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" (builtin-functions and Ex-commands) and the API, all of which can be used from Lua code (lua-vimscript vim.api). Together these "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 need only consider Lua 5.1, not worry about forward-compatibility with future Lua versions. If Nvim ever ships with Lua 5.4+, a Lua 5.1 compatibility shim will be provided so that old plugins continue to work transparently.

lua-luajit Nvim is built with luajit on platforms which support it, which provides extra functionality. Lua code in init.lua and plugins can assume its presence on installations on common platforms. For maximum compatibility with less common platforms, availability can be checked using the jit global variable:

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

lua-bit In particular, the luajit "bit" extension module is _always_ available. A fallback implementation is included when nvim is built with PUC Lua 5.1, and will be transparently used when require("bit") is invoked.

LUA CONCEPTS AND IDIOMS lua-concepts

Lua is very simple: this means that, 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

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.

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 treated as whitespace. But visually, this small bit of sugar gets reasonably close to a "keyword args" interface. Nvim code tends to prefer this style.

LUA PATTERNS lua-patterns

Lua intentionally does not support regular expressions, instead it has limited "patterns" lua-pattern 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', in the order they appear. 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

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

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

The result will look like this:

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

Note:

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 or :=expr is 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

: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("Current line [%d] has %d bytes",
        linenr, #curline))
EOF
endfunction

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

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

Examples:

:luado return string.format("%s\t%d", line:reverse(), #line)
:lua require"lpeg"
:lua -- balanced parenthesis grammar:
:lua bp = lpeg.P{ "(" * ((1 - lpeg.S"()") + lpeg.V(1))^0 * ")" }
:luado if bp:match(line) then return "=>\t" .. line end

:luafile :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 determine whether empty table is meant to be empty list or empty dictionary. Additionally Lua does not have integer numbers. To distinguish between these cases there is the following agreement: lua-list 0. Empty table is empty list. 1. Table with N incrementally growing integral numbers, starting from 1 and ending with N is considered to be a list. lua-dict 2. Table with string keys, none of which contains NUL byte, is considered to be a dictionary. 3. Table with string keys, at least one of which contains NUL byte, is also considered to be a dictionary, but this time it is converted to a msgpack-special-map. lua-special-tbl 4. Table with vim.type_idx key may be a dictionary, a list or floating-point value:

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(...)

In addition, functions of packages 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 prefixes do NOT work (the latter is still valid as a function call of itself, in case require returns a useful value).

The v:lua prefix may be used to call Lua functions as methods. For example:

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

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

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

Note: The module ("mymod" in the above example) must either be a Lua global, or use require() as shown above to access it from a package.

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>'))")

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. Note that every thread gets its own separate Lua interpreter state, with no access to Lua globals in the main thread. Neither can the state of the editor (buffers, windows, etc) be directly accessed from threads.

A subset of the vim.* API is available in threads. This includes:

VIM.LPEG lua-lpeg

vim.lpeg vim.re The Lpeg library for parsing expression grammars is being 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).

VIM.HIGHLIGHT vim.highlight

Nvim includes a function for highlighting a selection on yank.

To enable it, add the following to your init.vim:

au TextYankPost * silent! lua vim.highlight.on_yank()

You can customize the highlight group and the duration of the highlight via:

au TextYankPost * silent! lua vim.highlight.on_yank {higroup="IncSearch", timeout=150}

If you want to exclude visual selections from highlighting on yank, use:

au TextYankPost * silent! lua vim.highlight.on_yank {on_visual=false}

vim.highlight.on_yank({opts}) vim.highlight.on_yank() Highlight the yanked text

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

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

VIM.REGEX vim.regex

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

vim.regex({re}) vim.regex() Parse the Vim regex {re} and return 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

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

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

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|table|nil 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.

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

(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}
-- }

{[1]: string, [2]: string, [3]: string}[] 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.

vim.iconv({str}, {from}, {to}, {opts}) 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|nil) 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}, {args}, {...}) vim.rpcnotify() Sends {event} to {channel} via RPC and returns immediately. If {channel} is 0, the event is broadcast to all channels.

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

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

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

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

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

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

vim.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)

(number)

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.

(table)

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)

(number)

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

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

(integer) UTF-32 index (integer) UTF-16 index

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}, {options}, {callback}) vim.ui_attach() Attach to ui events, similar to nvim_ui_attach() but receive events as Lua callback. Can be used to implement screen elements like popupmenu or message handling in Lua.

{options} should be a dictionary-like table, where ext_... options should be set to true to receive events for the respective external element.

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

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.

