b, c = hi; next = pi')
assert(t.a == 'b')
assert(t.c == 'hi')
assert(t.next == 'pi')
local locale = lpeg.locale()
assert(type(locale.digit) == 'userdata')

(vim.lpeg.Locale)

vim.lpeg.match({pattern}, {subject}, {init}, {...}) vim.lpeg.match()
Matches the given pattern against the subject string. If the match succeeds, returns the index in the subject of the first character after the match, or the captured values (if the pattern captured any value). An optional numeric argument init makes the match start at that position in the subject string. As usual in Lua libraries, a negative value counts from the end. Unlike typical pattern-matching functions, match works only in anchored mode; that is, it tries to match the pattern with a prefix of the given subject string (at position init), not with an arbitrary substring of the subject. So, if we want to find a pattern anywhere in a string, we must either write a loop in Lua or write a pattern that matches anywhere.

Example:

local pattern = lpeg.R('az') ^ 1 * -1
assert(pattern:match('hello') == 6)
assert(lpeg.match(pattern, 'hello') == 6)
assert(pattern:match('1 hello') == nil)

(any) ...

vim.lpeg.P({value}) vim.lpeg.P()
Converts the given value into a proper pattern. The following rules are applied:

(vim.lpeg.Pattern)

vim.lpeg.R({...}) vim.lpeg.R()
Returns a pattern that matches any single character belonging to one of the given ranges. Each range is a string xy of length 2, representing all characters with code between the codes of x and y (both inclusive). As an example, the pattern lpeg.R('09') matches any digit, and lpeg.R('az', 'AZ') matches any ASCII letter.

Example:

local pattern = lpeg.R('az') ^ 1 * -1
assert(pattern:match('hello') == 6)

(vim.lpeg.Pattern)

vim.lpeg.S({string}) vim.lpeg.S()
Returns a pattern that matches any single character that appears in the given string (the S stands for Set). As an example, the pattern lpeg.S('+-*/') matches any arithmetic operator. Note that, if s is a character (that is, a string of length 1), then lpeg.P(s) is equivalent to lpeg.S(s) which is equivalent to lpeg.R(s..s). Note also that both lpeg.S('') and lpeg.R() are patterns that always fail.

(vim.lpeg.Pattern)

vim.lpeg.setmaxstack({max}) vim.lpeg.setmaxstack()
Sets a limit for the size of the backtrack stack used by LPeg to track calls and choices. The default limit is 400. Most well-written patterns need little backtrack levels and therefore you seldom need to change this limit; before changing it you should try to rewrite your pattern to avoid the need for extra space. Nevertheless, a few useful patterns may overflow. Also, with recursive grammars, subjects with deep recursion may also need larger limits.

vim.lpeg.type({value}) vim.lpeg.type()
Returns the string "pattern" if the given value is a pattern, otherwise nil.

("pattern"?)

vim.lpeg.V({v}) vim.lpeg.V()
Creates a non-terminal (a variable) for a grammar. This operation creates a non-terminal (a variable) for a grammar. The created non-terminal refers to the rule indexed by v in the enclosing grammar.

Example:

local b = lpeg.P({'(' * ((1 - lpeg.S '()') + lpeg.V(1)) ^ 0 * ')'})
assert(b:match('((string))') == 11)
assert(b:match('(') == nil)

(vim.lpeg.Pattern)

vim.lpeg.version() vim.lpeg.version()
Returns a string with the running version of LPeg.

(string)

VIM.RE vim.re

The vim.re module provides a conventional regex-like syntax for pattern usage within LPeg vim.lpeg. (Unrelated to vim.regex which provides Vim regexp from Lua.)

See https://www.inf.puc-rio.br/~roberto/lpeg/re.html for the original documentation including regex syntax and examples.

vim.re.compile({string}, {defs}) vim.re.compile()
Compiles the given {string} and returns an equivalent LPeg pattern. The given string may define either an expression or a grammar. The optional {defs} table provides extra Lua values to be used by the pattern.

(vim.lpeg.Pattern)

vim.re.find({subject}, {pattern}, {init}) vim.re.find()
Searches the given {pattern} in the given {subject}. If it finds a match, returns the index where this occurrence starts and the index where it ends. Otherwise, returns nil.

An optional numeric argument {init} makes the search starts at that position in the subject string. As usual in Lua libraries, a negative value counts from the end.

(integer?) the index where the occurrence starts, nil if no match (integer?) the index where the occurrence ends, nil if no match

vim.re.gsub({subject}, {pattern}, {replacement}) vim.re.gsub()
Does a global substitution, replacing all occurrences of {pattern} in the given {subject} by {replacement}.

(string)

vim.re.match({subject}, {pattern}, {init}) vim.re.match()
Matches the given {pattern} against the given {subject}, returning all captures.

(integer|vim.lpeg.Capture?)

vim.re.updatelocale() vim.re.updatelocale()
Updates the pre-defined character classes to the current locale.

VIM.REGEX vim.regex

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

regex:match_line()
regex:match_line({bufnr}, {line_idx}, {start}, {end_}) Matches line at line_idx (zero-based) in buffer bufnr. Match is restricted to byte index range start and end_ if given, otherwise see regex:match_str(). Returned byte indices are relative to start if given.

(integer?) match start (byte index) relative to start, or nil if no match (integer?) match end (byte index) relative to start, or nil if no match

regex:match_str({str}) regex:match_str()
Matches string str against this regex. To match the string precisely, surround the regex with "^" and "$". Returns the byte indices for the start and end of the match, or nil if there is no match. Because any integer is "truthy", regex:match_str() can be directly used as a condition in an if-statement.

(integer?) match start (byte index), or nil if no match (integer?) match end (byte index), or nil if no match

vim.regex({re}) vim.regex()
Parses the Vim regex re and returns a regex object. Regexes are "magic" and case-sensitive by default, regardless of 'magic' and 'ignorecase'. They can be controlled with flags, see /magic and /ignorecase.

(vim.regex)

Lua module: vim.secure vim.secure

vim.secure.read({path}) vim.secure.read()
If {path} is a file: attempt to read the file, prompting the user if the file should be trusted.

If {path} is a directory: return true if the directory is trusted (non-recursive), prompting the user as necessary.

The user's choice is persisted in a trust database at $XDG_STATE_HOME/nvim/trust.

Since: 0.9.0

(boolean|string?) If {path} is not trusted or does not exist, returns nil. Otherwise, returns the contents of {path} if it is a file, or true if {path} is a directory.

vim.secure.trust({opts}) vim.secure.trust()
Manage the trust database.

The trust database is located at $XDG_STATE_HOME/nvim/trust.

Since: 0.9.0

(boolean) success true if operation was successful (string) msg full path if operation was successful, else error message

Lua module: vim.version vim.version

The vim.version module provides functions for comparing versions and ranges conforming to the https://semver.org spec. Plugins, and plugin managers, can use this to check available tools and dependencies on the current system.

Example:

local v = vim.version.parse(vim.fn.system({'tmux', '-V'}), {strict=false})
if vim.version.gt(v, {3, 2, 0}) then
  -- ...
end

vim.version() returns the version of the current Nvim process.

VERSION RANGE SPEC version-range

A version "range spec" defines a semantic version range which can be tested against a version, using vim.version.range().

Supported range specs are shown in the following table. Note: suffixed versions (1.2.3-rc1) are not matched.