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

Note: this is equivalent to both :set and :setlocal.

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. Like :set. Invalid key is an error.

Note: this works on both buffer-scoped and window-scoped options using the current buffer and window.

Example:

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

vim.wo vim.wo Get or set window-scoped options for the window with handle {winid} and buffer with number {bufnr}. Like :setlocal 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 vim.cmd() Execute Vim script 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|nil) 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() Translate 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() Display 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() Display 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}) 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() when a conforming UI (such as the TUI) pastes text into the editor.

Example: To remove ANSI color codes when pasting:

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

(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_by_name('Normal', true))

any given arguments.

vim.region() vim.region({bufnr}, {pos1}, {pos2}, {regtype}, {inclusive}) Gets a dict of line segment ("chunk") positions for the region from pos1 to pos2.

Input and output positions are byte positions, (0,0)-indexed. "End of line" column position (for example, linewise visual selection) is returned as v:maxcol (big number).

(table) region Dict of the form {linenr = {startcol,endcol}}. endcol is exclusive, and whole lines are returned as {startcol,endcol} = {0,-1}.

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

(function)

vim.system({cmd}, {opts}, {on_exit}) vim.system() Run a system command

Examples:

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

See uv.spawn() for more details.

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!

(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

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}) 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.

(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

(function) 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.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)

(list) 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:

(table)

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

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

any?|nil

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

any?|nil

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

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

(function) for-in iterator over sorted keys and their values

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

Note that this modifies the input.

(table) o

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.

(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

(table) Table of filtered values

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

(table) Flattened copy of the given list-like table

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

(boolean) true if t is empty

vim.tbl_islist({t}) vim.tbl_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.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.

(list) 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.

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

Usage example:

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

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

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

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

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

2. (arg_value, fn, msg)

Lua module: vim.loader vim.loader

vim.loader.disable() vim.loader.disable() Disables the experimental Lua module loader:

vim.loader.enable() vim.loader.enable() Enables the experimental Lua module loader:

vim.loader.find({modname}, {opts}) vim.loader.find() Finds Lua modules for the given module name.

(list) A list of results with the following properties:

vim.loader.reset({path}) vim.loader.reset() 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}) 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.

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

Examples:

vim.ui.open("https://neovim.io/")
vim.ui.open("~/path/to/file")
vim.ui.open("$VIMRUNTIME")

vim.SystemCompleted|nil Command result, or nil if not found. (string|nil) Error message on failure

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.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 = {
    ['.*'] = {
      priority = -math.huge,
      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,
    },
  },
}

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.

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|nil) If a match was found, the matched filetype. (function|nil) 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() Adds a new mapping. Examples:

-- Map to a Lua function:
vim.keymap.set('n', 'lhs', function() print("real lua function") end)
-- Map to multiple modes:
vim.keymap.set({'n', 'v'}, '<leader>lr', vim.lsp.buf.references, { buffer = true })
-- Buffer-local mapping:
vim.keymap.set('n', '<leader>w', "<cmd>w<cr>", { silent = true, buffer = 5 })
-- Expr mapping:
vim.keymap.set('i', '<Tab>', function()
  return vim.fn.pumvisible() == 1 and "<C-n>" or "<Tab>"
end, { expr = true })
-- <Plug> mapping:
vim.keymap.set('n', '[%%', '<Plug>(MatchitNormalMultiBackward)')

Lua module: vim.fs vim.fs

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

(string|nil) Basename of {file}

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

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() Return the parent directory of the given path

(string|nil) 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:

-- location of Cargo.toml from the current buffer's path
local cargo = vim.fs.find('Cargo.toml', {
  upward = true,
  stop = vim.uv.os_homedir(),
  path = vim.fs.dirname(vim.api.nvim_buf_get_name(0)),
})
-- list all test directories under the runtime directory
local test_dirs = vim.fs.find(
  {'test', 'tst', 'testdir'},
  {limit = math.huge, type = 'directory', path = './runtime/'}
)
-- get all files ending with .cpp or .hpp inside lib/
local cpp_hpp = vim.fs.find(function(name, path)
  return name:match('.*%.[ch]pp$') and path:match('[/\\\\]lib$')
end, {limit = math.huge, type = 'file'})

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

vim.fs.joinpath({...}) vim.fs.joinpath() Concatenate directories and/or file paths into a single path with normalization (e.g., "foo/" and "bar" get joined to "foo/bar")

(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 any backslash (\) characters are converted to forward slashes (/). Environment variables are also expanded.