1.2.3             is 1.2.3
=1.2.3            is 1.2.3
>1.2.3            greater than 1.2.3
<1.2.3            before 1.2.3
>=1.2.3           at least 1.2.3
~1.2.3            is >=1.2.3 <1.3.0       "reasonably close to 1.2.3"
^1.2.3            is >=1.2.3 <2.0.0       "compatible with 1.2.3"
^0.2.3            is >=0.2.3 <0.3.0       (0.x.x is special)
^0.0.1            is =0.0.1               (0.0.x is special)
^1.2              is >=1.2.0 <2.0.0       (like ^1.2.0)
~1.2              is >=1.2.0 <1.3.0       (like ~1.2.0)
^1                is >=1.0.0 <2.0.0       "compatible with 1"
~1                same                    "reasonably close to 1"
1.x               same
1.*               same
1                 same
*                 any version
x                 same
1.2.3 - 2.3.4     is >=1.2.3 <=2.3.4
Partial right: missing pieces treated as x (2.3 => 2.3.x).
1.2.3 - 2.3       is >=1.2.3 <2.4.0
1.2.3 - 2         is >=1.2.3 <3.0.0
Partial left: missing pieces treated as 0 (1.2 => 1.2.0).
1.2 - 2.3.0       is 1.2.0 - 2.3.0

vim.version.cmp({v1}, {v2}) vim.version.cmp()
Parses and compares two version objects (the result of vim.version.parse(), or specified literally as a {major, minor, patch} tuple, e.g. {1, 0, 3}).

Example:

if vim.version.cmp({1,0,3}, {0,2,1}) == 0 then
  -- ...
end
local v1 = vim.version.parse('1.0.3-pre')
local v2 = vim.version.parse('0.2.1')
if vim.version.cmp(v1, v2) == 0 then
  -- ...
end

Since: 0.9.0

(integer) -1 if v1 < v2, 0 if v1 == v2, 1 if v1 > v2.

vim.version.eq({v1}, {v2}) vim.version.eq()
Returns true if the given versions are equal. See vim.version.cmp() for usage.

Since: 0.9.0

(boolean)

vim.version.ge({v1}, {v2}) vim.version.ge()
Returns true if v1 >= v2. See vim.version.cmp() for usage.

Since: 0.10.0

(boolean)

vim.version.gt({v1}, {v2}) vim.version.gt()
Returns true if v1 > v2. See vim.version.cmp() for usage.

Since: 0.9.0

(boolean)

vim.version.last({versions}) vim.version.last()
TODO: generalize this, move to func.lua

(vim.Version?)

vim.version.le({v1}, {v2}) vim.version.le()
Returns true if v1 <= v2. See vim.version.cmp() for usage.

Since: 0.10.0

(boolean)

vim.version.lt({v1}, {v2}) vim.version.lt()
Returns true if v1 < v2. See vim.version.cmp() for usage.

Since: 0.9.0

(boolean)

vim.version.parse({version}, {opts}) vim.version.parse()
Parses a semantic version string and returns a version object which can be used with other vim.version functions. For example "1.0.1-rc1+build.2" returns:

{ major = 1, minor = 0, patch = 1, prerelease = "rc1", build = "build.2" }

Since: 0.9.0

(vim.Version?) parsed_version Version object or nil if input is invalid.

vim.version.range({spec}) vim.version.range()
Parses a semver version-range "spec" and returns a range object:

{
  from: Version
  to: Version
  has(v: string|Version)
}

:has() checks if a version is in the range (inclusive from, exclusive to).

Example:

local r = vim.version.range('1.0.0 - 2.0.0')
print(r:has('1.9.9'))       -- true
print(r:has('2.0.0'))       -- false
print(r:has(vim.version())) -- check against current Nvim version

Or use cmp(), le(), lt(), ge(), gt(), and/or eq() to compare a version against .to and .from directly:

local r = vim.version.range('1.0.0 - 2.0.0') -- >=1.0, <2.0
print(vim.version.ge({1,0,3}, r.from) and vim.version.lt({1,0,3}, r.to))

Since: 0.9.0

(table?) A table with the following fields:

Lua module: vim.iter vim.iter

vim.iter() is an interface for iterables: it wraps a table or function argument into an Iter object with methods (such as Iter:filter() and Iter:map()) that transform the underlying source data. These methods can be chained to create iterator "pipelines": the output of each pipeline stage is input to the next stage. The first stage depends on the type passed to vim.iter():

The iterator pipeline terminates when the underlying iterable is exhausted (for function iterators this means it returned nil).

Note: vim.iter() scans table input to decide if it is a list or a dict; to avoid this cost you can wrap the table with an iterator e.g. vim.iter(ipairs({…})), but that precludes the use of list-iterator operations such as Iter:rev()).

Examples:

local it = vim.iter({ 1, 2, 3, 4, 5 })
it:map(function(v)
  return v * 3
end)
it:rev()
it:skip(2)
it:totable()
-- { 9, 6, 3 }
-- ipairs() is a function iterator which returns both the index (i) and the value (v)
vim.iter(ipairs({ 1, 2, 3, 4, 5 })):map(function(i, v)
  if i > 2 then return v end
end):totable()
-- { 3, 4, 5 }
local it = vim.iter(vim.gsplit('1,2,3,4,5', ','))
it:map(function(s) return tonumber(s) end)
for i, d in it:enumerate() do
  print(string.format("Column %d is %d", i, d))
end
-- Column 1 is 1
-- Column 2 is 2
-- Column 3 is 3
-- Column 4 is 4
-- Column 5 is 5
vim.iter({ a = 1, b = 2, c = 3, z = 26 }):any(function(k, v)
  return k == 'z'
end)
-- true
local rb = vim.ringbuf(3)
rb:push("a")
rb:push("b")
vim.iter(rb):totable()
-- { "a", "b" }

Iter:all({pred}) Iter:all()
Returns true if all items in the iterator match the given predicate.

Iter:any({pred}) Iter:any()
Returns true if any of the items in the iterator match the given predicate.

Iter:each({f}) Iter:each()
Calls a function once for each item in the pipeline, draining the iterator.

For functions with side effects. To modify the values in the iterator, use Iter:map().

Iter:enumerate() Iter:enumerate()
Yields the item index (count) and value for each item of an iterator pipeline.

For list tables, this is more efficient:

vim.iter(ipairs(t))

instead of:

vim.iter(t):enumerate()

Example:

local it = vim.iter(vim.gsplit('abc', '')):enumerate()
it:next()
-- 1	'a'
it:next()
-- 2	'b'
it:next()
-- 3	'c'

(Iter)

Iter:filter({f}) Iter:filter()
Filters an iterator pipeline.

Example:

local bufs = vim.iter(vim.api.nvim_list_bufs()):filter(vim.api.nvim_buf_is_loaded)

(Iter)

Iter:find({f}) Iter:find()
Find the first value in the iterator that satisfies the given predicate.

Advances the iterator. Returns nil and drains the iterator if no value is found.

Examples:

local it = vim.iter({ 3, 6, 9, 12 })
it:find(12)
-- 12
local it = vim.iter({ 3, 6, 9, 12 })
it:find(20)
-- nil
local it = vim.iter({ 3, 6, 9, 12 })
it:find(function(v) return v % 4 == 0 end)
-- 12

(any)

Iter:flatten({depth}) Iter:flatten()
Flattens a list-iterator, un-nesting nested values up to the given {depth}. Errors if it attempts to flatten a dict-like value.

Examples:

vim.iter({ 1, { 2 }, { { 3 } } }):flatten():totable()
-- { 1, 2, { 3 } }
vim.iter({1, { { a = 2 } }, { 3 } }):flatten():totable()
-- { 1, { a = 2 }, 3 }
vim.iter({ 1, { { a = 2 } }, { 3 } }):flatten(math.huge):totable()
-- error: attempt to flatten a dict-like table

(Iter)

Iter:fold({init}, {f}) Iter:fold()
Folds ("reduces") an iterator into a single value. Iter:reduce()

Examples:

-- Create a new table with only even values
vim.iter({ a = 1, b = 2, c = 3, d = 4 })
  :filter(function(k, v) return v % 2 == 0 end)
  :fold({}, function(acc, k, v)
    acc[k] = v
    return acc
  end) --> { b = 2, d = 4 }
-- Get the "maximum" item of an iterable.
vim.iter({ -99, -4, 3, 42, 0, 0, 7 })
  :fold({}, function(acc, v)
    acc.max = math.max(v, acc.max or v)
    return acc
  end) --> { max = 42 }

(any)

Iter:join({delim}) Iter:join()
Collect the iterator into a delimited string.