Examples:

vim.fs.normalize('C:\\\\Users\\\\jdoe')
-- 'C:/Users/jdoe'
vim.fs.normalize('~/src/neovim')
-- '/home/jdoe/src/neovim'
vim.fs.normalize('$XDG_CONFIG_HOME/nvim/init.vim')
-- '/Users/jdoe/.config/nvim/init.vim'

(string) Normalized path

vim.fs.parents({start}) vim.fs.parents() Iterate over all the parents of the given path.

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

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

Lua module: vim.secure vim.secure

vim.secure.read({path}) vim.secure.read() Attempt to read the file at {path} prompting the user if the file should be trusted. The user's choice is persisted in a trust database at $XDG_STATE_HOME/nvim/trust.

(string|nil) The contents of the given file if it exists and is trusted, or nil otherwise.

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

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

(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

(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.

(boolean)

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

(boolean)

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

Version ?|nil

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

(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" }

(table|nil) 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(), eq(), lt(), and gt() to compare .to and .from directly:

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

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 together to create iterator "pipelines". Each pipeline stage receives as input the output values from the prior stage. The values used in the first stage of the pipeline depend on the type passed to this function:

The iterator pipeline terminates when the original table or function iterator runs out of values (for function iterators, this means that the first value returned by the function is nil).

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" }

In addition to the vim.iter() function, the vim.iter module provides convenience functions like vim.iter.filter() and vim.iter.totable().

filter({f}, {src}, {...}) vim.iter.filter() Filter a table or iterator.

This is a convenience function that performs:

vim.iter(src):filter(f):totable()

(table)

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

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

Iter:each({f}) Iter:each() Call a function once for each item in the pipeline.

This is used for functions which have side effects. To modify the values in the iterator, use Iter:map().

This function drains the iterator.

Iter:enumerate() Iter:enumerate() Add an iterator stage that returns the current iterator count as well as the iterator value.

For list tables, prefer

vim.iter(ipairs(t))

over

vim.iter(t):enumerate()

as the former is faster.

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() Add a filter step to the 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:fold({init}, {f}) Iter:fold() Fold ("reduce") an iterator or table into a single value.

Examples:

-- Create a new table with only even values
local t = { a = 1, b = 2, c = 3, d = 4 }
local it = vim.iter(t)
it:filter(function(k, v) return v % 2 == 0 end)
it:fold({}, function(t, k, v)
  t[k] = v
  return t
end)
-- { b = 2, d = 4 }

any

Iter:last() Iter:last() Return the last item in the iterator.

Drains the iterator.

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() Add a map step to the iterator pipeline.

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() Return 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:nextback() Iter:nextback() Return the next value from the end of the iterator.

Only supported for iterators on list-like tables.

Example:

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

any

Iter:nth({n}) Iter:nth() Return the nth value in the iterator.

This function advances the iterator.

Example:

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

any

Iter:nthback({n}) Iter:nthback() Return the nth value from the end of the iterator.

This function advances the iterator.

Only supported for iterators on list-like tables.

Example:

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

any

Iter:peek() Iter:peek() Peek at the next value in the iterator without consuming it.

Only supported for iterators on list-like tables.

Example:

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

any

Iter:peekback() Iter:peekback() Return the next value from the end of the iterator without consuming it.

Only supported for iterators on list-like tables.

Example:

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

any

Iter:rev() Iter:rev() Reverse an iterator.

Only supported for iterators on list-like tables.

Example:

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

Iter

Iter:rfind({f}) Iter:rfind() Find the first value in the iterator that satisfies the given predicate, starting from the end.

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

Only supported for iterators on list-like tables.

Examples:

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

any

Iter:skip({n}) Iter:skip() Skip values in the iterator.

Example:

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

Iter

Iter:skipback({n}) Iter:skipback() Skip values in the iterator starting from the end.

Only supported for iterators on list-like tables.

Example:

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

Iter

Iter:slice({first}, {last}) Iter:slice() Slice an iterator, changing its start and end positions.

This is equivalent to :skip(first - 1):skipback(len - last + 1)

Only supported for iterators on list-like tables.

Iter

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

The resulting table depends on the initial source in the iterator pipeline. List-like tables and function iterators will be collected into a list-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 a list-like table with consecutive, numeric indices. To create a map-like table with arbitrary keys, use Iter:fold().

(table)

map({f}, {src}, {...}) vim.iter.map() Map and filter a table or iterator.

This is a convenience function that performs:

vim.iter(src):map(f):totable()

(table)

totable({f}, {...}) vim.iter.totable() Collect an iterator into a table.

This is a convenience function that performs:

vim.iter(f):totable()

(table)