Each element in the iterator is joined into a string separated by {delim}.

Consumes the iterator.

(string)

Iter:last() Iter:last()
Drains the iterator and returns the last item.

Example:

local it = vim.iter(vim.gsplit('abcdefg', ''))
it:last()
-- 'g'
local it = vim.iter({ 3, 6, 9, 12, 15 })
it:last()
-- 15

(any)

Iter:map({f}) Iter:map()
Maps the items of an iterator pipeline to the values returned by f.

If the map function returns nil, the value is filtered from the iterator.

Example:

local it = vim.iter({ 1, 2, 3, 4 }):map(function(v)
  if v % 2 == 0 then
    return v * 3
  end
end)
it:totable()
-- { 6, 12 }

(Iter)

Iter:next() Iter:next()
Gets the next value from the iterator.

Example:

local it = vim.iter(string.gmatch('1 2 3', '%d+')):map(tonumber)
it:next()
-- 1
it:next()
-- 2
it:next()
-- 3

(any)

Iter:nth({n}) Iter:nth()
Gets the nth value of an iterator (and advances to it).

If n is negative, offsets from the end of a list-iterator.

Example:

local it = vim.iter({ 3, 6, 9, 12 })
it:nth(2)
-- 6
it:nth(2)
-- 12
local it2 = vim.iter({ 3, 6, 9, 12 })
it2:nth(-2)
-- 9
it2:nth(-2)
-- 3

(any)

Iter:peek() Iter:peek()
Gets the next value in a list-iterator without consuming it.

Example:

local it = vim.iter({ 3, 6, 9, 12 })
it:peek()
-- 3
it:peek()
-- 3
it:next()
-- 3

(any)

Iter:pop() Iter:pop()
"Pops" a value from a list-iterator (gets the last value and decrements the tail).

Example:

local it = vim.iter({1, 2, 3, 4})
it:pop()
-- 4
it:pop()
-- 3

(any)

Iter:rev() Iter:rev()
Reverses a list-iterator pipeline.

Example:

local it = vim.iter({ 3, 6, 9, 12 }):rev()
it:totable()
-- { 12, 9, 6, 3 }

(Iter)

Iter:rfind({f}) Iter:rfind()
Gets the first value satisfying a predicate, from the end of a list-iterator.

Advances the iterator. Returns nil and drains the iterator if no value is found.

Examples:

local it = vim.iter({ 1, 2, 3, 2, 1 }):enumerate()
it:rfind(1)
-- 5	1
it:rfind(1)
-- 1	1

(any)

Iter:rpeek() Iter:rpeek()
Gets the last value of a list-iterator without consuming it.

Example:

local it = vim.iter({1, 2, 3, 4})
it:rpeek()
-- 4
it:rpeek()
-- 4
it:pop()
-- 4

(any)

Iter:rskip({n}) Iter:rskip()
Discards n values from the end of a list-iterator pipeline.

Example:

local it = vim.iter({ 1, 2, 3, 4, 5 }):rskip(2)
it:next()
-- 1
it:pop()
-- 3

(Iter)

Iter:skip({n}) Iter:skip()
Skips n values of an iterator pipeline.

Example:

local it = vim.iter({ 3, 6, 9, 12 }):skip(2)
it:next()
-- 9

(Iter)

Iter:slice({first}, {last}) Iter:slice()
Sets the start and end of a list-iterator pipeline.

Equivalent to :skip(first - 1):rskip(len - last + 1).

(Iter)

Iter:take({n}) Iter:take()
Transforms an iterator to yield only the first n values.

Example:

local it = vim.iter({ 1, 2, 3, 4 }):take(2)
it:next()
-- 1
it:next()
-- 2
it:next()
-- nil

(Iter)

Iter:totable() Iter:totable()
Collect the iterator into a table.

The resulting table depends on the initial source in the iterator pipeline. Array-like tables and function iterators will be collected into an array-like table. If multiple values are returned from the final stage in the iterator pipeline, each value will be included in a table.

Examples:

vim.iter(string.gmatch('100 20 50', '%d+')):map(tonumber):totable()
-- { 100, 20, 50 }
vim.iter({ 1, 2, 3 }):map(function(v) return v, 2 * v end):totable()
-- { { 1, 2 }, { 2, 4 }, { 3, 6 } }
vim.iter({ a = 1, b = 2, c = 3 }):filter(function(k, v) return v % 2 ~= 0 end):totable()
-- { { 'a', 1 }, { 'c', 3 } }

The generated table is an array-like table with consecutive, numeric indices. To create a map-like table with arbitrary keys, use Iter:fold().

(table)

Lua module: vim.snippet vim.snippet

vim.snippet.ActiveFilter

vim.snippet.active({filter}) vim.snippet.active()
Returns true if there's an active snippet in the current buffer, applying the given filter if provided.

(boolean)

vim.snippet.expand({input}) vim.snippet.expand()
Expands the given snippet text. Refer to https://microsoft.github.io/language-server-protocol/specification/#snippet_syntax for the specification of valid input.

Tabstops are highlighted with hl-SnippetTabstop.

vim.snippet.jump({direction}) vim.snippet.jump()
Jumps to the next (or previous) placeholder in the current snippet, if possible.

By default <Tab> is setup to jump if a snippet is active. The default mapping looks like:

vim.keymap.set({ 'i', 's' }, '<Tab>', function()
   if vim.snippet.active({ direction = 1 }) then
     return '<Cmd>lua vim.snippet.jump(1)<CR>'
   else
     return '<Tab>'
   end
 end, { descr = '...', expr = true, silent = true })

vim.snippet.stop() vim.snippet.stop()
Exits the current snippet.

Lua module: vim.text vim.text

vim.text.hexdecode({enc}) vim.text.hexdecode()
Hex decode a string.

(string?) Decoded string (string?) Error message, if any

vim.text.hexencode({str}) vim.text.hexencode()
Hex encode a string.

(string) Hex encoded string

vim.text.indent({size}, {text}, {opts}) vim.text.indent()
Sets the indent (i.e. the common leading whitespace) of non-empty lines in text to size spaces/tabs.

Indent is calculated by number of consecutive indent chars.

To "dedent" (remove the common indent), pass size=0:

vim.print(vim.text.indent(0, ' a\n  b\n'))

To adjust relative-to an existing indent, call indent() twice:

local indented, old_indent = vim.text.indent(0, ' a\n b\n')
indented = vim.text.indent(old_indent + 2, indented)
vim.print(indented)

To ignore the final, blank line when calculating the indent, use gsub() before calling indent():

local text = '  a\n  b\n '
vim.print(vim.text.indent(0, (text:gsub('\n[\t ]+\n?$', '\n'))))

(string) Indented text. (integer) Indent size before modification.

Lua module: tohtml vim.tohtml

:[range]TOhtml {file} :TOhtml
Converts the buffer shown in the current window to HTML, opens the generated HTML in a new split window, and saves its contents to {file}. If {file} is not given, a temporary file (created by tempname()) is used.

tohtml.tohtml({winid}, {opt}) tohtml.tohtml.tohtml()
Converts the buffer shown in the window {winid} to HTML and returns the output as a list of string.

(string[])